There’s plenty of evidence that ancient hominin species crossed paths on many occasions – but it’s never been quite as literal as a new discovery in Kenya. Paleontologists have discovered the first known example of fossil footprints left by two different species of ancient hominins on the same day.
The footprints date back 1.5 million years, left in the muddy shores of an ancient lake in what would have been a hot savannah environment. They show two separate species moving in perpendicular directions, visiting the same watering hole within a few hours of each other at most.
The two species are believed to be Homo erectus, a direct ancestor of us modern humans, and Paranthropus boisei, a more distant relative from a different branch of evolution that disappeared a few hundred thousand years after these footprints. Existing fossil evidence had suggested that these two hominins lived around the same time in the same place, but this marks the first direct evidence of possible interaction.
“Fossil footprints are exciting because they provide vivid snapshots that bring our fossil relatives to life,” said Kevin Hatala, first author of the study. “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. That's something that we can't really get from bones or stone tools.”
The researchers identified the creatures that left the footprints by conducting 3D imaging and analyses on them. This revealed clues about distinct gaits and stances, and the researchers used this data to hypothesize that the different sets of tracks belong to H. erectus and P. boilei.
“This proves beyond any question that not only one, but two different hominins were walking on the same surface, literally within hours of each other,” said Craig Feibel, an author of the study. “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.”
What kind of interactions they may have had remains unknown, but if the long sordid history of hominins is anything to go by, it likely included both competition and cooperation. They may have killed each other, largely ignored each other, or of course, they could have interbred.
The research was published in the journal Science.
Source: Rutgers University