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A new study, based on a famous set of fossilized footprints in Africa (pictured), shows that Australopithecus likely walked upright, like modern man.  (Source: John Reader/Photo Researchers)

However, Australopithecus's long body and stubby legs would make it ill-suited for a footrace with a human.  (Source: BBC)
Man's ancestors were standing and walking tall -- more so than previously realized

Evolutionary biologists and paleontologists admit there's a lot they don't know, but they've also made remarkable progress [1][2][3][4][5][6] in recent years.  From multiple hominid fossil discoveries [1][2][3] filling in mankind's "family tree", to direct observations of evolution, the field is seeing a veritable renaissance.

The fascinating discoveries continue with a study [abstract] published this month in the peer-reviewed journal Interface.  The work examines the footprints of Australopithecus afarensis, an early hominid and presumed ancestor of Homo sapiens.

It comes to the surprising conclusion that previous work -- which asserted that up to around 1.9 million years ago hominids likely walked in a crouched position, before undergoing a transition to upright posture -- was likely flawed.  

The new study found that the Laetoli footprints, found in the volcanic ash of the nearby Sadiman Volcano in Tanzania (east Africa) show arguably that hominids walked upright far longer ago than previously thought.

The study comments:
It was previously thought that Australopithecus afarensis walked in a crouched posture, and on the side of the foot, pushing off the ground with the middle part of the foot, as today's great apes do. We found, however, that the Laetoli prints represented a type of bipedal walking that was fully upright and driven by the front of the foot, particularly the big toe, much like humans today, and quite different to bipedal walking of chimpanzees and other apes.

Quite remarkably, we found that some healthy humans produce footprints that are more like those of other apes than the Laetoli prints. The foot function represented by the prints is therefore most likely to be similar to patterns seen in modern-humans. This is important because the development of the features of human foot function helped our ancestors to expand further out of Africa.
The new work was thoroughly vetted by a team of renowned Ph.D researchers from the University of Liverpool, University of Manchester, and University of Bournemouth.

The footprints were first discovered in 1976 by distinguished paleoanthropologist Mary Leakey.  They were dated to be 3.7 million years old, using the potassium-argon method (K/Ar), which allows the age of volcanic sediments to be estimated accurately to within a statistical window of a couple thousand years.

The remarkable discovery was made possible by the fortunate tendency of rain to turn loose volcanic ash to tuff, a rocky deposit.

The footprints were significant in that they showed no signs of handprints, which would indicate that Australopithecus walked with the assistance of its arms, like an ape.  Upright posture is seen as a distinguishing factor between hominids -- like humans, neanderthals, and Australopithecus -- versus apes and monkeys.

The new study suggests upright bipedalism could have evolved around the time that the earliest hominids descended from trees to roam the ground on two feet.  It comments:
Our work demonstrates that many of these features evolved nearly four million years ago in a species that most consider to be partially tree-dwelling. These findings show support for a previous study at Liverpool that showed upright bipedal walking originally evolved in a tree-living ancestor of living great apes and humans.
The study goes on to say that while bipedal, Australopithecus wouldn't be on a level playing field in a race with a modern human.  The team writes:
Australopithecus afarensis, however, was not modern in body proportions of the limbs and torso.

The characteristic long-legged, short body form of the modern human allows us to walk and run great distances, even when carrying heavy loads. Australopithecus afarensis had the reverse physical build, short legs and a long body, which makes it probable that it could only walk or run effectively over short distances.
While the location of the first primates (circa 35-40 million years ago) and the first humans (circa 500,000 years ago) are still the topic of active debate, most evidence points to the first hominids as having evolved in Africa, around 4-5 million years ago.

Now yet another piece of the puzzle has fallen into place.


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RE: Something's going backwards
By Maradon on 7/21/2011 11:56:49 PM , Rating: 3
You seem to believe that things "scientific" are held up as eternal, absolute truth, and that any adjustment to a theory must therefore be embarrassing in some way.

This could not possibly be farther from the truth. Science offers up the most probable, falsifiable explanation for all the available evidence and presents it as the most likely truth. New findings (or meta-findings as the case seems to be here; discovering that old methods may have produced an inaccurate result) only change the odds that a given theory is correct.

It does not mean that people were "wrong" to believe the old theory. The old theory was the most likely one, given the evidence presented and you would be right to believe such things. The new theory is as well.


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