Humans have about 1,000 genes to regulate our sense to smell. Of them, only about 500 work; the rest have mutated over time and no longer function.
Considering ,that the human genome is comprised of about 25,000 genes, it would seem that smell must be pretty important to us! By comparison, the next largest gene family controls serotonin receptors, which are influence our mental health and functioning. The whole serotonin family is just 15 genes.
Want to learn more? Check out the Naked Genetics podcast for their episode “Smells like gene spirit.”