Cold temps don't make you smarter but they provide an adaptive advantage to smarter animals who can create better shelter, plan for food shortages, make better tools, strategize for hunting, learn quicker and communicate more effectively. Smarter animals survive to reproduce while others starve, freeze or get driven out by smarter ones.

tell that to a quad core ;)

Yes it does. Environmental pressures force long term critical thinking and ingenuity.

Africa is full of food, which increased fertility and cause competitive pressures. These increased violent tendencies and athletic growth to win food and territory. The pressure was against each other.

Colder harsher climates meant less resources. Smaller tight knit groups working together to survive the environment. They had a larger territory and had less contact with other groups, and developed long term critical thinking and spatial awareness to compete against the environment instead of each other.