Do We Owe Our Sense of Smell to Epigenetics? University of California, San Francisco (UCSF) and Lawrence Berkeley National Laboratory Study

Olfactory sensory neurons – nerve cells in the nose – directly sense molecules that convey scent, then send the signals to the brain. Biologists have long wondered how it's possible for each nerve cell to be equipped with only one kind of olfactory receptor (OR). There are over a thousand different kinds of OR genes in humans, distributed widely over both chromosomes; mice, dogs, and other animals have many more.