Look: 3.6-million-year-old prints likely belong to an undiscovered ancient human

In the late 1970s, paleoanthropologists digging in modern-day Tanzania discovered something remarkable.

They unearthed a series of fossilized footprints made 3.6 million years ago and preserved in volcanic ash.

At the time, they weren’t sure who the footprints belonged to.

Were they made by animals, or perhaps an early human ancestor?

A team of researchers recently went back to the site to investigate further — discovering the prints may be a sign of a totally unknown hominin species.

They watched black bears for more than 50 hours — they walk upright sometimes, but it doesn’t seem habitual enough to suggest bears are the culprit.

And finding fossils of bear relatives that fall in the genus Ursus is extremely rare in Eastern Africa, so the researchers ruled that hypothesis out.

Melillo also writes that scientists don’t typically define new species based off footprints alone.

The simplest explanation, the researchers argue, is that we have another ancestor we don’t know about — and an exciting future discovery for paleoanthropologists to make.

If that’s the case, this archaic hominin would have likely coexisted with A. Afarensis — offering new insight into intra-species cooperation between our ancestors.