APE

The road towards madness: Thesis Devlog part 1: "Get started fool!"

2012-02-01T15:06:00.000+01:00

(In the vague hope of creating some kind of regularity in my writing, as well as to give myself some space where I could organise my thought, I decided to start a “Development-Blog” (or “Devlog” as it is called among us cool people) for my Thesis. I intend to write this once per month and I will present you what I have done so far and what I want to accomplish in the next few weeks. Watch as I make dumb mistake after dumb mistake and how the stress of this work will make me go insane as the year porgresses).

I’m sitting at my Thesis for quite some time by now. Well, “sitting” isn’t really the appropriate term. I circling around it, like a dog who isn’t sure if he should really lay down on the carpet or not. It goes without saying that this isn’t a really satisfying state of affairs, for three reasons:

1. This is the last thing I need to do to graduate from University.

2. I don’t have anything better to do.

3. I only have time until January 2013 to graduate before I have to re-do my Psychology-finals, which I already took in 2010.

So despite being more or less unprepared for the work that lies ahead of me, I decided to simply jump into the fray and hope for the best.
But before I start to tell you what kind of stuff I need to do, let me quickly tell you what exactly my Thesis is about.
The goal of my Thesis is to compare phylogenetic trees of the relationships between great Apes and Humans from different ontogenetic stages with each other. I want to do this mostly because it’s interesting to see how certain Traits are affected by ontogenetic processes and how those traits effect phylogenetic trees. Also this was the first Idea where none of my Professors told me that it is too big, too expensive, or just stupid.

So far my plans are to do this study with the following taxa:

Papio

Pongo

Pan

Homo

You probably have noticed that there are no Gorillas in my species sample. That’s because my advisor told that it would probably be better for my results if I exclude them. As I tried to show a few months ago, there are some problems when it comes to the reliability of phylogenetic trees who try to resolve the relationships between Gorillas, Chimpanzees and Humans. Excluding the Gorillas from my sample helps me to avoid that this “trichotomy-problem” is somehow effecting my results.
I’m not very happy about this, since it also limits my possibilities of drawing more wider ranging conclusions from my thesis.
But fortunately, nobody is expecting me to make some kind of ground breaking work. all I have to make sure is that my study is well executed on a technical level and that I don’t make any factual mistakes.

What I need to organise right now is where I get my sample from, where I’m going to get my measuring tools from and how I’m going to pay for this stuff.

The first question fortunately is quite easy to answer, since there are some rather big collections at several museums in the german-speaking area. So far I plan to go to the Senckenberg-Museum in Frankfurt (which is right around the corner), the Museum of the Institute of anthropology of the University of Zürich and the Museum of natural history in Berlin.
I hope that I’m able to collect all my data until June, but this means that I need to make sure I get access to those collections within the next few months.

The next point bothers me a little bit. I need to collect some osteometric data for my Thesis but funnily enough my Institute doesn’t seem to own the appropriate tools for these kind of work anymore. This strange because we still have rooms full of old skeletons where nobody knows where they’re from, but no means of analysing them in a proper manner.
Fortunately I think I know where I could get those tools from, but those things are fairly expensive, which brings me to the last problem.

Spending several weeks in different towns to have a look at primate skulls is a fun thing to do, but it costs money. I still need a place to sleep and something to eat from time to time. My initial plan was to apply for a grant which our biology department offers for students who are about to graduate. Unfortunately I needed a letter of recommendation from my advisor for this, something he refused to do because he wanted to see other projects to be supported. This grant would have been enough for me to ravel to each and every museum I desired without having to worry about how I’m going to pay my bills. I still get mad about this, although there’s really nothing a can do about this. Instead I decided to apply for a different grant, which doesn’t need the approval of my advisor, I still need to the application for this and I hope I’m able to do this by the end of this week. As an alternative route I took a side very boring side job and try to save as much money as I can. Luckily enough, my Institute will still pay for the stuff I directly need to do my work e.g. those expensive measuring tools, computer programs etc.

Essentially I was able to sort out most of the aforementioned points, the only thing I need to do right now, is to get going. The most important thing right now is to fix the time when I have to visit the different collections as well as to find out if there are really no tools in this Institute. I also try to get my application for this grant ready and I hope I can give you some more information on that sometime later this week.
I think that’s it for now, let’s just hope things will go as planned (which they probably won’t).

Apes (and other primates) on the internet -The digital morphology museum

2011-11-22T14:23:00.000+01:00

I’m a huge fan of Internet Databases, such as the Nespos Database, where you can get access to CT-Scans of original fossils as well as recent specimens for your work.. However what always bothers me is that all those databases aren’t completely open to the public. For example to get access to the Nespos Database, you need to explain why you need access to it, you need to be a member of an academic institution and you need to pay for a membership.
These things make it rather difficult, if for example biology teachers want to use these materials during their courses (which would be a really great thing).
This is why I was really excited, when I read on Lawn Chair Anthropology about the “Digital morphology museum” of the university of Kyoto. Here you can take a look at their whole stock of CT and MRT-Scans of a bunch of different Primate specimens and, after a small registration process, you can even download these Scans for free.

Right now I’m thinking about something for which I can use this Database. Perhaps some kind of online course? I don’t know but I’ll come up with something.

If you want to take a look for yourself, you can do it right here.

A lot of trees here...

2011-11-16T12:45:00.000+01:00

Those few and lucky people who read this blog on a more regular basis probably have realised that a lot of the stuff I wrote recently dealt in some manner with phylogenetic trees.
On one hand this does not seem to be very suprising since taxonomic questions always were some kind of focus of this blog. However the other reason for this is because I finally found a suitable topic for my M.A. Thesis (yaaaay!). I won't write about the exact topic as of yet simply because I still need to write it down properly, but if you're interested, just look at the comments under this Post, it's mentioned in one of them.

I plan on covering the whole process of me writing the thesis, analysing my data and whatever else I need to do on this Blog. This is going to be my first real scientific work so it might be interesting to see what kind of stupid mistakes I make and in what kind of pitfalls and Problem I might run into. Also, I want to use this blog as a Plattform where I can write down some of the ideas I get while working on my thesis. In fact this is why I wrote my last post and there's another one coming soon.

In other news: This week I'm in Frankfurt at the Senckenberg-Museum to attend a congress about the ecology and organisms of the eocene. Since I'm mostly interested in primates and I don't have that much knowledge about fossil invertebrates and I also have to prepare my Thesis (yaaaay!), I will probably visit the conference only on Friday, since this is the "primate day".
Of course, good ol' "Ida" will be a big topic on this day and from what I can tell from the abstracts, I'm pretty sure the discussions are going to be very "interesting".

Some thoughts on the phylogenetic relationships between great apes and humans (and why morphology fails to answer this question)

2011-11-09T16:43:00.003+01:00

Taxonomy isn’t a really satisfying branch of evolutionary biology, especially if you’re interested in the phylogenetic relationships between great apes, hominins and humans. You always tend to step on someone else’s toes and sooner or later this other person starts to harass you with critique. One of the standard arguments which are brought up against almost any kind of phylogenetic study is that the characters you used for your phylogenetic reconstruction are misleading, because they’re homoplasies. “Homoplasies” are characters which evolved independently in two closely related species and are usually your biggest enemy when it comes to taxonomic questions.

fig. 1 Today's topic: The "correct" phylogenetic relationships between great apes and humans and why morphologic characters fail to reproduce these results.

This problem seems to be overabundant in Paleoanthropology, since I have yet to see a single taxonomic paper which isn’t immediately criticized for using homoplasious characters for their hypothesises. This is probably due to the reason that morphological characters in general are having a hard time reconstructing the “correct” phylogenetic relationships between great apes and humans (fig.1), which was established with molecular characters (e.g. Wood & Collard, 2002; Wood & Harrison, 2010; Strait & Grine, 2004). And if your characters aren’t able to reproduce the correct phylogeny between extant species, how can you expect them to get it right with fossil species?

Recently one of my Professors pointed me towards an interesting problem which made me wonder if those difficulties are really due to too many homplasious characters in your datasets.

Imagine a Population “P”

This Population has some characters which are polymorphic, which means that they exist in different states within this population. For the sake of simplicity I will only use two characters. The first character has either the state “+” or “-“

The second character has either the state “circle” or “square” (I’m too inept to put those symbols within this text –sorry).

Now this Population starts to split up.

Shortly after P1 split up from P, the rest of the original population splits into two additional subpopulations (P2 & P3).

Eventually all those three subpopulations will evolve into three different species

If we look at the pattern in which those Populations split from each other, we can see that P2 and P3 are closer related, because they got separated after P1 split away.

Now imagine that we weren’t able to witness this pattern and instead we have to reconstruct it with a cladistic analysis, which is usually the case if you want to know how extant species are related to each other. The problem here is that there is no clear signal. Instead your results depend highly on the character you’re using. Here we are in a situation where we have three equivocal hypothesises just because you had an polymorphic, ancestral population which split up so fast, that it wasn’t possible to fixate one character state within the whole population. Instead the ancestral polymorphic state was carried into those new subpopulations and the trouble we encounter if we want to use those characters for phylogenetic reconstruction is simply because of this incomplete lineage sorting and not because the character were homoplasious.

Of course I came up with this example, because we can see the exact same phenomenon if we look at molecular studies which dealt with the phylogenetic relationships between great apes and humans. Satta et al. (2000) found that out of 46 genetic markers, only 60% supported the “true” phylogeny (see fig. 1), the other 40% either supported a Human-Gorilla dichotomy, a Gorilla-Chimpanzee dichotomy, or a trichotomy.

Salen et al. (2003) came to similar result as they used “Alu-SINEs” to reconstruct the great ape phylogeny. Although Alu-SINEs are probably the best characters you can use to resolve any kind of phylogenetic relationship within primates, simply because it’s highly unlikely that they independently occurred at the same place on the DNA. Nevertheless they found one Alu SINE which humans and Gorillas had, but Chimpanzees didn’t.

But how polymorphic was the ancestral population of Gorillas, Chimpanzees and Humans on a phenotypic level?

This question is almost impossible to answer, at least for now. we have no Idea how the genotype relates to the phenotype as long as we aren’t able to close this gap we’re not able to make anything more than vague assumptions about this question. Looking at this whole story of Neanderthals and “Denisovans” interbreeding with modern humans (Greene et al., 2010; reich et al., 2010), which probably means that we have to broaden up our own species to include at least the Neanderthals if not even Homo heidelbergensis, I think we can see that a species can vary pretty much on a phenotypic level without interfering with reproduction.

