Given a scientific question, generate a correct answer to it.

Ex Input:
A crow that becomes used to a scarecrow and lands on it is an example of what?

Ex Output:
habituation

Ex Input:
What joins within each testis to form the epididymis?

Ex Output:
seminiferous tubules

Ex Input:
What population on earth is already harming the environment due to less resources to go around?

Ex Output:
humans