Looked at slightly differently, it appears that people in the North have a tendency to work hard and maximize the potential use of their surroundings. People in warmer, more Southern areas have a tendency to kick back and take it easy. "Don't worry, be happy."
If one applied the same laws of nature to humans as are applied to wild life, one could surmise that a hard life in a demanding climate removed the weak and the stupid from the human gene pool before they could reproduce. This, of course, strengthened the human population in the northern areas, but just the opposite happened in the southern areas where there was little or no "pressure" on the human population.
And perhaps the challenge of surviving a cold snowy winter produced people with greater thinking capacity. Food is not available year 'round. One must prepare and plan ahead. And your tribe had to prepare and store food for the winter