How did the end of the ice age impact human civilization

Approximately one million years ago, early humans started to leave Africa and spread to other continents. This happened during one or more of the Ice Ages. During an ice age, oceans become smaller and lower, as the water freezes into glaciers. This uncovers land. With the sea level lowered, early humans were able to cross land bridges between continents, most probably following herds of animals or in search of food