Human Migration and Evolution
Migration has, through human prehistory, both spurred and slowed human evolution. Prehistoric humans were hunter-gatherers. Contingent on the local flora for something approaching seventy percent of their total calories, they hunted for the leftover thirty percent.
Fauna migrate as least as well as humans do, but flora is tied to their environment. The 3 determinants of floral population are mean temperature, available moisture, and distance from the equator. Mean temperature is a consequence of elevation – the higher a place, the less warm, and the inverse tends also to be true. Even the most basic gardener knows that some plants can and others can’t withstand freezing temperatures. Available moisture is self-explanatory.
