The domestication of animals has radically altered the lifestyle of humans since the beginning. Farm animals allow for more efficient food production but how does the mindset of the animal change? There are clear reasons why wild animals can’t live with humans, almost all of which are based on behavioral differences that have emerged in the domestication of different wild species.
“Egyptian Domesticated Animals”
Let’s start with the important question that we will likely never be able to answer completely, how did people domesticate wild animals? This is an interesting question for a few reasons, one being we don’t have a clear image of when the first animals were domesticated and another being we don’t know how complex the society that was able to animals would have been. Because of this, we can only make theories on the origin of domestication, two of which are, the orphaned wolf theory and the promise of food theory. The orphaned wolf theory is explained by humans removing an animal (in this case a wolf) from their pack at a young age and taming them to live comfortably with humans, which is quite different from the promise of food theory which claims wolves ‘domesticated themselves’. This theory is explained by wolves scavenging human waste and leftovers that would be left around their living environments. Wolves, like many animals, have a flight distance which is how close a human can get before they flee. The animals with a lower flight distance were more likely to be selected for domestication (more on this later). While everyone will have their own opinion on the origin of domestication, there are more changes that can very clearly be observed by looking at modern domesticated animals.
“7 weeks old” by Bolinda CC BY-SA 3.0
The most abundant animal domestication is man’s best friend, the dog, Canis lupus familaris is a subspecies of the gray wolf Canis lupus. It has been estimated that the dog was domesticated between 20,000 and 40,000 years ago which is very recent in an evolutionary view. Genetics also back this up, as both dogs and wolves have 39 pairs of chromosomes, 99.96% similarity in mitochondrial DNA, and they can even interbreed to produce a hybrid! So what’s so different about the two? Dogs are much more social than wolves and are much less independent, relying heavily on humans to provide for them, while wolves only rely on their close family unit. Being less dependant also has led to phenotypical changes in dogs like a smaller jaw, shorter teeth, and smaller paws, all of these are part how wolves are built to be aggressive hunters and what has been lost over time as dogs have become more and more tame. Dogs are also slower to develop than wolves, taking longer to open their eyes as puppies and don’t socialize until 4 weeks old, twice the age of wolf pups who need to mature at a quicker rate in order to survive in the wild. Winter is the most season to survive in as a wolf, so while domesticated females may go into heat multiple times a year, female wolves only do once a year in the spring, creating a greater chance of survival in the offspring.
“Wolfdog” by Margo Peron
The domestication of the Russian silver fox (Vulpes vulpes) is fascinating and a very informative study that sheds light on a of cascade effects that occur when tameness is bred for. In the 1950’s, a Russian geneticist known as Dmitry Belyaev bred foxes for a 10 generation span always selecting for the most curious and fearless foxes to breed. To do this, Belyaev and his team would put a glove in front of an individual fox in his/her cage. If the fox was scared or tried to bite the glove they would not be bred, but if they examined the glove they would be. Not only did the offspring of the later generations act more and more curious but a number of changes occurred that no one could have predicted. The coats of the foxes began to change color to white or black, the ears of the foxes could become floppy, they began to bark, and some would even come if their name was called. All of this occurred due to tameness being selected for, but why would being tamer cause a change in fur color? This occurs because of a chemical connection between the hormone adrenaline and melanin. Adrenaline is a key hormone in the fight or flight response which is how animals react when a threat is introduced. Because these foxes were calmer when the glove was introduced, they likely possess less adrenalin which has a biochemical connection with melanin, the pigment for skin and fur, so as adrenaline changes so does melanin.
“Dmitry Belyaev and Fox Experiments” By Liberate Prometheus
Domesticated animals will forever remain part of the society of humans and will continue to diversify from their wild counterpart. Further experiments will also likely shed light on behavior and phenotypical changes that have occurred and may even lead to the agreeance of a singular theory of how domestication may have occurred.