It’s an evolutionary study that would delight Darwin, but today’s scientists are concerned that the implications of “tuskless” elephants will send ripples through the ecosystem.
Human activity is once again forcing the hand of evolution. Current studies are investigating a rapid increase in the number of elephants born without tusks in areas under pressure from ivory poachers.
Seeing that poachers target elephants for their tusks, those born without them have a distinct evolutionary advantage. It seems that elephants are evolving to solve this problem – by being born without them.
The phenomenon occurs primarily in the female African elephant population, where historically only 2-4 per cent of members would fail to develop tusks. In populations that have suffered heavy poaching, up to 98 per cent of females have no tusks.
Mozambique’s Gorongosa National Park houses one such population. Elephants there bear the marks of the 15-year civil war that ended in 1992, when ivory was sold to buy weapons.
Just over half the female population that survived the war years have not developed tusks. Of the descendants of these females (who faced far fewer poachers), 32 per cent have no tusks.
In Tanzania’s Ruaha National Park, where poaching boomed in the 1970s and -80s, a similar trend occurred. Among older females, 32 per cent are tuskless. In those under 25, the figure drops to 13 per cent.
The trend continues at Addo Elephant National Park in South Africa, where 98 per cent of females were tuskless at the turn of the century. Populations like these are currently being studied closely by scientists.
Ryan Long, a behavioural ecologist at the University of Idaho and a National Geographic Explorer, told National Geographic:
“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.”
Just like human incisor size, tusk size is heritable and is influenced by genetic makeup. What is truly astounding however is the rate at which these evolutionary changes have occurred.
Scientists are primarily concerned with behavioural adaptations that will accompany the tuskless elephant population. Tusks are useful tools. Elephants use them in mating rituals, to dig for water and nutrients, as well as to strip or uproot trees when foraging.
The adaptation to alternative behaviours could influence elephant population health and have trickle-down effects throughout the entire ecosystem.
Elephants’ “role as a keystone species to topple trees and dig holes to access water is important for a variety of lower species that depend on them,” said Long.
This change in elephants could create myriad direct and indirect consequences for other species. While the full study is yet to be published, scientists are monitoring elephant populations closely.
According to Long, the “consequences of such dramatic changes in elephant populations are only just beginning to be explored”.