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Charles Darwin is well known for his work on natural selection, the process by which the members of a species adapt and change physically over time, producing offspring with traits that make them better suited to their environments.
Usually, these advantageous traits take hundreds of years (or more) to significantly alter a population. But scientists have now documented changes in the elephants of Gorongosa National Park in Mozambique – in only 15 years. More than 90 percent of the park's tusked elephants were killed during civil war in the African country between 1977 and 1992. Elephants without tusks were left alone, as they weren't valuable to poachers.
Today, researchers have pinpointed how those years led to a greater number of elephants that will never develop tusks. “What I think this study shows is ... the impacts that people have. We’re literally changing the anatomy of animals,” explained researcher Robert Pringle of the Department of Ecology and Evolutionary Biology at Princeton University.
Terrific, terrifying tusks:
- A set of tusks allows elephants to dig for water, strip bark from trees for food, and joust with other elephants. Before the Mozambique fighting, a fifth of females lacked tusks. Today, half the females are tuskless.
- Genes determine whether elephants inherit tusks from their parents. Although tusklessness was once rare in African savannah elephants, it's become more common, according to extensive DNA analysis.
- Scientists are also studying what more tuskless elephants means for its savannah environment. Fecal analysis suggests that the Gorongosa elephants are eating more grass, and fewer legumes and woody plants.