> Our closest living relatives — chimpanzees and bonobos — are confined to a belt of Central African forests.

Gorillas are similarly ecologically constrained. But, the ancestor of all African apes was (likely) more like us, adaptive. At the least... they were a species or complex with a very large, multicontinental range.

Neanderthals lived in a very wide range of habitats. Northern Russia during an ice age. But also.. Israel. Gibraltar. Denisovans also had an extremely varied range... including high altitudes where most of the flora and fauna is specialized.

I'm not negating the idea that 70kya our ancestral African "tribe" spread into new ecozones. They spread all over the world. No surprise that this was an adaptive population.

But... I think humans as a generalist species that can specialize using culture... I think this goes way back.

It explains how the earliest arguably-homo species (habilis-georgicus) appears in the caucus so soon after evolving in Africa. 1.8mya.

Gorillas aren't going to show up in europe.

It's the other way around: some apes left the jungle and started our lineage. Erectus, who first left Africa, was a species of early humans, not the common ancestor of all apes, he lived long after we branched from chimpanzees

It reminds me of how our knuckle-walking ape relatives likely evolved to do so _from_ bipedalism: https://en.wikipedia.org/wiki/Knuckle-walking#Evolution_of_k...

Evolution has a quite different view of the "linearity" of "progress".

It would be hard to explain orangutans in Indonesia if the great ape common ancestor wasn't particularly good at moving to new niches. Maybe pongo and homo independently developed the skills though.

Neanderthals and Denisovans are very, very close to H. sapiens, and prove nothing about the LUCA of Primates.

Your arguments do not support your belief about that ancestor of apes at all.

So perhaps the other great apes evolved more into specialists while out branch continued generalizing?