African elephants carry nearly 2,000 receptors for detecting smells
Everyone knows that African elephants boast versatile snouts, which can toss logs, grab food and spray water. But the towering mammals may also be the world’s best smellers, scientists report July 22 in Genome Research. The team found that African bush elephants (Loxodonta africana) carry about 2,000 genes for smell sensors, or olfactory receptors. Olfactory cells reside in the pachyderms’ nasal cavities near the tops of their trunks. Renowned sniffers like rats have around 1,200 olfactory receptor genes and dogs about 800. Humans and other primates possess relatively poor olfactory powers and just one-fifth as many olfactory genes as elephants. The researchers think that as mammal species diverged, the original smell-sensing gene duplicated in elephants. The broad smell palette perhaps explains why aromas can dictate elephant behavior. African elephants can communicate aggression via scents and can use smell to distinguish the Maasai, an ethnic Kenyan group that hunts elephants, from the Kamba, who are primarily farmers and pose no threat.
Y. Niimura, A. Matsui, and K. Touhara. Extreme expansion of the olfactory receptor gene repertoire in African elephants and evolutionary dynamics of orthologous gene groups in 13 placental mammals. Genome Research. Published online: July 22, 2014. doi: 10.1101/gr.169532.113.
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