The tuskless elephants of Gorongosa, in Mozambique, have become the most widely cited example of how poaching can reshape a species’ evolution in a matter of decades.
More than thirty years after the war that triggered it, scientists are still measuring the consequences.
From 1977 to 1992, Mozambique was gripped by a civil war in which forces on both sides systematically killed elephants and sold the ivory to fund their operations.
In the area that is now Gorongosa National Park, the killing drove the elephant population down from roughly 2,200 animals to fewer than 200 — a collapse of more than 90 percent.
When Tusks Became a Death Sentence
Among the survivors, a once-rare trait had become common: half of all females were tuskless, compared with fewer than one in five before the war.
The explanation, according to a 2021 study published in Science by a team from Princeton University in collaboration with ElephantVoices and the park itself, is that where hunters were selectively killing elephants for ivory, being born without tusks was no longer a disadvantage but an advantage.
Genetic analysis identified two genes linked to tooth development in mammals, one of them on the X chromosome.
Because the mutation is dominant and X-linked, a single inherited copy is enough for a female to be born tuskless.
In males, however, the same gene appears to be lethal before birth — which would explain why tusklessness appears almost exclusively in females, and why tuskless mothers produced twice as many daughters as sons.
An Evolutionary Shift Measured in Years, Not Millennia
What sets Gorongosa apart from other cases of natural selection is how fast the change happened.
The shift took hold in little more than a single elephant generation — a pace scientists called extraordinarily fast for a complex heritable trait.
Mozambique is not the only place this has happened.
Similar populations, with unusually high numbers of tuskless females, have emerged after intense poaching in Uganda, Tanzania, and Kenya, though Gorongosa provided the most complete data for identifying the genetic link.
What the Most Recent Data Show
A subsequent census of Gorongosa’s elephant families, published in the scientific journal Pachyderm, confirmed that tusklessness remains common among animals born after the war.
According to the study, half of the females older than 20, and a third of those between 10 and 20, never developed tusks. The sex ratio among older animals is still skewed — another genetic scar from the war.
The herd has made a remarkable recovery.
According to figures released in 2025 by the ecologist who leads the park’s elephant research program, the population has grown from just under 200 survivors to around 1,000 today.
Even so, the researcher noted that the animals still carry the marks of the war, in both their bodies and their behavior.
Scientists have also documented a secondary ecological effect: a preliminary dietary analysis found that tuskless females eat more grasses, while tusked females eat more legumes and woody plants whose bark has to be stripped away — a job for which tusks are essential.
That dietary shift matters. Tusked elephants act as ecosystem engineers, felling trees and opening up clearings that other savanna species depend on.
The fewer tusked females left in a population, the fewer trees come down — and the landscape that elephants shaped over generations begins to look less and less like the one their ancestors knew.
