Female African elephants in Mozambique's Gorongosa National Park have been born without their ever-crucial ivory tusks, and scientists are saying it's an evolutionary result of the brutal poaching and killing of the animals during the country's civil war.
According to new research released Thursday in the journal, Science, between the years of 1972 and 2000, elephants born without tusks – almost all female – tripled in number. In Gorongosa in the 1970s, 18.5% of female elephants didn't have tusks. Now that number is 51%. Analysis from the study revealed that tuskless elephants are five times more likely to survive.
"Evolution is simply a change in heritable characteristics within a population over successive generations, and based on the results of our study, the shift toward tusklessness among female elephants at Gorongosa fits this definition perfectly," Ryan Long, an author of the study and an associate professor of wildlife sciences at the University of Idaho, told CNN.
Fact check:: Image of an elephant carrying a lion cub is altered
An elephant's tusks help the animal lift heavy branches, topple trees, strip bark, fight, and dig holes for water and minerals.
The tuskless elephants started to balloon in numbers shortly after the end of the country's civil war in 1992 (it began in 1977) and analysis revealed they were five times more likely to survive during the war without tusks.
"The fact that it occurred so rapidly is rare indeed, and is a direct function of the strength of selection," Long said. "In other words, it happened so quickly because tuskless females had a MUCH higher probability of surviving the war, and thus a MUCH greater potential for passing their genes on to the next generation."
One anomaly with the evolutionary development is the fact that almost all of the elephants without tusks are female. Research revealed the trait to be sex-linked and related to specific genes that generated a tuskless phenotype more likely to survive in the face of poaching.
“When mothers pass (tusklessness) on, we think the sons likely die early in development, a miscarriage,” Brian Arnold, a co-author of the study and evolutionary biologist at Princeton, told The Associated Press.
This article originally appeared on USA TODAY: Elephants are evolving to have no tusks. Is it from years of poaching?