A recent study published in Current Biology has found that animals living at elevations of 1,000 meters and higher have a reduction in genes related to smell and a smaller olfactory bulb than similar low-altitude species. [...] Scientists found a 23% reduction in genes related to smell and an average of an 18% size reduction of the olfactory bulb, a kind of smell processing center located in the brain.

— Read more in Animals living at higher elevations found to have decreased sense of smell at Phys.org.