Two species of ancient humans walked beside each other 1.5 million years ago, fossil footprints have revealed.
Fossilised imprints from a lakebed in Kenya have revealed that a member of the Homo erectus species and a Paranthropus boisei walked along the same stretch of mud within hours of each other.
These two species are ancestral cousins of modern Homo sapiens and were the most common human species during the Pleistocene epoch.
Anthropologist Prof Craig Feibel has spent more than 40 years studying the fossil-rich lands of northern Kenya and found the footprints near Lake Turkana.
Analysis revealed the two species walked past one another at the same time, using the same stretch of the lake shore.
Scientists say it is possible the two individuals were there at the exact same time and bumped into one another, or crossed just minutes or hours apart.
The researchers uncovered the fossil footprints in 2021 when a team organised by Louise Leakey, a third-generation palaeontologist, discovered fossil bones at the site.
A 3D computer model of the area near Lake Turkana in Kenya shows fossil footprints of Paranthropus boisei (vertical footprints) and Homo erectus forming a perpendicular path – Kevin Hatala/Chatham University, SWNS
It was excavated in July 2022 and is the first-ever physical evidence of two types of hominin existing at the same time.
“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,” said Dr Kevin Hatala, the study’s first author at Chatham University in Pittsburgh.
“That’s something that we can’t really get from bones or stone tools.”
The two species were both able to walk on two feet and walked upright with good levels of agility. Homo erectus is a direct ancestor of modern humans and lived until around 500,000 years ago whereas P. boisei went extinct a few thousand years after the Kenyan lake encounter.
Professor Chris Stringer, research leader in human evolution at the Natural History Museum, who was not involved with the study, told The Telegraph: “We already knew these two species overlapped for several hundred thousand years in the same region from fossils found there.
“But direct evidence of precise co-existence is almost impossible to prove from fossils alone.”
A study once found Homo sapiens and Neanderthal bones just a metre apart, for example, but analysis found there was a 30,000-year gap between them.
Paranthropus boisei was one of the most common human species during the Pleistocene epoch – ullstein bild
“These two species overlapped for several hundred thousand years and must have encountered each other many times,” Professor Stringer added.
“The authors suggest that the two species with their different diets were probably not competing strongly at this time, hence their close and apparently tolerant proximity in time and space.
“Paranthropus boisei went extinct not long after the time of the footprints, however, but it’s unclear whether this was because of environmental changes, competition from other (non-human) species, or whether Homo erectus could have been involved.
“There is certainly evidence of violent deaths in the fossil record of Neanderthals and H. sapiens, but in most cases, it looks most likely to be from within-species conflict.”
The study has been published in the journal Science and Professor Feibel said it “proves beyond any question” that two different hominins were walking in the same area at the same time.
“The idea that they lived contemporaneously may not be a surprise. But this is the first time demonstrating it. I think that’s really huge,” he said.
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