Evolution and humans: all over Africa (Evolution)

by dhw, Wednesday, May 02, 2018, 14:39 (2395 days ago) @ David Turell

dhw: I would suggest that if organisms are thriving, they don’t need to change, and so it takes something special to trigger advances: e.g. a stroke of genius that makes life even better (tools, weapons), or a climate change that offers new opportunities but still needs individual geniuses to exploit the new potential for improvement.

DAVID: Chimps are still thriving, but Lucy and her bunch came down from the trees. Your answer does not explain Lucy. The trees were not satisfying?

Changes take place in individuals. Lucy’s bunch came down from the trees – maybe there were problems where they lived. Other chimps didn’t have problems and stayed in the trees. Common descent does not mean that every single pre-species turns into the new species.

DAVID: The long pauses at each stage of new brain size are compatible with having to learn to use the new size, opposite to your view.

dhw: If no advances are made, what is being learned? You only learn what already exists, so there is no need for expansion! Hence stasis.

DAVID: If a brain is built for more advanced thought by the s/s/c, why not start using it?

The obvious answer is that the new size was caused by the need for more capacity. Once the brain had expanded sufficiently to implement the new concept (now pre-sapiens could make his spear), there was no further need for change until the next major concept came along. The sapiens brain reached optimal size, and so when new concepts came along, it increased the efficiency of its complexification (so much so that it actually shrank).

DAVID: […] My point is simple. Its not just climate, but as usual in discussion about evolution, multifactorial issues to be considered.

dhw: I’m sure this is true, but as above, it is you who have constantly asked why there was a long period of stasis and then a sudden burst 12,000 years ago. […]

DAVID: Of course climate was a major factor, but given some more reflection I noted that there were previous good climate periods that were not used, and I noted that the best civilized ideas came from those who migrated north to colder climes. So which climate is best for advanced thinking? It is funny that a new single point you seize upon is a be all and end all for your theory, when lots of other factors need to be considered. Multifactorial is the proper approach.

It is not the be-all and end-all, and I agree with the reflections you came up with after initially agreeing with the reflections of the researchers. Your point all along has been that there were some 300,000 years of stasis, and then there was a sudden breakthrough. This coincides with a major change in climate. Maybe in earlier periods there were no geniuses around to realize the potential. Do please tell us your own explanation. Once the turning point had come 12,000 years ago, maybe the relatively colder climes created more problems than the warmer climes (e.g. how to keep warm): you need more sophisticated forms of dwelling, which is a not insignificant factor in the advance of civilisation.