Human evolution: new discoveries in footprints (Introduction)

by David Turell , Friday, November 29, 2024, 17:33 (5 days ago) @ David Turell
edited by David Turell, Friday, November 29, 2024, 17:46

A new study of two tracks:

https://www.livescience.com/archaeology/1-5-million-year-old-footprints-reveal-our-homo...

"A set of footprints found at the site of Koobi Fora in Kenya reveals that our ancestor Homo erectus coexisted with a now-extinct bipedal hominin, Paranthropus boisei, 1.5 million years ago.

"In a fossil first, researchers have announced the discovery of 1.5 million-year-old footprints that prove two different pre-human species coexisted in Kenya. The tracks hint that the species may have interacted, raising new questions about the behavior of our ancestors.

"'I would expect the two species would have been aware of each other's existence on that landscape, and they probably would have recognized each other as being 'different,'" Kevin Hatala, a paleoanthropologist at Chatham University in Pennsylvania, told Live Science in an email.

"Hatala led a team of researchers who analyzed the footprints, which were found at the site of Koobi Fora on the eastern shore of Lake Turkana in 2021.

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"...researchers noticed something unique about the Koobi Fora trackway: Two bipeds with significantly different feet made the tracks along the lake margin within hours of one another.

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"Hatala and colleagues used 3D imaging techniques to evaluate the shape and movement of the trackmakers' feet. They found that two of the isolated footprints had high arches and a heel-to-toe footfall like modern humans. These footprints were likely made by our direct ancestor H. erectus, which had a very human-like body shape and size.

"However, the trackway of a dozen footprints revealed a different pattern. These tracks were much flatter, with a deeper forefoot strike compared to the heel strike. The researchers also noticed that the big toe was somewhat spread out and not fully in line with the foot as it is in humans, suggesting that the trackmaker was likely Paranthropus boisei, a heavily built australopithecine with large jaws and a divergent big toe.

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"The dozen footprints were made by a P. boisei individual who would have worn a U.S. men's size 8.5 or women's size 10 shoe, he said, while the isolated H. erectus footprints were smaller, roughly a women's size 4 to a men's size 6.

"Zach Throckmorton, a paleoanthropologist at Colorado State University who was not involved in the research, told Live Science in an email that "Hatala and colleagues' comparisons of foot impressions provide compelling and convincing evidence of the coexistence of Homo erectus and Paranthropus boisei at Koobi Fora in Kenya about 1.5 million years ago." Stability of the big toe is key to humans' ability to walk and run without foot problems, Throckmorton said, and "the less modern human-like trackway attributed to P. boisei lacks this critical adaptation."

"In addition to revealing important anatomical differences, the footprints hint at the behavior of our hominin ancestors.

"Footprints are a snapshot of a moment in time," Jeremy DeSilva, a paleoanthropologist at Dartmouth College who was not involved in the study, told Live Science in an email. This new research means "we now know with certainty that these two different kinds of hominins not only lived at the same time, but they shared the same landscape and walked with slightly different gaits," DeSilva said. "I wonder what they thought of each other and how they interacted, if at all."

"The interaction between P. boisei and H. erectus may have been akin to chimpanzees and gorillas, Hatala said — two species that have been seen engaging in both positive and negative social interactions. But as the newfound footprints were discovered within a few feet of one another and made within a short window of time, P. boisei and H. erectus may have been closer than we ever thought.

"'It is fascinating to think about what they would have thought when they saw each other, and how they would have interacted," Hatala said."

Comment: this amazing discovery supports Bechly's theory that several species of hominins existed at the same time so that it was not a simple progression of one form to another, but several types appearing contemporaneously, with the most advanced surviving. A comment from the original article is in full support:

"In the 1950s, evolutionary biologist Ernst Mayr famously argued that no two hominin species overlapped in time and that the group evolved in a linear, gradualistic way (8). The discovery of numerous and often contemporary new species since has allowed rejection of this hypothesis, but its influence has nonetheless persisted in many aspects of paleoanthropological research. Bipedalism, a hallmark of hominins, is one of these areas, and the suggestion that there were many forms of hominin bipedalism has only emerged relatively recently. Hatala et al. add to the growing body of evidence that the evolution of humans’ rare and highly specialized form of locomotion was just as complex and interesting as other, more well-studied areas of human evolutionary history, such as dietary behavior or growth and development."

https://www.science.org/doi/10.1126/science.adt8033