A HEFTY set of tusks is usually an advantage for elephants, letting them dig for water, strip bark for food and joust with rivals. But amid episodes of intense ivory poaching, those big incisors become a liability. Scientists have now detailed how Mozambique’s civil war of 1977-1992 has spawned a new generation of tuskless elephants. After their population in Gorongosa National Park fell by 90 percent as they were slaughtered in huge numbers for their valuable ivory, the large mammals responded by going tuskless. Genetic variations of their X chromosome caused the proportion of tuskless female elephants to soar — from less than a fifth to more than half. The trend continued after the war ended, leading researchers to conclude the trait had been inherited. They also found increasing numbers of male elephants who received the chromosome with the tuskless variant were dying in their mother’s womb. “When mothers pass it on, we think the sons likely die early in development, a miscarriage,” said Brian Arnold, a co-author and evolutionary biologist at Princeton University. Commenting on the findings, University of Washington conservation biologist Samuel Wasser said: “When we think about natural selection, we think about it happening over hundreds, or thousands, of years. “The fact that this dramatic selection for tusklessness happened over 15 years is one of the most astonishing findings.” The researchers’ focus has shifted to what tusklessness means for the species and its fellow savannah inhabitants. (SD-Agencies) | 