Answer:
The answer to the first question:
People from Central and Northeast Asia moved to North America following the Ice Sheet that covered the area, including the Bering Strait, which at the time as a land bridge made of ice.
People from the Middle East emigrated to Northern Mesopotamia because the climate there is milder, and the land is very fertile.
Answer to the second question:
Society first becomes semi-nomadic, usually because it domesticates a few animals and plants. Then, it becomes fully sedentary.
The division of labor appears: some people work on the fields all day, while others raise animals, and others cook food.
Agriculture produces more food than hunting and gathering, so food surpluses lead to greater wealth, which tends to be appropriated by an elite: the ruling class.
Social stratification develop, which brings greater complexity to society, bringing about civilization.
