After reading the abstract of the paper mentioned here I started wondering, why did human groups migrate away from southerner (warmer) places towards the north which is far colder and has less possibilities to grow crops and wild animals to hunt?
Was the population density too high?
And after they migrated, what did they mostly survive on? Were they hunters-gatherers? Did they cultivate? Was it not more difficult to survive in colder climates?
Really? What if the better hunting grounds were taken? What if a rival tribe kept harassing another and people just didn’t want to fight? What if the ambitious youth didn’t agree with the tribal leaders, so they moved to make their own fortune?
At our core, we really haven’t changed all that much from our ancestors.