This whole story definitely doesn’t make things easier since we now have two problems: Convergent evolution and incomplete lineage sorting. But I think we can at least try to differentiate things a little bit more. Although we have no Idea how much incomplete lineage sorting has affected the phenotype of the African great apes and humans we can’t rule out that it had no effect at all. Therefore it’s pretty much futile to make any assumptions about the “quality” of certain characters, since we have no idea to what extent those characters were affected by incomplete lineage sorting. As we could see, characters can be pretty much invulnerable to parallel evolution and still indicate wrong phylogenetic relationships (Salen et al. 2003).

Maybe we should instead explicitly look at each and every character, especially those which support the “correct” tree and test, if they share a common origin.

References:

Collard M, & Wood B (2000). How reliable are human phylogenetic hypotheses? Proceedings of the National Academy of Sciences of the United States of America, 97 (9), 5003-6 PMID: 10781112

Green, R.,et al (2010). A Draft Sequence of the Neandertal Genome Science, 328 (5979), 710-722 DOI: 10.1126/science.1188021

Reich, D., et al. (2010). Genetic history of an archaic hominin group from Denisova Cave in Siberia Nature, 468 (7327), 1053-1060 DOI: 10.1038/nature09710

Salem, A. (2003). Alu elements and hominid phylogenetics Proceedings of the National Academy of Sciences, 100 (22), 12787-12791 DOI: 10.1073/pnas.2133766100

Satta Y, Klein J, Takahata N (2000). DNA archives and our nearest relative: the trichotomy problem revisited. Molecular phylogenetics and evolution, 14 (2), 259-75 PMID: 10679159

Strait DS, Grine FE (2004). Inferring hominoid and early hominid phylogeny using craniodental characters: the role of fossil taxa. Journal of human evolution, 47 (6), 399-452 PMID: 15566946

Wood, B., Harrison, T. (2011). The evolutionary context of the first hominins Nature, 470 (7334), 347-352 DOI: 10.1038/nature09709

P.S.: I just realised that used almost the exact same formulation for the title of this Post as I used for my last title. I'm deeply sorry for my lack of creativity. (11.10.2011)

The debate that should not be: Some thoughts about creationism, intelligent design and other "alternative explanations"

2011-10-29T23:42:00.000+02:00

If you blog about human evolution there’s one topic which is really hard to avoid. I’m of course speaking about creationism, or “intelligent design” or some other kind of unscientific explanation about human evolution. So far I tried to avoid this topic as best as I could, since I don’t feel competent enough to actually write something about it. However, last week I received an Email from one of my German readers which forced into writing something about it.

I don’t want to talk about the exact content of the email or about the (rather short) debate I had with the person who wrote me this Email. What I want to talk about is my point of view on this whole issue and why I think we shouldn’t even have these kinds of debates.
It goes without saying that this text only represents my opinion so don’t interpret the stuff I’m going to write as some kind of general explanation about this topic.
I’m going to split this Post into three different parts to make it a little bit easier to follow my line of argument.

1. Why Sciences and Religion shouldn’t interfere with each other.
To understand this point, first of all we need to define what we understand under the term “God”. This probably is a topic for not one but several posts itself, but for the sake of my argument, let’s put as simple as possible.
“God” is an entity which almighty and which isn’t completely detectable. The first premise directly leads to the latter, because if an entity is almighty then it also has power over those parts of reality which we can’t perceive.
Now, if we want to build a scientific hypothesis, we have to make sure that we can actually falsify it (if you want to know why, I wrote something about it here). But how can we falsify something which isn’t completely detectable? The simple answer is: We can’t.
Therefore, if we try to explain our world due to the work of a non detectable entity, we’re leaving the scientific framework.
The scientific method is not suited for those questions. You simply can’t prove or disprove God due to scientific methods. Or to put it more bluntly: “God doesn’t matter in Science”
This does not mean however, that each scientist is an atheist. You can believe in whatever you want, as long as you don’t try to mix up both “worlds”. Every attempt to do otherwise ends in a logical fallacy.

2. Why, in my opinion, Science produces reliable statements about our world.
Some of the more “advanced” criticisms of evolutionary theory try to show that the theory itself or the scientific method itself is somehow erroneous in some manner.
The interesting thing about the different perspectives on the world, whether they are scientific or more metaphysical is, that all of them need some kind of basic assumptions to actually work. If you don’t make those assumptions you will, at some point during your argument, come to a stage where your own arguments become circular.
But which are those basic assumptions for a scientific world-view?

The first assumption is that we live in a world which consists of laws.
-If there are no laws in nature, then we won’t be able to make any reliable statements about it.

The second assumption is that we’re able to recognize these laws.
-Science is a cognitive process. If we weren’t able to recognize any of these laws, than we couldn’t do any kind of science.

These basic assumptions are the fundamental aspects on which every other scientific theory is build upon and it’s the only context in which they make any kind of sense. The question, whether or not I “believe” in evolution isn’t a real question. It’s simply the explanation which, in the framework I presented here, makes the most plausible. The “question of faith” doesn’t ask itself if you look at separate scientific theories, it’s only important if you look at the basic assumptions of Science. And so far I haven’t found anything which convinced me that those basic assumptions are wrong.
However, this does not answer the question, whether or not science can answer every question. Unfortunately we will never receive a message which says: Achievement get! Explain every law of nature!” Or to say it with the words of Gerhard Vollmer:

"The degree of consistency between our theoretical knowledge of the world and the real world remains unknown to us, even if it's complete."

[From: Vollmer G. (1975) Evolutionäre Erkenntnistheorie Hirzel, Stuttgart, Leipzig, p. 137, (probably horribly) translated])

Ok, after we set the stage for the debate, let’s move on to the original point of this post.

3. What’s that stuff got to do with creationism?
The first point of my argument shows that it’s completely impossible to prove or disprove God within a scientific framework. Therefore any kind of “theory” which tries something like that is making a logical fallacy. This works in both directions. You can’t explain any kind of natural law with the work of God, as well as you can’t demonstrate that God doesn’t exist.

The second point shows that it’s not the question whether or not someone believes in a certain scientific theory, because its validity is the result of the scientific framework. Not “believing” in a certain theory means omitting any kind of ability to recognize laws in nature and therefore this person leaves the scientific framework. Any kind of argument which follows after this point is subject of my first line of argument.

Now about the debate on creationism: Both of my arguments show that any kind of argument which is brought up by these people is not part of the scientific framework. This means that their arguments don’t matter in a scientific discussion. But it also means that you’ll never be able to use purely scientific arguments if you want to debate with them. Someone who isn’t convinced that we’re able to recognize laws in nature will never be convinced by scientific arguments, simply because he doesn’t believe them.

In my opinion the only thing you can try to do is to show, that there are no conflicts between scientific and metaphysical (e.g. religious) views on the world, as long as both sided try to stay within their specific framework. Both sides have completely different premises and thus there is no reason for a conflict. Those conflicts only occur if one side tries to interfere with the other, but as I demonstrated, this is logically false.
Trying to debate this stuff on this level is pretty difficult, since you’re leaving the scientific framework and enter a purely philosophical one and I think this is the reason why this whole debate does not take place on this level. This and also because I think there isn’t much public interest in these kinds of debates. The public tends to direct its attention to the loudest participants and those aren’t often the most competent when it comes to actual discussions.

Anyway, this is my opinion about this whole story. I have to admit that I'm not very comfortable with this post. Firstly because I think I left some important questions unanswered and secondly because I’m not very confident that my English is actually good enough for this topic, in fact I’m pretty sure it isn’t. So, if you don’t understand some of my arguments, please tell me and I’ll try to clarify things. Furthermore I would really like to know how other people think about this debate.

Where to put Australopithecus sediba?

2011-09-28T15:42:00.005+02:00

It took me some time to decide what I should do with Australopithecus sediba on this Blog, in the end I decided to concentrate on the aspects I at least know a little bit of, one of them is taxonomy.

I had to reconstruct a bunch of phylogenetic trees in the last few months and I found some free online tools which enabled me to do this without using any fancy (and expensive) Computer Programs. The only disadvantage of these resources is that they were originally made for molecular data sets. This made my work a little bit more complicated since I had to modify my morphological datasets in a way that these programs were able to work with them. I won’t talk about the exact process right now; instead I want to show you some of the stuff I did with Australopithecus sediba.
First of all, let’s have a look at a classic tree which illustrates the phylogenetic relationships among the genus Homo. I took the tree from Strait et al. (1997) for this particular example:

Strait et al. (1997)

There’s nothing really special about this tree, sure you could discuss whether or not the shown phylogeny represent the true relationships of these fossils, but discussing this stuff always tends to get boring, since you have to look at the characters and you need to discuss the validity of each of them
To make things a little more interesting, I took the character matrix from Strait et al. and included Australopithecus sediba. The characters for Australopithecus sediba were taken from the initial description of this Fossil (Berger et al., 2010). This is the tree you get, when you run this modified matrix through an Analysis:

Same character matrix but with A. sediba.

Sediba ruined everything!
What in the first tree looked like a nice and clear relationship is now collapsed into something completely indifferent.
To make things clear, the taxonomic position of Homo habilis and Homo rudolfensis never was pretty clear. In fact, the latter species was established, because the initial hypodigm (the total sum of all fossils which describe a species) of Homo habilis was so diverse in its morphology that it was split up into two separate species. The “new” species was then called Homo rudolfensis. I won’t talk up the exact reasons why this was the case, since it would make this post too long, but I will eventually come back to this topic in another post.

Let’s go back to Australopithecus sediba for the moment. It’s not only that the fossil practically ruins the common taxonomic picture of relationships of early homo, it’s also very young. Right now, Australopithecus sediba is dated at about 1.9 million years, this is very young, if you keep in mind that there are fossils of Homo habilis and Homo rudolfensis which are much older then 2 million years. There are also possible fossils from Homo ergaster/erectus which are only slightly younger then the sediba fossils. Now add the about 1.7-1.8 million year old remains from Dmanisi/Georgia to this mess and you can see how complicated this whole story starts to look.
Fortunately the tree I showed you at the beginning of this post isn’t completely useless since it shows that Australopithecus sediba falls somewhere within the relationship of Homo ergaster/erectus, Homo rudolfensis and Homo habilis.

So let’s have look at the possible relationships and the possible consequences of each scenario:

Scenario if A. sediba would share a LCA with the Genus Homo

In this scenario, Australopithecus sediba would share a last common ancestor with the Genus Homo. The only problem which arises from this tree is that you have to discuss what you should do with the Homo rudolfensis and habilis fossils which pre-date the emergence of Australopithecus sediba in the fossil record.

