About 90% of elephants living in Mozambique's Gorongosa National Park were slaughtered for their tusks by poachers during Mozambique's 15-year civil war that ended in 1992. The poachers then profited by selling the tusks to finance weapons. As a result, we're now seeing a growing population of elephants in the country born without tusks. Tuskless females, for instance, have jumped from 2%-4% of the population to around 33%.
According to National Geographic:
Hunting gave elephants that didn't grow tusks a biological advantage in Gorongosa. Recent figures suggest that about a third of younger females—the generation born after the war ended in 1992—never developed tusks. Normally, tusklessness would occur only in about 2 to 4 percent of female African elephants.
Decades ago, some 4,000 elephants lived in Gorongosa, says Joyce Poole—an elephant behavior expert and National Geographic Explorer who studies the park's pachyderms. But those numbers dwindled to triple digits following the civil war. New, as yet unpublished, research she's compiled indicates that of the 200 known adult females, 51 percent of those that survived the war—animals 25 years or older—are tuskless. And 32 percent of the female elephants born since the war are tuskless.
Sadly, this isn't the only population of elephants losing their numbers – and their tusks – to poachers. In South Africa, "fully 98 percent of the 174 females in Addo Elephant National Park were reportedly tuskless in the early 2000s."
Used to defend themselves, as well as for digging, protecting their trunk, and helping them strip bark from trees in order to eat, tusks are enlarged incisor teeth that are essential to their daily well-being. Unfortunately, their tusks can't protect them from murdering poachers.