More than 1 million years before the early hominin known as Lucy crossed the Afar region of Ethiopia, the lesser known Ardipithecus ramidus wandered about the same area. Now a team of anthropologists has looked at the 4.4 million year old fossilized hand of a copy (affectionately called “Ardi”), claiming that the wandering of the human ancestors may have lurched more through the trees than previously thought.
Published Wednesday in the journal Science Advances, the team’s comparative analysis focuses on Ardi’s hand morphology in the context of extinct and extant relatives. In conversation with bones from elsewhere in our family tree, the properties of Ardi’s hand indicate when specific adaptations currently observed in different primates came about. In particular, knowing how Ardi moved brings us closer to knowing how we (homo sapiens) became a terrestrial, bipedal group of primates.
Thomas Cody Prang’s team, a biological anthropologist at Texas A&M University and lead author of the recent paper, noted some key features of Ardi’s hand that indicated how it may have moved. The phalanges of the specimen were long in proportion to its estimated body size. T.snake bones too bent inward, suggesting that the hand was prone to grabbing. “The fact that Ardipithecus overlaps in finger length and curvature with the most suspensory primates strongly implies that Ardipithecus was adapted to suspension,” said Prang.
“That doesn’t mean humans evolved from an ancestor that looked exactly like a chimpanzee,” he added in a phone call. It doesn’t mean that chimpanzees are living fossils, or that chimpanzees themselves haven’t evolved. Instead, our study shows that Ardipithecus, and probably the earliest fossil humans retain features of an ancestor most resembling chimpanzees and bonobos than any other living primate. “
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Originally excavated and described in the early 1990s by a team led by paleoanthropologist Tim White, Ardipithecus ramidus got more attention after the 2009 Description of a partial skeleton (nicknamed Ardi) in the journal Science White disagrees with the recent paper’s findings, based on the specific bones and specimens selected for analysis, and the exclusion of others.
“We do not dispute that the human hand has evolved over time. However, there is no new data or interpretations here, ”White wrote in an emailed statement. “We can’t take these authors seriously until they master the unique anatomy of Ardi’s hand, rather than using limited, selected measurements in a post-hoc argument that supports the discredited idea that our ancestors specifically chimpanzees. were like. “
If you’re relatively new to the debate about the nature of human origins and how our ancestors walked the ground or hurled through the trees, be prepared to hang out. In 2009, White’s team argued that Ardi lacked features that suggested it was fit for ape-like life; such absent traits include a morphological setup to swing through trees and climb them and walk on their knuckles. White’s team stated that the last common ancestor between humans and chimpanzees was probably very different from any extant ape.
Prang’s team argues the opposite in this article, arguing that the ancestor (which preceded Ardi) was closer to chimpanzees than anything else. They go on to report that more humanoid hands emerge first among the more famous Australopithecus afarensis, Lucy’s kind.
The scarcity of the fossil record doesn’t help much, although Ardi’s hand is more complete than that of the younger Lucy. Prang added that interpretations of Ardi’s hand are helpful in narrowing the goalposts of what may have been the circumstances of his evolution (and by proxy, which occurred before Ardi and after).
“It illustrates the point where in science we don’t prove something to be true. Instead, we reject hypotheses and alternatives that are likely to be untrue, ”said Prang. In this case, the hypothesis that humans evolved from an ancestor that had no suspensory characteristics, and an ancestor that was more ape-like, can be discarded based on Ardipithecus