More than 10,000 years ago, the Wolf -like ancestors of the dogs began to develop into the best friend of humans. But even after more than a century of research, experts still do not know exactly how this process of domestication went and why it came about. As a working group led by Miho Nagasawa from the Japanese Azabu University in the journal »Scientific Reports«, genetic changes have made sure that the forerunners of the dogs were able to endure human proximity. Apparently, the gene mutations led to a lower stress level in the animals.
"This is the first genetic evidence of the hypothesis that mutations in the stress reaction system have triggered the dog's domestication," says main author Nagasawa. She and her team acquired the owners of 624 dogs and let the animals complete two experimental tasks. The researchers divided the four -legged friends into two groups: the one of races such as Akitas and Siberian Huskys, i.e. those dogs that are closely related to the wolf -like ancestors; The second group included races that are further related.
In the first task, the researchers gave the dogs to the dogs through the direction of view or by interpreting their fingers, in which a treat was hidden from two shells. The test should show how well the dogs understand human communication signals. It also built up on older knowledge that even very young dog puppies understand human signals better than adults, people raised by people. As was to be expected, the research group around Nagasawa did not find different behavior between the two dog groups.
How intensively do dogs seek help from humans?
For the second test, the dogs were confronted with an unsolvable task: they should open a container with food that the animals could not possibly have opened alone. Nagasawa and her team documented how long the frustrated dogs looked for help while trying - because wolves also show less than dogs. With this experiment, the scientists now registered a significant difference between the two dog groups: the older races spent less time asking for people. Nagasawa and her colleagues concluded that the younger dog breeds are more socially bound by humans.
In a next step, the researchers analyzed four gene segments in the dogs; including those involved in the production of oxytocin – a hormone that affects social bonding in many species – and cortisol, an important stress hormone. There was indeed a difference on a gene for cortisol production. A similar result was provided by a study from 2009: In bred foxes, which were less shy and aggressive towards humans, low cortisol levels were also found.
The mutations on the gene as well as the behavior of the dogs in the experiments led the scientists to the conclusion that a lower stress level may have played an important role in dog domestication. More trust in humans would be an important first step for the animals to develop the necessary cognitive abilities for interacting with humans.
“Although it is not yet clear whether the stress marker cortisol is actually lower in dogs than with wolves, the presence of two mutations on one gene could show us - one of which is associated with changes in the production of intracellular cortisol - how dogs the ability developed to adapt to human society, «says Nagasawa. You and her colleagues now want to find out whether the cortisol values between the two dog bass groups actually differ.
Can genetic data be transferred from today's dogs to their prehistoric ancestors?
The study in "Scientific Reports" provides exciting new evidence that the extraordinary ability of dogs to cooperate and communicate with us is the result of a natural selection - to wolves that approach man and finally show friendly behavior could «, says the evolutionary anthropologist Brian Hare from Duke University, who was not involved in the study.
Maria Lahtinen, a visiting scientist at the Finnish Museum of Natural History, who also did not participate in the new study, doubts, however, that the new findings necessarily apply to dog ancestors. "The problem with this work is that modern dogs have been studied to find out about the past," says Lahtinen. "I would not use the results of the study for this, but understand it as an indication of how modern dogs behave.«
In order to avoid this problem, Hare suggests extending future studies on populations of other old dog breeds. If the mutations identified in the new study actually played an important role in the fact that dogs can communicate differently with people, says Hare, "then it should be possible that dingos and neulic-dingos also have the same relationship between understanding human gestures and this Have genes. "
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