Foraging in trees might have pushed human ancestors to walk on two feet

Foraging in trees might have pushed human ancestors to walk on two feet

Although walking on the moon is often hailed as one the greatest human achievements it’s likely that biological anthropologists would say it was the ability to stand upright on two legs. It is still unknown what drove the shift in locomotor behavior in our early human ancestors. A new study was published in today’s issue. Science Advances It is suggested that our ancestors switched to two-footed movement to be able to forage on tree branches for food. These research findings could change a long-held theory about human bipedalism.

“Bipedalism is a key feature of the human lineage. It is the first thing that separates our fossil ancestors and other apes. Rhianna Drummond Clarke, the study’s principal author and a Ph.D. student in biological anthropology at the University of Kent, UK, said that understanding how it evolved is crucial to understanding what made us human.

The authors explain that if something threatened a basic need, such as food, water, and shelter, evolutionary pressures to survive would have forced our ancestors to adapt. Anthrologists support the “savanna hypothesis” as the most plausible explanation. This is where our ancestors adapted to changing environments by walking on two feet. Around 10 to 2.5 million years old, tropical forests started shifting into open savannas. The number of food options was limited by the loss of trees, which forced human ancestors from gathering food on the ground to forage in trees. Bipedalism is believed to have resulted from this habitat transition.

Some anthropologists are skeptical about this explanation. The dwindling forest may have influenced, but not necessarily driven us to two-legged walking. Alexander Piel, a senior study author and biological anthropologist at University College London.

One reason that there hasn’t been an answer is the fact that fossil records of our ancestors from the time that human bipedalism was first discovered are very limited. The evidence that is available doesn’t seem align with the savanna hypothesis. Past research has shown that fossils were not found in open grasslands, but in ancient habitats. This is based on past research. Wooded areas. The hominin is even more amazing. fossils That are available show signs Forelimbs that look like apes That would have allowed you to swing and climb trees. Piel believes in an “arboreal hypothesis”, which states that humans evolved to stand upright to forage for food in trees.

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The current study involved the study of 13 chimpanzees’ behavior in the Issa savannas, Tanzania. This was done over 15 months. Piel says that the Issa community was chosen because it is a closely related ape and lives in a habitat similar to the one from a million centuries ago. “What better place than to examine some of the key features and the pressures that shaped their evolution that define our species?”

Primate species, the Issa chimpanzees, spend approximately half their lives in trees and the rest on the ground. The study authors wanted the researchers to determine if living in a savanna increases their time on the ground compared to living in forested habitats. The results showed that Issa Chimpanzees spent the same amount of time in trees, regardless of whether they were in a forest setting or a savanna one. The locomotion data from other chimpanzee populations revealed that Issa chimpanzees spent a lot more time in trees than those who live in forested areas. Their behavior was most similar to that of Kibale chimpanzees who live in forests.

Researchers noticed something unusual in chimps when it comes to standing upright. Issa chimpanzees were more likely to be seen walking on their two feet higher up in the trees than they were on the ground. Bipedal movement was often seen when searching for food in a forest. These results suggest that bipedalism may have evolved as a way to spend more of your time searching for food in trees in the savanna.

A chimp stands upright on his hind legs, up in trees.
An adult male chimpanzee stands upright to navigate the flexible branches of the open canopy in the Issa Valley savanna habitat. Rhianna C. Drummond-Clarke

Scott WilliamsA New York University evolutionary morphologist and paleoanthropologist, who was not associated with the study, said that this research is a “fantastic contribution of locomotional data.” He maintains that bipedalism evolved primarily from savannas. He believes that the data showing that savanna Issa-chimps engage in bipedal locomotion between 4 and 25 times more than those in forests can be read differently. “This suggests almost the opposite of the interpretation by the authors–that savanna habitats were selected for bipedal locomotion in early hominins.” Williams suggests that chimps might have spent more time in trees searching for food because they may have been safer than foraging on the ground in open savanna environments.

Some anthropologists are open to the possibility that bipedalism is a result of more than changing landscapes. Alyssa CrittendenProfessor of Anthropology at the University of Nevada in Las Vegas,, said that the study supports the arboreal hypothesis because of the location of the research. In an email, she stated that while discussions on bipedalism often focus on savanna ecologies, it is rare that we have the opportunity learn from chimpanzees who live in such habitats. PopSci. “This important study supports the hypothesis that hominin bipedalism evolved in an arboreal environment and continued long after hominids started living in more open areas with less vegetation.”

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Williams points out that despite the location being very similar to the prehistoric landscape Williams also points out that the arboreal hypothesis does not explain why non-tree dwellers, such as kangaroos and hopping mice, have evolved to have bipedal movement.

“The traits that we identify in hominins are…” Ardipithecus, Australopithecus, Homo Williams states that they are clearly related to terrestrial bipedalism, and not arboreal bipedalism.” “Most species seem to have retained some of their genes,” Williams says. [other] Arboreality adaptations, which are useful when food is in trees and predators on the ground.

The next step in the research of the authors is to study the resources available for Issa Chimpanzees. This will help us understand why our ancestors spent so many hours in trees, given the limited supply of savannas.

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