Archaeologists have found ancient footprints of surprisingly large size in Kenya.
On the shore of an ancient lake in northern Kenya, scientists have discovered fossilized footprints about 1.43 million years old, which allowed us to reconstruct one of the episodes of the life of ancient hominins. The discovery showed that some of them could be much larger than previously thought, and also provided a rare opportunity to study their movement, behavior, and perhaps even social connections. The mystery posed by the ancient prints to researchers and why they turned out to be more valuable than many fossil bones is described in the Izvestia article.
Ancient footprints that preserved one day from the life of human ancestors
According to Arkeonews magazine, traces were found at the GaJi10 site in Eastern Turkana, one of the most important regions in the world for studying human evolution. The location itself has been known to scientists since 1978, but the expansion of excavations in 2016 and 2023 allowed the discovery of significantly more prints. Today, researchers have documented 21 hominin footprints, combined into five continuous chains. They are tentatively believed to belong to eight different individuals.
Unlike bones, which can accumulate in one place for hundreds or even thousands of years, footprints appear almost instantly and preserve events that occurred in a very short period of time. That is why they allow us to see not only the appearance of ancient people, but also how they moved and interacted with each other.
The researchers found that most of the hominins were moving west, while one individual was walking in the opposite direction. The tracks were left on fresh mud, covered with a layer of water about two to ten centimeters deep, along the shore of the ancient Lake Loren Yang. Later, the prints were quickly filled with fine sand, so they were well preserved, and subsequent precipitation finally preserved the surface.
Interestingly, not only human footprints were found in the same area. Archaeologists have recorded 146 more animal prints, including hippos, polorhynchus, birds and representatives of the equine family. All together, they allow us to imagine the lively shore of an ancient lake, which was simultaneously used by ancient people and numerous animals.
What feature of ancient hominins did the footprints reveal?
To study the find in detail, the scientists created three-dimensional models of the prints and compared them with other ancient footprints from East Africa, as well as with hundreds of prints experimentally left by modern humans. It turned out that the feet of ancient hominins were noticeably different from those of humans. Their arch was flatter, the movement of the foot when walking was different, and the thumb was positioned at a greater angle to the rest of the fingers. In some cases, this angle reached almost 40 degrees.
According to these features, the prints turned out to be similar to other footprints from East Turkana, which were previously associated with Paranthropus boisei, as well as the famous footprints from Laetoli, about 3.66 million years old. At the same time, the tracks that were previously attributed to Homo erectus, on the contrary, demonstrate much more modern walking mechanics.
The most unexpected discovery was the size of the prints. Since it is not yet possible to determine the type of their owners, the researchers calculated height and weight using two models — for Paranthropus boisei and for Homo erectus.
Assuming that the tracks were left by Paranthropus boisei, the height of the seven individuals ranged from about 1.31 to 1.81 m, and the weight ranged from 39.8 to 74.6 kg. All calculated growth rates turned out to be higher than the average value known for this species, and most weight estimates also exceeded previously published data. This may mean that Paranthropus boisei was much larger and more diverse in body size than previously thought.
If we use the proportions of Homo erectus, the estimated height of ancient humans ranged from 1.55 to 1.81 m, and the weight from 55 to 79.6 kg. Such sizes are also considered large, but they already fit into the range known from the found bone remains of this species.
This is where the main mystery of the study arises: the footprints are more similar in structure to Paranthropus boisei, while their sizes look more characteristic of Homo erectus. Therefore, the authors claim that it is still impossible to definitively determine who exactly left the traces.
What has been learned about the life of ancient people
In addition to the structural features of the feet, the prints allowed the researchers to obtain rare information about the behavior of ancient hominins. At the GaJi10 site, five large individuals were moving in a westerly direction, heading from the shallower part of the lake to the deeper one. At the same time, their tracks practically do not overlap each other, which suggests that they crossed the surface at about the same time.
If the prints really belong to Paranthropus boisei, then based on the estimated body size, several individuals could be adult males. According to the researchers, this indicates at least that the large males were quietly next to each other. It is possible that they were even part of the same social group, although the authors emphasize that it is impossible to draw unambiguous conclusions about the structure of the community based on body size alone.
Another feature of the find was the ability to estimate the speed of movement of ancient people. According to the three best-preserved chains of footprints, scientists calculated that the hominins moved slowly — at a speed of about 0.32 to 0.50 m/s. However, the researchers note that this indicator reflects only a specific moment captured in the prints, and does not allow us to judge their usual walking speed.
This is precisely the uniqueness of such finds. Unlike individual bones or skulls, footprints allow us to see not only the appearance of ancient human relatives, but also to reconstruct their actions at a specific moment in time: where they were going, how fast they were moving and how they were positioned relative to each other. According to the authors of the study, such information is practically unavailable when studying fossils alone.
Why the discovery may change the understanding of human evolution
The GaJi10 site is just one of several Early Pleistocene sites discovered along the ancient shores of East Turkana. According to the researchers, such wetlands were especially attractive to ancient hominins due to the constant source of water and diverse food resources. Papyrus and other marsh plants could play an important role for Paranthropus boisei, while shallow water provided access to fish, shellfish and other aquatic prey.
The authors of the study note that Homo erectus, judging by data from other monuments, used a wider range of natural landscapes and more often included food of animal origin in the diet. At the same time, Paranthropus boisei was probably more strongly associated with coastal ecosystems and areas where stable vegetation was preserved. At the same time, previous finds in East Turkana show that both species repeatedly visited the same shores of the ancient lake and could sometimes be there almost simultaneously.
Despite the results, the researchers are not yet ready to definitively determine which species the prints belonged to. The features of the foot structure are more indicative of Paranthropus boisei, while the body size is more consistent with Homo erectus. The authors also admit the theoretical possibility of the existence of another, as yet unknown species of hominin, however, they emphasize that over the decades of research in these geological layers, the remains of only Paranthropus boisei and Homo erectus have been discovered.
Whichever answer turns out to be correct, the find has already become one of the most informative for studying early human evolution. The prints preserved not just individual footprints, but a whole episode from the life of ancient hominins — the moment when several large representatives of the human race crossed the shallow waters of an ancient lake among hippos, ungulates and birds. According to the researchers, it is precisely such discoveries that make it possible to understand the anatomy, lifestyle and behavior of ancient human relatives much better than is possible only from fossil bones.
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