SUMMARY: Careful Climbing in the Miocene: The Forelimbs of Ardipithecus ramidus and Humans Are Primitive
When I was in Myanmar a few years ago, I got to hold hands with several extant monkeys and apes. Believe me when I say that the weirdest part of being face to face with a non-human primate is how similar their hands look and feel up close. They are, however, specialized in many ways that ours aren’t. During climbing, apes must support their body weight, right? It’s like when we were little and played on the monkey bars, except they do this on uneven and sometimes unreliable tree branches for extended amounts of time. Because of this, they have elongated palms and fingers and stiffer hand joints, which leaves us with shorter palms and more mobile wrists.
Ape’s terrestrial locomotion, typically knuckle walking, is typically thought of as primitive. The nearly complete Ardipithicus hand fossils put this into question. Ardipithicus hands were much more flexible than those of African apes, with the midcarpal joint being even more flexible than our own. Basically, the human hand is likely the more primitive between humans and apes. As I’ve said in past blogs, non-human primate evolution needs to be studied separately from human evolution because we’ve been on our own evolutionary paths for so long. Lovejoy points out that “it is African apes who have evolved so extensively since we shared our last common ancestor, not humans or our immediate hominid ancestors” (70).
The paper goes on to break down several parts of the hand fossils, which all point to early Pliocine hominids lacking the derived forelimb features of extant apes. Finding nearly complete and intact hand fossil sets for Ardi is a huge deal, because it allows new connections to be made about how early hominids moved around. For this paper, the most probably hypothesis drawn is that early hominids were never evolutionarily pushed towards adaptations for suspension, vertical climbing or knuckle walking.
For fun here’s me holding hands with a western hoolock gibbon
nice post! love the photo and the story behind it. and the quote you took from the paper is perfect encapusliton of their theory. i wonder if we know more about hominoid origins now (11 years later) and how the data fit these models. But yes, thinking about how the LCA might have not been chimp-like is really impt in our models of human origins
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