By 1931, all but 11 elephants living in what is now South Africa's Addo Elephant National Park had been killed, mostly for their ivory. Of the eight female elephants left, half had no tusks. Now 98% of female elephants in Addo are tuskless, the Independent reports. The normal rate for African elephants is between 2% and 6%. Researchers say more and more elephants are being born without tusks as poachers kill off individuals with tusks and leave the rest to pass on their tuskless genes, according to Nautilus. “Females who are tuskless are more likely to produce tuskless offspring,” elephant expert Joyce Poole explains to the Times. In Mozambique's Gorongosa National Park, 90% of elephants were killed between 1977 and 1992; 30% of female elephants born since then are tuskless.
And the problem isn't getting better. Poaching has been on the rise since 2007. Approximately 144,000 elephants were killed between 2007 and 2014. Over the past decade, nearly a third of African elephants were killed by poachers. That's left African elephants facing extinction and in a tough place, evolution-wise. While being born tuskless protects them from poachers, it's dangerous in other ways. Elephants need their tusks for self-defense, sexual display, and digging for food and water. Without them, they're considered "crippled"—more likely to be malnourished and susceptible to disease. Sadly, researchers say the entire species could soon be tuskless if something isn't done. (The Great Elephant Census returns jarring news.)