How hominins were bumping into each other: An X-ray study of the skeleton and toe motion of Lucy

Even the term “human” is arguable. Many scholars reserve it for modern humans like us, even though we have Neanderthal genes, and they shared at least 90 percent of our hominin history from its beginnings around 8 million years ago. The essence of hominin evolution ever since has been gradual change, with occasional rapid phases. The record of evolution in our own genus, Homo, is already full enough to show we cannot separate ourselves with hard lines.

The evolution of humankind is tied with the beginning of the universe in pursuit of knowledge. Even when an exciting find hits the headlines, the field of paleoanthropology has not gained as much scientific support and funding as it should have.

Since then, the picture has changed repeatedly and dramatically, shaped by waves of new fossil discovery, technology, and scientific techniques—often accompanied by arguments about the veracity of claims made for each new piece of the puzzle.

The partial skeleton of a small-brained female caught the attention of the public. Lucy was a paleo-rock star who took the major fossil evidence for hominins beyond 3 million years. The race was on to explain how humans became what they are now.

Bernard Wood says that there are as much as 1.5 million years’ worth of fossil footprints left in the eastern African lakeshore.

Previous studies, based mostly on the fossil record, have suggested that different hominin species lived alongside each other. fossils are scattered over large areas with estimated dates that go on for thousands of years. Kivell says you don’t know if they’re bumping into each other.

“This is the first snapshot we have of those two species living on the same immediate landscape, potentially interacting with one another,” says study co-author Kevin Hatala, a palaeoanthropologist at Chatham University in Pittsburgh, Pennsylvania. There was a study in Science.

The footprints of H. erectus are very close to P. boisei. We can only assume that they were aware of each other. Exactly how they interacted, or whether they learned from each other or what, that’s still a mystery,” says Wood.

The motion of a foot is studied using 3D X-ray-based technologies. They compared arch depth and toe angles in the hominin footprints with those of humans. The analysis suggests that the isolated footprints belong to individuals of H. erectus, thought to be the first human species to walk and run upright like modern humans.

Alongside the hominin footprints, the site contained preserved tracks from 30 relatives of cattle, three horse-like animals and 61 birds, including a giant extinct stork, Leptoptilos falconeri.

Hatala hopes to combine data from fossil footprints and bone fossils to “give a really high-resolution picture of what’s happening in this area during this phase of human evolution”.

Wood says that future studies could focus on the animals and birds. It is difficult to do with regular fossil evidence, and that brings the whole thing alive.