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The oldest hominin fossil ever found in the Levant

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Barash et al 2022

When the first members of our species ventured out of Africa, they walked into a world that earlier hominins, such as Homo erectus, had first explored a million years earlier. According to a recent study of a 1.5 million-year-old vertebra, those earlier hominins may have expanded beyond Africa in several waves—each following different environments and equipped for different ways of life.

Taking a second look

Anthropologists found a single vertebra from the lower back of a hominin child who died 1.5 million years ago. Mixed with the fossilized bones of hippos, mammoths, giraffes, saber-toothed tigers, and warthogs, the bone had sat among the remains of Pleistocene fauna since the 1966 excavation that unearthed it. But when University of Tulsa anthropologist Miriam Belmaker, a co-author on the recent study, looked through the animal fossils as part of another recent study (an effort to narrow down the age of the site), she recognized the vertebra as belonging to a member of our genus, Homo.

And the fact that the pieces of the vertebra hadn’t all fused together into a single hard, bony piece meant that it came from a child who hadn’t yet finished growing and maturing. They were probably somewhere between 6 and 11 years old when they died.

This child had lived during an important moment for human evolution. Between 1.9 and 1.1 million years ago, some of the earliest members of our genus began to expand into Europe and Asia for the first time. Our species repeated a similar journey out of Africa about a million years later, but much earlier hominins did it first.

The owner of the ‘Ubeidya vertebra almost certainly didn’t think of her life in those terms. The venture out of Africa wasn’t a deliberate march into the unknown, just a gradual expansion into a little bit of new territory each season. In what’s now the Jordan Valley, these early hominins lived in a warm, humid woodland. They shared the landscape with classic Pleistocene species like mammoths, saber-toothed tigers, and giant buffalo, along with animals like baboons, hippos, jaguars, and warthogs. To prepare their food, they used a style of stone tools that archaeologists call Acheulean.

Other styles

Farther north, at Dmanisi Cave in what’s now Georgia, other hominins lived in a drier, open grassland and used a type of stone tool technology now known as Olduwan. The fact that groups of hominins in different parts of Eurasia used different collections of tools, according to some paleoanthropologists, suggests that hominins left Africa in several separate waves. Each wave brought different cultural adaptations—including stone tools—with them.

However, Bar-Ilan University anthropologist Alon Barash and his colleagues say the vertebra suggests those waves of migrants may have been not just different cultural groups, but members of more than one hominin species, each even more different from the other than we were from the Neanderthals or Denisovans. That’s because, based on what the ‘Ubeidya vertebra suggests about the size and growth rate of its former owner, the child seems to have developed at a different pace than the hominins at Dmanisi.

If you want to draw conclusions about a long-dead person’s stature, a single vertebra isn’t much to go on. Most of the time, anthropologists use the long bones of the arm and leg for height estimates. But when the only bone you have is a lumbar vertebra, you consult the applicable set of tables and formulas, and you make do with an estimate.

Barash and his colleagues estimated that the child at ‘Ubeidya probably stood about 155 centimeters tall. That’s the average height for a 13-year-old boy or a 12.5-year-old girl in the modern US. If the child was between 6 and 11 years old when they died, as the unfused parts of the vertebra suggest, then they were pretty tall for their age. As an adult, this person probably would have stood somewhere around 198 centimeters tall—about 20 centimeters taller than the average American today.

That means that not only did the hominins living in the Jordan Valley 1.5 million years ago use different tools to survive in a different environment than those at Dmanisi, but the two groups were very different in size. It might be reasonable to call them different species.

At this height, the child at ‘Ubeidya must have been one of what Barash and his colleagues call the large-bodied hominins: something like Homo erectus, which had evolved modern human limb proportions and stature by around 2 million years ago. It’s hard to say exactly which species ‘Ubeidya belonged to, however.

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At least 2 hominin species lived at Laetoli site 3.6 million years ago

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Enlarge / A human relative left these five tracks in a 3.6 million-year-old layer of sediment at the Laetoli Fossil site in Tanzania.

