Answer:
Climate change, Availability of resources
Explanation:
1. Soon enough when the climate on the planet started to become more arid and become too hot, so humans started to migrate from Africa.
2. People started to move away to the places where resources were available.
<span>Early people of the Americas used a combination of animals to further their exploration and expansion into new territories. Some populations used horses and oxen as food sources, and did much of their travel on foot, bringing only what they could carry. Others settled in towns, where food and supplies could be purchased or traded.</span>
Effect and Causation are two terms that fit this criteria.
