Two species of ancient humans who were thought to be unknown to each other roamed the plains of Africa side by side 1.5m years ago, a study suggests.
Archaeologists uncovered four sets of footprints preserved in the mud at the Turkana Basin in Kenya, a site that has been crucial in understanding human evolution.
The discovery is the first direct evidence that very distinctly different kinds of human relatives inhabited the same place at the same time, the researchers said.
And the tracks also opens the possibility the two groups may have interacted with each other and influenced one another
The footprints belonging to the Paranthropus boisei, a bipedal primate with smaller brains and wide, flat faces with massive teeth, and Homo erectus, which more closely resemble modern humans and are thought to be our direct ancestors
Researchers noted that the foot structure of P. boisei may not have been ideal for running long distances, which could explain why the arching found among H. erectus survived in later generations.
‘One hypothesis posits that H. erectus was the earliest hominin to practice fully modern, human-like bipedal walking and endurance running, and that this adaptation set them on a different evolutionary trajectory,’ the team shared in the study.
Whether the two individuals passed by the eastern side of Lake Turkana at the same time—or a day or two apart—they likely knew of each other’s existence, said study co-author Kevin Hatala, a paleoanthropologist at Chatham University in Pittsburgh.
‘They probably saw each other, probably knew each other was there, and probably influenced each other in some way,’ he said.
Archaeologists uncovered four sets of footprints preserved in the mud at the Turkana Basin in Kenya, a site that has been crucial in understanding human evolution.
One set belonged to a Homo erectus that more closely resemble modern humans and are thought to be our direct ancestors
The newly discovered footprints provide a snapshot of two human species walking through the muddy, submerged edge of a lake millions of years ago.
Researchers were able to distinguish one set of footprints from another using newly developed methods, including 3D analysis techniques that allowed them to capture digital models of the prints for deeper examination.
‘This is the first evidence of two different patterns of bipedalism among Pleistocene hominids appearing on the same footprint surface,’ the team shared in a statement.
Homo erectus appeared to walk in a manner similar to modern humans, striking the ground heel-first, rolling weight over the ball of the foot and toes, and pushing off again.
The other species, P. boisei, was also walking upright but in a ‘different way from anything we’ve seen before, anywhere else,’ said co-author Erin Marie Williams-Hatala, a human evolutionary anatomist at Chatham University.
The researchers found that prints made by P. boisei shared similarities with other ancient human tracks, including those found in Laetoli, Tanzania, dating back 3.6 million years.
These tracks belonged to Australopithecus afarensis, a species with pelvis and leg bones nearly identical in function to those of modern humans.
This footprint belonged to the Paranthropus boisei, a bipedal primate with smaller brains and wide, flat faces with massive teeth
Whether the two individuals passed by the eastern side of Lake Turkana at the same time—or a day or two apart—they likely knew of each other’s existence
The new discovery suggested that P. boisei had different heel strikes or push-off patterns from those in Tanzania and modern-day humans.
P. boisei has been nicknamed ‘Nutcracker Man’ because of its powerful jaws and huge teeth, which attached to the large crest on the skull.
Its unique walking features implied that this transformation to bipedalism – walking on two feet — did not happen at a single moment, in a single way.
Researchers noted that the foot structure of P. boisei (left) may not have been ideal for running long distances, which could explain why the arching found among H. erectus survived in later generations
Rather, there may have been a variety of ways that early humans learned to walk, run, stumble and slide on prehistoric muddy slopes.
Read More
Cuts made on a bone from a mysterious human relative 1.5 million years ago reveal they were butchered and likely eaten by one of their own
The researchers determined that P. boisei would have been a size 8.5 in men’s or a 10 in women’s, Live Science reported
While the H. erectus was roughly a women’s size four to a men’s size six.
Hatala explained that the new data from are revealing fascinating details about the evolution of human anatomy and locomotion, and giving further clues about ancient human behaviors and environments.
‘With these kinds of data, we can see how living individuals, millions of years ago, were moving around their environments and potentially interacting with each other, or even with other animals,’ he added.
‘That’s something that we can’t really get from bones or stone tools.’