McNutt et al. 2021

The first evidence of human relatives walking on two feet comes from about 70 footprints left by at least two Australopithecus afarensis walking across soft volcanic ash about 3.6 million years ago. A. afarensis was a short hominin with a jutting lower jaw, which walked upright but may also have spent some time in the trees; the most famous member of the species is a fossil woman now called Lucy.

Not far from that site, another set of footprints reveals that Lucy and her kin may have lived alongside another bipedal hominin species, one that moved very differently.

The forgotten footprints

When the footprints were first spotted in 1976, the paleoanthropologists who unearthed them from what’s called Site A weren’t sure what to make of them. Paleoanthropologist Mary Leakey suggested they could be hominin tracks, but others weren’t so sure. One anthropologist even suggested the tracks could have been left by a young bear walking on its hind legs for a few steps.

Two years later, Leakey and her colleagues discovered the two sets of A. afarensis tracks at Site G; the now-famous trackway was a sensational-enough find to completely overshadow Site A. Ohio University anthropologist Ellison McNutt and colleagues recently revisited Site A and its five footprints, using Leakey and her colleagues’ field notes to find the site (it’s not far from a trail of equally old elephant tracks). They re-excavated the footprints, carefully cleaned them, and recorded them with 3D photogrammetry, a technique that uses multiple two-dimensional photos of an object to map the object in three-dimensional space.

After measuring the prints and comparing them to the tracks of modern people, ancient hominins like A. afarensis, chimpanzees, and bears, McNutt and colleagues concluded that the footprints belonged to a hominin—but a member of a different species than Lucy and her kin.

Bipedalism wasn’t a one-off

McNutt and colleagues don’t know which hominin species might have left the five footprints at Site A, and they don’t offer any hypotheses in their recent paper about it. However, the footprints offer some clues about how the individual moved and what its feet looked like. Whoever left the footprints at Site A was noticeably shorter than an average A. afarensis, and the trackmaker’s feet were wider and differently shaped than those of Lucy and company.

Unlike our big toes, apes’ big toes stick out to the side and move more freely than the other four, almost like a thumb; A. afarensis‘ big toes still very noticeably stuck out to the side, although not as much as an ape’s. And the hominin who left the tracks at Site A had an even more thumb-like big toe than A. afarensis.

But while apes can bend and curl their feet at the middle, for more flexibility while climbing, A. afarensis seems to have had a stiffer foot, more like ours, which works better for walking. Based on the impressions left behind, the Site A hominin may have had a more flexible, ape-like midfoot than A. afarensis.

“A minimum of 2 hominin taxa with different feet and gaits co-existed at Laetoli,” wrote McNutt and colleagues. This species was adapting to the bipedal life at around the same time as Lucy and her A. afarensis relatives, but its footprints suggest that it was taking a different evolutionary route.

(A 2018 study went into more detail on the mechanics of our early relatives’ strides.)

  • This is the best-preserved footprint from Site A, showing the left foot of an unknown hominin. In the right image, the blue areas show the toe impressions, and the red area shows what McNutt and colleagues say might be evidence of a more flexible, apelike midfoot.


    McNutt at al. 2021

  • On the left is the best-preserved footprint from Site A, and on the right is one of the best-preserved A. afarensis footprints from Site G. Both impressions are from left feet.


    McNutt et al. 2021

Walk this way?

Overall, the prints look more like they were made by a chimpanzee foot than a modern human foot, except that the heels are too wide for a chimpanzee. And, despite its chimp-like feet, this hominin didn’t actually walk like a modern ape.

When a chimpanzee walks on two legs, the wide set of its hips keeps its legs held apart. As a result, chimpanzee steps are wider and shorter than a human’s would be. But the hominin at Site A moved differently, crossing one foot in front of the other, as if it were trying to pass a Pliocene field sobriety test.

