To "right" an essay would be to correct an essay. The word you're looking for is "write."
Definitionally, you are an animal. How do your senses help you survive?
Touch: you can feel unbearable temperatures (too hot, or too cold). Touch acts as the primary mechanism through which we feel pain: it's what keeps you from leaving your hand in boiling water (though you may dip it in for a second to see just how hot it really is).
Hearing: your eyesight is limited--you don't have a 360° view of the world. Hearing enables you to detect potential dangers that you can neither see, nor smell.
Smell: if food smells rotten, you have a bad reaction to it, which prevents you from eating it (or it should, except in somewhat extreme circumstances).
The taste sense is similar to, and closely linked with, olfactory senses (smell). If a food passes the smell test, an animal will take a small bite of it. If the taste is unpleasant, it's a good indication that whatever the animal just bit should not be consumed. Certain tastes release chemicals in the brain (specifically, dopamine) that provide neurochemical motivation to seek out more of whatever was just eaten.
