Remarkable fossil footprints discovered in northern Kenya are giving scientists a rare glimpse into how Paranthropus boisei moved, traveled, and interacted with one another approximately 1.4 million years ago.
Researchers identified eight sets of footprints preserved near the shoreline of an ancient lake. The tracks appear to have been made by Paranthropus boisei individuals who were in the same location at roughly the same time. Scientists describe the discovery as a snapshot of “fossil behavior” because, unlike bones that accumulate over long periods, footprints can preserve brief moments from an individual’s life.
An international team from the United States and Kenya concluded that all eight trackmakers were probably adults. Several individuals also appear to have been considerably larger than previous estimates for Paranthropus boisei, a species whose body size has been difficult to determine because the fossil skeleton is limited.
Ancient footprints reveal unexpected body size
Using analytical methods developed by the research team in 2024, scientists attributed the footprints to Paranthropus boisei. The classification was based on the anatomical features of the feet, as well as evidence of how the individuals walked and distributed their weight.
“The size of the footprints indicates a human-like body size, with some individuals reaching up to 1.8 meters in height and weighing approximately 75 kilograms,” said lead author Kevin Hatala of Chatham University. Hatala is also a collaborator in the Department of Human Origins at the Max Planck Institute for Evolutionary Anthropology in Leipzig.
For decades, the best-known fossils of Paranthropus boisei consisted primarily of skulls, including specimens with exceptionally large jaws and teeth. Scientists know far less about the rest of the body because fossils from the neck down are much rarer.
The newly discovered footprints challenge earlier research suggesting that Paranthropus boisei was significantly smaller than Homo erectus, another hominin that lived during approximately the same period and is considered a possible direct ancestor of modern humans.
Fossil footprints offer clues to ancient social behavior
Fossil footprints reveal more than anatomy. Because footprints can form and become preserved over a short period, they may provide direct evidence of movement, group size, travel patterns, and potential social interactions.
In this case, the eight individuals appear to have been traveling through the same area. Most were likely adult males, with no clear evidence of females or children among the trackmakers.
“The fact that most of the eight individuals were adult males, along with the absence of females or offspring, suggests that Paranthropus boisei may have had a complex social structure,” said co-author Neil Roach of Harvard University. “They may have lived in large groups in which males competed for mates but sometimes tolerated one another to improve safety in dangerous environments.”
This possibility adds a new dimension to scientists’ understanding of Paranthropus boisei. The species shared the landscape with early members of the genus Homo, but it followed a distinctly different evolutionary path.
Why ancient hominins returned to Lake Turkana
The discovery is part of a much larger collection of hominin footprints found in ancient lakeside environments around Lake Turkana in northern Kenya.
The repeated presence of footprints suggests that lake margins were important habitats. These environments may have provided water, food, and other resources that repeatedly attracted extinct human relatives.
“It is surprising that two areas located 40 kilometers apart in East Turkana contain similar lake-margin deposits dating to approximately the same period,” said co-author Kay Behrensmeyer of the Smithsonian Institution.
Researchers have now documented hundreds of hominin footprints at more than half a dozen archaeological sites in the region. Determining why these tracks were created and preserved could help explain why ancient humans continued to visit lakeshores for such long periods.
“If we can identify the geological conditions that allowed these footprints to be preserved, we could learn more about why hominins repeatedly returned to lakeside environments for more than 100,000 years,” Behrensmeyer said.
Building a record of life 1.4 million years ago
The research team plans to return to Kenya this year to continue investigating the fossil footprints.
Each newly documented surface can preserve a different moment from the distant past. Together, these tracks provide evidence of anatomy, walking behavior, social interactions, and environmental conditions that traditional fossil remains cannot always reveal.
“Each site represents a snapshot of our past, and we are rapidly building a photo album with several different windows into the anatomy, locomotion, behavior, and environment of early Pleistocene humans,” Hatala said.
The findings further highlight the importance of the Lake Turkana region, one of the world’s richest areas for studying human evolution.
“The discovery of these fossil footprints along the edge of Lake Turkana reinforces the global importance of this region for understanding human evolution,” said co-author Purity Kiura of the National Museums of Kenya. “It also strengthens Kenya’s status as one of the world’s most important paleoanthropological landscapes and highlights our responsibility to protect this irreplaceable heritage.”
Advanced analytical techniques, combined with the unusually well-preserved tracks, have allowed researchers to study details that cannot be obtained from bones alone. These ancient footprints reveal how our extinct relatives were built, how they moved, where they traveled, and possibly how they interacted with one another 1.4 million years ago.
Source: www.sciencedaily.com