All other scenarios basically ruin our contemporary picture of the Genus Homo:

<>

Two of the possible relationships if A. sediba would be place somewhere within the Genus Homo

No matter which scenario we look at, none of them shows the Genus Homo as a monophyletic group. This means that either we have to include Australopithecus sediba within the genus Homo which I’m not very fond of since it would lead to an even weaker definition of it. Or we have to exclude Homo habilis and/or Homo rudolfensis from the genus Homo. The Genus Homo would then begin with Homo ergaster/Homo erectus and everything before that species would be either inside the genus Australopithecus or in a complete new genus.
Personally, I have no Idea what I should make out of this stuff. Right now everything seems to contradict itself and I think we need to have much more knowledge about this certain period of time. This means of course more fossils from this period but also more research on the already known fossils.
What I think we can safely right now is that the emergence of the genus Homo didn’t happen in a gradualistic fashion where one species slowly evolved into the next one. I think what we have here is a series of, possible independent, speciation events. This would explain why we have that many species that look similar to another but who overlap in spatial as well as temporal aspects and whose phylogenetic relationships are completely unclear. I have some more thoughts on this matter and I will write another Post where I go into much more detail. For now, all I can say is that, although Australopithecus sediba completely ruins the contemporary phylogeny, it might help us to really understand what happened back then.

References:
Berger, L., de Ruiter, D., Churchill, S., Schmid, P., Carlson, K., Dirks, P., Kibii, J. (2010). Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa Science, 328 (5975), 195-204 DOI: 10.1126/science.1184944
Strait, D., Grine, F., Moniz, M. (1997). A reappraisal of early hominid phylogeny Journal of Human Evolution, 32 (1), 17-82 DOI: 10.1006/jhev.1996.0097

Back from Leipzig

2011-09-26T14:15:00.002+02:00

Well, the Congress is over and after a very long and very weird train ride, first there was someone who decided to jump in front of another train, which led do a 45 minute delay and after that, some Idiot decided it would be a good Idea to forget his suitcase within the train. And since some other Idiots decided to fly two airplanes into some buildings 10 years ago, a forgotten suitcase in a train is a case for the police. To make a long story short: I arrived in Mainz with a total delay of around two hours yesterday and was as exhausted as I was the days before.

The conference itself was great. I’ll have to admit that I thought I would be able to participate in the discussions there, but I saw pretty quickly that most of the other People there were on a completely different level then I was. This bothered me for quite some time, but then I realised that, as an undergraduate student, I don’t need to know all this stuff by now. So instead of showing off my tremendous knowledge (which I didn’t had) I started to enjoy listening to the stuff other people said and there was a lot of really interesting stuff going on.
In the end, the days in Leipzig were a very exhausting, intimidating and humbling experience, but I’m glad I went there. I saw how much stuff I still need to learn to really understand this field but I also realised that I really want to learn all this stuff. The last days gave me even more motivation to continue my studies so that maybe by the same time next year, I have something to present at the next ESHE Meeting, or somewhere else.
I’ll try to write about some of the stuff I heard in Leipzig within in the next weeks and there’s also this stuff about Australopithecus sediba which I wanted to write. I hope to get this Post done within this week.

At last I want to thank Anna Barros and Tracy Kivell who were both kind enough to answer a bunch of my questions and listened to some of my weirder thoughts during the Poster session on Friday.

Eric in Leipzig: Lessons from the first day

2011-09-23T07:07:00.002+02:00

Scientific congresses are, especially if you're a little student a place to learn a lot of new stuff. So far I learned the following lessons:

1st Lesson: Don't be cheap.

I wanted to save 12,50€ for an addional night in a bed in a cheap hostel and decided to arrive at Leipzig the day the conference started. Only Problem: The conference started at 10am. This forced me to spend my night in a train, which lead to the nice fact, that I had around 1 hour of sleep in the night from Wednesday to Thursday.

2nd Lesson: Don't attend to a course on geometric morphometrics when you're deprived of sleep.

Lesson 1 leads directly to Lessen 2. I remember some of the stuff that was mentioned in this course yesterday but the most parts of it, and I think those were the more important parts, I forgot about five minutes after they were told.

3rd Lesson: Speak more english!

I think that I understand english fairly well, be it spoken or written. I think I'm also able to write in english in a at least partially understandable way. But my spoken english is abyssimmal. I have next to zero practice in speaking english and therefore my pronounciation is just bad and unsophistacated. And as you might guess, it's pretty hard to ask intelligent questions if hearing yourself speaking gives you nausea.

Well, those are the lessons I learned yesterday. I also learned something anthropological, but nothing of it is related to this congress and besides, I learn something about Anthropology almost all the time.

Let's see what interesting stuff happens today.

P.S.: I'm pretty sure, the english in this post isn't very good as well. But please keep in mind that it's around 7am and I'm still a little bit tired.

Sediba Post: Status report

2011-09-20T12:13:00.000+02:00

I said I was going to write something about Australopithecus sediba, and believe it or not, I still intend to. However there were two things which mainly kept me from doing so within the last weeks:

1. Time:
In the last two weeks, my studies kept me from doing anything related to A. sediba other then reading the papers.

2. My Head:
To make things worse, I got a really good Idea what I can do with this fossil. There's something really neat which I wanted to demonstrate for quite a long time now, and I think the sediba fossils are the perfect objects for this little project. However I will need some time to prepare this post properly.

And at last, I'm about to go to Leipzig at Wednesday evening, where I will have the pleasure of walking around on a scientific congress until sunday. So don't expect something related to Australpithecus sediba until next week, but I might write something about this congress if I find something interesting.

Until then, why not read something about Australopithecus sediba at "Lawn Chair Anthropology"?

Australopithecus sediba: First (small) information dump

2011-09-11T12:59:00.000+02:00

I didn't had enough time to completely dig through all the information towards Australipithecus sediba, but I intend to do so tomorrow. Until then, why not heare some words about Australopithecus sediba by some people who are far more competent then I am?

For example, you can read/hear an Interview with Lee Berger on the Science Podcast: Right here

Or you can read/hear an Interview with Lee Berger and Bernard Wood at NPR: Over there

The slump is over!

2011-09-09T13:48:00.001+02:00

(well, at least kind of...)

Sometimes it's funny how things turn out in the end. Just as I'm about to finish the Assignment that ate up all my further interest in anything even remotely related to science so I could get started to get back into maintaining this Blog, Science released a bunch of Papers regarding Autralpoithecus sediba. This species was first announced last year, an announcement I somehow completely ignored back then, probably because the authors didn't put any effort into making some waky claims that could've set me up.
Anyway, I haven't looked much into the articles but I intend to do so within the next few days and report on what I think about them.

And since I have a little more time at my hands, I'll try to write about some of the other stuff that circles in head as well.

Speculation on Speciation

2011-07-20T09:39:00.004+02:00

There is one topic which somehow touches almost every major debate in Paleoanthroplogy and this is the question about how speciation actually works. There were a lot of very smart people, who already wrote about this stuff, and I even read some of them. But a large proportion of what I’m going to say about this topic comes from my own thoughts on this topic. So if someone finds a mistake in my arguments, please let me know.

When it comes to speciation, there are basically two different opinions on how speciation could work. The first one is sometimes called “punctualistic” or “phylogenetic” and says that speciation usually results in a split in which the ancestral species splits into two different “offspring-species” (there is probably a more suitable term for it, I just can’t remember the English translation).

The second one is called “gradualistic” or “anagenetic” speciation and says that one species can, if there is enough time; evolve into another species without any form of splitting.

Now although there are many species concepts out there, the main criterion to recognize a species is, if their members are able to interbreed with other animals. This means that no matter what type of speciation process we propose, at some point during this process there has to be some kind of “breeding barrier” (once again, I’ve no Idea how to translate this term), be it either geografical, behavioural or otherwise.

Now let’s take a look on how this stuff actually works in case of a punctualistic speciation:

Exdample for a punctualistic speciation: Assume a Species "A" lives in a certain habitat "X". Now due to some reasons (e.g. a geological event), a barrier arises in said habitat. This barrier changes the enviroment on both of its sides and furthermore prevents the now separated populations of "A" to exchange their genes. With time, those two sperate populations will adapt to their new enviroments and will become two distinct species.

Ok, this was quite easy wasn't it? But how about gradualistic speciation? Her I'll have to admit that although I spent quite some time on this question, I just could come up with one scenario:

1. Let’s assume the species we’re looking at is restricted to one habitat

2. Let us further assume that all population of said species are able to exchange there genes with on another.

3. Now the habitat of said species changes and due to the wonder of natural selection the species adapts to those changes.

4. As time goes by the species within that habitat would differ significantly from the species we had before this process started, so that we could safely say that we have discovered a new species.

There is only one big problem with this model. If we assume a constant gene flow between the seperate populations of our example species, than this means that there never was any kind of mating barrier at any point in time. So how can we be sure that the species we witnessed at the end of that process isn’t able to interbreed with the species we observed before this whole thing started? Sure, we could assume that since both “forms”, as I might call them right now, are so different that they probably wouldn’t have interbred, if they would’ve lived at the same time.
This assumption is pretty similiar to the concept of a “Chrono-species” which defines species solely after their chronological appearances in the fossil record.
The Problem here is that we’re not able to test, whether or not, those species really weren’t able to interbreed. It is as always when we have to deal with extinct species, we simply can’t be sure about it. In the end the only safe thing we can say is that every model on the evolution of a certain species, which relies on a gradualistic model of speciation, is highly speculative.

There are two recent examples within Paleoanthropology where this Problem occurs. The first one is the possibility to draw a direct line from Australopithecus anamensis to Australopithecus afarensis (Kimbel et al. 2006, Haile-Selassie et al. 2010). The other one are the genetical evidences of interbreeding between modern Humans and Neandertals (Green et al. 2010) and modern Humans and those strange people from the Denisova Cave (Reich et al. 2010).
In both cases we have clues, if not even hard evidence in the second example, of constant gene flow between several populations over a long period of time.

The interesting question now, is what we should do with these findings. Should we just keep these different species and use some kind of dodgy chrono-species concept or should we lump all those different species into one or probably two?

I have to admit that, due to my education, I am a little bit biased towards the “lumping” part.

Right now I am not convinced that gradualistic speciation is possible, or to be more precise, that it is detectable by us. So the scientifically safer way for us right now, is to stay cleer of this concept unless we can find some way to test it.

Surely, the last word isn’t spoken on this one, and right now a can think of several flaws in my own argumentation, but I’m still convinced that it is the preferable way of thinking.

