Poachers hunting elephant ivory may have met their match in one of nature’s greatest forces: natural selection. In at least two national parks in Africa, where poaching has been a huge problem, most female elephants are now born without tusks.

Until the 1990s Gorongosa National Park in Mozambique was home to about 2,500 elephants. But during the civil war that raged from 1972 to 1992, about 90 per cent of that population was killed.

Many of those elephants were slaughtered for their ivory tusks, which were sold to purchase weapons and food to feed the fighters. It now seems that this slaughter was a strong form of evolutionary selection on the elephants, which has increased the frequency of genetic variations that result in tusklessness in female elephants and smaller tusks in males.

From tusked to tuskless

Ordinarily, fewer than four per cent of female elephants are born without tusks. But behavioral ecologist Ryan Long from the University of Idaho told Quirks & Quarks host at CBC radio, Bob McDonald that there’s been a massive shift in the population in Gorongosa.

“Suddenly tusks become detrimental; they become a liability. So animals that have tusks and therefore have the genes to grow tusks are removed from the population by poachers. Animals that don’t have tusks survive because they don’t appeal to the poachers,” Long explained. “And so their genes are passed on to the next generation. And you get an increase in the number of individuals that are born without tusks.”

The article was published first on the CBC Radio website. Continue reading…