Evolution expert Charles Darwin and others acknowledged the close evolutionary link between humans, chimpanzees, and gorillas based on their shared anatomies, raising some big questions: how are humans related to other primates, and how exactly did early humans move? Research by a professor at A&M University in Texas may provide some answers.
Thomas Cody Prang, an assistant professor of anthropology, and his colleagues studied the skeletal remains of Ardipithecus ramidus (“Ardi”
Researchers are comparing the shape of Ardi’s hand with hundreds of other specimens of hands representing recent humans, monkeys and monkeys (measured from bones in museum collections around the world) to make comparisons of the type of locomotor behavior used by the earliest hominins (fossils). human relatives).
The results provide evidence of how early humans began to walk upright and make similar movements that all humans perform today.
This finding is described in a study published in this issue of Scientific progress.
“Bone shape reflects adaptation to certain habits or lifestyles – such as the movement of primates – and by drawing links between bone form and behavior between living forms, we can infer the behavior of extinct species, such as Ardi, that we can.” directly, Prang said.
We also found evidence of a major evolutionary “leap” between Ardi’s arm type and all later hominin arms, including Lucy’s (a well-preserved 3.2 million-year-old skeleton found in the same area in the 70s). This “evolutionary leap” occurs at a critical time when hominins develop adaptations to a more human-like form of upright walking and the earliest evidence for the production of stones for hominin tools and the use of stone tools such as cutting scars on animal fossils. , are found. “
Prang said the fact that Ardi represents an earlier stage in human evolutionary history is important because it potentially illuminates the species of ancestor from which humans and chimpanzees evolved.
“Our study supports a classic idea first proposed by Charles Darwin in 1871, when he had no fossils or understanding of genetics that the use of hands and upper limbs for manipulation appeared in early human relatives in connection with standing walking, ”he said. “The evolution of human arms and legs probably happened in a correlated way.”
Because Ardi is such an ancient species, it can retain skeletal features that were present in the last common ancestor of humans and chimpanzees. If this is true, it may help researchers place the origins of the human line – in addition to upright walking – in a clearer light.
“This potentially brings us one step closer to explaining how and why people developed our form of upright walking,” Prang said.
He added that the major change in the anatomy of the hands between Ardi and all later hominins occurred at a time between approximately 4.4 and 3.3 million years, coinciding with the earliest evidence of the loss of the big toe in the human evolution. This also coincides with the earliest known stone tools and stone-carved animal fossils.
He said it appears to be a significant change in the lifestyle and behavior of human relatives during this period.
“We suggest that this include the evolution of more advanced upright walking, which has allowed human hands to be modified by the evolutionary process of improved manual manipulation, possibly involving stone tools,” Prang said.
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Thomas C. Prang et al, Ardipithecus hand provides evidence that humans and chimpanzees evolved from a precursor with suspension adaptations, Scientific progress (2021). DOI: 10.1126 / sciadv.abf2474
Provided by the University of Texas A&M
Quote: A 4.4-million-year-old skeleton could reveal how early humans began to walk upright (2021, February 25), extracted on February 25, 2021 from https://phys.org/news/2021-02- million-year-old-skeleton -reveal-early-people.html
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