References:

Kimbel, W., et al. (2006). Was Australopithecus anamensis ancestral to A. afarensis? A case of anagenesis in the hominin fossil record Journal of Human Evolution, 51 (2), 134-152 DOI: 10.1016/j.jhevol.2006.02.003
Green, R., et al. (2010). A Draft Sequence of the Neandertal Genome Science, 328 (5979), 710-722 DOI: 10.1126/science.1188021
Haile-Selassie, Y., et al. (2009). New hominid fossils from Woranso-Mille (Central Afar, Ethiopia) and taxonomy of early Australopithecus American Journal of Physical Anthropology DOI: 10.1002/ajpa.21159
Reich D., et al. (2010). Genetic history of an archaic hominin group from Denisova Cave in Siberia. Nature, 468 (7327), 1053-60 PMID: 21179161

I'm still alive!

2011-07-18T19:42:00.000+02:00

Unfortunately this isn’t a Post with any real content. In fact, it’s one of those “I’m just writing something to show that I still intend to write something”-like Posts.

The last weeks were pretty boring on when it came to interesting paeloanthropology-related news and those Posts I tried to write were in fact so bad, that I didn’t finish them. And at last, right now I’m desperately trying to finish my studies and unfortunately even this isn’t going as easy as it used to be. I even thought (and tried) to write about the stuff I’m working on right now, because it’s indeed quite interesting, but I just couldn’t find a suitable way to write about it, yet.

Anyways, things are looking a little bit brighter in the near future since I’m going to two conferences later this year. The first one is the meeting of the “European society for the study of human evolution”, which is held in Leipzig by the end of September. I have no idea about the exact program of this meeting, but I’m always excited to get in touch with other people from my own field, so I think it’s going to be pretty interesting.

The second one is the one I’m really looking forward though, partly because it’s held in Frankfurt which means that I can sleep at home and not in some cheap hostel. The topic is also quite interesting since it’s about ecology of the eocene and the early evolution of primates. Giving the fact that there was a lot of noise around Ida in the last two years I’m pretty sure, that this meeting won’t be very boring. I intend to write something about those meetings, be it in preparation for them, or while I attend them, so keep looking forward to it.
I’m still trying to write something within the next weeks though. I have some Ideas which could be suitable for interesting posts, so let’s hope that I can at least finish at least two of them.

If you need to fight, stand upright.

2011-05-20T10:02:00.000+02:00

Did our ancestors began to stand on two legs, because it gave them an advantage in beating up their rivals? Well at least this is what David Carrier tried to find out in his most recent study, as he looked at how hard people were able to punch when they stood upright and when they didn’t.

First of all, how does someone come to this kind of idea? Carrier explains that an upright stance is a common behaviour seen ion other mammals when they want to threat/fight their opponents and that especially apes often display this kind of behaviour.
And indeed, an upright posture is more effective when it comes to smack people in the face, but does this mean that male to male aggression has anything to do with the evolution of human bipedalism?

It’s funny that my last post was about how we’re able to build up testable hypothesises in evolutionary biology and which kind of problems you face while doing so, because this study completely made some huge mistakes in this regards. First of all, the study only relies on data from present day organisms. We have little knowledge about how our earliest ancestors (or their ancestors) even looked like, which makes it even more difficult to make any serious assumptions on how they behaved. Therefore evolutionary models solely relying on behavioural evidence from extant animals are almost untestable via the fossil record. But we need to test those models with fossil evidence if we want to avoid telling “just so” stories. I have mantra that I picked up from one of my teachers: “The past is a foreign country, they did things differently there.” Surely we need observations on recent animals to build up our models, but they can never be a complete substitute of the fossil record.

Papers like this make me wonder if I might get something wrong in how I approach this field. In my eyes it completely omits all standards of how to build a scientific theory in favour of making some wild assumptions on human evolution and I don’t understand how this can happen or how such stuff gets published in the first place.

References:

Carrier, D. (2011). The Advantage of Standing Up to Fight and the Evolution of Habitual Bipedalism in Hominins PLoS ONE, 6 (5) DOI: 10.1371/journal.pone.0019630

The "Stop"-Button does not open the door: What going by bus can teach us about Science.

2011-05-03T14:46:00.001+02:00

I don’t have driver’s license and therefore have to rely on public transport (mostly the bus) to get around. Although it’s sometimes annoying, there are a lot of interesting behaviours you can witness by taking the bus.

Usually, there are three kinds of buttons in the busses around here: One that signals the driver to stop at the next Bus stop, one for people in wheelchairs to “order” a ramp and one (usually at the last door) which opens the door once you press it. The last button is important, since it’s the only one that actually opens a door; the other doors are controlled by the bus driver.

As you can see, when it comes to door-opening, we're encountering two different conditions:

One time the action “press button” is followed by the reaction “door opens” and the other time it isn’t.
The Problem with these conditions is that people who, for example push the "stop" button next to one of the other doors, don’t get the feedback that their action didn’t do anything. Instead the door, unrecognised by the person who pushed the “stop” button, is opened by the bus driver.

So instead of the (right) connection:
Button on the last door opens it.

They're learning something like this:
Every button next to a door opens it, no matter what it says.

You can say that they've built up a false theory about how the doors in the bus work.

The question now is how they find out that their theory is wrong. The bus driver always opens the first two doors of the bus and somehow this action will always coincide with their action of pressing a button, so people won’t be able to recognize their mistake by verifying their current theory. The only way to show that their theory is wrong is by falsification.
So instead of always pressing a button, let’s see what happens if one never presses a button when he/she wants to exit the bus. After a short while, they would recognize that on some cases the door will open without their actions and sometimes it won’t. This procedure might lead to the conclusion that only the last door of the bus is controlled by a button.
Through constant observation and the falsification of their own theories, people would learn the “true” principle of how the doors in the bus are controlled. By this method, people would not only stop looking like pavlovian dogs when they want to exit the bus, they would also learn how science works.

Whether you want to learn how the doors in the bus work, as I did back when I was still going to school, or if you want to be a scientist: The only reliable way to get a better knowledge about the world is to try to falsify already existing theories. You can never be sure if the causal principle you described is true. It could be controlled by something completely different, like the bus driver in my example. The only thing you can be sure of is that if a theory is wrong, it stays wrong. So the only true way to get to reliable knowledge about our world is by ruling out any alternative explanations.

This stuff sounds pretty easy and if we’re looking at sciences like physics, it’s quite easy to execute. But if we look at evolutionary biology, things become pretty difficult.
Evolutionary theory itself is, from a philosophy of science-perspective, a pretty nasty theory (to explain why would need some elaboration) and what’s really problematic is that most hypothesises drawn from it are retrospective in their nature.
You cannot simply make an experiment on whether or not the evolution of our bipedal gait is connected to a more open habitat or the emergence of pair bonding. The only way to test these theories is by looking for clues in the fossil record and by reconstructing the environment in which the postulated transition happened. Therefore all hypothesises regarding a certain evolutionary scenario, or the relationship between two groups of animals, need to be connected somehow to the fossil record to make them testable.
In some cases it’s not that difficult but if we’re looking at the evolution of our behaviour and cognitive abilities, the margin between science and story-telling is very thin. Unfortunately a pile of bones doesn’t help very much if you want to find out how our ancestors behaved, if they were able to talk or how far developed their cognitive abilities were. Fossils don’t talk and unfortunately bones do not yield much information on the exact behaviour of their represented species.

This leaves a lot of room for speculation in those fields and therefore they’re often prone to be interpreted in an ideological fashion. We always have to keep in mind that making assumptions on the evolution of our species is not only of scientific importance; by doing this we’re also making a philosophical statement on what defines us as human beings. That’s why I think it’s important to know the limitations of your field and how you’re able to build “good” scientific theories.

I don't want to be a Bonobo

2011-04-27T18:55:00.001+02:00

This Post is a reaction on the Post from “Ariel Cast out Caliban” by Eric Michael Johnson.

There are many things in the world that annoy me: People in the bus who desperately hammer on the “stop” button to open the door, Professors who seem to know where my exact interests are although they haven’t talked in years and stupid ideologies which use biological examples to justify their view on the world.
Although I’d love to talk about all those things (especially the first one) let’s stick to the third one for now.
Every now and then, I encounter the following sentence in some way or another: “We should be like Bonobos.”

What’s really interesting is that the extremes of what could be called “human nature” are represented by our closest living relatives: Chimpanzees and Bonobos, at least if we rely on popular representations of those two species. Chimpanzees are usually presented as egoistic, brutal and aggressive. Whether Bonobos are the ultimate pacifists, their groups are led by the female individuals and conflicts and stress are usually resolved by some way of sexual interaction -instead of just bashing the head of a rival or tearing apart a helpless Colobus Monkey.
One of my favourite German biologists, Hubert Markl wrote in 1983 that all models on human nature usually have two aspects. The first one is the description of the present state of human nature, which is always pretty negative. The second one is the ideologically tainted vision of how humanity should be.

If we use this model on our closest relatives, the Chimpanzees represent our present state, while the Bonobos is the Vision of what we should become. From time to time I encounter this case, be it in the media or from people I meet and it might come up again in the next time, after some of the results of this study from Perelman et al. (2011) get more public attention.
This study, which deals with the Phylogenetic relationships of all primates, found that after the split between Chimpanzees and Bonobos, there was a higher rate of Change within the Genome of Chimpanzees as within the one of Bonobos. To make a long story short: This higher rate of change could lead to the conclusion that Bonobos are closer related to us, then Chimpanzees. Until now it was assumed that both species are equally related to us.
This of course changes everything! Our closely related living relative is the ultimate example for altruism and cooperation. The true picture of our own nature! Once again, Man cut himself from his own natural heritage. Now we simply have to return to our own biological roots and all our problems are solved! I’d bet a large amount of money that someone will write something like that, just a little more elaborated and maybe a little more esoteric. Maybe I should write this stuff myself, put in a book and sell it to bolster my very slim budget.

Jokes aside, my point is as follows:
Both Chimpanzees and Bonobos are just models for our own ancestors. Those Models fit in some cases more and in some cases less well on our past. We can’t just transfer our observations on present day animals into the past, just to help us to support some kind of weird ideology, as we can’t use them to justify acts of brutality against ourselves.
Furthermore, these genetic differences between chimpanzees and Bonobos are by now just statistical differences. We have no Idea if those differences are within regions which are related to behaviour or not.
If we look at ourselves, we can see that we’re capable of both extremes: exceptional brutality as well as exceptional altruism. Bonobos and Chimpanzees could help us to understand how we acclaimed those behaviours and how they’re funded in our own biological heritage. Sure, there’s no potentially World-saving conclusion within this stuff, but we need it, if we want to understand our biological “nature”.

