Careful Climbing in the Miocene- Lovejoy2009

https://www.youtube.com/watch?v=zyl6eoU-3Rg
First three minutes of this video are a good preview for this paper: https://app.perusall.com/courses/human-evolution-3/99d_lovejoy_et_al_2009_careful-climbing-in-the-miocene

Good information about rays and mobility:

https://www.orthonet.on.ca/core-topics/hand-and-wrist-topics/hand-anatomy-1/




Ardipithecus ramidus hand



When determining the defining features of a species and where it fits in evolutionary history, we typically think of looking at the skull, spine, teeth, jaw and probably some leg bones, but an important discovery was made studying the hand of Ardipithecus ramidus. This makes sense because some defining characteristics of primates are grasping hands and highly mobile forelimbs. Bones in other areas pointed to a common ancestor that had more climbing abilities and spent more time in the trees (suspensory locomotion, vertical climbing, knuckle-walking) than we do today. The nearly complete fossils of Ardipithecus ramidus' hand show that we are much closer to our relative than previously believed. Studies published in 2009 point to a human hand is probably more primitive than a chimpanzee hand is. This amazes me because whenever scientists are studying chimpanzees and claim that studying them will tell us about our past, it is assumed that the chimpanzees are the more primitive of the two.
There are some key differences (very condensed because I have not taken human anatomy or osteology and can barely tell phalanges from a femur) that tell us some interesting things about the potential locomotion of our ancestors:
-Human palms are shorter and our wrists are more mobile which helps us to have a "power grip" (the important grasping hands that I mentioned before)
-Ardipithecus hand fossils show that they did not knuckle walk or have the adaptations for reducing injuries that come with climbing/spending time in trees that great apes have
-"We now know that our earliest ancestors only had to slightly enlarge their thumbs and shorted their fingers to greatly improve their dexterity for tool-using" (Lovejoy et. al, 2009)
-Ardipithecus ramidus was both terrestrially bipedal and arboreally capable
-Thickening of CJC ligaments is a sign that a species engages in suspension (examples are Pongo, Pan, and Gorilla)
-The CJC of Ardipithecus suggests that "the earliest hominids and their immediate ancestors did not engage in habitual suspension or vertical climbing"


Since the "Careful Climbing in the Miocene : The Forelimbs of Ardipithecus ramidus and Humans Are Primitive" scientific paper came out in 2009, I figured that maybe some new information came out (because the goal is to keep professors and students always wondering if the iformation is still relevent, right?) so I looked into some newer articles. One I came across, "The African ape-like foot of Ardipithecus ramidus and its indications for the origin of bipedalism," which is from 2019 makes it seem like the Lovejoy et. al paper is not the whole story (ofc).
"The hand of Ar. ramidus was argued not to display traits associated with forelimb suspension in extant taxa or show evidence of a knuckle-walking ancestry (White et al., 2015; Lovejoy et al., 2009b; Almécija et al., 2015), but many of those observations have not yet been independently validated. The terrestrial specializations of the hominine foot are likely to be homologous because they are present in Ar. ramidus and they are consistent with model-based ancestral estimations. Critically, they carry a similar set of implications for the origin of bipedalism regardless of the terrestrial hand posture of the Homo-Pan LCA."


So....vertical climbing? Semi-terrestrial quadrupedalism? More chimp than the Ardipithecus ramidus hand shows?
https://elifesciences.org/articles/44433

And since I think memes are perfect I will add some more I think are funny and relevant...