Posted on 02/28/2006 11:27:44 AM PST by blam
Early Humans Walked Peculiarly?
By Jennifer Viegas
Discovery News
Evidence In The Bones
Feb. 27, 2006 — At least two species of early humans were knock-kneed and walked rather uniquely, according to a new study on seven anklebones that belonged to various early human ancestors from eastern and southern Africa.
The study, which will be published in the April issue of the American Journal of Physical Anthropology, suggests that although the early humans walked on two feet, they did not always do so with our relatively smooth stride.
"This is hard to explain, but easy to demonstrate," said Dan Gebo, who co-authored the paper with Gary Schwartz, an Arizona State University anthropologist.
Gebo told Discovery News that modern humans, and our more recent ancestors, possess a walking technique that first involves the heel hitting the ground. As the body moves over the foot, the person stands on one foot while the other foot is starting to swing forward. We then "toe off as we go through a normal stride."
Gebo, a Northern Illinois University anthropologist, then explained that muscular early humans, called robust australopithecines, who lived between 2 and 1.4 million years ago, had a different gait.
"The robust australopithecines have modified their upper ankle joint so that when the lower leg moves forward to stance phase, it must follow the track of the joint and this joint curves inward," he said. "It then must backtrack as the leg and foot push off at toe off."
Gebo added, "In short, the knee of robust australopithecines must move in and out during each stride. It would look like the knee is slightly bent, where ours is straight. The gait is less efficient, especially over long distance walkings or runnings."
The shape of the anklebones suggests that at least two early human species, Australopithecus robustus and Australopithecus boisei, walked in this unique manner. Both looked very apelike and furry.
While the researchers think such early human relatives "had some gait peculiarities," they believe the ability to walk on two feet (bipedality) evolved only once because it requires so many anatomical changes in the pelvis, knees, lower legs and feet.
"We find it difficult to believe that all of these changes could occur more than once," Gebo said.
The scientists think bipedality must have occurred very quickly in human evolution, particularly since there was no three-limbed transitional phase.
During the period of evolution, our ancestors lost their grasping big toe muscles. This "toe" in African apes, such as chimpanzees, helps in climbing trees. Gebo said we also developed platform-like, weight-bearing bodies, short toes, stocky foot bones and joints that can lock up so we do not need muscle power to remain erect.
Bruce Latimer, executive director of The Cleveland Museum of Natural History, told Discovery News that he agrees bipedality evolved no more than once within the human lineage, but he does not believe "that any non-pathological hominid ever walked with tibiae that inclined medially (knock-kneed)."
Latimer added, "Moreover, it is quite impossible to reconstruct such behavior from isolated bones. The authors have taken on the ambitious task of trying to make sense out of isolated anklebones. They have done a nice job but have, perhaps, pushed the functional analysis a little too far."
Gebo and Schwartz, however, plan to continue with their research to determine if their theorized knock-kneed gait might have conferred some unknown advantages.
Schwartz told Discovery News, "Paleoanthropologists have long been fascinated with the robust australopith phase of human evolution as they are one of the most highly specialized and derived group of fossil humans.
They have massive teeth, large, heavily constructed jawbones, and enormous chewing muscles, but they have always been thought of as fairly ‘standard-brand’ (for a hominin) from the neck down."
Schwartz added, "We know now, based on our work, that they were as interesting from the knee down as they are from the neck up."
Gee, I've heard that they think we might have evolved from australopithecines, but I never heard them try to claim that they were human... Wish they could make up their minds...
With one, many people sit with up their A## a lot, the other, not so much....
"In this case, semantics that you're trying to hide behind to cover the fact that your desire to be a smartass in this case overshadowed your knowledge of the subject."
Apes are not quadrupeds, Sofa King. If that strikes you as a semantic quibble, so be it.
"Satanicus Robustus"
They don't call me ole silver-back for nothing. :)
I saw that line I posted in some email list going around, I knew it would prompt some discussion.
"Hillary's ankles look pretty australopithecine. And very robustus."
Alley Oop, on her distaff side: http://www.toonopedia.com/oop.htm
YES!! Again, if you haven't already, go online to Amazon and get yourself a cheapie used copy of "Scars of Evolution" by Elaine Morgan. Absolutely fascinating. Helps explain possibly WHY human babies know instinctively to hold their breath when placed in water, why they're born with a large amount of white fat (it floats!) as opposed to chimp and ape babies, which are born with a thin layer of brown fat, which has no flotation qualities. So it is that after Christmas when I have put on a bunch of fat from eating too much fudge and chocolate-covered cherries, I rationalize it and figure it's just that much more flotation for me when I go swimming. And swim I do -- as a means of burning off said fat to keep my girlish figure! *sigh* So many contradictions, so little time!
Then you probably shouldn't involve yourself in science threads of this type.
Did you ever try to hitch a ride sticking out your big toe?
See my post 54 and 69. So cool to find others who know of the Aquatic theory, which according to Morgan, was actually first presented in the mid 1800s.
Hummmmmmm ..... OK
You're right, I'm just instigating. :)
Only women can do that, while wearing a skirt.
True. Yet I'm always careful that my ping list has only evolution supporters on it. Somehow, the others seem to find our threads. Nothing I can do about it except to give blam a clear field and avoid pinging my list to his threads.
Makes perfect sense to me. A new breed of dogs does wipe out all previous breeds. I can clearly see that at any park, on any Saturday, so it fits all the observational evidence.
The aquatic theory is interesting, but I think it may well be flawed. We seem equally well-suited to the open savannah, and are good long distance runners and walkers. There seems equal weight there.
Still, if you're looking for evidence of early man, you'll find it at the edge of the water, certainly. I think that's due to the easy availability of food, though, rather than an aquatic environment.
I used to surface collect Chumash artifacts in the area in CA where I used to live. Lots of the area was pretty picked over, though, so I studied a topo map of the area and identified areas where the water's edges would have been in times of higher ocean levels. Immediately, I began finding new places to locate artifacts.
The Chumash were there at least 6000 years, maybe more. I found signs of encampments in places nobody had even looked before. Very interesting. All near water, or where water used to be.
LOL, very definitive.
/not
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