The gracile australopithecines (members of the genus Australopithecus) are a group of extinct hominids that are closely related to humans.

Evolution

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Gracile australopithecines shared several traits with modern apes and humans and were widespread throughout Eastern and Southern Africa as early as 4.4 to as late as 1.7 million years ago. The earliest evidence of fundamentally bipedal hominids can be observed at the site of Laetoli in Tanzania. These hominid footprints are remarkably similar to modern humans and have been positively dated as 3.7 million years old. They have generally been classified as Australopithicine until recently, because that had been the only form of pre-human known to have existed in that region at that time. Australopithecus afarensis. A. afarensis and A. africanus are among the most famous of the extinct hominids. A. africanus used to be regarded as ancestral to the genus Homo (in particular Homo erectus). However, fossils assigned to the genus Homo have been found that are older than A. africanus. Thus, the genus Homo either split off from the genus Australopithecus at an earlier date (the latest common ancestor being A. afarensis or an even earlier form, possibly Kenyanthropus platyops), or both developed from an as yet possibly unknown common ancestor independently.

According to the Chimpanzee Genome Project, both human (Ardipithecus, Australopithecus and Homo) and chimpanzee (Pan troglodytes and Pan paniscus) lineages diverged from a common ancestor about 6 million years ago, if we assume a constant rate of evolution. However, more recently discovered hominids are somewhat older than the molecular clock would theorize. Sahelanthropus tchadensis, commonly called "Toumai" is about 7 million years old and Orrorin tugenensis lived at least 6 million years ago; the location of the mastoid of both indicate that they were bipedal and had therefore diverged from the common ancestor much further back along the evolutionary trail. Since little is known of them, they remain controversial among scientists since the molecular clock in humans has determined that humans and chimpanzees had an evolutionary split at least a million years later. One theory suggests that humans and chimpanzees diverged once, then interbred around one million years after diverging.

As molecular evidence has accumulated, the constant-rate assumption has proven false—or at least overly general. However, while the molecular clock cannot be blindly assumed to be true, it does hold in many cases, and these can be tested for. For example, molecular clock users are developing workaround solutions using a number of statistical approaches including maximum likelihood techniques and later Bayesian modeling.

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http://nds.wikipedia.org/wiki/Australopithecus
Thad59 (Thad Gunter) Thu, 10 Dec 2009 10:02:52 -0000
http://nds.wikipedia.org/wiki/Australopithecus
Australopithecus would really have been sick of us ...
SquishySquishie (Samantha Allison) Thu, 10 Dec 2009 04:15:43 -0000
Australopithecus would really have been sick of us ...
Husband is looking a little less like Australopithecus after taking kid to school and having a shower. Has evolved a little...
pittkethley (fiona pitt-kethley) Wed, 09 Dec 2009 07:51:42 -0000
Husband is looking a little less like Australopithecus after taking kid to school and having a shower. Has evolved a little...
Husband looks like australopithecus this morning, a very cross one....
pittkethley (fiona pitt-kethley) Wed, 09 Dec 2009 07:08:15 -0000
Husband looks like australopithecus this morning, a very cross one....
HEY. Australopithecus garhi. I don't care about you.
nicolysis (Nicole M) Wed, 09 Dec 2009 02:13:10 -0000
HEY. Australopithecus garhi. I don't care about you.
australopithecus would really have been sick of us, we're debating if we're here, they're catching deer...
IN_N_OUT_Burger (IN-N-OUT BURGER) Tue, 08 Dec 2009 23:17:05 -0000
australopithecus would really have been sick of us, we're debating if we're here, they're catching deer...

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