First: discovery of footprints from two different hominin species in the same location 🦶

In the heat of an African savanna 1.5 million years ago, two distinct hominin species appear to have walked the same grounds. These tracks, preserved in sediments near the present-day Lake Turkana in Kenya, provide unprecedented insight into their coexistence.

A chance encounter or simply crossing paths? The fossil footprints, studied by an international team, reveal a time when Homo erectus and Paranthropus boisei shared the same habitat.


These footprints, analyzed using 3D technologies, constitute the first direct evidence of the simultaneous presence of these two species on a single surface. According to Craig Feibel, an Earth sciences specialist at Rutgers University, the prints were formed over a very short period, likely within a matter of hours. A discovery made possible thanks to the rich fossil record in the region, which has been explored for decades by both local and international teams.

Fossil footprints are "trace fossils": they reflect behavior, unlike bones or teeth, which only indicate biological remains. This type of evidence provides crucial insights into the locomotion and anatomy of hominins, as well as how they interacted with their environment. Kevin Hatala, lead author of the study published in Science, explains that these traces show how our ancestors moved through their environment and interacted with other species or animals.

Homo erectus and Paranthropus boisei, while coexisting at the time, were significantly different. Analyses reveal distinct anatomical traits and modes of movement. Homo erectus, a direct ancestor of modern humans, was more slender and mobile, whereas Paranthropus boisei, known for its powerful jaw, appeared better adapted to chewing hard plant materials.

The precise dating of the footprints was made possible by Craig Feibel's expertise in stratigraphy, showing they date back 1.5 million years. This ancient ground was preserved by sedimentary deposits, a rare phenomenon highlighting the importance of local geological conditions.

This discovery challenges certain hypotheses about potential interactions between these two species. While their cohabitation was already known through bones, these footprints are the first evidence that they occupied the same space at the same time. Yet, researchers remain unsure whether they cooperated, competed, or simply crossed paths.

Additionally, the differing fates of these two species provoke curiosity: Homo erectus survived nearly a million years beyond this period, while Paranthropus boisei went extinct much earlier. This contrast raises questions about their respective abilities to adapt to ever-changing environments.

The footprints, uncovered in 2021 by a team led by Louise Leakey, are also the result of a rigorous methodology. The use of three-dimensional analyses, a first for these fossils, allowed researchers to clearly distinguish the specific characteristics of the two species. This technological advancement opens new avenues for studying other similar sites.

Researchers hope this discovery will lead to others in the region, which remains a veritable treasure trove for understanding human evolution.