Human evolution; savannah theory fading (Introduction)

by David Turell , Monday, July 11, 2022, 17:23 (866 days ago) @ dhw

QUOTE: Although open environments played a major role in early human evolution, tropical forests and forest patches still provided a significant backdrop for our first hominin ancestors as they emerged in the tropics of Africa. They likely took their first tentative steps as bipedal mammals in tropical forests, or at least mixed forest habitats

dhw: The first sentence is crucial. The implication seems to be that our intelligent ancestors learned to take full advantage of whatever conditions they found themselves in. They were therefore not forced into change by the loss of their original forest habitat, but instead exploited BOTH environments.

DAVID: The evidence in this article shows we evolved to take advantage of new environments not as the result of new environments.

dhw: Sorry, but I don’t see any difference. New environments require new skills, so we could hardly develop the new skills until the new environments were there. The implication is that like all other cell communities that speciated, ours had the (perhaps God-given) intelligence and the plasticity to TAKE ADVANTAGE of new conditions (in my posts I often use the word “exploit”) in order to innovate and not just to adapt. However, the article doesn’t talk expressly of new environments. The last sentence of the quote leaves it open: the forests were definitely still there, but if open environments played a “major role”, then we certainly can’t discount “mixed” habitats.

DAVID: The point still is, and you haven't changed it, we evolved to use all sorts of environments in a warm jungle area (AFRICA) and then migrated all over to every climate on the Earth to easily adapt. The jungle origin did not provide that degree of adaptability for future use. The new big brain did just that and appeared in advance of migrations as the article shows.

dhw: The “point” of the article actually shifts from the origin of bipedalism to much wider considerations, and you have chosen to focus on the brain, but the sentence I have bolded moves in the same direction. The brain - which incidentally is a community of cell communities - had the (perhaps God-given) ABILITY to adapt and innovate, and it used this ABILITY to cope with and exploit new environments. Why do you say the “new big brain”? The early ancestors “dating from around 7 to 5 million years ago” had tiny brains compared to ours! We know that the brain responds to new requirements by complexifying, and so each exploitation/innovation (possibly triggered by migration to new environments), would have increased the brain’s complexity and in due course created the need for greater capacity. We needn’t go into the subject of expansion here, as we have dealt with it repeatedly elsewhere, but quite clearly our earliest ancestors’ brains can only have evolved into new bigger brains AFTER (and I would say as a result of) “their first tentative steps as bipedal mammals in tropical forests, or at least mixed forest habitats”.

The erectus brain developed in Africa and the erectus wandered all over the Earth handling new environments with ease. You can talk all around that without changing the import of that history. The brain came before all the required uses in subsequent migrations.