Ardi Video Mining

[Vogter2100]

Amazing and wow.. new knowlegde FTW :)

Great video!!

5'd and fav'd

[musekiteer]

Thanks, Tomas ;)

I made this video because Comfort and Cameron are lying "Kents".

I just created a playlist for the entire documentary. It is very interesting and much less hokey than some science documentaries.

[AncientAtheist]

Nice work, Muse.

I don't understand something. Why do we conclude from this that the common ancestor of humans and chimps didn't knuckle-walk? Isn't it just as likely that it was simply earlier (closer to the split than the spot occupied by Ardi) in hominid evolution that we gave up knuckle-walking?

It would seem to this layman like a more parsimonious hypothesis. We don't really know the exact point of split. Ardi goes 4.4 MYA, but the split could have been at 6 or 7 MYA.

[AncientAtheist]

If we take the higher number - 7 MYA, then we have an intervening 2.6 MY to evolve full bipedalism, sans knuckle-walking.

If we were sure that Ardi was *at* or at least extremely close to the human/chimp split, then I could understand the hypothesis that the common ancestor was a bi-ped. But this, to my knowledge, is not the case. The very latest number I have ever heard for the split is 5 million, but most now think it was sometime prior to that due to S. tchadensis and O. tugenensis.

[musekiteer]

Chimps and gorillas knuckle-walk in slightly different ways, but I don't think that this necessarily indicates separate evolution of k-w.

As soon as a hominin became fully bipedal, an inflexible wrist could become something of a liability. Brachiation does not require stiffened wrists, but chimps appear to palm-walk ( 4:07 ) along branches.

Has anyone been allowed a good look at the location of the foramen magnum in S. tchadensis? At least Orrorin fossils include the proximal femur.

[AncientAtheist]

Damn it, Muse. I *love* women who talk like that! Don't go getting me turned on. That's very sexy!

(and, no, I'm not being sarcastic)!!

[musekiteer]

Ha! You just need to hang out around more physicians and physical anthropologists - not to mention people who can read Wiki.

Frankly, I think that anatomy classes would have been much more interesting if this sort of applicability had been made obvious.

[musekiteer]

I agree. Ardi retained chimp-like feet, but its wrist morphology could well have "unstiffened" from that of an earlier knuckle-walking common ancestor. Otherwise, biologists would have to postulate that gorillas and chimps separately evolved knuckle-walking.

I think it very likely that the split was earlier than 5 Mya. Earlier calculations placed the split at 6-8 Mya. Individual alleles have distinct timelines, so the calculations are based on an average for multiple loci.

[AncientAtheist]

"Otherwise, biologists would have to postulate that gorillas and chimps separately evolved knuckle-walking."

That was exactly my thinking when I referred to the idea as less than parsimonious.

Well, it's all fascinating and, naturally, what we really need are more fossils.

[musekiteer]

I agree, and I think that it is also more parsimonious to think that we lost the feature, rather than that they individually evolved from a pre-gorilla-pre-common-ancesto­r that had a "limp wrist".

You are right -- we need more fossils. The problem is that fossilized miocene apes are not thick on the surface of the ground.

It blows the mind how many scientists were involved for so long in putting together one entire issue of science, and that creationist presume to deny Ardi.