100 points! how does variation, adaptation, and increased fitness all connect

Fitness, in your case, means strong according to the dangers you face in your environment. You might have needed to adapt in order to be fit for your environment, which is just a more scientifical term for variating.

a motor homunculus represents a map of brain areas dedicated to motor processing for different anatomical divisions of the body.

homunculus represents the importance of various parts of your body as seen by your brain. as a result, they take up a lot of brain space. although the cortical homunculus is a curiosity, penfield's work in mapping the brain's relationship to the body was invaluable.