What is believed to have caused people to first move out of africa? where did they go?

it's anything that aren't producers and consumers.

explanation:

you've got to be clear on what "this" is

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms