Domestication involves small changes in many genes and not drastic changes in a few
Somewhere between 9,000 and 15,000 years ago, human beings began domesticating animals like dogs, cattle, sheep, goats and pigs. This, along with learning to grow crops, has been one of the most important technological breakthroughs, as it allowed agriculture to develop. But what genetic changes occurred in wild animals that made them conducive to taming has long baffled the scientific community.
A new study, for the first time, has spotted the genetic variation that occurs when wild animals become tame. The researchers found that there are no specific ‘domestication genes’ that are critical for domestication, but that a diversity of gene variants affecting the brain and nervous system are important for it. They argue that a similar diversity of gene variants affecting the brain and the nervous system occurs in humans as well, and contributes to the differences in our behaviour and personalities.
For the study, which was published in Science, the researchers studied the rabbit. Unlike other animals that were domesticated thousands of years ago, the rabbit was domesticated only about 1,400 years ago in France. It is claimed that the animal was domesticated at Catholic monasteries, as the Church had declared that young rabbits were not considered meat, but fish, and hence its flesh could be consumed during Lent.
After sequencing the entire genome of a domestic rabbit to develop a reference genome assembly, the researchers then sequenced entire genomes of domestic rabbits representing six different breeds and wild rabbits sampled at 14 different places across the Iberian Peninsula and southern France.
The researchers found that the domestication of rabbits had occurred with alterations in the frequencies of gene variants that were already present in the wild ancestor. They found that domestication involves small changes in many genes and not drastic changes in a few. They also found that very rarely do the gene variants common in domestic rabbits completely replace the gene variants present in wild rabbits. Hence, if a domestic rabbit is released into the wild, there is the possibility for back selection involving genes that have been altered during domestication.