Ana B. Marín Arroyo
Full Professor of Prehistory and Director of the EvoAdapta Group at the University of Cantabria
The study of hominin footprints found in Kenya provides a unique window into the earliest stages of human evolution. Evidence of sympatric speciation and differences in foot biomechanics found at this site, called FE-22, suggest that the evolutionary history of hominins is much more complex than we thought.
This work provides the exceptional discovery of footprints made by two hominids with different foot kinematics at a very specific time and place and which are not often found in such ancient fossil contexts.
The study of these footprints has led researchers to propose that they are the footprints of two different hominins: Homo erectus and Paranthropus boisei. This finding provides, for the first time, direct evidence of two hominin taxa coexisting and potentially interacting with each other in environments outside Lake Turkana during 1.5 million years ago, something that we could assume, but that with the time scales we use we could not determine if they really occurred in the same space-time.
The conclusions of the study are well supported by the different material evidence that not only includes the analysis of the hominin footprints, but also the fossil remains of hominids found in the surrounding area, the detailed geological study of the site and footprints of other animals, such as birds and bovids, which offer relevant information about the ecosystems that these hominids inhabited and exploited for their subsistence.
Future research, including the discovery and analysis of other sites with new tracks, as well as a better understanding of the environmental context and intraspecific variation, will help to answer open questions about the interactions between early Pleistocene hominins.