Their goal is to uncover more information about how these animals move, eat, and what their genomes look like. Long hopes to detail how elephants without the benefit of tusks as tools may alter their behaviour to get access to nutrients. Rob Pringle, at Princeton University, plans to look at dung samples for insights about both diet and the army of microbes and parasites that live inside each elephant’s gut. Another collaborator, Shane Campbell-Staton, an evolutionary biologist at the University of California Los Angeles, will study blood, searching for answers about how genetics influences the phenomenon of tusklessness.

Exactly how this trait is inherited is “puzzling,” Campbell-Staton says. Tusklessness does seem to occur disproportionately among females. It makes sense that tuskless males wouldn’t be able to compete for breeding access to female elephants, he says. But if this trait was traditionally X-linked—passed down along the X chromosome, which helps determine sex and carries genes for various inherited traits—we would think that because males always get their X chromosome from their mothers that you’d have a really large population of males that are tuskless. “But we don’t see that. Tuskless males are extremely rare in African elephants,” he says.

Joyce Poole corroborates this. She says that in her entire career she’s seen only three or four tuskless males—none of them in Gorongosa.

WORK-AROUNDS

Although tuskless elephants’ nutritional and behavioural characteristics haven’t yet been formally compared to those of tusked elephants in any herd, Smit says anecdotally that in her research she’s seen that elephants without tusks appear to have found work-arounds.

“I’ve observed tuskless elephants feeding on bark, and they’re able to strip bark with their trunks, and sometimes they use their teeth.” They may also be relying on other elephants’ inadvertent help, she says. Perhaps the elephants are targeting different kinds of trees that are easier to strip, or trees that have already had some stripping by other elephants—giving them a prepared leverage point for tearing off bark.

Recent bans on the ivory trade in China and the U.S. may help reduce demand for tusks, but exactly how long it could take a population with a high proportion of tusklessness to recover some of its numbers—and its tuskedness—varies. Among Asian elephants, for example, a long history of hunting for ivory—as well as removing tusked elephants from the wild for labour—likely helped contribute to higher tuskless numbers there.

“If you look at Asian elephants, females don’t have tusks at all, and depending on which population you look at in which country, most males are also often tuskless,” Poole explains. Exactly why the Asian and African elephant populations have such different rates of tusklessness remains unexplained.

Yet Poole and others note that in areas in Asia that historically have been targeted for ivory hunts, tuskless levels are high—just as in Africa—underscoring that humans are leaving a lasting mark on Earth’s largest land mammal.

Wildlife Watch is an investigative reporting project between National Geographic Society and National Geographic Partners focusing on wildlife crime and exploitation. Read more Wildlife Watch stories here, and learn more about National Geographic Society’s nonprofit mission at nationalgeographic.org . Send tips, feedback, and story ideas to ngwildlife@natgeo.com.