Ideologies are always made by humans; and Primates, especially apes, were always used as a screen on which we can project ourselves on. The Chimpanzees were used for all that’s negative about us, while the Bonobos stand for everything positive. But we must not forget that both species are not “unfinished humans” or “almost human”, they are Apes. They got their own history, as we do. Their history might help us to understand our own history, and therefore our “nature”, in a much better way, but as closely as we’re related to them, they can never be role models for us.

References:

Markl, H. (1983) Wie unfrei ist der Mensch? Von der Natur in der Geschichte. In: Markl, H. (ed.). Natur und Geschichte. R. Oldenbourg, München, Wien. p. 11-40.
Perelman P, Johnson WE, Roos C, Seuánez HN, Horvath JE, Moreira MA, Kessing B, Pontius J, Roelke M, Rumpler Y, Schneider MP, Silva A, O'Brien SJ, & Pecon-Slattery J (2011). A molecular phylogeny of living primates. PLoS genetics, 7 (3) PMID: 21436896

Fashionably late: The 116th Four Stone hearth.

2011-04-14T13:45:00.000+02:00

I know I’m late, so let us don’t waste any more time with weird stories how I managed to completely forget that I canceled my Internet-contract a few months ago, leaving me in a completely Internet-less home and therefore making such mundane tasks like reading Blogs a pretty complicated and time consuming issue.

So instead, let us concentrate on more important things, like Anthropology and Blogs and what happens if you combine those two things. Personal submissions were nonexistent this time, so I dug around and tried to gather all the interesting stuff I can find.

Probably one of the more popular topics was the “Gay Caveman Story”, which was covered by three Blogs:
"The Gay Cavemen" -John Hawks
"Gay Caveman ZOMFG!" -Christina Killgrove
"Gay Cavemen & Buried Shamans" -"Genealogy of Religion"

It’s interesting to see how the most popular story of the last two weeks intertwines with the saddest news this week, as Lewis Binford, the “inventor” of Archeological middle range-theory, died this Monday. Christina Killgrove at (Bone Girl) wrote a nice obituary and although I'm not very interested in Archeology, the news of Binford's death really affected me.
I first heard of Binford’s work as I read Robert Foleys “Just another unique species” where he adapts Binford’s middle Range theory to evolutionary model-building. I still keep this theory in the back of my mind when I try to think about a proper approach to scientific modeling in Paleoanthropology.

On the front of behavioural studies, there are two Posts worth to be mentioned.

I’m happy, that there’s at least one Post which deals with primates in this weeks edition:

Jason Goldman, wrote about a study dealing with contagenious yawning in Chimpanzees.
"Sleeping or empathic: What does yawning mean?"
I yawn a lot, so this is a story in which I’m naturally interested, although I have some problems with the study itself. But on the other hand, I have Problems with almost every behavioural study. But I think, there are some nice things to discuss in this Post.

Same goes with the next Post:
"If I objectify you, will it make you feel bad enough to objectify yourself? On shopping sexiness and hormones, by Cathrine Clancy, of "Context and Variation".

Furthermore, John Hawks wrote a nice little piece about data sharing in paleontology:
"Opening up paleontology"

The next one already is pretty dusty, but it’s my favourite Post so far in this year and I think everyone in the world should read it. "Evolution: What it is and why humans aren't immune to it." by Zaccharoo over at Lawn Chair Anthropology. Probably one of the best summaries on the general principles of evolutionary theory I’ve read so far.

I wasn’t the only one who had his birthday in the last days. In fact, “This is serious monkey business” turned One year old a week ago and celebrated this event with a collection of its most popular posts. So, if you haven’t already stopped by, do it right now.

That's it for this week. I really hope you enjoy this edition and I really hope, I'd be able to host another one sometime soon. The next edition (April 27th) is still vacant, so if anybody wants to fill in this position, just tell Krystal D'Acosta.

Let me close this edition with the only funny photograph of an Ape I got (I really need a bigger collection of those).

Dunja, a female Orang-Utan of the Leipzig-Zoo, probably commenting the request of some visitor to "do something".
The Photograph was taken sometime around 2008/2009 by "David B." a good friend of mine and excellent Photographer.

A special Announcement

2011-04-07T13:08:00.000+02:00

This Year’s April 13th is a very special day. First of all, it’s my birthday, but there is nothing special about birthdays, since you got them each year on the same day besides, everyone has a birthday. So what makes this date so special to me this year? Well, it’s because it will be the first time that I have the honour to host the “Four Stone hearth”.

The four Stone hearth is a bi-weekly Anthropology (in the broadest sense possible)-related Blog Carnival. This means that every two weeks, one person has the duty to sum up and present a conglomeration about what happened across the whole Anthropology-Blogosphere (I hate those buzzwords). So, if you have a Blog and want to submit one of your posts, or if you found a post from which you thought it might fit within the four stone hearth, just write me an Email (my Address is somewhere on the right sidebar, or under the “about” tab). Depending on the number of submissions I might add additional Posts, even if their authors didn’t submit them on their own.

I’m really looking forward to next week and I’m pretty sure it’ll be a very interesting edition.

GfA Fail

2011-02-27T19:47:00.006+01:00

Yesterday, while I did some research for a Post I originally intended to write today, I visited the Homepage of the "Gesellschaft für Anthropologie" (GfA), which is the Association for Anthropologists in Germany. There I found a public “statement” of the GfA regarding the debate of evolutionary theory “vs.” Creationism. This statement had a very interesting, and somewhat disturbing back-story:

Back in 2009, due to my raising concerns about the situation of Anthropology on German Universities, I attended to the Congress of the GfA in Munich, so that I could get a better picture about, what exactly Anthropologists in Germany do. On the general Assembly of all GfA-Members, which I attended to as a non-member, a debate was opened whether or net, the GfA should make a public Statement on this issue. During this debate, one person stood up and said, the she would appreciate it, if kids in school were lectured in both “visions” (in German it was “Vorstellungen” –I have no Idea how to translate it properly), Evolutionary Theory AND Creationism.

Now you must know, that German Anthropology contains only of what most of you might describe as “physical” or “biological” Anthropology.
During the arising ruckus, which lead to a statement from myself and after it to the request that only members of the GfA should say something, the debate was more or less aborted.

Well, after almost 2 years, there finally is a statement, which you can read here. You'd probably have no problem reading it, because it’s in English. Why in English you might ask?
Well, because the GfA kindly got the permission to use the Statement of the AAA regarding the debate on creationism. Now let us ignore all the fuss about this “AAA-Fail”* thing, and that the statement itself seams a little bit watered down to me. I’m bothered about something else, which in my opinion leads to the reasons why Anthropology in Germany is on the way to becoming an insignificant part at German Universities.

As I said, German Anthropology is foremost a biological discipline. And we all know which theory is the central, and maybe the only theory in biology. Dobzhansky even said that nothing in biology would make sense without it.

And now, if we look at this statement again or more on the fact that they had to use the Statement of the AAA instead of making their own statement, it seems that there is no one within the GfA with enough competence to actually write something about evolutionary theory, human evolution and creationism. Well, there are people in Germany who would be able to do something like this, in fact they would probably do a great job, but they don’t want to be affiliated with the GfA. How could this happen?

Throughout its history, Anthropology in Germany remained an almost complete descriptive and somewhat atheoretic discipline. It might claim, that its goal is to understand “the evolution of man in time and space” (or something like that -all those descriptions are horrible), but in reality only a small part of it, tried to do this.

Almost thirty years ago, in 1982 the German anthropologist Christian Vogel, who was a Professor at the University of Göttingen and was one of the establishers of Socio-biology and modern Primatology in Germany, addressed this issue in his Essay “Biologische Perspektiven der Anthropologie: Gedanken zum sog. Theorie-Defizit der biologischen Anthropologie in Deutschland” (“Biological perspectives of Anthropology: Thoughts on the so called ‘Theory-deficit’ of biological Anthropology in Germany”-my translation).

You probably can compare his appeal to the appeal of Sherwood Washburn to the AAPA back in the 1950s.

I read his essay back in 2009 as I prepared myself for the GfA Congress and I wanted to know, how much of the problems Vogel addressed in his paper, were even considered by German Anthropologists. After my visit and my disturbing experiences on the general Assembly, I dare saying, that none of them were considered. In fact, I think things even got worse.

Recently I read some Posts where people tried to describe what they love about Anthropology, or why they love it. And although I would probably have some difficulties to answer this question for myself, I can say for sure, that my fascination is mostly based on the aspects of our own evolutionary history and its implications for our present day life.
And it makes me mad, how these aspects are treated within the GfA. Anthropology deals with some of the most important questions we can ask (“Where do we come from?” “What is human nature” “What defines a human?”) and the GfA abandons these question in favour of being a helper for Archaeologists who want to know what kinds of skeletons they have excavated.** Instead of a flurish discussion about how evolutionary theory could help us to understand ourselves in a much better way, my experiences as student of Anthropology looks like this:
In some of my Psychology-courses (Psychology is one of my minor subjects) people started to groan as soon as I tried to put certain phenomena in a evolutionary perspective.
A friend of mine, who, besides studying Anthropology, also studies Ethnology faced open hostility when he mentioned the word “Socio-biology” in one of his courses.
Some of our (Anthropology) Students have no idea about human evolution or even the basic principles of evolutionary theory, because they think it’s not important for them and our curriculum enables them to ignore courses about this topic.
Every time I tell someone what I study, the first question I’m being asked is: “Ah, and what exactly are you doing there?”***.
And the worst part of all, those people who try to explain evolutionary theory on a public level, have absolutely no Idea about human evolution and always present it in a “march of progress”-like manner, speaking about “missing-links” and “chimpanzee like ancestors”****.

Here, the GfA had the opportunity to make not only a statement against the equal teaching of creationism and evolutionary theory; they had the opportunity to make a statement why Anthropology is an important science, and how it can contribute to modern day issues.

The GfA completely failed at this. Instead they gave a statement about their own incompetence.

Right now, Anthropology in Germany is a descriptive, atheoretic and almost abiologic “science”, which is doomed to become an insignificant hoard for people who don’t find a place within their own field of science (such as medicine, educational science, psychology etc.) and I don’t want to be represented by this kind of association.
Surely, many people from the GfA will disagree with me on this point. On their next congress, which is in September, they’ll probably say again (as they did in 2009) how important they are and at the same time, wonder why they're the only ones who think that.

In the past months I often tried to compare the situations of Anthropology in Germany (and my own experiences with it) with the events around the AAA last year. And although I don’t think, we can directly compare them; there are some parallels, when it comes to questions what Anthropology exactly should try to achieve.

Looking at both stories, the only thing I learned so far is that you never should rely on scientific associations to define and defend your field of research. If you want to keep aspects of your field which are important to you, then do it yourself and think of means to convince other people, that those aspects are worth to be kept..

*Although I have to admit this story leaves a somewhat bitter taste.
** This is no degradation of Archaeology or prehistoric Anthropology, I just think, that Anthropology can do more then just this.
*** This I wanted to know for a long time: How often do Anthropologists from other countries get asked this question?
**** Besides, most of them are arrogant douchebags.

References:

Vogel, C. 1982. Biologische Perspektiven der Anthropologie: Gedanken zum sog. Theorie-Defizit der biologischen Anthropologie in Deutschland. Z. Morph. Anthrop., 73, 225-236.

What happened to Sahelanthropus tchadensis? (Part 2: Conclusions)

2010-12-10T22:46:00.000+01:00

Two weeks ago, I finished my Post regarding the (almost non-existing) controversy about Sahelanthropus tchadensis with a more or less cryptic statement, which I thought should deserve a separate post to elaborate.

I ended my post asking the question whether or not the exclusion of Sahelanthropus would diminish this fossil from its scientific value. Well, the answer itself is pretty easy: Of course it wouldn’t do it. The more interesting question is: Why?

To answer this question we should take a closer look at the situation on the base of human evolution:

Timeline showing the estimated age of the earliest putative homids. As indicated by the red circle, these fossils almost perfectly fall inside the timeframe of the Chimpanzee/Human divergence based on molecular-clock estimations. (pictures taken from Johanson & Edgar, 2006; Suwa et al. 2009)

As we can see on this picture, we’re more or less in the right time frame when it comes to finding putative hominid ancestors, since we’re pretty much inside the estimated date of divergence between humans and chimpanzees (as indicated by the red circle). On one hand, this is pretty great because now we have much better resources to actually build up and test hypothesises about human origins. On the other, we got the problem that it’s actually pretty hard to classify these fossils in a proper way. The reason why there is this problem is because the closer we get to the actual date of divergence between humans and Chimpanzees the more the fossils we find will resemble the most recent common ancestor (MRCA). This means that these fossils to a great extant would still reflect the ancestral condition of the MRCA and would not have developed a huge amount of derived characters which could provide us with enough information to classify them properly.

Samuel Cobb (2008) came to the same conclusion, when he tried to reconstruct the facial morphology of the MRCA:

„In light of the problem summarized above and the paucity of the fossil evidence of the face in the hypodigms of these four taxa [Sahelanthropus tchadensis, Orrorin tugenensis, Ar. ramidus, Ar. ramidus kadabba -my addition], it is not possible to determine with any confidence whether any of them is the LCA , or a stem taxon in either lineage, or a member of an extinct, and until now unrecognized, hominid lineage.” (Cobb, 2008; p.482)

So, in the end we’re stuck in a situation which looks something like this:

Possible classification of the earliest putative hominid fossils. Because of their (probably) very ancestral condition, they could be either stem hominids, on the lineage to the Chimpanzee/Huma LCA, stem Chimpanzees or stem Gorillas.

On the first hand this picture might look a little bit depressing (at least I found it to be depressing), but, and now I finally come to my original statement, even if we’re not able to classify these early putative hominids with absolute certainty, they’re still providing us with lots of valuable information. Each fossil from this specific timeframe helps us to reconstruct the ancestral morphology of the Chimp/Human common ancestor, to reconstruct the original ecological niche of the MRCA and they help us to build up and test hypothesises on how exactly and under which circumstances the divergence of the Chimpanzee/Human clade took place.
All these things actually are much more important then the exact classification of the fossils we use dot draw conclusions from. Sure it might not sound very spectacular if someone publishes the description of a new putative hominid and states that he isn’t sure where to exactly place It., but it’s probably much closer to reality then all those ground breaking discoveries we encountered in the last 10 years.

Ok, this doesn’t sound very optimistic, but I still think that we, even if it seems futile, should still try to classify each fossil we find. I also want to add that this might look futile, from a present day perspective. But right now we also have to face the fact that there is one huge, but very critical gap in the fossil record. I’m of course speaking about the almost non-existent fossil record in the Chimpanzee and Gorilla lineage. Right now we have actually no Ideas how and in which way these genera evolved since they split from our lineage. Usually the lack of a Chimpanzee/Gorilla fossil record is explained by the fact that rainforests don’t provide the circumstances for good fossilisation. Right now this sounds like a sorry excuse, at least in my eyes.

In the last century we were able to get a very good coverage about the whole timeline of human evolution. We got this coverage, because there were huge efforts put into the search for fossil hominids. And right now, I’m pretty sure that, if we put even a small bit of this effort into the search for Chimpanzee and Gorilla ancestors, we will find them. On the other hand it’s pretty clear that if we do not search explicitly for these kinds of fossils we pretty sure won’t find any.

Just to show that I’m not the only one with this opinion and since it’s always good to support one’s argument with some famous words, here’s one of my favourite quotes from the paper of Esteban Sarmiento (2010), whose critique on the classification of Ardipithecus I start to like more and more:

“(...) it is curious that in a century-old race for superlative hominid fossils on a continent currently populated with African apes, we consistently unearth nearly complete hominid ancestors and have yet to recognize even a small fragment of a bona fide chimpanzee or gorilla ancestor.” (Sarmiento, 2010 p.1105b )

References:

Cobb, S. (2008). The facial skeleton of the chimpanzee-human last common ancestor Journal of Anatomy, 212 (4), 469-485 DOI: 10.1111/j.1469-7580.2008.00866.x

Sarmiento, E. (2010). Comment on the Paleobiology and Classification of Ardipithecus ramidus Science, 328 (5982), 1105-1105 DOI: 10.1126/science.1184148

Pictures:

Johanson D., Edgar, B. (2006). From Lucy to language. Simon and Schuster, New York
Suwa G., et al. (2009). The Ardipithecus ramidus Skull and Its Iimplications for Hominid Origins. Science 326, 68.

2010-12-08T22:31:00.003+01:00

"The degree of consistency between our theoretical knowledge of the world and the real world remains unknown to us, even if it's complete."

(From: Vollmer G. (1975) Evolutionäre Erkenntnistheorie Hirzel, Stuttgart, Leipzig, p. 137, (probably horribly) translated.)

So much for the proposition that something is "fact".

What happened to Sahelanthropus tchadensis?

2010-11-26T22:54:00.002+01:00

This Wednesday I had to do a Presentation on the description and classification of Sahelanthropus tchadensis for my Seminar on Human Evolution. I loved working on this topic, because two years ago, while I already attended a similar course, I watched a pretty impressive presentation about the same topic. This Presentation was one of those “enlightening” moments I had in this time and I always wanted to dig deeper into this whole story.
Anyways, I think I did pretty well, although I again realised that many other students do not share my enthusiasm for cladistics and the search for “good” characters. This or maybe it was just boring.

To come to my original reason for this post: While I prepared my talk, reading all those papers about the original discovery of Sahelanthropus and the upcoming critique of its classification, I could not help but ask myself: “What happened to this discussion?”
To give short recap on this story: Michel Brunet and his colleagues base their interpretation of Sahelanthropus tchadensis being a hominid on the following traits:

-A large supraorbital Torus, which Brunet et al. (2002) associated with a male individual (this sex estimation is pretty important for the next trait).

Brunet et al. (2002)

-A small canine, with a distal and apical wear facet and no C/P3 honing facet. (There were more characters described for the Canines, but I will skip them here)

-An enamel thickness between the chimpanzee and the Australopithecus condition.

-A flat, horizontally orientated Planum nuchale

-A more anterior positioned Foramen magnum

Zollikofer et al. (2005)

-A more perpendicular angle between the Foramen magnum and the Orbital Plane

The last three characters were associated with the probability of Sahelanthropus being a Biped.

Now, two years ago when I first heard about above listed traits I nearly went mad on their assumption that Sahelanthropus was a male. I just couldn’t, and still can’t understand how you’re able to estimate the sex of a single individual without knowing how those characters you use for your Sex estimation vary within this species.
This estimation is crucial because if we look at the canines, they are only small if Sahelanthropus was a male individual. If it was female, the size of the canine falls within the variation of other female Miocene apes and becomes much less diagnostic.

Speaking of canine morphology, there is a huge probability, that the morphology of the canine and its wear pattern is not an apomorphic character for hominids, but in fact a plesiomorphic character of at least all African Apes, which renders it almost useless for classification. Wolpoff and Colleagues (2006) stated that the wear pattern of the Sahelanthropus canines is probably the result of powerful masitcation, because similar patterns could be found in other Miocene Ape Taxa, such as Ouranopithecus and Gigantopithecus.

Canine of Gigantopithecus showing slight distal and apical wear. According to Wolpoff et al. (2006) this tooth shows an earlier stage of the wear pattern of Sahelanthropus tchadensis. (Wolpoff et al., 2006).

They continue in their critique, showing that none of the traits, Brunet et al. (2002) and Zollikofer et al. (2005) showed, could be interpreted as clear signs for bipedalism. This doesn’t mean of course, that those traits couldn’t be seen as apomorphic for hominids*, but at least you’re not able to state that it’s more possible that Sahelanthropus was a biped, than that it was not (as ist was by Zollikofer et al., 2005).

From my point of view, Wolpoff et al. (2006) raised some serious doubts on the classification of Sahelanthropus being a hominid and I was pretty sure that there should be some kind of answer on these issues by now. Well, apparently I was wrong about that,The only thing I found so far was this little passage:

“Scientifically it is impossible to understand why some authors ignore these derived characters and concentrate on primitive ones to reach the conclusion that S. tchadensis is related to modern apes and even more precisely to a palaeogorilla (Wolpoff et al. 2002, 2006; Pickford 2005). This attempt to undermine the clear affinity of the Chadian hominid is curious mainly when it is coming from, among others, two who have not yet had the opportunity to check Toumaı¨ casts in their laboratory. Is it what they believe, or is it only because they want to keep Orrorin as the earliest hominid?“ (Brunet, 2010, S.3318)

I found this to be pretty disappointing. Mostly because, a little bit before that passage, Brunet listed exactly the same “derived” characters, Wolpoff et al. criticized in their 2006 paper.

And instead of countering the critique on a scientific base, Michel Brunet points to the involvement of two of his “critics” (Martin Pickford and Brigitte Senut) into the discovery and description of Orrorin tugenensis. Well you can do exactly the same kind of argument with Michel Brunet, pointing out his extensive work in Tchad and the fact that it surely is pretty lucrative to announce an “earliest known hominid”.

