Poaching Has Caused 'Rapid Evolution' of Tuskless Elephants, New Study Reveals

Princeton University evolutionary biologist Shane Campbell-Staton spent his entire career studying lizards.
He was surfing YouTube at 3:00 AM one morning in 2016 when he came across an African elephant video. The video described a strange trend: Many female elephants living in Mozambique’s Gorongosa National Park did not have tusks.

This was unusual as only 2 percent of African female elephants have tusks. Staton-Campbell was intrigued and reached out to her colleagues in research on elephants. However, no one had investigated the mystery.

Robert Pringle, a Princeton biologist, invited Robert to visit the park to examine the phenomenon for himself.

Insider reported that Staton-Campbell said it took her 1.5 seconds to respond, "Yea, I'll definitely do this,"

He was able to count elephants in a helicopter seven months after he had viewed that video. Pringle and he came to an alarming conclusion after comparing the current population to Gorongosa's historical video footage.

Between 1977 and 2004, the percentage of females without tusks increased from 18.5 percent up to 33 percent.

Their research was published in Science on Thursday.

Victims of civil war

According to the study, it is not accidental that tusks are starting to disappear.

In 1977, Mozambique was engulfed in a civil war. Over 15 years, both sides killed African elephants to obtain their tusks and sold the ivory to fund war efforts. The Gorongosa elephant population had dropped by over 90 percent between 1992 and 1992.

The park saw almost three times as many tuskless females during the war. One in two of these females was unable to have tusks.

Poachers often targeted tusked elephants. It makes sense that their rare, tuskless cousins would have a better chance of survival.

Even after the civil war, this advantage remained. However, the number of tuskless women who were born in the park did decrease. One in three females born in the park in 1995 were tuskless in 2004, compared to one in five before the war.

The researchers found that five females with no tusks survived between 1972 and 2000 for every one female with a tusk.

This suggested to Campbell-Staton's team that poaching had driven rapid evolution.

He said, "It is extremely, extremely unlikely to achieve that magnitude of change by chance alone."

A Tusked African elephant resting on its trunk on its tusk. (David Clode/Unsplash)

Males are prone to this deadly trait

Researchers were however puzzled as to why tusklessness was only a female trait.

There are only a few anecdotes about tuskless males in areas that have large African elephant populations, but not in Gorongosa. This suggests that tusklessness is a result of elephant sex.

The researchers discovered that AMELX, a dominant gene responsible for tusklessness in females, was identified by sequencing their genomes.

AMELX is passed from mothers to their offspring via the X-chromosome. Humans also have the gene. Campbell-Staton stated that the disruption of this gene can lead to brittle teeth in people and decrease tooth growth in women. However, when a male human inherits the AMELX gene that is not working on his X-chromosome, it usually leads to death.

According to the study authors, it could also be true for African elephants. A male elephant with a disrupted AMELX genetic mutation will die. However, a female elephant would not suffer from the same fate.

A loss of tusks can cause ripples in entire ecosystems

Campbell-Staton stated that while tusklessness may seem to be a minor issue, it could have a significant impact on the entire ecosystem of African elephants.

He said that tusks can be used to remove bark from trees, find valuable minerals or locate subterranean water resources. "If your tusks are not present, your behavior will change. You won't be pushing trees because they can't be stripped of their bark.

These behaviors are essential for other animals of the African savanna. Elephants pushing over trees creates space for grassland plants that in turn create habitats and habitats for other species. This process is impeded by a decline in the number of tusked Elephants.

Campbell-Staton stated, "This is an example how human activity changes the evolutionary trajectory of species across the tree of Life," and added, "humans have been the most influential evolutionary pressure since the five major mass extinctions."

Mozambique's civil conflict is over. However, it could take 100 years for the ratio of tuskless women to return to pre-war levels.

Campbell-Staton stated that it will likely take five, six or seven generations for the 2 percent you would expect to return to if there is no poaching pressure.

This is obviously much longer than the "one generation" that "it took for it to go wrong," he said.

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