Material conditions—differences in the environment and food sources---do
not alone create cultural changes. That would be Marxism. Cultural changes
also take place by diffusion (borrowing) and inventions by individual
leaders (like Ray with Neanderthin)

Sociobiology says, for example, that religious ethics, such as mutual love
and self-sacrifice, were created because they helped the group be
successful in survival and reproduction. Without these ethics groups tended
to fall apart. When it came to food, people ate what was available, or what
they could invent, or copy, to help them survive successfully. Grains,
though perhaps necessary for survival for some people at some point, turned
out to be unhealthy for humans.

Now it's become a very crowded planet and grass fed meat is hard to come by
for all, so grains continue, unhealthy as they are. How to we get around
this problem? Do we have to accept unequal-in-health food conditions?....A
variety of people and food is natural, I suppose.

Ken