A remarkable set of footprints preserved along the shores of Kenya’s Lake Turkana from more than one million years ago is giving scientists an unusually detailed look at how one of humanity’s extinct relatives may have lived, moved and socialized. The newly published study, appearing in the Proceedings of the National Academy of Sciences, analyzed 21 fossilized footprints left behind by eight individuals belonging to Paranthropus boisei, an ancient human relative that lived alongside Homo erectus during the Early Pleistocene. In an interview with CTVnews.ca on Monday, lead author and associate professor of biology at Chatham University Kevin Hatala said: “They probably weren’t all there at exactly the same time, but they’re definitely all moving through this space, maybe within hours of each other, or at least within a day or two.” “We think there’s potentially a group of them who are moving through this area together as well, just based on the orientations of their trackways,” he added. “They seem to be moving in the same direction and at similar speeds too.” Researchers say footprints provide something fossilized bones rarely can: a snapshot of behaviour captured in a single moment. “The special thing about footprints, scientifically, is that they preserve an instant in time,” Kay Behrensmeyer, senior research geologist and curator of vertebrate paleontology at the Smithsonian’s National Museum of Natural History, said in a press release issued by the museum. “They also allow people to relate to these fossils much more easily than an isolated piece of bone or jaw.” The tracks were first discovered in northern Kenya in 1978 after Behrensmeyer noticed what turned out to be a fossilized hippo footprint while colleagues were excavating ancient sediment. The site was later reburied to protect it before researchers returned in 2016 and 2023, uncovering many more footprints preserved in the same layer of rock. Volcanic ash surrounding the site allowed researchers to date the trackway to about 1.43 million years ago. A bigger, more social species than expected By studying the shape and movement recorded in the footprints, researchers concluded they were made by Paranthropus boisei, rather than Homo erectus. The findings also challenge long-held assumptions about the species’ size. “The sizes of the footprints indicate human-like body sizes, up to six-feet tall and around 165 pounds,” Hatala said in the press release. The discovery suggests Paranthropus boisei may have been much closer in size to Homo erectus than previously believed. Researchers also say the footprints indicate that eight individuals, most of them adult males, were travelling together, offering rare clues about the species’ social behaviour. “The fact that eight, mostly adult male, P. boisei individuals seemingly travelled together as a group, without females or children, hints at a complex social structure in this species,” said co-author Neil Roach of Harvard University. Scientists caution that the footprints capture just a moment in time, but they believe the evidence suggests these ancient relatives may have lived in larger social groups than previously thought. In the press release, Hatala said each new footprint site is helping researchers build a clearer picture of human evolution. “Each site represents a snapshot of our past, and we are quickly building a photo album with several different windows to hominin anatomy, locomotion, behavior and environments during the Early Pleistocene.” In the interview with CTVNews.ca, Hatala concluded that when researchers find bones or their stone tools, you get “indications that they were alive during a certain time period.” “It’s always so exciting when we’re excavating these sites because you can actually see the hominins moving around their environment,” he said. “You can see how they might have been interacting with one another.” Researchers plan to return to Kenya later this year in hopes that more ancient footprints will help fill in the story of humanity’s distant past.
