Scientists Uncover Hormone make Social Behavior in Fish

Researchers have found that the formula of oxytocin - a hormone responsible for making people to fall in love - have similar effects like those of fish, suggesting that this hormone is a major regulator for social behavior have evolved and survived since ancient times.This discovery, published in the current issue of the journal Animal Behaviour, helps answer an important evolutionary question: why some species develop complex social behavior while other species spent more time alone?"We know how these hormones have an effect on humans," said Adam Reddon, lead researcher and a graduate of the Department of Psychology, Neuroscience & Behaviour at McMaster University. "It deals with love, monogamy, even risky behavior, but not so well known effect on the fish."Specifically, the researchers examined the fish Neolamprologus Pilcher, highly social species found in Lake Tanganyika, Africa.The fish is quite unusual because they establish a permanent social groups based on the dominant breeding pair and the many who helped care for the children as well as defend their territory.To conduct the experiment, the researchers injected isotosin in fish - oxytocin "version of fish" - or control saline solution.When placed in the competition with rivals, these fish become more aggressive against larger foes. However, when placed in a big group, these fish become more docile in the face of aggression from members of the dominant group. These signals are important for species such as soothing dominant members in a group, the researchers said."This hormone increases the ability of response to social information and can serve as an important social bond," said Reddon, "This ensures the fish to handle conflict well and maintain group cohesiveness because it will lessen and shorten fights harmful.""We already know that this class is a class of ancient neuropeptides and is found in virtually all vertebrate groups," said Sigal Balshine, a professor in the Department of Psychology, Neuroscience & Behaviour. "What is particularly interesting is these findings support the idea that the function of this hormone, which is a modulator of social behavior, have also been preserved."