Fossil Footprints in Tanzania Reveal Snapshot of Group Behavior in Prehistoric Humans
Kevin Hatala, Assistant Professor of Biology at Chatham University, is the primary author of a new study published in Nature Scientific Reports that provides in-depth analyses of the largest human fossil footprint site that has ever been discovered in Africa.
Within an area of approximately 300 square-meters, the site near the village of Engare Sero in Tanzania contains over 400 human footprints, preserved in volcanic ash, that are estimated to have been made between 6,000 and 19,000 years ago. The footprints represent the distinct pathways of at least 20 different individuals. Hatala is part of the multidisciplinary team, led by Appalachian State University professor Cynthia Liutkus-Pierce, that has been excavating and analyzing the Engare Sero footprints since 2009.
“Footprint sites are rare in the human fossil record and they preserve exciting, direct windows into the past,” says Hatala. “Here we have a richly-detailed snapshot of a group that walked across this landscape at a very specific moment in human history. Based on our analysis of the sizes, spacings, and directions of the footprints, we believe they were made by a group of mostly adult females who were traveling together. When we look at ethnographic literature, that kind of group structure is consistent with those observed during sexually divided foraging activities. Of course you can’t make a one-to-one comparison and there are other possibilities, but the potential to directly observe such group behaviors from fossil evidence is intriguing.”
Liutkus-Pierce notes that the footprints have been remarkably preserved within an ancient volcanic mudflow produced by the nearby Oldoinyo L’engai, a still-active volcano in the East African Rift. “These prints were pressed into wet ash, which dries almost like concrete,” explains Liutkus-Pierce. “The resilience of the hardened ash helps preserve the details of the footprints despite the natural erosion of the surrounding area over thousands of years.”
In addition to the paper summarizing the group’s findings, a full 3-D recreation of the site has been generated and made available online for study and download by the Smithsonian’s Digitization Program Office. William Harcourt-Smith, professor at Lehman College CUNY and research associate at the American Museum of Natural History, explains: “This site preserves a rare and wonderful direct window into the past. Making a full-scale model available for others to access online is crucial for sharing these data with the scientific community and the public, and also as a long-term safeguard against the potential erosion of the physical site.”
Briana Pobiner, paleoanthropologist at the Smithsonian’s National Museum of Natural History, notes, “Several of the human footprint trails lead to a nearby sand dune. We purposefully left the additional footprints, which are presumably preserved under the dune, unexcavated until we can work with the Tanzanian government to develop a conservation plan to limit erosion”. Future plans also include further examining the site’s data as they relate to paleoanthropology, paleoecology, and associated fields.
The Engare Sero research project has been made possible through collaboration with the Tanzanian government and local Maasai communities, and with financial and material assistance from National Geographic, the Leakey Foundation, the National Science Foundation, the Evolving Earth Foundation, the Explorer’s Club, Appalachian State University, The George Washington University, the Smithsonian Institution, and the American Museum of Natural History.
Kevin Hatala currently lives in Pittsburgh, PA, where he has been an Assistant Professor of Biology at Chatham University since 2016. He earned his Ph.D. in Human Paleobiology from The George Washington University and his B.S. in Biological Anthropology & Anatomy with a minor in Chemistry from Duke University.
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