African savannah elephant in Amboseli National Park, Kenya
Shutterstock/Martin Peranek
Wild elephants are one of the few species known to show signs of self-domestication. This phenomenon has only been documented in bonobos, primates closely related to humans.
Humans have bred animals to maximize traits such as friendliness, sociability, and docile disposition, in a process called domestication. Some researchers believe that humans and bonobos have gone through a similar process but naturally did it to themselves.
Limor Raviv of the Max Planck Institute for Psycholinguistics in the Netherlands wondered if other species were also self-domesticating. She decided to start with the African savannah elephant (loxodonta africana), a species she already knows well. She and her colleagues examined how elephants compare to bonobos (Panicus) and 20 different scales in humans.
They found that all three species exhibited similar behavior and shared certain physical characteristics. Take care of other children in the group. Wild African elephants also share shortened jawbones, a trait common to many domesticated animals, and show restraint in their aggression towards others.
Next, the researchers looked for commonalities between the genomes of domesticated animals and those of wild elephants. We used studies of 261 mammals, including cattle, dogs, cats, and horses, to develop a list of genes frequently associated with domestication. He then identified 674 genes likely to be passed on from earlier generations of elephants.
The team found that 79 of the genes in African elephants were linked to domestication in other species, further reinforcing the idea that elephants evolved these traits without direct human intervention. This is important because elephants and humans are not closely related, suggesting that domestication may evolve convergently on multiple branches of the mammalian evolutionary tree. Raviv said.
Raviv suspects an Asian elephant (biggest elephant) may also show signs of self-domestication, but genomic data were only available for African elephants at the time of the study. Social animals may also have evolved self-domestication, he says.
Melinda Zeder of the Smithsonian’s National Museum of Natural History in Washington, DC disputes the term self-domestication. No one species can do it alone, she says, because domestication is a reciprocal process between her two species. She says, “There are interesting parallels to domestication to explore, but by branding them as domestication, they’re muddling the water.”
Self-domestication may seem like a “pretty strange idea,” says Raviv, but the phenomenon is worth investigating, even if other explanations are underway. Raviv and her team are now looking for signs of self-domestication in seals, dolphins, whales and bats.
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