>Also, slightly contradictarily, natural selection/evolution don't provide much pressure for a species to change after it's gotten wildly successful.
It provides pressure for the species to change to adapt to its wild success (e.g. to become "fat and lazy"). That development of the wild success may also lead to significantly changed conditions (e.g. global warming as a result of the wild success of homo sapiens)
>Have we had any physiological brain changes since agriculture?
it is only 10000 years, and yes, we had. The physiological changes are observable even for the last 100 years.
>And now that medicine is becoming so effective, natural selection doesn't really work on the fitness of people, just their ability to have more children.
that phrase sounds like oxymoron.
Anyway, natural selection is like Newton's laws - it can't be turned off. It works non-stop. It ensures fitness to whatever current conditions are. In particular, right now, it ensures fitness of human species to the condition of "medicine is becoming so effective".
I'd counter with: Natural selection in the classic sense ceases to have any meaning in an environment where all members of a species survive into adolescence, and reproduce.
Now natural selection is still occurring, but it may be leading to specization rather than intra-species evolution.
>I'd counter with: Natural selection in the classic sense ceases to have any meaning in an environment where all members of a species survive into adolescence, and reproduce.
That just even more shifts the weight of human species selection machinery from r-selection (muliple, and thus more diverse, offsprinfgs, i.e. selection mainly by the best static fit) to K-selection - selection mainly by the best ability for behavioral adaptation. Ie. the natural selection, in the classical sense, is still there. It is the most important traits for defining best fit that are changing.
It provides pressure for the species to change to adapt to its wild success (e.g. to become "fat and lazy"). That development of the wild success may also lead to significantly changed conditions (e.g. global warming as a result of the wild success of homo sapiens)
>Have we had any physiological brain changes since agriculture?
it is only 10000 years, and yes, we had. The physiological changes are observable even for the last 100 years.
>And now that medicine is becoming so effective, natural selection doesn't really work on the fitness of people, just their ability to have more children.
that phrase sounds like oxymoron.
Anyway, natural selection is like Newton's laws - it can't be turned off. It works non-stop. It ensures fitness to whatever current conditions are. In particular, right now, it ensures fitness of human species to the condition of "medicine is becoming so effective".