Humans Emerged Much Earlier Than Thought

A digital makeover of the supposedly earliest known human, Homo habilis aka "Handy Man," finds that this species could not have been at the base of the human family tree, which moves the origins of our entire genus back tens of thousands of years.

When the 1.8-million-year-old remains of Handy Man were announced in 1964, it was thought that they belonged to the first ever human, but the new study, published in Nature, shows that cannot be true. A jaw for yet another early human dating to 2.3 million years ago turns out to be too modern to be ancestral to Handy Man.

"Our evidence suggests that earliest Homo must be well older than 2.3 million years old, because the Homo upper jaw of that age is already too evolved to fit with the primitive Homo habilis jaw," lead author Fred Spoor from the Max Planck Institute for Evolutionary Anthropology explained to Discovery News.

Using state-of the-art computer reconstruction techniques, Spoor and his team created a digital model of Handy Man's remains. Found in Olduvai Gorge, Tanzania, by famed anthropologist Louis Leakey and his colleagues, the fossils consist of a lower jaw, parts of a braincase and the hand bones of a single individual.

The new digital "makeover" reveals that Handy Man had a large brain, similar to that of the other early human species Homo erectus (Upright Man), but a lower jaw that was more like a much older species, Australopithecus afarensis, which is well represented by the "Lucy" set of fossils. Handy Man also had longer arms than today's humans, which was probably a trait passed down from our tree-swinging ancestors.

As for the 2.3-million-year-old upper jawbone, it was found in Ethiopia. Spoor and his team now think that Handy Man from Tanzania and this early Ethiopian individual represent separate evolutionary lineages that likely split well before 2.3 million years ago.

Now the question is, who was the ancestor of these two, and how long ago did this individual live? It could be that the very first human dates closer to 3 million years ago, the researchers suspect.

Yet another extraordinary possibility to consider is that Handy Man, Upright Man and another early human Homo rudolfensis might have overlapped in time and geographic location.

"Given that the three species differed in how their jaws and face were built, it seems reasonable to speculate that they occupied different ecological niches characterized by different diets," Spoor said.

Even so, they had one important feature in common that suggests how our genus evolved in the first place.

"As all three recognized species of early Homo share an equally enlarged brain compared with Australopithecus species, it can be inferred that their common ancestor at the beginning of the Homo lineage had an enlarged brain," Spoor said.

Bernard Wood, who has also studied early humans, is a professor at George Washington University and an honorary professor at the University of Kent. Wood told Discovery News that the new study is "one of the coolest papers (I've read) in a long time."

Read more at Discovery News