1.4-million-year-old Kenyan footprints reveal Paranthropus boisei stood 1.8 meters tall
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Fossil footprints in northern Kenya show eight Paranthropus boisei individuals traveled together 1.4 million years ago. The tracks indicate body sizes up to 1.8 meters tall and 75 kilograms, larger than earlier estimates. The find challenges assumptions that the species was substantially smaller than Homo erectus.
Key Facts
- The footprints, preserved near an ancient lakeshore in northern Kenya, record eight Paranthropus boisei individuals at the same place and time.
- Track sizes indicate body heights up to 1.8 meters and weights around 75 kilograms, according to lead author Kevin Hatala of Chatham University.
- All eight trackmakers were likely adults, and most were likely adult males, with no obvious evidence of females or children.
- The tracks were identified as Paranthropus boisei using analytical techniques first developed by the team in 2024.
- The discovery challenges earlier research suggesting Paranthropus boisei was substantially smaller than Homo erectus.
The Footprint Discovery
A set of fossil footprints from northern Kenya offers a rare glimpse of how an extinct human relative moved and interacted about 1.4 million years ago. The tracks, preserved near an ancient lakeshore, appear to record eight Paranthropus boisei individuals occupying the same place at roughly the same time. Researchers describe the discovery as a snapshot of "fossil behavior" because footprints can capture a brief moment in the lives of individuals, unlike bones that can accumulate over long periods. The international team, made up of researchers from the US and Kenya, concluded that all eight trackmakers were likely adults.
Body Size Estimates
The researchers used analytical techniques first developed by their team in 2024 to identify the footprints as belonging to Paranthropus boisei. The classification was based on clues in foot anatomy as well as the way the individuals appear to have moved. The size of the tracks came as a surprise: "The sizes of the footprints indicate human-like body sizes - up to 1.8 meters tall and around 75 kilograms," says lead author Kevin Hatala of Chatham University. For decades, most known fossils of Paranthropus boisei consisted of skulls, including specimens with exceptionally large jaws and teeth, while fossils from the rest of the skeleton are far rarer. The new tracks now challenge earlier research suggesting that Paranthropus boisei was substantially smaller than Homo erectus, another hominin that lived during the same general period.
Social Behavior Evidence
Footprints can reveal more than anatomy: because a walking surface may be formed and preserved over a very short span of time, fossil tracks can provide direct evidence about movement, group size, and possible social interactions. In this case, the eight individuals appear to have been traveling together, and most were likely adult males, with no obvious evidence of females or children among them. "The fact that eight, mostly adult male, Paranthropus boisei individuals seemingly traveled together as a group, without females or children, hints at a complex social structure in this species," says co-author Neil Roach of Harvard University. Roach adds that they may have lived in large groups, where males competed for mates but also tolerated each other at times for safety in a dangerous environment.
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1.4-million-year-old Kenyan footprints reveal Paranthropus boisei stood 1.8 meters tall
