Muddy Footprints Reveal Neighbouring Early Human Species in Kenya 1.5 Million Years Ago

Muddy footprints discovered on a lakeside in Kenya suggest that two early human ancestors lived as neighbours around 1.5 million years ago. These footprints, left by two distinct species, were made within hours or days of each other, according to paleontologist Louise Leakey. The findings were published in the journal Science.

Previously, scientists knew from fossils that Homo erectus and Paranthropus boisei coexisted in the Turkana Basin. However, dating fossils is not precise, with a margin of error of several thousand years, explained paleontologist William Harcourt-Smith from Lehman College and the American Museum of Natural History. Fossil footprints, on the other hand, capture a specific moment in time.

Footprint Discovery and Analysis

The fossil footprints were found in 2021 at Koobi Fora, Kenya, Leakey noted. Whether these individuals walked by Lake Turkana simultaneously or within a couple of days, they likely knew of each other's presence, said study co-author Kevin Hatala from Chatham University. "They probably saw each other, probably knew each other was there and probably influenced each other in some way," he stated.

Scientists identified the species based on footprint shapes, which reveal foot anatomy and usage. H. erectus walked similarly to modern humans, striking the ground heel first and rolling weight over the foot. The other species walked upright but differently from any known species, according to co-author Erin Marie Williams-Hatala from Chatham University.

Evolutionary Insights

The footprints indicate more mobility in the big toe compared to H. erectus or modern humans, Hatala mentioned. Researchers believe our primate ancestors had feet adapted for grasping branches, but human ancestors evolved feet for upright walking over time. This study adds to evidence suggesting bipedalism evolved in diverse ways rather than a single event.

Harcourt-Smith highlighted that different gait mechanics existed among early humans. "It turns out, there are different gait mechanics – different ways of being bipedal," he said. This implies early humans developed various methods for walking and running on prehistoric terrains.

The discovery of these footprints provides valuable insights into how early human ancestors interacted and adapted to their environment. It underscores the complexity of human evolution and the diverse paths taken by different species towards bipedalism.