"We believe romantic love is a developed form of one of three primary brain networks that evolved to direct mammalian reproduction," says researcher Helen Fisher, PhD, of Rutgers University in New Brunswick, NJ. "The sex drive evolved to motivate individuals to seek sex with any appropriate partner. Attraction, the mammalian precursor of romantic love, evolved to enable individuals to pursue preferred mating partners, thereby conserving courtship time and energy. The brain circuitry for male-female attachment evolved to enable individuals to remain with a mate long enough to complete species-specific parenting duties."
In the new research, Zak and his colleagues find that when someone observes that another person trusts them, oxytocin - a hormone that circulates in the brain and the body - rises. The stronger the signal of trust, the more oxytocin increases. In addition, the more oxytocin increases, the more trustworthy (reciprocating trust) people are.
"Interestingly, participants in this experiment were unable to articulate why they behaved they way they did, but nonetheless their brains guided them to behave in `socially desirable ways,' that is, to be trustworthy," says Zak. "This tells us that human beings are exquisitely attuned to interpreting and responding to social signals.
(Or, perhaps, that what we know as the conscious mind doesn't so much make decisions or control our behaviour as rationalise it; could it be that the conscious mind does little more than provide a running commentary for the many physical processes happening in the brain and nervous system, and the (advantageous) illusion of a coherent, unified "self"? But I digress.)
And in other related news: a wink sends testosterone soaring:
He paid male students $10 to come into the lab and leave a saliva sample. Unbeknownst to the men, the scientists staged a five-minute chat with a twentysomething female research assistant before they spit. This brief brush set the men's hormones surging: testosterone levels in their spit shot up around 30%. The higher a man's hormone soared, the more the female research assistant judged that he was out to impress - by talking about himself, for example.