Newly discovered footprints show that at least two hominid species were walking through the muddy submerged edge of a lake in Kenya's Turkana Basin at the same time, about 1.5 million years ago. The find from the famous hominid fossil site of Koobi Fora described by Kevin Hatala and colleagues provides physical evidence for the co-existence of multiple hominid lineages in the region—something that has only been inferred previously from overlapping dates for scattered fossils. Based on information on gait and stance gleaned from the footprints, Hatala et al. think that the two species were Homo erectus and Paranthropus boisei. This is the first evidence of two different patterns of bipedalism among Pleistocene hominids appearing on the same footprint surface. After examining the new Koobi Fora footprints, the researchers analyzed other similar-age hominid footprints and conclude there is a distinct pattern of two different types of bipedalism across the East Turkana region. The overall analysis indicates that the different species were contemporaneously using these lake habitats, with varying possibilities of competition or niche partitioning that could have impacted trends in human evolution. William Harcourt-Smith discusses the implications of the footprints in a related Perspective.
Podcast: A segment of Science's weekly podcast with Kevin Hatala, related to this research, will be available on the Science.org podcast landing page after the embargo lifts. Reporters are free to make use of the segments for broadcast purposes and/or quote from them – with appropriate attribution (i.e., cite "Science podcast"). Please note that the file itself should not be posted to any other Web site.
