The story of how humans evolved is the whole story

A fossil evidence for two different archaic hominin species living in the same landscape – Lucy the paleo-rock star discovered in Koobi Fora

The term “human” is arguable. Despite having Neanderthal genes, many scholars reserve it for us because we had a lot of the same ancestors as us before 8 million years ago. The hominin evolution has been gradual with periodic rapid phases. The full evolution record of Homo shows we cannot separate ourselves with hard lines.

The origin of life and the universe are ranked in pursuit of knowledge. When an exciting find hits the headlines, the scientific community gets less financial support and funding than it would if there had been more.

The picture has changed frequently since then, being shaped by waves of new fossil discovery, technology, and scientific techniques, often accompanied by arguments about the truthfulness of claims.

The partial skeleton of this small-bodied, relatively small-brained female captured the public’s imagination. Lucy the “paleo-rock star” took our major fossil evidence for bipedal walking, human-like creatures (collectively known as hominins) beyond 3 million years for the first time. The race to explain how humans became what we are now was well and truly on.

In July of this year, the researchers discovered several sets of footprints in Koobi Fora, which includes a continuous path of impressions left by one person and at least three others. The surface dates to 1.52 million years ago, and impressions of rippled sand, reed beds and fish nests suggest that the area was a lake shore with shallow water.

Fossil records have been used to suggest that different hominin species lived alongside each other. Fossils can be found in large areas and their estimated dates are thousands of years old. Kivell is unsure if they are actually bumping into each other.

“This is the first snapshot we have of those two species living on the same immediate landscape, potentially interacting with one another,” says study co-author Kevin Hatala, a palaeoanthropologist at Chatham University in Pittsburgh, Pennsylvania. The study was published in Science on 28 November1.

The more distant relative Paranthropus boisei was the forebear of modern humans, according to analysis of the impressions. The two individuals walked through the lake area within hours or days of each other — leaving the first direct record of different archaic hominin species coexisting in the same place.

There are 13 footprints on the path. The hominin walked at an estimated 1.81 metres per second, similar to a modern human walking briskly.

Alongside the hominin footprints, the site contained preserved tracks from 30 relatives of cattle, three horse-like animals and 61 birds, including a giant extinct stork, Leptoptilos falconeri.

Hatala hopes to combine data from fossil footprints and bone fossils to “give a really high-resolution picture of what’s happening in this area during this phase of human evolution”.

Wood says that future studies could focus on the animals and birds. It’s difficult to do with regular fossil evidence but that brings the whole thing alive.