The origin of the ant and the grasshopper tale?
These is a tremendous incentive to be an ant if you live in a climate with a real winter where you have to rely on food you have put away and you have to have a heating source stored up (firewood)
The peoples and tribes who failed this test died off
If you live in a more moderate climate without these challenges the brain doesn't need to develop so much and you can have a "live for today" attitude. No need to plan for the future when you have no winter. Dry seasons can be a challenge to survival that you have to plan for and so can living in the desert. You can find both in the tropics and other places with no winter