Crossing evolutionary paths: New research finds different hominin species coexisted

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The bones they found in the sand were a clue that something more was buried beneath the surface. When a team of excavators in the Turkana Basin, an archaeological site in Kenya, dug deeper, they found more evidence that ancient human ancestors had existed in the region: footprints.

“One long trail was super obvious and really spectacular,” said Craig Feibel, a geographer at Rutgers University who was called in to study the site.

Archaeologists had been able to determine that two different kinds of hominins, or living beings that evolved after the split from the apes 6 or 7 million years ago, existed near this ancient lake in Kenya at the same time based on bones that had been discovered in the region. But these remarkably preserved footprints were the first to indicate that two different species of hominins — including Homo erectus, which is a direct ancestor to humans, and Paranthropus boisei, which was a different species that also descended from the ape ancestor but died off around 1 million years ago. Both coexisted around 1.5 million years ago in this space, Feibel said.

In fact, the footprints indicate these two species were walking along the lakeshore within hours or days of each other, according to a study published this week in Science that Feibel co-authored.

“You can never tie down where bones come from [because] they could be transported or carried off by carnivores or scavengers,” Feibel told Salon in a phone interview. “With the footprints, we know these two species were right here on the same beach within a short period of time.”

A 3D computerized model of the surface of the area near Lake Turkana in Kenya shows fossil footprints of Paranthropus boisei (vertical footprints) with separate footprints of Homo erectus forming a perpendicular path. (Kevin Hatala/Chatham University)Over time, sediment accumulated on the lakeshore and the footprints were preserved underground. In the past half a million years, activity in the Rift Valley has pushed up these layers of sediment with the footprints, exposing this fossil evidence, Feibel said.

“With the footprints, we know these two species were right here on the same beach within a short period of time.”

In addition to these two species of hominins, researchers in the region have also found evidence of ancestors … Read More