We have just confirmed that Homo habilis really existed

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Homo habilis is a paradoxical species. On the one hand, they have a familiar name and have the status of the first members of our lineage Gay: the first people, if you will. On the other hand, we’ve never known that much about them, and what we do know is a bit strange. How can a species be well known and little known at the same time?

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 named in 1964 by a trio of paleoanthropologists: Louis Leakey, Phillip Tobias and John Napier. Although, as they acknowledged, it was not their idea – their colleague Raymond Dart had suggested “habilis” from Latin for “skilled, handy, mentally capable, 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 quite 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 young individual.

Crucially, the researchers claimed Homo habilis were the makers of Oldowan stone tools, which had been found in the site. In saying this, they made the broader claim that tool making was a defining feature of the genus Gay. Smaller “human-like” hominins such as Australopithecus probably didn’t make tools, but Homo habilis and their increasingly smarter descendants did, and that’s what marked them as special.

It’s a lot of interpretation to put on a handful of fossils, but let’s be forgiving. Very few hominin fossils were known at the time, and Leakey and his colleagues did the best they could with what they had.

Over the following 62 years, researchers found more fossils that they assigned H. habilis. However, the additional remains have not clarified our understanding of the species. on the contrary, H. habilis has disappeared.

“It’s what they call a wastebasket taxon,” says Ian Tattersall of the American Museum of Natural History in New York. “Every time (scientists) found something that they weren’t quite sure what it was, they just threw it in Homo habilis. And then pretty soon, Homo habilis became quite an unwieldy collection of things that you would find very difficult to define.”

So, can we understand this defining species and its place in our origins?

A new discovery

All this has become relevant again because a new H. habilis the test has arrived today. It was excavated in 2012 and 2014 from the Koobi Fora Formation at Ileret, Kenya. Researchers led by Frederick Grine at Stony Brook University in New York and Ashley Hammond at the Catalan Institute of Palaeontology Miquel Crusafont in Barcelona described the remains in The anatomical record on 13 January. Grine and Hammond were unable to speak to me, but Tattersall published a comment about the find on January 24th and we spoke on the phone (both struggling with the worst connection ever).

The new copy is the most complete H. habilis ever found. It includes a collarbone (clavicle), fragments of the shoulder blade (scapula), both upper arm bones (humerus), both of each of the two forearm bones (ulna and radius) and fragments of the base of the spine (sacrum) and hip bone (os coxae).

There is still much missing: the head, chest, spine, hands, legs and feet. But there is still a lot to find out about H. habilis.

The most obvious 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 decidedly shorter. Compared to others Gay species which Homo erectus, H. habilis had long arms.

For Tattersall, this is proof of that H. habilis still spent a fair amount of time in trees, where long arms are an advantage. Before Gayearlier hominins like Australopithecus appear to have lived hybrid lifestyles where they spent some time in trees and some time walking on two legs on the ground. “It’s a lifestyle that has no equivalent in the modern world, but it was obviously a very successful one for a long time,” he says. While later Gay species which H. erectus was quite obliged to walk bipedally on the ground, H. habilis still had one foot in the trees.

The skeleton also suggests that H. habilis was quite small. The researchers estimated that the person was about 160 centimeters tall, but weighed only 30 to 33 kilograms. That’s less than most H. erectus samples, again labeling H. habilis as distinct.

There are still many things we do not know. We have very little information about its diet H. habilis or their social dynamics and group size. It is also unclear how long the species was around or how widespread they were.

Still, it seems like H. habilisits days of being a wastebasket taxon may be over.

An identity

In his commentary, Tattersall lists the fossils that have been assigned H. habilis over the past six decades. They include a fragmentary skeleton and cranium from East Turkana in Kenya, a fragmentary skeleton and palate from Olduvai, another palate from Hadar in Ethiopia, a partial mandible from Ledi-Geraru in Ethiopia and a single cranium 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 has led to decades of uncertainty. Some of the alleged H. habilis fossils may not belong to the species, or even Gay kindred. In particular, the South African one is believed to be one Australopithecussuggests H. habilis lived only in East Africa.

Some scientists have even argued that the entire species is a kind of mirage: a pile of bits in the past Australopithecus and early Gaylumped together for no good reason.

The new specimen suggests that we can rule out this most extreme possibility and accept most of the alleged samples. Incomplete as it is, it “appears to have the basic characteristics of most of the other skeletons that have been called Homo habilis“, says Tattersall. These isolated pieces do indeed correspond to the more complete skeleton.

That is not to say that this clears it all up. Tattersall says everything above the neck is still a bit of a mystery: “The skulls and teeth make quite a strange collection when you put them all together.” Since the new skeleton doesn’t contain anything from the head, it doesn’t help us figure out which ones belong together.

The timeline and range of H. habilis also needs cleaning. “Homo habilis is something we now know, thanks to the new specimen, was around, at least in Tanzania and Kenya, between 1.8 and 2 million years ago, says Tattersall.

It is possible that the species existed earlier or later, but it is less clear. The oldest claimed specimen is a partial mandible from Ledi-Geraru in Ethiopia, dated to 2.8 million years ago. “In my view it is not Homo habilissays Tattersall. Although it seems to be more closely related to Gay than to Australopithecusthat doesn’t mean it necessarily is H. habilishe says. Tattersall suggests that the group that gave rise to Gay appeared around that time.

This means that it is an open question whether H. habilis was actually the first member of Gay kindred. It used to look like Homo erectus (African specimens as 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 from at least 1.85 million years ago and even 2 million years ago. Combine that with the surrounding uncertainty H. habilis fossil record and it is not obvious which species is older.

Ultimately, what all this means is that the origins of our lineage remain something of a mystery. We have fossils that tell us something about it, but we can’t be absolutely sure what they say. The “simple” narrative is that a group of Australopithecus developed into H. habilis and some of them later developed into H. erectus (aka H. ergaster). But perhaps there were many Gay species that live in parallel, right from the off. Or maybe something else happened.

If that seems a little unsatisfying, just remember: we know now Homo habilis was probably real. Last year it was not obvious.

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