Neuropeptides as facilitators of domestication.

Animal domestication was an important stage in the human history, which coincided with or probably even promoted the advent of a turning point at which part of the humankind switched from hunting and gathering to husbandry. The leading factor in evolutionary changes at the dawn of domestication was probably selection for behavior towards humans: first natural (as the animals were habituating to a new ecological niche close to humans), then nonconscious, artificial. Selection was supposed to work on the systems that regulate behavior by reducing stress response and aggression and by inducing an emotionally positive response to humans. A possible role of the neuropeptides adrenocorticotropic hormone (ACTH), oxytocin (ОТ), arginine vasopressin (AVP), and their receptors is in the reduction in stress response and in the shaping of domestic behavior. Effects of oxytocin on the behavior of domestic animals have been actively explored in the last 10 years, with special focus on the dog. The results obtained so far suggest that this neuropeptide is substantially important for human-canine interactions, together with sex, amount of aggression experienced, and other factors. The study of AVP demonstrated its importance in aggression in domestic animals. This work lends support to the hypothesis that a substantial factor in the shaping of domestic behavior and in the reduction in stress-response might be selection for an enhanced activity of the central OT system and a reduced activity of the central AVP system, which have effects on ACTH and social behavior.