Human evolution: savannah theory fading (Introduction)

by David Turell , Friday, February 28, 2025, 20:24 (6 days ago) @ dhw
edited by David Turell, Friday, February 28, 2025, 20:52

Savannah theory fading

dhw: Probably my fault, but I find all this a bit confusing. Does “humans” in the first quote mean different homos or just sapiens? The second quote suggests mating between different forms of humans led eventually to sapiens, and rainforests were only one type of habitat where they mixed. I don’t know how this solves the problem of sapiens’ origin. Or why it should disqualify the savannah theory. Maybe sapiens originated in the savannah and spread his seed in other environments, including back in the trees from which he descended. But I’m only asking for clarification of the statements made in this article. Did sapiens evolve from different homos mating, or did “readymade” sapiens mate with different homos?

DAVID: The 300,000 years ago proviso tells us this discussion is about sapiens. But it roughly covers intermating with Neaderthals and Denisovans.

dhw: In that case, it tells us nothing about the origin of sapiens. So how does intermating come to mean the savannah theory is fading?

You are disconnecting the early quotes in the article. This interbreeding was a late discussion not related to the earlier evidence of the study.

https://www.sciencenews.org/article/humans-african-rainforests-evolution

Another article: https://www.nature.com/articles/s41586-025-08613-y

"Humans emerged across Africa shortly before 300 thousand years ago (ka). Although this pan-African evolutionary process implicates diverse environments in the human story, the role of tropical forests remains poorly understood. Here we report a clear association between late Middle Pleistocene material culture and a wet tropical forest in southern Côte d’Ivoire, a region of present-day rainforest. Twinned optically stimulated luminescence and electron spin resonance dating methods constrain the onset of human occupations at Bété I to around 150 ka, linking them with Homo sapiens. Plant wax biomarker, stable isotope, phytolith and pollen analyses of associated sediments all point to a wet forest environment. The results represent the oldest yet known clear association between humans and this habitat type. The secure attribution of stone tool assemblages with the wet forest environment demonstrates that Africa’s forests were not a major ecological barrier for H. sapiens as early as around 150 ka.

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"Most importantly, however, our results confirm a deep-time connection between human evolution and tropical forest biomes, opening up a new chapter in the human past in which our species occupied dense, wet tropical forests much earlier than widely thought. This association confirms the predictions of the pan-African model of human evolution, and highlights the importance of Africa’s many regions and ecosystems in this process9."

Comment: based on this evidence we weren't forced out into savannahs