At Kenya’s Lake Turkana, 21 ancient footprints from 1.43 million years ago don’t fit the known hominins, and the size clues point in two directions

We spend our lives following in other people's footsteps. People in science are normally aware of who they are following. However, a collection of 21 fossilized footprints on the mudflats of Kenya's Lake Turkana has left researchers in a state of bafflement.

The prints, roughly 1.43 million years old, were first uncovered by paleontologist and research geologist at Smithsonian’s National Museum of Natural History Kay Behrensmeyer and team about 50 years ago. They capture a moment in deep time that doesn't easily align with the narrative of human evolution we've long been told.

Chatham University professor Kevin G. Hatala and his team led the study, and in their research paper “Footprint evidence for locomotor diversity and shared habitats among early Pleistocene hominins,” published in the journal Science, they further indicated that the tracks don't match those of the hominin that researchers had expected to find there. Could they have come from an unknown branch of our extended family, or were they possibly created by an unanticipatedly large Paranthropus boisei? The mystery brings up one of paleoanthropology's favorite reminders: evolution was never a straight path; it was a crowded neighborhood.

When footprints speak louder than fossils

It is often fossils that get all the spotlight. Skulls, teeth, and femurs are given the center stage while footprints are considered to be supporting evidence. But footprints have a uniquely amazing advantage: they record real-time behavior. The impressions of the 21 unidentified footprints were left on soft mud along the lakeshore before being sealed under volcanic sediments, capturing an almost cinematic moment from the Early Pleistocene.

These do not depict the appearance of a deceased individual, but rather showcase how ancient relatives moved, and where they walked and possibly with whom. Footprints are not scattered across millennia like skeletons, but rather they compress time into minutes or hours. They are more than just anatomical evidence; they are moments frozen under layers of earth.

A size problem nobody expected

The actual mystery lies in the size of these footprints. A recent New Scientist article summarizes that twenty-one tracks were observed, at least eight of which were quite large. They do not fit in with the reconstruction of the hominins around Lake Turkana.

If they are from Paranthropus boisei, the stout and broad-faced species with powerful jaws, it indicates that individuals were much taller and heavier than previously thought, and that some were nearly six feet tall. That would bring into question the variation in body size of a species that was until now overshadowed by Homo erectus. According to Smithsonian, the tracks mean that the footprints greatly increase the range of possibilities for P. boisei's physical abilities.

But another intriguing possibility is left hanging, as pointed out by New Scientist: the prints could actually belong to a yet-to-be-known hominin from skeletal remains. For bones to be fossilized, conditions must remain extremely favorable; a whole population may disappear, leaving behind only the footprints in ancient mud.

An ancient lakeshore was anything but empty

Lake Turkana is one of the most important sites for human evolution. The region has been a good source of fossils for several hominin species that coexisted in the same time period for decades. In Hatala’s 2024 research as well as a recent publication in Proceedings of the National Academy of Sciences, it was revealed that Homo erectus and Paranthropus boisei walked along the same lakeshore within hours (or perhaps days) of each other.

These newly analyzed tracks further flesh out the details. But Turkana tells a much more complicated story than a relay race, in which multiple human relatives were sharing the same ecosystems, exploiting similar resources, and perhaps even crossing paths. It's not a family tree, more like a big family forest.

Reading society through ancient steps

Perhaps the most intriguing revelation is not anatomical but social. The new trackway indicates that there were multiple occupant movements along the lakeshore. The footprints could be a flock of adult males moving in a group, according to Hatala and his team.

The interpretation is still conservative, but it pushes paleontology beyond bone to behavior. One of the few direct sources of information about prehistoric social organization and movement comes from footprints. It’s perhaps a reminder that long before there were cities, roads or languages, our relatives were already moving through landscapes as communities and not just as individuals.

The danger of looking for a single 'missing link’

It was not a single lineage that marched towards us, but rather early Pleistocene Africa was home to several species of hominins. Some blossomed, some withered, and only one ultimately emerged as a survivor.

The Lake Turkana footprints reinforce that complexity. Researchers don't simplify the origin of human beings; they present evolution as an experiment, rather than an engineering project, with many branches, many dead ends, and many unexpected survivors. That complexity also challenges the comforting idea that humanity was inevitable. We're simply the descendants that survived.

Why twenty-one footprints matter today

Some 21 footprints in comparison to huge dinosaur skeletons and ancient monuments might seem a bit minuscule. But their significance lies in their ordinariness. Across wet ground came one who never dreamed these steps would outlast mountains, civilizations and languages.

They may be giant Paranthropus boisei, an unidentified hominin, or something completely else yet to emerge from beneath Kenya’s sediments, but they remind us of one simple fact: our knowledge of human origins remains incomplete. Sometimes history can be rewritten by footprints that refuse to fit in.