Wild rats that have been seen by humans are found to change significantly in appearance
The research team at the University of Zurich announced that the appearance of the rat has changed significantly as a result of taming the wild mouse. Until now I knew that "appearance will change when animals are selectively mated so as to make it easier for humans to tailor", but in this study the appearance has changed without selective breeding It was confirmed that it was confirmed.
UZH - Mice Change Their Appearance as a Result of Frequent Exposure to Humans
(PDF file) Madeleine Geiger, Marcelo R. Sánchez-Villagra and Anna K. Lindholm. A longitudinal study of phenotypic changes in early domestication of house mice.
pigOriginallyboarIt is known as a domesticated living creature. Also,WolfIt is thought that it is a species derived from domesticationDogBy selec- tively mating to human beings easily, a big change appeared on the appearance such as "the ears dripped" and "the fangs got smaller". In this way, the appearance change seen in animals raised is sometimes called "The Domestication Syndrome" (Domestic Syndrome).
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The research team led by Anna Lindholm belonging to the Department of Evolutionary Biology and Environmental Studies at the University of Zurich has caught a wild mouse in the barn near Zurich and kept breeding for about 15 years but it is not ten years We have confirmed the apparent change that "white spots appear on brown fur" and "nose becomes a bit shorter". The following image is a mouse actually tamed by the research team.
Research on such domestication syndrome was also conducted in the Soviet Union in 1959. He is a geneticist of the Soviet UnionDmitriy BellaevHe studied breeding and observing wild ginsengs.
Mr. Bellaev selectively married a fox that is familiar to humans as possible. Then he seems to discover that it can obtain apparent change in evolution that takes thousands of years, such as "get smaller physique" and "roll up with tail" in only a few years. And it seems that sagging ears and spotted patterns are seen in the fox nine generations after the start of the mating, and it began to take actions that are impossible in the wild, squealing and amening while shaking the tail against humans Thing.
It is not clear yet why domestication syndrome is seen, but the early embryoNeural crestofStem cellsIt is believed to have a cause. Neural crest stem cellsMelanocytesAnd hormone-producing cells. Small stem cell group of the neural crest produces stress hormoneAdrenalIt is said that it becomes a character that is small, calm and scared to humans. At the same time, formation of cartilage of the ear and pigmentation of the skin can be suppressed, so selective crossing of animals that have a character easily tolerant to humans results in easier appearance changes such as sagging ears and white spots as side effects It is predicted that it is not.
However, the wild mouse mice kept by the research team at the University of Zurich did not do intentional mating which would make it easy for human beings to become familiar, only to keep observing while regularly giving food and water. Nevertheless, as if a mouse were kept from human beings to himself, it was possible to observe how the appearance of rats changed, so that wild mice live while being exposed to human eyes , Showed the phenomenon "self-domestication".
Mr. Madeleine Geiger, who belongs to the research team, said, "It was thought that rats started to live in the immediate vicinity of human beings for food preservation more than 10,000 years ago by this self-domestication, and the origins of the dogs It is not aggressive breeding by humans, but may be due to wild wolves becoming living near humans and self-domestication. "