Posted on 05/29/2002 2:11:46 PM PDT by Salman
Origin Of Bipedalism Closely Tied To Environmental Changes
Champaign - May 01, 2002
During the past 100 years, scientists have tossed around a great many hypotheses about the evolutionary route to bipedalism, to what inspired our prehuman ancestors to stand up straight and amble off on two feet.
Now, after an extensive study of evolutionary, anatomical and fossil evidence, a team of paleoanthropologists has narrowed down the number of tenable hypotheses to explain bipedalism and our prehuman ancestors' method of navigating their world before they began walking upright.
The hypothesis they found the most support for regarding the origin of bipedalism is the one that says our ancestors began walking upright largely in response to environmental changes in particular, to the growing incidence of open spaces and the way that changed the distribution of food.
In response to periods of cooling and drying, which thinned out dense forests and produced "mosaics" of forests, woodlands and grasslands, it seems likely that "some apes maintained a
forest-oriented adaptation, while others may have begun to exploit forest margins and grassy woodlands," said paleoanthropologist Brian Richmond, lead author in the new study. The process of increasing commitment to bipediality probably involved "an extended and complex opening of habitats, rather than a single, abrupt transition from dense forest to open savanna," he said.
Richmond, from the University of Illinois, with anthropologist David Begun from the University of Toronto and David Strait from the department of anatomy at the New York College of Osteopathic Medicine, describe their findings, which involved a comprehensive review and analyses of the five leading hypotheses on the origin of bipedalism, in a recent issue of the Yearbook of Physical Anthropology. Other hypotheses that remain viable, according to the team: "freeing" the hands for carrying or for some kind of tool use, and an increased emphasis on foraging from branches of small fruit trees, which is the context in which modern chimpanzees spend the most time on two legs.
For their study, the researchers combined data from biomechanics movement and posture, pressure distributions and strain gauge and from finger-shape growth and development. They found that our prehuman ancestors had terrestrial features in the hands and feet, climbing features throughout the skeleton, and knuckle-walking features in the wrist and hand; that finger curvature is responsive to changes in arboreal activity during growth. Evidence from the wrist joint, in particular, "suggests that the earliest humans evolved bipedalism from an ancestor adapted for knuckle-walking on the ground and climbing in trees."
The YPA article, according to Richmond, is "the first attempt in decades to bring together all of the available evidence for the argument that the earliest human biped evolved from ancestors that both knuckle-walked and climbed trees, rather than from ancestors living exclusively in trees and 'coming down from the trees,' or walking on the ground in ways similar to modern baboons."
A. is correct for the reasons cited plus reasons related to the ability to vary rates of breathing without direct reference to stride.
However, enter the following creature in the race. A human being in all respects but one. It runs on all four.
Now who is your winner? The 4man is.
Now take your 4man and enter him into the 100 against some nasty preadators. The nasty preadators win.
Now take 4man and while chasing his pray confront him with a quick predator. Chomp he is dead.
Now take 2man and while chasing his pray confront him with a quick predator. Thrust stab the predator is kept at bay.
The compromise from four to two legs under the savanah model only makes sense if your 2man is already a tool/weapon weilder. Alternativley it makes sense in the aquatic model even if tool making/weapon weilding has yet to appear.
This line of logic, if valid, has an interesting implication. It would appear that the question of which came first, bipetalism or weapon weilding/tool making, is crucial.
Answers?
That's the same sort of negative theological argument that Darwin used, with great effect. The only problem is, saying, God wouldn't have done it that way" is not a scientific argument. It is a simply a metaphysical argument based on certain notions of what God would or wouldn't do. Apparently evolutionists are the only ones who are supposedly allowed to invoke supernatural explanations and remain naturalists at the same time.
Cordially,
Thanks, now I know why the desert is loaded up with two legged coyotes.
(You can take it as a pun, or as sarcasm; I don't get many twofers)
His handiwork speaks for itself, ie, it's flawed.
There's nothing particulary intelligent about Intelligent Design. Evolution explains what theology would have us swallow unexamined.
Enlightenedly,
You seem to have missed the point that your argument is not a scientific argument; it is a metaphysical argument predicated entirely upon certain assumptions, which may or may not be true, about what God might or might not do.
There's nothing necessarily wrong with making a theological argument, but it is still not a scientific argument. Even worse, what does "flawed" mean in the first place from an evolutionary standpoint? An accusation like that implies a standard. Unless your yardstick is independent of the thing measured there can be no measurement. How does evolution yield a measuring stick? What is it, and where do you get it from? How in the world can evolution produce anything "flawed"? What are you comparing the universe to when you say something is flawed?
There's nothing particulary intelligent about Intelligent Design.
Again, you have to assume intelligence in the first place to make such a judgment, even though your mind is, on your view, a product of the the non-rational. You have to also assume that intelligence and logic are valid in a non-rational universe, even though you cannot account for it.
Your theological argument is like a pot saying to the potter, "why did you make me like this?".
Cordially,
I don't think the Vitamin C argument is theological, but its conclusion lessens the appeal of the notion of a perfect creator, making it somewhat theological, I suppose.
lol, how in the world did our discussion degenerate to hopping and waddling creatures. :)
This forum rocks.
Have a good one mamelukesabre and see you on another board sometime.
Well, necessity is the mother of invention. God created us and created the universe, and God knows how it will all end, but our part in it is not static and in fact God put us in charge of the Garden.
When people freak out about global warming and other approaching crises, I always shrug and see them, real or not, as yet another stimulus to human invention.
Ancient Humans Walked But ‘Struggled To Run’
The Telegraph (UK) | 9-11-2007 | Roger Highfield and Nic Fleming
Posted on 09/11/2007 10:51:26 AM EDT by blam
http://www.freerepublic.com/focus/f-news/1894625/posts
Early Human Ancestors Walked On The Wild Side
Eureka Alert - ASU | 2-16-2006 | Garu Schwartz - Skip Derra
Posted on 02/16/2006 1:14:54 PM EST by blam
http://www.freerepublic.com/focus/f-chat/1579810/posts
Early Humans Walked Peculiarly
Discovery News | 2-28-2006 | Jennifer Viegas
Posted on 02/28/2006 2:27:44 PM EST by blam
http://www.freerepublic.com/focus/f-news/1587166/posts
Ape To Human: Walking Upright May Have Protected Heavy Human Babies
Science Daily | 12-17-2007 | Springer.
Posted on 12/17/2007 4:50:35 PM EST by blam
http://www.freerepublic.com/focus/news/1940836/posts
Upright Walking Began 6 Million Years Ago
Newswise | Stony Brook University Medical Center
Posted on 03/20/2008 5:54:39 PM EDT by blam
http://www.freerepublic.com/focus/news/1989044/posts
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Just updating the GGG info, not sending a general distribution. |
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I just read another thread that it was because of the weight of human babies that had to be carried
Will someone make up their mind, please!
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