FLICKR, ROSS HUGGETTAfrican elephants have the largest number of olfactory receptor genes known in mammals, nearly twice as many as dogs have, and five times more than humans. The large mammals’ extensive repertoire of receptors spans almost 2,000 genes, according to a study published yesterday (July 22) in Genome Research.
Yoshihito Niimura of the University of Tokyo and his colleagues compared the genome sequences of 13 mammals, which together encompass more than 10,000 genes for olfactory receptors. They found that each species had a unique ensemble of receptors—only three smell receptors were shared and evolutionarily conserved across all the mammals studied. Some gene lineages were completely lost in certain species, while others expanded and diversified. One gene, found only in a single copy in humans and other primates, was found to have formed 84 distinct genes in elephants.
But whether these receptors are behind the elephant’s superior sniffing powers is still unknown. “We don’t really know how the number of olfactory receptor genes relates to olfactory ability,” Niimura told The Washington Post. “For example, dogs ...
