The increase in quantity and reliability of food supply mean that biological selection pressures became much, much less powerful.
Why would you think that? If anything this should make evolution more powerful in shaping us.
Humans are not just a species or a family of them, they where also an ecological neiche. A type of animal is stable or slowly changing in its form over millions or tens of millions of years (like say the crocodile), not because evolution can’t cook up massive changes in a much shorter time span but because over those eons the sweet spot of the various trade offs for the animal living in that part of the ecosystem don’t much change.
Let us in this light review Fischer’s fundamental theorem of natural selection:
“The rate of increase in the mean fitness of any organism at any time ascribable to natural selection acting through changes in gene frequencies is exactly equal to its genetic variance in fitness at that time”
In other words crocodiles also didn’t have much variance after being pushed for so long towards that sweet spot. The advent of both agriculture and modern medicine have massively changed the evolutionary trade offs. In other words it has moved the sweet spot from under our feet or at least moved it from where we used to be moving towards to a completely different place in the fitness landscape. Thus theoretically one should see massive differentials between the fitness of various populations of humans and between individuals in those populations.
Why would you think that? If anything this should make evolution more powerful in shaping us.
Humans are not just a species or a family of them, they where also an ecological neiche. A type of animal is stable or slowly changing in its form over millions or tens of millions of years (like say the crocodile), not because evolution can’t cook up massive changes in a much shorter time span but because over those eons the sweet spot of the various trade offs for the animal living in that part of the ecosystem don’t much change.
Let us in this light review Fischer’s fundamental theorem of natural selection:
In other words crocodiles also didn’t have much variance after being pushed for so long towards that sweet spot. The advent of both agriculture and modern medicine have massively changed the evolutionary trade offs. In other words it has moved the sweet spot from under our feet or at least moved it from where we used to be moving towards to a completely different place in the fitness landscape. Thus theoretically one should see massive differentials between the fitness of various populations of humans and between individuals in those populations.
And this precisely what we observe.