A strange thing has been observed among the young female elephants of Mozambique’s Gorongosa National Park: About a third of them never developed tusks.

While tusklessness is not unheard of in female African elephants, normally it would only happen in about two to four percent of them. The tuskless crew in question here are amongst the first generation born after the end of Mozambique’s 15-year-long civil war, a war in which much was financed through the slaughter of elephants for ivory. Ninety percent of the area’s elephants were killed, yet those without tusks survived. And now they’ve passed the trait on to their daughters.

Watch this video to learn more about the tuskless elephants: