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."
At this point, mainly because the upper echelon of humans are creating and managing wildlife preserves and zoos with breeding programs. Absent that, the lower echelons of humans would have exterminated every last one of them by now.
Yeah, but look how well the suit fits!"
(old joke)
"Four. Like, you know, other apes."
Apes had four feet? Who knew? /sarcasm
Yeah, yeah. Saw it after I posted mine.
Interesting that Monty Python is still funny decades later, whereas other humor of the same approximate era (Rowan and Martin's Laugh-In for example), makes us wonder why anyone ever thought it was funny.
eesh. It's becoming impossible to keep a thread light and fun around here. Often you're immediately attacked by the "Pet agenda" bloggers....
Common misconception. Apes and humans are part of the same genus and the DNA evidence is hard to dispute. But the former are adapted to life as an ape, and we are adapted to whatever environment our ancestors found themselves in eons ago. Based on our lack of fur, large brain, subcutaneous fat layer, and slightly webbed fingers and toes (none of which modern apes have) I think we were adapted to life in the water. But hey, it's only a theory.
"Often you're immediately attacked by the "Pet agenda" bloggers..."
Well, I certainly didn't mean to step on any toes, especially not the quadrupedal apes, lol.
Nice opposable toes, there.
"To acknowledge a jammer or intruder confirms to them their effectiveness.
Ignoring them and continuing with normal traffic will often cause them to seek a softer target."
While what you say is, no doubt, true, I tend to follow my own drumbeat in these matters. It's one of the reasons I'm not on the ping list.
hahahaah!!! You know how those darn things always get in the way....
Recommend: Elaine Morgan's book "Scars of Evolution." Fascinating book.
Ever heard of the "Aquatic Ape Hypothesis"? It's a pretty darn compelling description of the development of aquatic adaptations in modern humans.
At the theory's root is the assumption that, rather than heading off into the savannah as the environment slowly cooled and dried, the tree-dwelling apes who eventually evolved into humans stayed in the trees as long as they possibly could. In a drying climate, the final place you'll find trees is near riverbeds and ocean shores, and the apes that were most successful in such an environment were the ones that were able to make the most out of the new aquatic resources in their environment.
"You know how those darn things always get in the way..."
Durned nuisance, that's what them opposable toes is.
You're on my ping list. Heck you're one of the original members.
That's the MI list, right? That one's fine. I try to stay off the CREVO lists, though. I seem to find the threads all on my own, anyhow.
Thanks for the MI list. I don't always get involved with the threads, but I appreciate the pings.
What do you suppose the distinction is, between big toe and thumb? Might it be that the former is attached to a foot, and the latter is not?
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