“The gait seems somewhat shambling, with one foot crossing in front of the other,” wrote Mary Leakey in 1976. A chimpanzee—or a bear, for that matter—would have found the cross-stepping feat nearly impossible, even for just a few steps. Modern humans don’t walk this way very often; usually it’s a way of regaining balance after a stumble (your faithful correspondent sustained only minor injuries in the attempt to replicate it).

If the hominin at Site A was able to walk this way, say McNutt and colleagues, it must have had one or both of two key features that help modern humans walk upright. Compared to a chimpanzee, our hips are adducted, or turned inward, so that we move with our legs closer together. And our knees are set at an angle that puts our feet just below our body’s center of mass. So these traits had appeared in more than one species by 3.6 million years ago, although their feet still looked quite different.

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Archaic Hominin Made Elephant Bone Tools 400,000 Years Ago, Study Finds

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Archaeologists examining artifacts collected from a site in Italy found that an archaic hominin species had made elephant bone tools, including pointed tools for carving meat and wedge-shaped tools for cracking open large femurs and other long bones, 400,000 years ago. This is hundreds of thousands of years before such a thing had been considered possible. These innovative toolmakers lived in the Middle Pleistocene epoch, at least 100,000 years before modern man first appeared in far-off Africa.

Fig 12 from the study showing unifaces and pointed tools made with elephant bones found at the  Castel di Guido site, Rome, Italy.  A-C: unifaces with a side scraper edge;  D: pointed wedge (base is battered).  E-F: pointed tools on bovid diaphysis fragments, catalogue numbers 326, 2807.  G-H: pointed tools. ( Plos One )

A Total of 98 Flaked Elephant Bone Tools Were Found

This astonishing discovery was made by a team of researchers from Italy, France, South Africa, and the United States, headed by University of Colorado-Boulder archaeology professor Paola Villa. They studied elephant bone tools excavated between 1979 to 1991 from the Castel di Guido site near Rome, and in the process revealed fascinating details about the craftsmanship involved in making these  bone tools .

Writing about their findings in the  Plos One journal study  the archaeologists note that the 98 verified  elephant bone  tools found at Castel di Guido represent “the highest number of flaked bone tools made by pre-modern hominids published so far.” Acknowledging the advanced techniques used to make these rare tools, the archaeologists credit the ancient toolmakers with completing “the first step in the process of increasing complexity of bone technology.”

In the Middle Pleistocene, there was a stream running through Castel di Guido. An extinct Eurasian straight-tusked elephant species used the stream as a source of fresh water, and  archaic humans  were drawn to the area as well and likely settled very nearby. Occasionally one of these 13-foot (four-meter) tall elephants would die of natural causes, and the local hominins would then scavenge the massive remains for hides, meat, and bones.

These elephant bones were strong and sturdy, which made them suitable for use as tools. They were often broken randomly into pieces and used as they were. But sometimes toolmakers would customize the bones by using rocks or other pieces of bone to break off flakes or chunks, carefully working the bone’s shape until it was just as they wanted.

Not all the bone tools found at the Castel de Guido site were made from elephant bones. Fig 14 from the study shows the polished tip of an aurochs (a species wild cattle) bone, compared with an ancient horse bone tool from Germany (bottom right). These tools are known as  lissoirs, which ancient humans used to treat leather with. ( Plos One )

In this case, the tools were modified in ways that were unusual 400,000 years ago.

“We see other sites with bone tools at this time,” Professor Paola Villa, who is also the adjoint curator at the CU Boulder Museum of Natural History, explained in  a University of Colorado-Boulder press release . “But there isn’t this variety of well-defined shapes.”

“At Castel di Guido, humans were breaking the long bones of the elephants in a standardized manner and producing standardized blanks to make bone tools,” Villa continued. “This kind of aptitude didn’t become common until much later.”

“Much later” in this instance means up to 100,000 years later!

“Until recently the generally accepted idea was that early bone technology was essentially immediate and expedient, based on single-stage operations, using available bone fragments of large to medium size animals,” Villa and her colleagues wrote in their Plos One article. “Only  Upper Paleolithic  bone tools would involve several stages of manufacture with clear evidence of primary flaking or breaking of bone to produce the kind of fragments required for different kinds of tools.”

