Aoife Hardesty looks at the changes humans have wrought on different species through the process of domestication.
HUMANS evolved on this planet along with millions of other species of life; microorganisms, fungi, plants, animals. But no other life form has altered so many other species the way we have. We have harnessed microorganisms for making alcohol, baking bread, manufacturing antibiotics. We have selectively bred plants to provide us with better grains, bigger fruit or vegetables, or even just for prettier flowers. And we have domesticated a great variety of animals.
The earliest evidence of domestication dates from 12,000 BC, with a fossilised jaw bone of man’s best friend, the dog. Genetic studies have shown dogs to be descendants of wolves, and the evolution of wolves to dogs is believed to be due to domestication.
Animal domestication was important as it enabled the move from hunting and gathering to farming. The first animals to be domesticated for food were nomadic grazers, likely goats or sheep, followed by cattle and pigs.
Cats were domesticated to keep down vermin and remain very similar to wild cats, largely due to the difficulties in selectively breeding such independent creatures.
In South America, llamas and alpacas were domesticated, and being domesticated actually saved the species from extinction. Alpacas were domesticated for their woolly coats which would provide wool for clothing, whilst the larger and meatier llamas were kept for eating.
Up until the Industrial Revolution, humans relied hugely on horses as a means of transport; horses were domesticated around 3000 BC, with the same purpose of transporting people and goods. Attempts to domesticate zebras, a close cousin of the horse, have been unsuccessful, and it is thought the reason why lies in genetic differences between the two species.
Scientists who research domestication believe that some animals have differences in their genomes that mean they can be domesticated.
Domestication is not the same thing as taming. Taming is where a wild animal can learn to trust humans and can accept a human presence. However the offspring of a tamed animal will have their natural wild instincts and will not be tame. When an animal is domesticated, the domestication is passed on to their offspring, as it results in genetic changes.
A project in Russia since 1972 has been attempting to recreate the domestication process with foxes on the basis of selective breeding. In each generation of foxes, the foxes most okay around humans were bred and so on so forth. The foxes from this program today actually seek human affection, showing that domestication can occur in a relatively short time span. The project itself began in relative secrecy, because in Soviet Russia the study of genetics was illegal.
In order to ensure domestication and not tameness, researchers had minimal contact with the foxes; they were selectively breeding according to the behaviour around humans and so they hoped that this would become stronger in each generation, based on genetics.
The foxes in the experiment were not red foxes, but a particular variety which have silver-black fur. This colour morph had become popular in fur farms, as that’s where the foxes for the experiment came from. The cubs that did not respond happily to humans were removed from the study, and were sold back to fur farms.
The foxes make sounds that do not sound like wild fox sounds, they bark. In 50 generations, foxes have been bred that wag their tails, lick humans, respond to orders from humans, come when they’re called and bark like dogs.
The foxes also experienced physical changes. Domesticated animals appear to have altered appearances to their wild cousins, becoming spotty and floppy-eared, tails becoming shorter and curlier. These physical changes occur at later generations to the behaviour changes. Possible reasons for the physical changes could be due to the changed genetics, resulting from the gene changes, or that traits that were silenced in the wild flourished in captivity. Other reasons may include humans choosing to breed for those traits.
Occasionally researchers have taken foxes home as pets, and the foxes are also sold as pets, although depending on where you live, keeping one as a pet may be illegal.
At the same time as breeding the friendly foxes, the researchers bred foxes based on their aggressive traits, using the same principle in reverse, breeding the most hostile towards humans every time. Then, taking new-born cubs from aggressive fox mothers and having them be reared by friendly fox mothers, they found that the babies were still of the aggressive disposition, showing this to be nature over nurture. The behaviour was genetic rather than learned.
The importance of the fox experiment has shown that in the right conditions, animals can be domesticated, and that this is a change which affects the animals’ genetic core. There are opponents to the domestication of animals, including the animal rights organisation PETA, who view keeping animals in captivity as animal slavery.
However, through domestication, humans have changed the genetic makeup of these animals so much that we have the responsibility to ensure their survival. A major part of domestication is that animals become dependent on humans and so it is up to us to ensure we treat these creatures, whose lives our ancestors altered so profoundly, with care and respect.