Word: leakey
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Dates: during 1990-1999
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Several of the bones underscore that A. anamensis did indeed walk upright, some 500,000 years before the next oldest two-legged hominid known. But these creatures didn't walk in the modern sense. As Leakey explains, "They weren't nearly as efficiently upright as we are, and they had relatively short legs. They had a form of locomotion that we don't know today because there isn't anything equivalent...
Precisely where do A. ramidus and A. anamensis fit into the scheme of human evolution? Leakey believes the latter is a direct ancestor of A. afarensis and thus a direct ancestor of modern humans. White and his colleagues have tentatively labeled the older ramidus a "sister species" of all later hominids; it's either our direct ancestor or a close relative of that ancestor. Whichever ramidus turns out to be, it's clear that paleontologists are closing in on the split between apes and humans. "We're in the ballpark. Five or 10 years ago, we couldn't even have...
...ancestor, White hints that his team has already discovered hominid fossils that are more than 5 million years old, though he refuses to elaborate before detailed studies are completed. But Leakey and Walker readily acknowledge that they are studying two 5.5 million-year-old hominid teeth and a similarly ancient jaw fragment with an embedded tooth from a site in northern Kenya. "They look like australopithecines with lots of primitive features," Walker says, but there isn't enough evidence from these fossils alone to claim a new species...
...these, White suggests, was the ability to exploit a broader range of habitats, eventually enabling our ancestors to leave Africa and colonize most of the globe. But even more important was the expansion of our brain, with all the potential that went with it. Explains Meave Leakey: "The brain is a very expensive organ in terms of metabolism." It can grow larger only in a species that's routinely consuming high-energy food. One impetus for such growth--and in particular, the growth of the cognitive areas that distinguish ours from other large brains--could have come from our increasingly...
...COMMENT] May be an ancestor of A. boisei and A. robustus. The fossil above, found by Richard Leakey's team, is called the Black Skull...