A research team led by Takefumi Kikusui of Azabu University has announced a new hypothesis of the mechanism by which humans and dogs can promote symbiosis.
Dogs are the oldest domestic animals and are highly tolerant to humans and sensitive to signals used by humans (pointing, gaze, etc.).So far, the research team has found that dogs and humans have been able to establish a special relationship by secreting the hormone "oxytocin," which is involved in bond formation and trust, through the line of sight.However, the origin and factors of such relationships are still unknown.
In this regard, Dr. Brian Hare of Duke University said, "Human and dog have acquired social tolerance, the living environment of each other has overlapped, and gradually the common social cognitive ability has been acquired." He advocates the evolutionary hypothesis.
It is important that the living environment overlaps with that of humans, and as a result, domestic animals such as dogs have acquired traits that are gentle and easy to handle with respect to humans.In the background is the involvement of the endocrine hormone "cortisol" that controls anxiety and attack.It seems that the cortisol level in dogs decreased, and as a result of the decrease in aggression and fear response and the improvement in social tolerance, it became possible to coexist with the different species of humans.
In addition, dogs became more sensitive to social signals exhibited by humans, and their ability to communicate with other species expanded.At the same time, the decrease in the basal secretion of oxytocin seems to have eased limited bond formation and cooperation within the same species, and expanded the scope to bond formation and cooperation between different species.
This time, we introduced the latest findings on the role of endocrine system that supports the convergent evolution hypothesis and the hypothesis of the mechanism that enabled symbiosis.From the perspectives of genetics, archeology, behavior, and endocrinology, it is hoped that an integrated understanding of the symbiosis between humans and dogs will elucidate the background behind the birth of dogs, the "greatest friends of humans."
Paper information:[Trends in Endocrinology and Metabolism] Endocrine regulations in human-dog coexistence through domestication