The discovery of the work of the Castel di Guido toolmakers has shattered the previous timeline. It’s left archaeologists questioning everything they thought they new about the development of  human toolmaking practices  on the Eurasian continent. It seems that the process was not linear and that it progressed much faster in at least one small part of the world.

Did the Neanderthals Live at Castel di Guido?  The lead author of the study, archaeology professor  Paola Villa ( Colorado University Boulder) , believes the Neanderthals as the likely makers of these extremely old elephant bone tools. ( Gorodenkoff / Adobe Stock)

Did Neanderthals or Homo Erectus Live at Castel di Guido?

So far, archaeologists working at Castel di Guido have failed to find the fossilized remains of ancient humans. Such a discovery could have helped them to pin down the true identity of the ancient toolmakers.

Nevertheless, Paola Villa  has a theory about who they might have been. She believes they were Neanderthals, the long-extinct cousin of modern humans who  were in Eurasia  during the Middle Pleistocene.

“About 400,000 years ago, you start to see the habitual use of fire, and it’s the beginning of the Neanderthal lineage,” Villa explained. “This is a very important period for Castel di Guido.”

It is hardly surprising that Villa would identify the Neanderthals as  the likely toolmakers . She is considered one of the world’s top experts on the Neanderthals, and her contributions have helped reverse previous negative judgments about their intellectual capacities and their level of cultural and social development.

Another possible candidate for who made these bone tools would be  Homo erectus . ( York / Adobe Stock)

Another possible toolmaking candidate would be  Homo erectus . This ancient ancestor of  Homo sapiens  (modern man) first emerged more than two million years ago, and by 400,000 years ago they were living throughout Europe and Asia. They were the first hominin species to demonstrate impressive toolmaking skills, although they would have had to have been more advanced than believed to have produced the elephant bone tools found in Italy.

Whoever the manufacturers were, the tools they created were impressively diverse. The crafted objects found at Castel di Guido included tools with sharp points, which could have been used to cut meat. There were also bone wedges that could have been used to splinter large, long, and heavy elephant bones into smaller pieces.

One tool was especially sophisticated. Long and smooth at one end, this object was identified as a lissoir, which ancient humans used to treat leather. All previously discovered lissoirs have been dated to 300,000 ago or later, and of all the tools discovered at Castel di Guido this is the one that pushes the archaeological record back the furthest.

Interestingly, this particular tool was not made from an elephant bone. It was shaped from a wild cattle bone instead. The ancient toolmakers at Castel di Guido were obviously happy to use elephant bones whenever possible, but they didn’t rely on them exclusively as a source of raw material.

Professor Paola Villa lead author of the study  doesn’t think the Castel di Guido hominins who made the elephant bone tools were unusually smart, compared to Neanderthals living in other areas . ( Leakey Foundation )

Innovation Determined by Circumstance

Paola Villa doesn’t think the Castel di Guido hominins were unusually smart, compared to Neanderthals living in other areas. She believes they used the resources that were available to them as best they could, and because they didn’t have access to large pieces of flint at their location they turned to elephant bones as an alternative. Elephant bones weren’t so easy to find elsewhere, so other hominin groups wouldn’t have had the opportunity to explore the tool manufacturing possibilities so thoroughly.

“At other sites 400,000 years ago, people were just using whatever bone fragments they had available,” Villa noted. “The Castel di Guido people had cognitive intellects that allowed them to produce complex bone technology. At other assemblages, there were enough bones for people to make a few pieces, but not enough to begin a standardized and systematic production of bone tools.”

The Castel di Guido hominins were pioneers. But they remained relatively isolated, with limited chances to pass on what they’d learned to others. Consequently, the techniques they perfected would need to be rediscovered independently by others, at various times in the future.

Top image: A closeup of a few of the 98 verified elephant bone tools found in Rome, Italy, which have been attributed to an archaic hominin species based on a recent study published in the Plos One journal. Source:  Plos One

By Nathan Falde

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