Crocodiles could hold clues to beating deafness

By Jim Leffman via SWNS

Crocodiles could hold the clue to beating deafness, according to a new study.

The ancient reptiles often live beyond 70 but unlike us don't lose their sense of hearing.

Scientists believe this is due to the ability to regrow tiny hairs in their ears that humans lose and they are now trying to find out how they do it.

A group from Uppsala University in Sweden hopes their research will aid the 1.2 billion people worldwide who suffer from impaired hearing.

Helge Rask-Andersen, professor of experimental otology at Uppsala University said: "We can see that new hair cells seem to be formed from the activation of so-called support cells, which is connected to crocodiles having certain cell structures that humans appear to lack.

"Our hypothesis is that nerves that carry impulses from the brain, so-called efferent nerves, trigger that regrowth."

The most common cause of hearing impairment is receptors in the ears that have stopped working and these receptors cannot be regenerated in humans.

But they can in animals that are not mammals, such as crocodiles, which despite living upwards of 70 years, have good hearing throughout their lives.

It is known that animals can quickly regenerate the hair cells in their ears if they are damaged. But it is not really known how.

Crocodiles have excellent hearing that is adapted for being on land and underwater.

The researchers used electron microscopy and molecular technologies in their study published in the journal Frontiers in Cell and Developmental Biology.

One interesting discovery was that small cell particles are secreted in the crocodile’s ear.

The particles resemble exosomes and can secrete enzymes that break down or form the membrane against which the hairs in the ear rub as sound comes in.

The exosomes form small alveoli, cavities, that make it easier for the hairs to bend when sound vibrations reach the ear.

Prof Rask-Andersen added: “One hypothesis is that this increases sensitivity to sound and hearing improves.

"Our hope is to learn how crocodiles regenerate their hair cells and to eventually be able to use that on people in the future."