When you think about nature's champion sniffers, you probably think of dogs, whose noses are incredibly sensitive. But a new study published in the journal Genome Research shows that they may have competition. Researchers compared the number of olfactory receptor genes in 13 different mammalian species - these are the molecules in the nose that detect different odours - and discovered that African elephants have the largest number, clocking in at around 2,000. This is twice as many as dogs and five times more than humans.
As part of the study, the scientists also discovered more than 10,000 olfactory receptor genes in total across all the species, but that each animal's repertoire was pretty much unique - only three receptor genes were shared across all 13 species. The diversity has arisen thanks to hundreds of genes being copied and lost during evolution, and highlights the differences in the sense of smell across the different animals.