Thousands of years later, the largest collection of footprints from the human fossil record continues to tell the stories of early hominin species who left their tracks preserved in perpetuity.
First discovered by members of the Maasai people in 2008, more than 400 fossilized human footprints located at Engare Sero, at the base of Tanzania’s volcano Ol Doinyo Lengai (“Mountain of God”), offer “snapshots of organisms in their immediate ecological and behavioral contexts.” Researchers first described the prints preserved in volcanic ash in 2010 and cataloged them six years later, estimating that they date to between 5,800 and 19,100 years ago, the former being a time of agricultural development among human societies. Previous research focused on geological context and preservation. This time, however, scientists have focused their efforts on deciphering what the footprints tell us about the ancient hominins that left them.
“Footprints are often ephemeral but when preserved in the geological record, these ichnofossils can provide unique snapshots of the lives of ancient organisms,” write the researchers in Scientific Reports. Fossilized tracks are created and subsequently preserved on much shorter timescales than other forms of fossils, such as skeletal fossils, which can lead to a “distinct set of hypotheses that can be developed and tested with this form of evidence.”
In total, 408 human footprints were excavated and analyzed to determine their owners’ body size and size variation as well as foot anatomy, function, and locomotion. Speed estimates show both running and walking behavior, indicating multiple groups of people likely visited the area at different times. One group, in particular, had around 17 individuals of mixed-sex and ages, now attributed to 14 adult females, two adult males, and one young male all walking together. This societal makeup is still seen in modern hunter-gatherer groups, which leads the researchers to believe that ancient societies may have divvied up the workload by sex.
“In the context of modern ethnographic data, we suggest that these trackways may capture a unique snapshot of cooperative and sexually divided foraging behavior in Late Pleistocene humans,” note the authors. Specifically, the authors add that the makeup of the footprints suggests a division of labor based on gendered sex within different communities.
Another set of six tracks of footprints oriented to the northeast showed a broader range of speed, which suggests that the footprints were not left by a single group traveling together but rather various individuals walking and running at different points in time.
Altogether, the findings help to illuminate an understanding of how ancient groups of early humans lived, moved, and behaved in east Africa during this timeframe.
“The Engare Sero footprint assemblage provides a tantalizing snapshot of the movements of a group of modern humans living in East Africa in the Late Pleistocene. These trace fossils offer windows into anatomy, locomotion, and group behavior, which help to supplement what is known from other forms of fossil and archaeological data,” conclude the study authors.