Most mammals have 1000 or more genes that encode receptor proteins on the surface of odor-receptor neurons, so why do some mammals have a better sense of smell than others?

Question

Quizplus · Accepted Answer

Even though most mammals have many genes that encode receptor proteins for smell, some of these genes may have undergone mutations that rendered them inactive in certain species. Thus, some species may have a smaller repertoire of functional receptor proteins for smell, leading to a poorer sense of smell.

Most Mammals Have 1000 or More Genes That Encode Receptor