Elephants are evolving to lose tusks following decades of ivory poaching

Sarah Knapton
Nearly one third of females in Gorongosa National Park in Mozambique are now tuskless  - Caters News Agency

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.

A tuskless adult female African elephant eads her group at sunset in Gorongosa National Park, Mozambique Credit: Jennifer Guyton / CATERS NEWS 

Doctoral student Dominique D'Emille Correia Gonçalves, an ecologist and conservation biologist from the University of Kent, who is studying the population, said: “The elephant population today is derived from most of the elephants who survived the war, where they were heavily poached for their tusks.

“The key explanation is that in Gorongosa National Park, the tuskless elephants were the ones which eluded poaching during the civil war and therefore passed this trait onto many of their daughters.

“We could be talking about the removal of certain genes from the population.”

Even where the elephants are born with tusks they are often smaller than usual, again because poachers tended to pick out the animals with most ivory.

Poaching has also led to a decrease in tusk sizes in southern Kenya where survivors of a period of intense poaching had much smaller tusks, a pattern which was repeated in their offspring. And in Addo Elephant National Park in South Africa, 98 per cent of the females are now tuskless.

“The prevalence of tusklessness in Addo is truly remarkable and underscores the fact that high levels of poaching pressure can do more than just remove individuals from a population,” Ryan Long, a behavioural ecologist at the University of Idaho told National Geographic.

“The consequences of such dramatic changes in elephant populations are only just beginning to be explored.”

Researchers in Gorongosa have also noticed that the females have developed a ‘culture of aggression’ and have a low tolerance to vehicles and people, which is likely to stem from a desire to protect their group against poachers, but also could be linked to the lack of tusks, which makes them more vulnerable.

A herd of elephants which survived intense ivory hunting have given birth to daughters without tusks  Credit: Jennifer Guyton / CATERS NEWS

“This is a big change, as anecdotal records from people that have been in Gorongosa before the war suggest the family units used to be calm and almost indifferent to people presence,” added Miss Gonçalves.

“Many of the matriarchs and lead females of the family units were alive during the slaughter and saw their families and friends being hunted.

“They are survivors and the trauma is still present, which would explain such intolerance to humans.”

Elephants use their tusks when digging for water, debarking trees to secure fibrous food, and they helping males compete for females.

Scientists are now monitoring the elephants by attaching GPS satellite collars to 10 females from different family units to find out if being tuskless affects their ability to feed and breed.

Evolutionary biologists at the University of California Los Angeles, are also studying blood to find out how genetics influences the tusklessness and why it occurs predominantly in females.