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SMELL YOU LATER, LOSERS – Dumbo tells rats, dogs... humans

Junk in the trunk? That's what people have

Elephant

Few people can fail to notice that an elephant's appendage is way bigger than a dog's, but it may come as more surprise that it can use it better too.

Boffins have named elephants as the top sniffers in the animal kingdom, possessing twice as many functional olfactory receptors (ORs) genes as hounds. ORs help organisms detect odours in their environments.

Proving that Dumbo really is the mutt's nuts, the researchers also found that pachyderms outclassed the olfactory abilities of the rat - once thought to have the best nose of any animal.

"Rats had the record for the largest number of [these] genes," said Yoshiihito Niimura, a molecular evolution researcher at The University of Tokyo in Japan. "Elephants have much more. It's almost double, so it's very surprising."

To analyse different animals' smelling abilities, boffins examined genome sequences from 13 different mammals, examining a total of 10,000 genes.

They found that each mammal's smell genes were highly unique, with just three shared between them.

An elephant has a mammoth 2,000 olfactory receptor genes, whereas humans have far fewer, as we stopped relying on our nose way back in the mists of evolutionary time.

The animals examined in the study are all descended from a common ancestor that lived 100 million years ago and is thought to have 781 OR genes.

All the primates in the study lost more than half of all their smell genes during the process of evolution. Orangutans, for instance, shed some 70 per cent of their olfactory receptor genes. Humans have just 396 OR genes left and just one passed down from the common ancestor.

The study is published in the journal Genome Research. ®

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