Surely, there might be some kind personal interest behind many critical papers, but you still have to confront those critics in a scientific way. And the only way to get some kind of scientific progress is to falsify hypothesises of other people. In fact, the only thing we can be sure of in science is that if something is false, it is false (to put it simple). So the best way, to show that you’re right, is to show to other people that they are wrong. But if we look at this case here, I can’t see that this process is happening right now.

Judging from what I know so far about this story, I would not classify Sahelanthropus tchadensis as a hominid. This doesn’t mean on the other hand that this conclusion diminishes the scientific value of Sahelanthropus.
What I exactly mean by this sentence I will explain in my next post, which I hopefully manage to put in a few days.

* I’m a little bit confused about that right now, since I got this thought while writing this post.

References:

Brunet, M., Guy, F., Pilbeam, D., Lieberman, D., Likius, A., Mackaye, H., Ponce de León, M., Zollikofer, C., & Vignaud, P. (2005). New material of the earliest hominid from the Upper Miocene of Chad Nature, 434 (7034), 752-755 DOI: 10.1038/nature03392
Brunet, M., Guy, F., Pilbeam, D., Mackaye, H., Likius, A., Ahounta, D., Beauvilain, A., Blondel, C., Bocherens, H., Boisserie, J., De Bonis, L., Coppens, Y., Dejax, J., Denys, C., Duringer, P., Eisenmann, V., Fanone, G., Fronty, P., Geraads, D., Lehmann, T., Lihoreau, F., Louchart, A., Mahamat, A., Merceron, G., Mouchelin, G., Otero, O., Campomanes, P., De Leon, M., Rage, J., Sapanet, M., Schuster, M., Sudre, J., Tassy, P., Valentin, X., Vignaud, P., Viriot, L., Zazzo, A., & Zollikofer, C. (2002). A new hominid from the Upper Miocene of Chad, Central Africa Nature, 418 (6894), 145-151 DOI: 10.1038/nature00879
Brunet, M. (2010). Two new Mio-Pliocene Chadian hominids enlighten Charles Darwin's 1871 prediction Philosophical Transactions of the Royal Society B: Biological Sciences, 365 (1556), 3315-3321 DOI: 10.1098/rstb.2010.0069
Wolpoff, M. H., Hawks, J., Senut, B., Pickford, M., & Ahern, J. (2006). An Ape or the Ape: Is the Toumaï Cranium TM 266 a Hominid? Paleoanthropology, 36-50
Zollikofer, C., Ponce de León, M., Lieberman, D., Guy, F., Pilbeam, D., Likius, A., Mackaye, H., Vignaud, P., & Brunet, M. (2005). Virtual cranial reconstruction of Sahelanthropus tchadensis Nature, 434 (7034), 755-759 DOI: 10.1038/nature03397

It's been a while...

2010-11-10T12:40:00.000+01:00

I just want to make sure, that I haven't forgotten about this Blog here. It's just that most of my german Posts I made in the last few months weren't really "worthy" to be translated. Also I was pretty lazy in the last few months, so that might be also a reason for this long period of inactivity.

Anyways, I'm going into my last "regular" Semester and hopefully I'm going into my last year as a undergraduate Student. So there are some pretty exciting things coming towards me and I hope that some of them would make good material for my Blog(s).
Until then, there will be some rather philosophically oriented posts in the next few weeks, since I'm attending a seminar with a really nice title, which I'm not able to translate (believe me I tried). In general, the seminar deals with philosophy of science and ethics in regards to the field of evolutionary Anthropology. I'm really interested in those kinds of questions and I'm really happy that there's is acutally a whole seminar dedicated to these things. And because I think, that those questions should interest a lot of people, I intend to write about some of them.

Why we shouldn't speak of "primitive" traits.

2010-06-27T08:35:00.000+02:00

(While reading please keep in mind, that English is my second language so I might have different understandings of certain words.)

While reading Papers (and also in some Blogs) I very often come across the word “primitive” when people refer to a certain character state.

In an evolutionary context, a “primitive” trait is a trait that evolved quite early in the evolution of a certain group of animals. For example our Nails are “primitive” traits, because all primates got them. In our everyday Live we use the term “primitive” in rather different way. Something is “primitive” when it’s underdeveloped or antiquated.
Looking again at our Nails, you cannot say that these are underdeveloped or inefficient in some kind. In fact, without our Nails we are barely able grasp something. Also whether or not a trait is “primitive” differs from your caldistical perspective. Looking at primates alone, you would say that Nails represent the “primitive” condition of all primates while the claws of marmorsets are “derived”. If you look at all mammals you got a slight different view. Here the representation of claws is the “primitive” condition while the nails of primates represent a more “derived” state. By the way the claws of marmosets develop in different way than the “standard” mammal-claw.
You see there is a fundamental difference between the use of the word “primitive” in biology and the way it’s used in our everyday life.

In fact, the usage of the word primitive in evolutionary biology is somewhat “primitive” itself. Back at the beginning of the 20th century to its middle, many evolutionary biologists proclaimed a “scala naturae” like view on evolution. “Scala naturae” means that you have a direction in Evolution from simple (“primitive”) Forms to more complex forms; very often our own species sits at the top of that ladder.
But this assumption is wrong. Every living being on earth has undergone the same time of evolution since the origin of Life itself. From this follows that every living being is, in more or less the same amount adapted to its specifical niche. If one species is in some way “underdeveloped” or “inefficient” in the way it exploits its niche, then it would simply come extinct by time. You see, there’s literally no need to use the term “primitive” in this context, because there are words that describe the relationship of traits in much better way.
Also there is also the danger in producing misunderstandings in using words which meanings differ between the scientific communities and everybody else. And the last thing we should produce in evolutionary biology, are misunderstandings about the way evolutionary theory works.

I think we got rid of the scala naturae and now it’s time to get rid of its terms. Instead of speaking of “primitive” traits it is way more accurate if we use the word “ancestral” instead. You will avoid many misunderstandings and also describe our actual picture of how evolutionary theory works in a much better way.

Looking for a Master Thesis

2010-06-15T00:44:00.001+02:00

I have to admit, I was a little bit desperate when I started studying Anthropology five years ago. I began my “career” as a student of biology, but after a few months I was more or less disgusted by the way “modern biology” works. This was quite shocking for me, because back in school I was quite sure that biology would be the field of science where I belong to. This whole story put me into some kind of intellectual crisis, which led me to the conclusion that studying politics, philosophy and cultural Anthropology would be the right thing for me. In Germany, cultural and physical Anthropology are separated so I only heard a tiny little bit about physical Anthropology. But since the subjects I chose back then were either quite boring (politics) or very annoying (philosophy) I decided one more time to switch my subjects, saying to myself, if this isn’t the right thing either, I will stop messing around at the university and attend an apprenticeship as pastry chef. Mostly because baking fancy cakes is the only talent I have besides of this whole intellectual stuff.
In contrast to my earlier attempts, after a short time studying in Anthropology I said to myself: “This is where I belong.” And even though I lost almost one year due to my stupid laziness, I haven’t changed my point of view.

The reason why I took Anthropology back then and why I didn’t become a pastry chef (yet) is very simple: Curiosity. There are so many things we don’t know about ourselves. Just look on this whole Ardipithecus topic and the questions about the origin of our species. How can you hope to understand human nature, when we aren’t able to understand our own natural history?
Because I want to find answers to that question, or at least try to find some, one and a half years ago I decided to try my luck at Paleoanthropology.
Unfortunately, this decision coincided more or less with the Retirement Winfried Henke, some of you might know him as one of the Editors of the “Handbook of Paleoanthropology”. He was the only Professor at our Institute that supervised Master and PhD-Theses in Paleoanthropology.
I’ve spend the whole last year to think about a proper resolution for this problem but besides some nice insights into various topics, the outcome of this whole process was very poor.

Sure, I could easily go on with this stuff, reading publications, thinking about what I could do, if someone just gives me the opportunity and meanwhile feeling extremely intelligent while doing so. But this wouldn’t help my chances in getting into Paleoanthropology.

This is why I finally decided to take a more direct approach to this problem.

I will simply ask a lot of people in a lot of countries if there is an opportunity to write my Master-Thesis under their supervision.
Sure, most of these people got better things to do than to reply to the desperate begging of some unknown student and honestly I don’t expect very much from this. But nothing will change for sure if I continue to do nothing. And sitting around, thinking about all this over and over again will change nothing either.

As far as I can see, in a Situation like this, you have two options: 1st Option: You can sit around and complain how cruel and unfair the world is treating you or you can try the 2nd Option which means that you stop complain and try to change something.
Until now, I tried Option number one and it didn’t work out very well, now I want to try the second option.

Just a mere thought: The upper limb of Apes and parallel Evolution of bipedalism.

2010-06-03T18:16:00.001+02:00

Last week I wrote the following sentence:

” I have the impression that as soon as you find a fossil ape that probably walked on two legs, its being put into the human lineage without asking further questions about its true relationships.”

I think this needs some further explanation:
One of the key features for the classification of hominins is bipedalism, simply because we are bipedal. But are those very early, probably bipedal, fossil Apes really hominins? There are some arguments which reject theses hypothesises. Molecular genetics nowadays put the divergence between Chimpanzees and humans somewhere between 4 and 5 million years. Most of the fossils (Sahelanthropus tchadensis, Orrorin tugenensis and at least Ardipithecus kadabba) are older than this date. There are strong reasons to suggest, that you cannot move the date of divergence very far into the past. For more information on this issue I suggest reading John Hawks Post "Reviewing the clock and phylogenomics". Also some traits which were used to classify those fossils as hominids are far from being unequivocal, as you can see at the discussion of Ardipithecus ramidus last week.
Ok, let’s assume that all those early hominins in fact are not hominins. They still show some traits that could be related to bipedalism aren' they? How can we explain that? The answer could be that bipedalism evolved more than once.

Is there any evidence for the convergent evolution of bipedalism?
Well, there is no direct evidence, but here I will present you a hypothesis where parallel evolution of bipedalism could be possible.
Reynolds (1985) showed that Apes in general (some in a larger degree than others) try to put more weight on their hind limbs. The main reason for this seems to lay in the more laterally oriented glenoid fossa of recent Apes. The lateral orientation of the glenoid fossa results in more flexible upper limb and enables suspensory Locomotion while in trees (Aiello, Dean, 1990). On the other Hand it generates higher stress on the shoulder-joint while terrestrial locomotion. This problem could be one of the reasons for the evolution of knuckle walking in Gorillas and Chimpanzees.
Now there is some evidence which points to the possibility that knuckle walking in Chimpanzees and Gorillas evolved twice (Kivell, Schmitt, 2009; Wunderlich, Jungers, 2009; Lovejoy et al., 2009), which means that hominid bipedalism didn’t evolved from a knuckle walking ancestor. What does that mean for the evolution of bipedalism?

