A cranium found in 1972 and the lower jaw of a newly discovered fossil,
shown reconstructed and combined above, are believed to be from
the same ancient hominid species.
The big-brained, upright primates of the genus Homo—the group to which we modern-day humans belong—evolved in East Africa around 2.4 million years ago. By half a million years later, Homo erectus, from whom we’re directly descended, was walking the plains near Lake Turkana in what is now Kenya. But anthropologists have increasingly come to believe that Homo erectus wasn’t the only hominid around. Three newly discovered fossils, detailed online this week in Nature, confirm that at least two other Homo species lived nearby—providing the strongest evidence yet that several evolutionary lineages split off in the genus’s early days.
According to one group of scientists, figuring out the answer required only a pair of high-tech gloves and a trained craftsman who could make both simple stone knives and more complicated hand axes. The craftsman wore gloves studded with electronic sensors that tracked his his hand movements. Lead researcher Aldo Faisal of Imperial College London found that simple and complex tools required the same amount of dexterity to produce.
“From these results, dexterity can be ruled out, and we can infer it has something to do with the complexity of the task,” says Faisal. Axes are made in several stages, which requires switching between tasks, suggesting that a higher level of complexity is required in the brain. [New Scientist]