Scientists find 1.5 million-year-old footprints of two different types of human ancestors in the same location – Eurasia Review

More than a million years ago, two completely different species of hominins may have encountered each other while searching for food in a hot, wildlife-filled savannah on the shores of what would become Lake Turkana in Kenya.

Scientists know this because they examined 1.5 million-year-old fossils they unearthed and concluded they were the first example of two sets of hominin footprints made around the same time were created on an old lake shore. The discovery will provide further insight into human evolution and the way species cooperated and competed with each other, the scientists said.

“Hominin” is a newer term that describes a subdivision of the larger category of hominids. Hominins include all extinct and living organisms that belong to the human lineage that arose after the split from the ancestors of the great apes. This is believed to have happened around 6 to 7 million years ago.

The discovery, published today in Science provides clear evidence that different hominin species lived simultaneously in time and space and overlapped as they evaded predators and met the challenges of obtaining food safely in the ancient African landscape. Hominins belonging to the species Homo erectus And Paranthropus boisei, The two most common living human species of the Pleistocene left the traces, the researchers said.

“Their presence on the same surface, close in time, puts the two species at the lake edge and sharing the same habitat,” said Craig Feibel, an author of the study and a professor in the Department of Earth and Planetary Sciences Department of Anthropology at Rutgers School of Arts and Sciences.

Feibel, who has been researching this area of ​​northern Kenya, a rich fossil site, since 1981, used his expertise in stratigraphy and dating to prove the geological age of the fossils to 1.5 million years ago. He also interpreted the depositional setting of the footprint surface, narrowed down the path of the tracers to a few hours, and showed that they were formed in the exact location of soft sediment where they were found.

When the hominins didn’t cross paths, they crossed the coast within hours of each other, Feibel said.

While skeletal fossils have long provided the most important evidence for the study of human evolution, new data from fossil footprints reveal fascinating details about the development of human anatomy and locomotion and provide further clues about ancient human behaviors and environments, said Kevin Hatala, lead study author and associate professor of biology at Chatham University in Pittsburgh, Pennsylvania.

“Fossil footprints are exciting because they provide vivid snapshots that bring our fossil relatives to life,” said Hatala, who has been studying human footprints since 2012. “With this type of data, we can see how living individuals millions of years ago moved in their environment and possibly interacted with each other or even with other animals. That’s something we can’t really achieve with bones or stone tools.”

Hatala, an expert in foot anatomy, noted that the species’ footprints reflected different patterns of anatomy and locomotion. He and several co-authors distinguished one set of footprints from others using new methods they recently developed to perform 3D analysis.

“In biological anthropology, we are always interested in finding new ways to extract behavior from the fossil record, and this is a great example,” said Rebecca Ferrell, program director at the National Science Foundation, which funded this part of the research. “The team used cutting-edge 3D imaging technologies to create an entirely new way of looking at footprints, helping us understand human evolution and the role of collaboration and competition in shaping our evolutionary journey.”

Feibel described the discovery as “a bit of a coincidence.” Researchers discovered the fossil footprints in 2021, when a team organized by Louise Leakey, a third-generation paleontologist, granddaughter of Louis Leakey and daughter of Richard Leakey, discovered fossil bones at the site.

The field team, led by Cyprian Nyete, consists mainly of a group of well-trained Kenyans who live locally and search the landscape after heavy rains. They noticed fossils on the surface and dug to find the source. While cleaning the top layer of a bed, Richard Loki, one of the excavators, noticed some huge bird tracks and then discovered the first human footprint. Leakey then coordinated a team that excavated the surface of the footprint in July 2022.

Feibel noted that there has long been a hypothesis that these fossil human species coexisted. According to fossil finds Homo erectusa direct ancestor of humans, survived another 1 million years. Paranthropus boiseibut died out within the next few hundred thousand years. Scientists don’t know why.

Both species had an upright posture, were bipedal and very mobile. Little is still known about how these coexisting species interacted, both culturally and reproductively.

The footprints are significant, Feibel said, because they fall into the category of “trace fossils” — which can include footprints, nests and caves. Trace fossils are not part of an organism but provide clues about behavior. Body fossils such as bones and teeth provide evidence of past life but can be easily moved by water or predators.

Trace fossils cannot be moved, Feibel said.

“This proves beyond a doubt that not one but two different hominins walked on the same surface literally hours apart from each other,” Feibel said. “The idea that they lived at the same time is perhaps no surprise. But this is the first time it is being demonstrated. I think this is really huge.”