Footprints offer a rare look at ancient human relatives crossing paths

Two ancient hominid species with a bit different gaits crossed paths in East Africa.

Footprints preserved on what became once a muddy lakeshore indicate that both species, each built to walk in its own way, hung on the market around 1.5 million years ago.

Newly revealed foot impressions on the northern Kenyan site, and footprints previously unearthed at a detailed-by location, offer glimpses of coexistence and possibly direct contacts between ancient hominid species over a span of up to 200,000 years, say paleoanthropologist Kevin Hatala of Chatham University in Pittsburgh and colleagues.

Two patterns of upright walking appear in foot tracks found along an ancient lake at Koobi Fora, a bunch of deposits on the eastern margin of present-day Lake Turkana, the scientists report within the Nov. 29 Science. A comparable distinction applies to footprints excavated in fieldwork led by Hatala nearly twenty years ago at Ileret, every other roughly 1.5-million-year-old Kenyan site, the team says (SN: 2/26/09).

Prints displaying signs of a humanlike foot anatomy and gait belonged to Homo erectus, a likely direct ancestor of H. sapiens, Hatala says. H. erectus, which lived from nearly 2 million to roughly 117,000 years ago, ate quite an exceptional deal of energy-rich foods to make stronger its large brain (SN: 12/18/19).

Impressions showing fewer similarities to the feet and striding pattern of people as of late belonged to Paranthropus boisei, the investigators suspect. Small-brained, big-jawed P. boisei, which dates to between 2.3 million and 1.2 million years ago, had a taste for grasses and flowering plant life referred to as sedges (SN: 5/2/Eleven).

Researchers have known for nearly 50 years that East African fossils of H. erectus and P. boisei date to about the same time in nearby locations. But those fossils accumulated slowly, and researchers may perhaps now not pin down whether both species resided simultaneously within the same place.

Preserved footprints analyzed within the new learn about solve that problem, says paleoanthropologist Jeremy DeSilva of Dartmouth College, who became now not section of Hatala’s team. “We now know with walk in the park that these two different types of [hominids] shared the same landscape and walked with a bit different gaits.”

Closely spaced footprints on the new Koobi Fora site, consisting of three H. erectus impressions and a trail of 12 impressions left by a P. boisei individual, were formed after which buried by lakeside sediments within some days at most, the researchers say. So were footprints of large birds and animals equivalent to antelopes and wild horses.

“Whether Homo and Paranthropus individuals passed during the area hours to a day apart, or seconds to a minute apart, they'd have been aware about each other’s existence on this shared landscape,” Hatala says.

If chimpanzees and gorillas can feed peacefully within the same tree, then it’s you may that H. erectus and P. boisei “met in a 1.5-million-year-old version of a 7-Eleven store” at a lake that featured a number of desirable foods, says paleoanthropologist Bernard Wood of George Washington University in Washington, D.C. Wood did now not participate within the new learn about.

While the footprint findings suggest that H. erectus and P. boisei interacted, “whether or when they competed, potentially as a consequence of climatic or environmental pressures, can't be determined with the current evidence,” says paleoanthropologist Rita Sorrentino of the University of Bologna, Italy.

Whatever transpired along the ancient lakeshore, the Kenya footprints make stronger a previous report of divergent upright stances among even older hominid species. At Tanzania’s Laetoli site, 3.6-million-year-old footprints encompass humanlike impressions of Lucy’s species, Australopithecus afarensis and more chimplike tracks of an unidentified hominid species (SN: Eleven/13/24 ; SN: 12/1/21).

Around the world the new learn about, researchers when compared digital 3-d models of ancient hominid footprints and trackways to those made by people as of late — including Kenyan herders who infrequently or never wear shoes — traversing muddy soil like that along the ancient lake. Muddy tracks made by chimps provided an additional comparison.

Arches formed in human footprints when walking through mud look a terrific deal like those left by H. erectus on the ancient lake, Hatala says. That finding indicates that H. erectus moved its feet a terrific deal as we do now, he contends.

P. boisei footprints displayed a flatter arch than those of present-day humans, showing that their foot motions and perchance their foot anatomy differed from ours, Hatala says.

P. boisei — but now not H. erectus — also possessed big toes that splayed more than those of people as of late, but lower than observed in chimps. P. boisei’s big toes may have been more mobile than those of H. erectus or modern humans, Hatala suggests.

These foot disparities underlie two comparably effective different types of walking. “The trackway that we attribute to P. boisei reflects a fairly fast walking speed, and there is not any such thing as a evidence that they were off-balance or any less adept at walking on two legs than H. erectus,” Hatala says.