Mother‘s milk has been always known to form bond between mother and her child. But new study shows that the same hormone that stimulates milk production in nursing mothers also fosters bond between parents. Researchers at the University of Wisconsin-Madison found interesting links between hormones usually linked to mother-child relations and pleasurable emotions between paired monkeys.
Researchers were conducting non-invasive study of urine from cotton-top tamarins, a small, endangered monkey native to Colombia. This specie of monkeys has one similarity with humans – they live in monogamous family groups where both parents help care for the young. This tamarin colony lived in the UW-Madison psychology department. In 2008, the colony was closed and the animals were transferred to zoos, sanctuaries and other colleges.
This study found a link between prolactin levels and sexual activity and cuddling among paired adults. Previously, similar link was found for oxytocin, a hormone that stimulates childbirth and is linked to a range of pleasurable emotions. In short, prolactin levels were higher in those mothers who frequently had sex and cuddled with their partners.
This study, by elaborating on the picture of hormonal activity in pair bonding, sheds a new light on the critical role that hormones play in rewarding behaviour related to monogamy. Scientists think that high levels of prolactin are a consequence of parenthood. In other words, it is a reward for parental care. Prolactin may, among other things, function as a reward mechanism for sex. It is thought that both hormones –prolactin and oxytocin – act together.
Oxytocin’s role has been discovered about 25 years ago. It was discovered that oxytocin was not just about parenting, or the mother-infant bond, but about the pair bond between the adults as well. Now scientists claim that there is an amazing overlap between prolactin and oxytocin – the same hormones and brain areas are involved in controlling a behaviour that is as important to survival as parenting and pair bonding.
What do these discoveries mean for humans? Scientists say that good pair bond is a precursor for good paternal care in monkeys as well as humans. Study also supports argument that monogamous relations in some primates are actually genetically programmed. However, further research has to be done and it remains unclear what kind of implications these results may have on our understanding of parenthood and relations between parents.