Over many thousands of years, an animal species closely related to wolves has slowly evolved into something that wants to snuggle up in your lap, rub your belly, and eat kibble three times a day .
These changes in dogs are not just behavioral. In fact, changes in body plan – such as shorter snouts, floppy ears, more expressive faces, less body hair, and prolonged childhood – are common in many pets.
An international team of researchers has now pointed out that similar features exist within elephant populations, prompting the question of who or what may have domesticated them.
The answer proposed by the researchers is also surprising: Elephants may have bred themselves.
At a basic level, domestication is the process of artificially selecting representatives from each generation of animals (or plants) that fit the best criteria for living among humans. Number one on that list should be ‘play nice’. No one wants to wrestle a large, furry mammal for its milk or risk their eyes for a scrambled egg in the morning.
While many common traits can be inadvertently selected for, some genes go hand in hand with those for a docile companion, giving many animals a leaner, less threatening appearance. Called ‘domestication syndrome‘, the collection of traits that come with calm, cute, and content animals may not help them in the wild, but it certainly makes them more suitable for human society.
Back in 2017Duke University anthropologist Brian Hare took the concept of domestication syndrome a step further, wondering if it could also apply to our humans.
If we can choose which dogs, sheep, pigs, and cows should have babies based on their temperament and preferences, why don’t we do it ourselves?
Known as the Human Self-Domestication Hypothesis, it posits that our evolution was increasingly guided from the middle to late Paleolithic by a preference for less aggressive, more pro-social partners.
This has put increased pressure on our ability to communicate, which facilitates complex language skills. Changes in how our brains work may have an effect on the size and shape of our skulls, not all that dissimilar to how the skulls of domestic animals have changed.
We may not be the only primates to have experienced this desire for a more peaceful, expressive path to a violent existence. Hare recognized our close relative, the bonobo (Pan Paniscus), as a candidate for self-domestication based on claims of the species’ lack of aggression compared to its other close relative, the chimpanzee.
Now African and Asian elephants are nominated as two new examples of self-domestication, likely to have undergone similar selection processes as humans and bonobos.
The authors of this new study provided an extensive laundry list of similarities between the groups that serve as evidence of a shared domestication process. For example, in all three cases, the jaw and cranium changed shape, with the jaws becoming shorter or the skulls becoming more elongated, and the teeth being reduced in number.
Behaviorally, there is a tendency for peaceful interaction, with examples of aggression tending to be proactive rather than reactive. Infants of all species tend to engage in social and nonsocial play that often facilitates socialization and interaction. There is also significant evidence of ‘alloparenting’, where offspring are guided and nurtured by adults who are not their direct ancestors.
The team conducted a review of hundreds of genes thought to be involved in changes in embryonic tissues thought to be partly responsible for domestication, finding some evidence that evolution has favored at least a few dozen such a sequence in elephants.
The examples given may just be cases of cherry picking what fits. For example, other animals that have undergone domestication become breeds with floppy ears and curly tails.
The researchers argue “Domesticated species do not usually show the full range of features associated with domestication”, because different blocks of features can disintegrate and become unselectable. That is, elephants are more likely to lose the modified structure in their ears, given how useful they are for thermoregulation.
To what degree the three types of elephants may or may not take the evolutionary path to pro-social, domestic ‘happiness’ depends primarily on whether the hypothesis itself makes a good theory capable of explaining why the some social traits may be commonly found in different species.
If this happened, we might find other animals on a continuum of domestication. Dolphins, perhaps, or various species of birds or rodents may also undergo similar changes that favor levels of social complexity over brawn and anger.
Once seen as an exclusively human virtue, the tendency to prioritize peaceful guidance, complex emotional expression, and a general affection for one another may be an option open to many social animals.
Like many traits that once defined our species, humans just took domestication to the next level.
This research was published in PNAS.