Why were the previous expansions out of Africa dead ends? Presumably they mean ones that ended up being Denisovans and Florensis.
They were very successful, at least, some of them. Not as good as us, but expanding to another continent and surviving there for hundreds of thousands of years is not exactly a complete failure. Unfortunately for this planet, our species is just too good at procreating and killing everything on our way
In a general sense it’s more like unfortunately for us, the planet will endure after we die as a species and then blossom again eventually, just without us.
Barring some cataclysmic natural event beyond our control, humans will cause the extinction of humans (or not).
Richard Dawkins would say that descendants are common. Ancestors are rare. Most populations of all species leave little or no genetic trace.
The first human radiation was georgicus... 1.8mya. That is arguably the original homo species. Arguably pre-homo, if not for some long legged or large brained individuals in the tribe.
They may be ancestral to later Eurasian species of homo... even the erectus lineage as a whole. But likely not.... because ancestors are rare.
The recent/last great out of Africa population is one of those rare ancestor populations. Most lineages are dead ends.
We don't know much about them. We don't know which bones are theirs, or where they lived before dispersal. We don't know if they had been a distinct population for long... or a recent admixture homogenized before dispersal.
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.
Evolution has a quite different view of the "linearity" of "progress".
Your arguments do not support your belief about that ancestor of apes at all.
jdougan•7mo ago