What theory/theories has/have been proposed to account for humans' poor olfactory sensitivity compared to that of other mammals?

Question

Quizplus · Accepted Answer

All of these theories have been proposed to explain why humans have poorer olfactory sensitivity compared to many other mammals. Humans have fewer olfactory receptors and a smaller olfactory epithelium compared to many animals, and the development of color vision has also been suggested as a compensatory evolutionary adaptation that might have led to a reduced reliance on the sense of smell.

What Theory/theories Has/have Been Proposed to Account for Humans' Poor