Ancient footprints show how early human species lived side by side

Fossils preserved in Kenya record two different species of ancient humans on the same muddy lake shore, probably within days of each other. It is one of the most dramatic pieces of evidence ever found that multiple hominin species lived side by side in the world.

“It’s really extraordinary to find this evidence of two different species walking across that surface,” he says Kevin Hatala at Chatham University in Pittsburgh, Pennsylvania.

footprints They were discovered in 2021 In Koobi County, Kenya, near the eastern shore of Lake Turkana. Richard saw Loki teammates for the first time Turkana Basin Institutesays Hatala: “It was originally a group from Kania that was working there.”

Tucked away in a dry layer of sand and silt, the team discovered a track of 12 feet of footprints (see image above), apparently left by an individual walking in a straight line. Next to the main group there were also three isolated engravings, apparently made by three different people. The absence of evidence of mud cracking or overprinting of tracks with others indicates that the prints were all made at the same time. “These sites probably capture a window of time from minutes to days,” Hatala says.

The sediment has been dated to about 1.52 million years ago. The isolated tracks resemble those left by modern humans: the heel struck the ground first, then the foot moved forward before pushing off with the sole. Hatala and his colleagues suggest that these were made The man stood upthey obviously lived in that area.

Rather, the continuous track was made by a flatter hominin. Hatala and his colleagues suggest that this could be the case Paranthropus boiseianother type of hominin that lived in the region.

“With footprints, you can never be 100 percent sure who made them,” he says Ashleigh Wiseman at University College London, who was not involved in the research. However, H. erectus and P. boisei are the remains of the only hominins that have been found in the area, “so we can guess that they are those two”.

If the track is actually made by a P. boisei individual, shows they were bipedal, says Wiseman. Skulls, arm and leg bones have been attributed to them Paranthropushe says, “we have never found a skull united with the rest of the skeleton.” This means that we know little about their bodies apart from their heads, and their walking style has been a mystery. The track changes that: “It’s clear evidence of walking on two legs.”

These two species were very different. H. erectus was one of the first members of our genus, Homo. they had bigger brains It preceded the hominids and was the first of the clade to travel out of Africa. On the contrary, P. boisei they were small-brained, with large teeth and jaws, apparently adapted to eating chewy foods such as grasses and grasses.

Hatala and his team then analyzed other known remains found in the same region and time period and found that they matched one species or another. “We see a similar pattern at many other sites, and they can last more than 100,000 years,” he says. “These two species seem to have coexisted in the same immediate landscape for a long time.”

“We think there might have been a low or neutral level of competition between them if they were able to coexist for more than 100,000 years,” says Hatala. Previous studies have suggested that the two eat different foods. Unlike P. boisei, H. erectus It is believed that he ate a varied diet that included hunting large animals.

“Both could create their own existence in this shared landscape,” says Hatala. Later, it may have been driven by environmental changes P. boisei to extinction, while being more adaptable H. erectus he survived.