African apes and the evolutionary history of orthogrady and bipedalism
Scott A Williams cs 2023 Yb AJPA doi org/10.1002/ajpa.24684

Since the first discovery of human fossils in the mid-19th cent., 2 subjects have driven the majority of discourse in the study of human origins:
- our phylogenetic relationship to living & fossil apes,
- the ancestral locomotor behaviors preceding BPism.
... there exists a rich hominin fossil record, and the acceptance of chimps & bonobos as our closest living relatives is nearly universal,
yet consensus about the ancestral condition from which hominins evolved remains elusive.
The earliest known hominins are generally congruent with parsimonious inferences of an African ape-like LCA,
but our more distantly related Miocene ape cousins are frequently invoked as evidence in favor of more complex scenarios that require substantial homoplasy.
Debate over these alternatives suggests:
how we infer ancestral nodes, and weigh evidence to test their relative likelihoods, remains a stumbling block.
Here we argue: a key contributor to this impasse includes the history of terminology ass.x positional behavior, which has become confused over the last century.
We aim to clarify positional behavior concepts, and contextualize KWing & other forms of posture & locomotion chimpanzees & gorillas engage in,
and argue: the presence of homoplasy in ape evolution does not alter the weight of evidence in favor of an African ape-like evolutionary history of hominins.

________

We humans never had Afr.apelike ancestors: KWing evolved in parallel in Gorilla//Pan!
Homoplasy, parallel or even convergent evolution is very frequent, and in fact proof that Darwinian evolution is correct.

BPism precedes KWing, of course:
the evolution from ventral (palmigrady) to dorsal (KWing) QP hand-walking requires an intermediate phase, where the hands ware seldom used: orthogrady.
Miocene apes were already orthograde & BP, of course:
they waded upright in swamp forests & climbed vertically arms overhead in the branches above the swamp,
they still do this now+then, google e.g. "bonobo wading" (for waterlilies) or "gorilla wading" (for sedges).
Google "aquarboreal".

Besides, aquarborealism not only easily evolves into KWing (P//G) but OTOH also into Pleistocene Homo's locomotion,
google e.g. "human evolution Verhaegen".

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littor...@gmail.com wrote:

BPism precedes KWing, of course:
the evolution from ventral (palmigrady) to dorsal (KWing) QP hand-walking requires an intermediate phase, where the hands ware seldom used: orthogrady.
Miocene apes were already orthograde & BP, of course:
they waded upright in swamp forests & climbed vertically arms overhead in the branches above the swamp,
they still do this now+then, google e.g. "bonobo wading" (for waterlilies) or "gorilla wading" (for sedges).
Google "aquarboreal".

Besides, aquarborealism not only easily evolves into KWing (P//G) but OTOH also into Pleistocene Homo's locomotion,
google e.g. "human evolution Verhaegen".

I think at this point the only argument remaining is when bipedalism evolved.

If Lucy's ilk are "Established" as bipedal, from the Laetoli footprints, and Sahelanthropus tchadensis appears MORE not less adapted to bipedalism
in important ways, then we're already talking 7+ million years ago.

So, throwing out guesses here... 8.7 million years ago.

Why? Because Yellowstone erupted and it was earth shattering.

https://en.wikipedia.org/wiki/Tortonian

It was a global catastrophe.

It was, in any and every real sense, the kind of "Sink or swim" event where populations had to evolve or die -- "Publish or Perish."

And that's the sort of thing which is going to heavily favor populations
that both live towards the equator AND live along the ocean. Not inland,
the coast. When you have a super volcanic eruption on that scale you...

#1. Don't want to be in the northern hemisphere. That's who is always
going to take the brunt of it, recover last.

#2. You want to be as close to the equator as you can, because when
the Volcanic Winter hits you want as much padding as you can possibly
get.

#3. You want to be on the coast. The ocean moderates the climate. The
coast is cooler in the summer because it takes a hell of a lot of energy
to warm up all that water. And it's warmer in the winter because it's
holding a lot of energy, releasing it.

#4. Seafood is orders of magnitude more stable than anything you're
going to find inland. A mega disaster strikes, vegetation dies, all the
animals dependent upon it dies... the predators dependent upon them.

So that's my best guess for you: 8.7 million years.

I don't like linear models. I don't like "They stood upright and then six million years later they became us."

I'm not saying anything similar to that.

But I am saying is this is my best guess for the start of "Aquatic Ape" and bipedalism: 8.7 million years ago.

Ideas/criticisms welcome



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