African elephants are evolving to grow without tusks after being hunted for decades by poachers, researcher says.

Animals have always adapted to their environments to become more successful as a species and avoid dangers presented to them.

It's a well-known fact that elephant populations across the globe have been in steep decline in recent years because of poaching.

Despite a ban on international ivory trade, poachers often still target elephants for their ivory tusks as, according to the WWF, they are often carved into ornaments and jewellery.

And it is now thought that almost a third of the females among Mozambique's elephant population now have no tusks due to the threat from poachers.

Poachers aren't just targeting elephants on the ground either, as National Geographic reports some shoot at the beautiful animals from helicopters and planes allowing them no chance to defend themselves or escape from the danger.

Their tusks are not just used for ornaments and jewellery, as in some cultures it is believed that they hold "restorative" or healing powers, with them being used in some medicines.

China has the biggest demand for such products and ivory is sought after, sometimes being worth more than gold.

The ivory is ground up and ingested to 'cure' diseases, as well as increasing virility, strength, and fertility.

And even though there's no scientific evidence to back up the use of powdered ivory in Western medicine, tusks are in high demand and are sold on for huge sums of money in parts of Africa and Asia.

Males are often targeted because they have the biggest tusks, causing the population to have a higher number of tuskless females.

"Once there's been heavy poaching pressure on a population, then the poachers start to focus on the older females as well," Joyce Poole - an elephant behavior expert - told the publication. "Over time, with the older age population, you start to get this really higher proportion of tuskless females."

This is causing the animals to ultimately evolve slowly without tusks in a way to fight back against the poachers.

Previously only two to four per cent of the population had no tusks, but now it is up to a third. Scientists are now trying to work out the effect this will have on the species.