It’s a development that would have delighted Darwin.

African elephants are losing their tusks in an astonishing example of evolution by natural selection which protects them against ivory poachers.

Until the 1990s, around 2,500 elephants lived in Gorongosa National Park in Mozambique, but 90 per cent were killed during the 15-year civil war which raged from 1977 to 1992 - with their ivory used to finance weapons.

Now scientists have noticed that nearly one third of the female elephants born since the war have lost their tusks.

Normally fewer than four per cent of a population are born without tusks, but because tuskless animals were ignored by poachers, they gained a biological advantage and were able to mate, and pass on their genes. A team from the University of Kent is now carrying out genetic studies to learn more about the new traits.