Footprints in Kenya reveal the cohabitation of two species of hominins

In 1976, at the site of Laetoli, Tanzania, paleontologist Andrew Hill discovered 3.7 million year old footprints by literally falling on them. He tripped to avoid an elephant dung thrown by a facetious colleague. Such a scent of legend is missing from the story of the latest discovery, at the Koobi Fora site in Kenya.

But these tracks, dated 1.5 million years ago, are just as captivating: they interweave the footsteps of two species of hominins – a term which designates the representatives of the human lineage since its separation from that of chimpanzees.

“These traces were discovered in 2021 by one of my colleagues, Richard Loki [université Stony Brook, New York]while working with a team excavating fossilized skeletons from sediments just above”says Kevin Hatala (Chatham University, Pittsburgh, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany), first author of the study published on November 29 in Science and describing these traces. He was responsible for continuing to uncover these prints and taking photogrammetry images, to obtain three-dimensional models in order to analyze them.

“A fascinating suggestion”

The researchers focused on the so-called “TS-2” track, where they distinguished a series of thirteen steps attributed to the same individual, and isolated footprints. The former, according to an analysis of the curvature of the arch of the foot, do not resemble those of modern humans, and are attributed to Paranthropus boisei – a species belonging to an extinct lineage. The latter, on the other hand, are more “human” – they resemble five-hundred-year-old traces described in soils comparable to Walvis Bay, in Namibia, and are presumed to have been left by The man stood up (also known by its African name ofhomo ergaster), closer to us on an evolutionary level.

Finding these traces, contemporary a few hours or days apart, confirms that these two species, whose fossils were found in the region, coexisted. “Given the clear differences in nutrition, life history and encephalization between Homo et Paranthropusit’s a fascinating suggestion”comments William Harcourt-Smith (New York Museum of Natural History) in Science.

The revelation of such cohabitation led the team to look again at traces found forty kilometers away, on the site of Ileret (Kenya). “We found that there too, there was evidence of footprints of several hominin species, which we had not previously identified”said Kevin Hatala.

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