ps418

Based on what?

And what does the text really say?

Thanks for providing the reference, Geotheo, and the quote, LordV. Not only were you (GT) wrong to state that Leakey doubts that the australopiths walked upright, your own source directly contradicted this assertion. I am in amazement (perhaps wrongly so) that you missed this. Perhaps alot of the other things you believe about homonid fossils are equally ill-founded (e.g. your claim that A. afarensis and H. spp. were contemporaries).

Patrick

[ August 06, 2002: Message edited by: ps418 ]</p>

MrDarwin

This article was in yesterday's New York Times (you need to subscribe to the online edition to read it):

<a href="http://www.nytimes.com/2002/08/06/science/06SKUL.html" target="_blank">Skulls Found in Africa and in Europe Challenge Theories of Human Origins</a>

GeoTheo

So If Lucy ran on her knuckles she is a biped.
k.
Or are you saying she had no ability to run at all?
What does not having the ability to run bipedally mean?
I think not having the ability to run would make her pretty vulnerable to predators. It was my opinion that being a transitional form does not mean being ill adapted.

Oolon Colluphid

Oh come on Theo, you're slipping back into your old thought patterns. Do you know anything about chimpanzees? Even I've watched enough David Attenborough to know that they can both walk and run on their back legs. It looks awkward, and they don't do it for long, but they can and do.

Why could a knuckle-walking ancestor, in order to free its hands, not have moved similarly? And do so more often? So if freeing forelimbs from locomotive duties conferred an advantage, why couldn't the musculo-skeletal system change gradually towards more and more bipedalism?

And being upright and not much of a runner isn't automatically ill-adapted. Perhaps early ones dropped to their knuckles to run; perhaps it’s why they were still adapted to trees. But as they got better at upright walking, so upright running would improve too. One can be pretty sure that the ones that were less good at moving fast somehowdid indeed feed the leopards! (There is in fact a hominid skull -- I forget which -- with leopard-canine holes in it.)

Nobody doubts that A afarensis was a biped. But modern chimps are facultatively bipedal too. (Apes hang by their arms below branches, rather than walking on them as monkeys do, so all ape bodies are already partly geared for upright posture.) And nobody afaik claims -- or even needs to claim -- that 'Lucy' walked exactly like us. 'More like us than other apes' is good enough, and is pretty well demonstrated.

Cheers, Oolon

GeoTheo

Yes, I agree, but I think she is a lot closer to the ape end of the spectrum than the human end.
By saying that She along with modern chimps are both facultatively bipedal kind of proves my point. If I were a paleontologist and I found a new skeleton that was closer to the human form of locomotion, I would point out how comparatively ape like Lucy was. I still think a.afarensis is misrepresented in illustrations and reconstructions. I still think there are large gaps. For example, Tukana boy had a brain half the size of Homo. Sapians Sapians but seemed to be fully bipedal the way modern humans are.

Oolon Colluphid

So? I don't understand what you're expecting to see. Evolution predicted such things should exist long before they were discovered. Lo and behold, there's a load of them, all fitting the approximate pattern expected. You're slipping into another creationist trap: Show them fossils A and B, and they point to a gap between them. find an intermediate, and there's suddenly two gaps! Fill those, and there's four gaps!

Gaps do not matter. What matters is the confirmed predictions that filled the wider gaps.

As to facultative bipedality, there's a bit more to it than just legs, you know. Look up foramen magnum, for instance. If you're mostly on your knuckles, you don't want your head pointing at the ground all the time!

Oolon

Ergaster

Who said "Lucy" "ran on her knuckles?" Certainly no researchers working today.

Who said she couldn't run? She probably didn't sprint like Michael Johnson, but then, she was an australopithecine. She probably ran like an australo, not a human.

Who said she was "ill-adapted"? Australos were around for well over 3 million years, which is not a sign that a species is poorly adapted, by any means.

As I have repeatedly suggested, it would be easier to understand australos if they are regarded as unique creatures and not as somehow "almost humans". They may be ancestral to humans, but they were australos nonetheless, living australo (and not human) lives.

MrDarwin

Time to remind everybody about Theo's initial posting in this discussion, and the assertions he made:

No, based on relationships alone, we can't necessarily conclude this--in part because the relationships are what we're trying to figure out in the first place. But there are other ways to figure out if a particular fossil species was bipedal, such as the relative lengths of bones, position of the foramen magnum, etc. Other people have already addressed this at length.

This statement has been shown to be incorrect, by the very source you cited to support it.

Again, it would appear this statement is incorrect.

Did Leakey point out any such thing?

Well, sure, but remind me of the difference between apes and humans again? (It was my impression that humans are apes.)

Okay, I'll give you that one.

Theo, you are arguing the way I see many creationists argue: speaking authoritatively about a subject outside your own area of expertise and about which you don't actually know very much, seemingly saying whatever it takes to support your arguments--then rather than admitting you're wrong when you are proven wrong outright, just changing your argument slightly. You're going to have to do much better than that. "Evolutionists" don't get a free pass with sloppy arguments or shady debate tactics, any more than creationists do. What's at issue is your credibility in future discussions, and you're not doing much good for your credibility so far.

[ August 07, 2002: Message edited by: MrDarwin ]</p>

ps418

It depends. If what you mean is "All the species of the genus Australopithecus coexisted with all of the species of the genus Homo," then its just plain false. If you mean that the range of the genus Australopithecus overlapped with the range of the genus Homo, then it is true, but trivial and unproblematic for the aceepted view of human evolution.

I assume that Theo had something like the first meaning in mind, since otherwise it would make no sense to bring it up as an 'objection' to the Australopithecine ancestry of the genus Homo.

Patrick

Valentine Pontifex

He does not quote anyone as far as I can determine who don't think Lucy was a biped. He quotes people who think she was a biped but not in the same way we are (which is hardly shocking).

Leakey does mention the bit about the rib cage.

But again the take home lesson is that Leakey and the people he cites do accept australopithecine bipediality.