Human evolution: Ardipithecus ramidus. (Introduction)

by David Turell @, Thursday, November 19, 2020, 23:26 (10 days ago) @ David Turell

A very early hominin-like form happy to be in trees and on the ground:

https://www.sciencenews.org/article/evolutions-bad-girl

"First, White and his colleagues assert, Ardi’s unusual mix of apelike and monkeylike traits demolishes the long-standing assumption that today’s chimpanzees provide a reasonable model of either early hominids or the last common ancestor of people and chimps — an ancestor which some scientists suspect could even have been Ardi, if genetics-based estimates of when the split occurred are borne out.

"Second, the team concludes, Ardi trashes the idea that knuckle-walking or tree-hanging human ancestors evolved an upright gait to help them motor across wide ancient savannas. Her kind lived in wooded areas and split time between lumbering around on two legs hominid-style and cruising carefully along tree branches on grasping feet and the palms of the hands.

***

"In a third slap at scientific convention, Ardi fits a scenario in which a few closely related hominid lineages preceded the larger-brained Homo genus that emerged around 2.4 million years ago, White says. In contrast, many anthropologists think of hominid evolution as a bush composed of numerous lineages that, for the most part, died out.

***

"Ardi sports a peculiar skeletal medley that pushes chimps and gorillas out of the evolutionary spotlight, says anthropologist Owen Lovejoy, a member of White’s team. Ardi’s ancient remains indicate that the last common ancestor of humans and chimps must not have looked much like living chimps, as many researchers have assumed, asserts Lovejoy, of Kent State University in Ohio.

"Since a split 8 million years ago or so, chimps and gorillas have evolved along evolutionary paths that eventually produced specialized traits such as knuckle-walking, he says.

"In his opinion, Ardi indicates that a human-chimp ancestor had monkeylike limb proportions and feet, a flexible and unchimplike lower back, and an ability to move along tree branches on all fours, rather than swinging chimp-style from branch to branch and hanging by outstretched arms.

“'Ardipithecus, not living chimps, offers a remarkably good perspective on the last common ancestor,” he says. “We can’t modify the truth to make chimps more important.”

***

"Questions remain about whether Ardi had the build for regular upright walking — a clear marker of hominid status — or for primarily moving through trees, with occasional two-legged jaunts on the ground, adds anthropologist John Hawks of the University of Wisconsin–Madison.

"Consider Oreopithecus, an ape that lived on an island near Italy between 9 million and 7 million years ago. This creature possessed a pelvis, legs and feet that supported tree climbing as well as slow and somewhat stilted walking.

***

"If Ardipithecus adopted upright walking in a big way and was a precursor of the human lineage, Hawks posits, “it could be the first hominid or perhaps even the common ancestor of humans and chimps — if we take genetic studies seriously.” DNA analyses suggest that people and chimps split from a common ancestor between 5 million and 4.5 million years ago, around Ardi’s time."

Comment: This discussion of the earliest possible proto-hominins rules out the theory that tress disappeared and early forms had to learn to walk. These forms were prepared to do both at will. My point is I believe God designed them this way as a transitional form, not a change forced by natural changes to the environment as trees disappeared. Lucy was built the same way million of years later.


Complete thread:

 RSS Feed of thread

powered by my little forum