Born dog lovers
The study of twins showed the genetic roots of dog breeding
It turned out that people get dogs because of genes, but which ones are still unknown
Maxim Abdulaev, "The Attic"
A study of 70,000 Swedish twins has shown that the reason why a person lives with a dog depends at least half on genes. This means that the benefits of keeping dogs, known from some previous studies, may be explained by genetic variants associated with animal care, and not by the direct influence of animals.
According to archaeological data, the dog is the first animal domesticated by man. Most likely, this happened about 15,000 years ago, although some data push the time of the beginning of friendship between humans and dogs another 15,000 years into the past. Some scientists believe that close and long coexistence could not but affect both species. For example, according to some reports, living with a human has made children's traits in dogs more pronounced and has given them the ability to digest carbohydrates.
The other side of the partnership has also benefited: there are studies that show that having a dog is positively associated with human health. Owners of such pets are physically more active, feel less lonely, feel more comfortable, live longer and suffer less from asthma. Nevertheless, it cannot be said that this relationship is causal. Perhaps the whole point is that dogs are started by people on average healthier, more active, prosperous and less likely to suffer from asthma.
Scientists from Uppsala University decided to find out if there is a link between genes and addiction to dogs. They used two data sources – the Swedish Registry of Twins and the national Dog registry.
The Registry of Twins is the world's largest database of twins, which the Swedish Karolinska Institute has been collecting since the 60s of the XX century. Now it stores information about almost 200,000 thousand twins born since the 1920s. The database is often used for medical research.
In this study, it was useful because monozygotic (identical) twins are exact genetic copies of each other, and only about half of the genes match in dizygotic (fraternal) twins. Thus, it is possible to understand how genes affect a trait - in monozygotic pairs it will be more often expressed in both brothers or sisters than in dizygotic ones. In addition, thanks to this, the environmental factor is almost leveled, because usually twins live in very similar conditions.
The second register is maintained by the Swedish Council for Agriculture. According to the laws of the country, each dog must be registered, the register contains its identification number and information about the owner. The owner must inform the council if his pet has changed his nickname, place of residence or about any other important events in the life of his animal.
For the study, scientists used information about twins born from 1926 to 1996, excluding those who died before 2006, those who did not live to be 20 years old, and those whose zygosity was not known. The result was a set of 35,000 pairs of twins, both mono- and dizygotic. In the dog registry, scientists looked at which of the twins kept pets, combined these data and statistically processed them.
It turned out that women most often have dogs – 65% versus 54% for men. The most popular breed is "mixed", the golden retriever is in second place, and the German Shepherd is in third place. However, the main thing that scientists paid attention to was the difference between mono- and dizygotic twins. In the case of monozygotic dogs, both siblings were almost twice as likely to have a dog. This means, the authors of the study believe, that the question of whether to get a dog was largely determined by the genetic predisposition of people. According to calculations, it turned out that genes caused the love of dogs by 51% for men and 57% for women.
The study showed only that the domestication of the dog was apparently largely associated with some genes in human DNA, but did not show which ones. Now, as the authors write, additional work is needed to find out exactly which genetic variants helped a person make friends with a wolf and make a dog out of it.
Article by Fall et al. Evidence of large genetic influences on dog ownership in the Swedish Twin Registry has implications for understanding domestication and health associations published in the journal Scientific Reports.
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