We’ve only just confirmed that Homo habilis really existed

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Homo habilis is a paradoxical species. On the one hand, they have a famous name and hold the status of the first members of our genus. Homo: the first humans, if you will. On the other hand, we never know much about them, and what we do know is rather strange. How can a species be both known and little known?

We have to start with the name, if only because it’s one of the few things we can be sure of. The species was given its nickname in 1964 by a trio of paleoanthropologists: Louis Leakey, Phillip Tobias and John Napier. But, as they admitted, it wasn’t their idea – their colleague Raymond Dart had suggested “habilis» from Latin meaning “capable, handy, mentally skillful, vigorous”.

They applied the name to a collection of bones and teeth they had found in the Olduvai/Oldupai Gorge in Tanzania, East Africa. The remains were rather diverse: a lower jaw with teeth, an upper molar, skull bones called parietals and some hand bones. The trio interpreted them as belonging to a single minor individual.

Above all, the researchers claimed that Homo habilis were the makers of Oldowan stone tools, which had been found in the locality. In saying this, they were asserting more broadly that toolmaking was a defining characteristic of the genre. Homo. Fewer “human-like” hominins like Australopithecus I probably didn’t make any tools, but Homo habilis and their ever-smarter descendants did, and that’s what made them special.

That’s a lot of interpretation for a handful of fossils, but let’s be lenient. Very few hominid fossils were known at the time, and Leakey and his colleagues did the best they could with what they had.

Over the next 62 years, researchers found more fossils that they attributed to H. habilis. However, the additional remains have not clarified our understanding of the species. On the contrary, H. habilis languished.

“It’s what we call a trash taxon,” says Ian Tattersall of the American Museum of Natural History in New York. “Every time [researchers] they found something they weren’t sure what it was, they just threw it in Homo habilis. And so very soon, Homo habilis has become a rather heavy collection of things that would be very difficult to define.

So, can we make sense of this crucial species and its place in our origins?

A new find

All this has become relevant again because a new H. habilis a specimen was brought to light. It was excavated in 2012 and 2014 in the Koobi Fora Formation in Ileret, Kenya. Researchers led by Frederick Grine of Stony Brook University in New York and Ashley Hammond of the Catalan Institute of Paleontology Miquel Crusafont in Barcelona described the remains in The anatomical file on January 13. Grine and Hammond were unable to speak to me, but Tattersall posted a comment about the discovery on January 24 and we spoke on the phone (we were both dealing with the worst connection ever).

The new specimen is the most complete H. habilis never found. It includes a clavicle (clavicle), fragments of the shoulder blade (scapula), the two bones of the upper arm (humerus), each of the two bones of the forearm (ulna and radius), and fragments of the base of the spine (sacrum) and the hip bone (os coxae).

There is still a lot missing: the head, the ribcage, the spine, the hands, the legs and the feet. But it’s enough to know a lot about H. habilis.

The most obvious thing is that H. habilis had relatively long arms. One of the major trends in human evolution is the shortening of arms: our ape cousins ​​have long arms relative to their legs, while our arms are significantly shorter. Compared to others Homo species like Homo erectus, H. habilis had long arms.

For Tattersall, this is proof that H. habilis I still spent a lot of time in the trees, where long arms are an advantage. Before Homoearlier hominids like Australopithecus appear to have lived hybrid lifestyles where they spent time in trees and time walking on two legs on the ground. “It’s a way of life that has no equivalent in the contemporary world, but which has obviously been very successful for a long time,” he says. While later Homo species like H. erectus were rather attached to bipedal walking on the ground, H. habilis still had one foot in the trees.

The skeleton also suggests that H. habilis was quite light. Researchers estimated that the individual was around 160 centimeters tall and weighed only 30 to 33 kilograms. It’s smaller than most H. erectus specimens, marking again H. habilis as distinct.

There is still a lot we don’t know. We have very little information on the diet of H. habilis or their social dynamics and group size. It is also unclear how long the species has existed or how widespread it was.

However, it seems that H. habilisThe days when we were a trash taxon may be over.

An identity

In his commentary, Tattersall lists the fossils that have been attributed to H. habilis over the past six decades. They include a fragmentary skeleton and skull from East Turkana in Kenya, a fragmentary skeleton and palace from Olduvai, another palace from Hadar in Ethiopia, a partial lower jaw from Ledi-Geraru in Ethiopia, and a single skull from Sterkfontein in South Africa.

Tattersall calls these fossils a “motley assortment,” and he’s not wrong. There are few H. habilis bones of which we have more than one copy, so we cannot be sure that the ones we have are representative.

This led to decades of uncertainty. Some of the alleged H. habilis the fossils might not belong to the species, or even to the species. Homo gender. In particular, the South African system is widely considered to be a Australopithecussuggesting H. habilis only lived in East Africa.

Some researchers have even argued that the entire species is just a kind of mirage: a pile of pieces Australopithecus and early Homogrouped together without good reason.

The new specimen suggests that we can rule out this most extreme possibility and accept most of the so-called specimens. However incomplete it may be, “it appears to have the basic characteristics of most other skeletons called Homo habilis“, says Tattersall. These isolated pieces correspond, on the whole, to the more complete skeleton.

That doesn’t mean it clears everything up. Tattersall says everything above the neck is still a bit of a mystery: “The skulls and teeth make a rather strange assemblage when you put them all together. » Since the new skeleton doesn’t include anything about the head, it doesn’t help us figure out which ones belong together.

The timing and scope of H. habilis it also needs to be clarified. “Homo habilis “This is something that we now know, thanks to the new specimen, existed, at least in Tanzania and Kenya, between 1.8 and 2 million years ago,” says Tattersall.

It is possible that the species is present earlier or later, but it is less clear. The oldest claimed specimen is a partial lower jaw from Ledi-Geraru in Ethiopia, dated to 2.8 million years ago. “In my opinion, it is not Homo habilis“, says Tattersall. Although it seems to be more closely related to Homo than AustralopithecusThat doesn’t mean it’s necessarily H. habilishe said. Tattersall suggests that the group that gave rise to Homo emerged at that time.

This means that the question remains open as to whether H. habilis was really the first member of the Homo gender. Before it looked like Homo erectus (African specimens of which are sometimes called Homo ergaster) only appeared later. However, recent fossil discoveries have pushed the species back in time: we now have specimens of H. erectus dating back to at least 1.85 million years ago and even 2 million years ago. Combine this with the uncertainties around H. habilis fossils and it is not clear which species is the oldest.

Ultimately, all this means that the origin of our genre still remains a mystery. We have fossils that tell us something about this, but we can’t be sure what they say. The “simple” story is that a group of Australopithecus evolved towards H. habilis and some of them later evolved into H. erectus (alias H. ergaster). But maybe there were a lot Homo species living in parallel, from the start. Or maybe something else happened.

If this seems a little unsatisfactory, remember: we now know that Homo habilis was probably real. Last year, it wasn’t easy.

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