On a farm in Siberia, a six-decade-long experiment is still ongoing: selectively breeding foxes to try and replicate the process of domestication. It began in 1959 with 130 ordinary silver foxes (a variant of the familiar red fox). The farm is now populated by foxes that wag their tails, love to be petted, and lick people’s hands. After generations of selecting the tamest foxes to breed, the entire population is completely tame. That seems logical, but what’s strange is that the silver foxes now look different: their ears are floppy, their tails are curly, their snouts shorter, and their coats are piebald instead of just one colour. However, this is exactly what Dmitri Belyaev, the Russian geneticist who started the experiment, expected to see. This genetic link between animals’ appearance and friendly behaviour has been known for some time and is called domestication syndrome.
More recently, researchers have been casting doubt on whether domestication syndrome really exist. Firstly, Belyaev’s experiment might not be completely valid – the foxes he used were from a fur farm, and there are photos from the 1920’s showing some of the farm foxes already tame enough to be kept as pets. They weren’t wild to start with. And secondly, there are so many traits claimed to be caused by domestication syndrome that it has no real definition.
Domestication syndrome of some form appears in many animals bred by humans. As a clear example, picture a pug next to a wolf. Shorter snout, curly tail, floppy ears, small body, like petting… all these features have at some point been attributed to the list of domestication syndrome ‘symptoms’. And there’s something else strange that we can see withinthe same example. It involves how a pug looks more like a wolf cub.
All these traits of domestication make animals look like their young; in other words, these animals retain juvenile features. The word to describe this is neoteny, derived from the Greek words for ‘young’ and ‘to stretch’. Think about it: smaller bodies, different proportions and cuter faces do seem more like traits found in baby animals. And in terms of behaviour, domesticated animals can learn more as adults than wild animals (even old dogs can learn tricks) and are generally more sociable (no wild fox would like cuddling as Belyaev’s silver foxes do). These behaviours in the wild are mainly for young animals to learn, not needed for fully grown animals.
The possibilities surrounding domestication and neoteny are wide-ranging, but many things are far from certain.
Neoteny also affects humans. Modern humans have shorter jaws, larger skulls and shorter limbs than our ancestors did. We have a greater ability to learn and communicate as adults too. Neoteny has brought us closer to our childhoods, in a weird parallel that suggests we have domesticated ourselves.
So how did humans do it? It seems that we unknowingly selectively bred domestication syndrome traits in ourselves. One hypothesis, called the Multiple Fitness Model, says that cute baby-faced prehistoric humans were more likely to get sympathy and help from others, hijacking adults’ natural reaction to their young. Or possibly, according to psychiatrist Stanley Greenspan, we evolved faces with bigger eyes and less hair to aid rapid communication, through facial expressions. Another hypothesis, by Doug Jones, a professor in anthropology at the University of Utah, says youthful features in female adults came by natural selection as a way to attract mates by looking premenopausal, as longer human lifespan caused this problem for reproduction. Or maybe the evolutionary ecologist Aldo Poiani of Monash University, Australia is closer to the truth, that selection was for psychological traits first: as humans evolved genes for greater intelligence, the other domestication syndrome genes came with it. Possibly a mixture of these hypotheses, and even more, resulted in the ‘domesticated’ humans we are today.
Even now, these possible causes play a part in society. Cartoon characters use the neotenous features of big heads and big eyes to look cute. Cosmetics aim to rejuvenate you, utilising the idea of ‘younger equals attractive’ that still applies today.
The possibilities surrounding domestication and neoteny are wide-ranging, but many things are far from certain. As we have seen, some are hard to define. And some are hard to discover; decades-long experiments don’t happen easily. Unfortunately, we cannot observe first-hand the evolution and domestication of our favourite species, Homo sapiens, without either a time machine or a spare few million years. But sixty years and a farm of silver foxes have done a reasonable job for now.
This post was written by Catriona Roy and edited by Miles Martin