Let’s assume we have a more generalized, not fully suspensory Miocene Ape with a flexible shoulder. Let’s assume further that this Ape has to climb down from his tree. Because the lack of strong flexors in the Forearm, he isn’t able to do efficient knuckle walking and his flexible shoulder makes it impossible to walk in a “normal” quadrupedal gait. The consequence would be that this Ape completely avoids walking on his upper limbs and instead will start walking bipedally. Looking at Ardipithecus ramidus this scenario seems not that unlikely. According to the Authors, Ardi was an above-Branch Quadruped while in the trees. On the other Hand, she had a flexible shoulder, at least of what could be told from the remains.

Under the light of this model, the evolution of traits related to bipedalism would be the logical consequence of the functional morphology of said Ape. This means, that if you put similiar selection pressures on different populations of this hypothetical Ape, it would result in the parallel evolution of bipedalism in these populations.

Well okay, everything I said above is more or less hypothetical, but what could be done to put it on a more solid ground?
Well momentarily I can think of two things: First you have to look how Apes exactly stress their forelimbs during terrestrial locomotion, there is some research done with it, but for what I know is that it’s not enough.
Secondly I think one should try to simulate this above mentioned “hypothetical Ape” and look what kind traits it needs to have that bipedalism is the most efficient option for terrestrial locomotion. With this set of traits you can start looking at the fossil record and try to falsify this hypothesis. The last thing is, in my opinion, the most important one, because not many models in human evolution are directly falsifiable through the fossil record.

I’ve been working on this thing for several months but two weeks ago I’m stuck. So I thought the best Idea would be to tell this stuff to a wider audience, which I have done now.
What do you think of it? Is it rubbish? Is it some old Idea which has been given up long time ago and I simply didn’t realized it yet? And if not, what else could be done to build it up to a real model and not some simple thought-experiment by an undergraduate student who has way to much time.

So, if you have any suggestions, please tell me. You will help me a big deal with it.

P.S.: If anyone got accsess to the "Journal of Zoology" and could mail me the following article (Email: edgarneubauer[at]gmx.de), I would be very, very happy:

Larson, S. G., Stern, J. T. (2009). EMG of chimpanzee shoulder muscles during knuckle-walking: problems of terrestrial locomotion in a suspensory adapted primate. Journal of Zoology, 212 (4). S. 629-655.

References:

Aiello L., Dean, C. (1990) An Introduction to Human Evolutionary Anatomy. Elsevier Academic Press, London.

Kivell, T., Schmitt, D. (2009). Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor Proceedings of the National Academy of Sciences, 106 (34), 14241-14246 DOI: 10.1073/pnas.0901280106

Lovejoy, C., Simpson, S., White, T., Asfaw, B., Suwa, G. (2009). Careful Climbing in the Miocene: The Forelimbs of Ardipithecus ramidus and Humans Are Primitive Science, 326 (5949), 70-70 DOI: 10.1126/science.1175827
Reynolds, T. (1985). Stresses on the limbs of quadrupedal primates American Journal of Physical Anthropology, 67 (4), 351-362 DOI: 10.1002/ajpa.1330670407
Wunderlich, R., Jungers, W. (2009). Manual digital pressures during knuckle-walking in chimpanzees American Journal of Physical Anthropology, 139 (3), 394-403 DOI: 10.1002/ajpa.20994

It's on! Is Ardipithecus really a hominid?

2010-05-28T15:02:00.004+02:00

Today, Zinjanthropus over at "A Primate at modern aspect" asked an interesting question, while commenting on the critique of the original Interpretation of Ardipithecus ramidus.

But before I’m trying to answer that question a short summary about today’s Ardi discussion.

Esteban Sarmiento criticized the original classification of Ardipithecus ramidus as a hominid by showing that most of the characters which were used to classify Ardipithecus as a hominid are cladistically not very reliable.
White and colleagues tried to show in there answer that there is a morphokline of characters reaching from Ardipithecus to Australopithecus.

Now, the question that was asked over at “A primate of modern aspect” was:” Which traits are good traits?”
If we’re looking at morphological traits, this question is really hard to answer; in fact I don’t think that I can answer this question for myself.
But I can try to answer this question in amore general way. Good traits are traits with a very low probability of being homoplasious.
Well now that we’ve stated the obvious, let’s ask a different, more interesting question: “Does a large number of ambiguous traits leads to "good" phylogenetic trees?”

If we’re looking at molecular cladistics we can easily answer this question.
In 2002 Arnason and colleagues analyzed the relationship of present day mammals with a huge amount of sequence Data obtained from mitochondrial DNA. The most interesting result was, that the Flying lemurs, one of the potential sister Groups of primates, were put as a sister group of Anthropoidea inside the primates. In their analysis they simply compared the sequences of each mammal, treating each nucleotide as one character. As you can see, you get a lot of characters this way. On the other hand, since every character can only have four states (A, C, G, T), there is a large probability of convergent evolution. This is even more the case in the mitochondrial genome of Primates, as their mutation rate is much higher then in other mammals, which leads to a faster loss of phylogenetically relevant information(Lee, 1999).
The hypothesis of Arnason and colleagues was later rejected by Schmitz et al. (2002), who used so called “rare genomic changes” for their study. As you can guess by their name, those changes occur not very often and hence are not very prone to convergent evolution.

Now what has this stuff tot do with the issues on Ardipithecus? Well, just because you have a lot of characters with a low phylogenetical relevance, it doesn’t mean per se that your classification is right. Even if you have a large amount of them, each character for itself is still prone to convergent evolution.
This doesn’t mean that I share the same opinion as Samiento, but I can understand his point and it’s good to see that someone asks such questions.
I have the impression that as soon as you find a fossil ape that probably walked on two legs, its being put into the human lineage without asking further questions about its true relationships.
I think the accusation of Samiento that White et al. (2009) were following some kind of scala naturae like model of human evolution, should be understand in a similar matter.

I could go on on this topic all day, but I will spare you this until next week after I finished the Exposé for a potential Master theses.

References:
Arnason, U. et al. (2002). Mammalian mitogenomic relationships and the root of the eutherian tree. Proc Natl Acad Sci USA, 99, 8151-8156.
Lee, M.S.Y. (1999). Molecular phylogenies become functional. Trends Ecol. Evol. 14, 177–178
Sarmiento E.E. (2010). Comment on the Paleobiology and Classification of Ardipithecus ramidus. Science, 328 p. 1105.
Schmitz, J. et al. (2002). The colugo (Cynocephalus variegatus, Dermoptera) the primate gliding sister. Mol Biol Evol. Vol. 19, 2308-2312
White, T.D. et al. (2009). Ardipithecus ramidus and the Paleoenviroment of early hominids. Science 326 p. 64-86.

Primate evolution- When, where and how did it happen?

2010-03-26T23:27:00.009+01:00

One of the most exciting subjects in Primatology are that of the origin of primates and their early evolution. Mostly because many of the "big questions" are still far away from answered.
One of those quetsions is about the geographical and chronological origin of primates.
To give you a little introduction to some these issues I want to present you a (very rough) tree which shows the relationship between the larger groups of primates and there estimated dates of divergence:

Within this tree ther are two dates which are problematic, namely the ones between Old- and New World Monkeys and between Lemurs and Loris.

New World Monkey are only found in South and Middle-america, Lemurs only on Madagascar. Unfortunately both, South America and Madagascar split from the African Continent many million years before the Radiation of Primates occured.

The general explanation, why these two groups reached their modern day habitat is, that it was either through floating (for example on fallen trees) or through "island hopping". But if this is true, why you might ask, didn't other primate groups crossed the Gap between Indosia and Australia?

There are other Problems as well, for example there is a gap of at least 10 milion years between the estimated divergence date of primates and the first fossil primate.

Two weeks ago I stumbled over an article which tries to give some kind of alternative model for chronological and geographical origin of primates.

The author, Micheal Heads says that the main part of the early radiation of primate didn't happen during the cretatious or even later periods but rather within the jurassic. If you place the origin of primates within that period, you have the advantage, that New world monkeys and Lemurs didn't have to cross large gaps of water. Both groups originated when the ancient continent of Pangea broke apart. Following this line of argument, both groups and their modern day distribution are rather the result of geographic isolation and not of migration from a center of origin.

Their are also other facts which come to my mind that could be used as indicators for that model:

It is really difficult to determine the sister group of primates. Dependend on which methods or characters you use, you get different results. Especially studies which use genetic markers state the the divergence of primates and their next living relatives occured very fast. One study (Janecka et al. 2007) gives a timeframe from more or lesse than two million years.

This fast split of the ancestral population of primates and their closest relatives could be explained by geographical separation.

But of course there are things in this paper which make me a little bit sceptical.

If you are looking at my figure you can see that, for example, there is a difference of at least 60 million years between the estimated date of divergence of Old- and New-World Monkeys and the date which was proposed in the paper.

Let's assume Heads is right, than we probably have to adjust any other date of divergence within Old- and New-World Monkeys.

To be honest, I really don't know what to think of this paper. All in all it sounds quite plausible and it tries to answer questions which I asked myself in the last year.

On the other hand, sometimes it sounds to speculative for me. Sure the model it proposes fits well within the geological events in that timeframe, but at the moment there just isn't enough hard evidence to really support it.

At least, one thing I can say for sure. It's good that someone tries to give a complete new perspective on age old questions. Very often the same answers were repeated and repeated over an over again without giving any new insights on the questions they were accorded to.

I think we should, at least, see this paper as a challenge to the old models. As I stated at the beginning, we know very little about the origin and early evolution of primates and such a, also a little bit provocative, hypothesis maybe helps to get a better grip on these issues.

References:

Heads, M. (2010). Evolution and biogeography of primates: a new model based on molecular phylogenetics, vicariance and plate tectonics Zoologica Scripta, 39 (2), 107-127 DOI: 10.1111/j.1463-6409.2009.00411.x

Janecka, J., Miller, W., Pringle, T., Wiens, F., Zitzmann, A., Helgen, K., Springer, M., & Murphy, W. (2007). Molecular and Genomic Data Identify the Closest Living Relative of Primates Science, 318 (5851), 792-794 DOI: 10.1126/science.1147555

Eizirik et al. (2004) Molecular Phylogeny and dating of early primate divergence. In: Ross, C.F., Kay, R.F. Anthropoid origins. New Visions. Kluwe Academic/Plenum Publications, New York.