Humans alone can control lust, but most don't

Remarkable advances in sophisticated "functional magnetic resonance imaging" technology have permitted scientists to determine that coquetry, infidelity, watching erotica and other prurient behaviours have an extraordinarily powerful impact on the "reward circuitry" in the human brain.

Recent studies by researchers at the University of Montreal indicate erotica impacts disproportionately on the brain's medial prefontal, orbitofrontal, insular and occipitotemporal cortices, as well as the amygdala, ventral striatum and anterior cingulate cortex. In males only, erotica also stimulates the hypothalamus and thalamus.

Studies at Northwestern University indicate that lust and cuckoldry are almost "compulsive" as a direct result of their impact on the brain's reward centres, which are foci of sensual interpretation. Erotic stimuli create a neurological frenzy.

Reseachers at the University of Melbourne have discovered that lust intensity depends on the size of the amygdala in the brain. According to Helen Fisher at Rutgers University, lustfulness involves brain systems that differ from those involved with love or affection; lust is usually "kick-started" by testosterone.

Studies at Rutgers University, the State University of New York and elsewhere show infidelity and lewd behaviour in mammals and birds result from a "constellation of neural correlates." Researchers agree that lust probably evolved to generate mating behaviour among any appropriate partners.

According to Cornell University researchers, there are very few species of mammals or birds that do not regularly engage in infidelity and promiscuity. Such activities have been confirmed in elk, mice, squirrels, deer, wolves, hares, rabbits and virtually all bird species so far studied.

In humans, lust is one of the most enjoyable sins, according to researchers, owing to its huge impact on the pleasure centres in the brain. But, according to research by Beauregard Mario and colleagues at the University of Montreal, powerful lust and lechery impulses can be controlled in humans by the brain's right superior frontal gyrus and right anterior cingulate gyrus. Control is by means of a conscious regulatory process that is absent in birds and mammals.

According to the U.S. National Institutes of Health, the human brain has no "sin centre." A comprehensive "Human Connectone Project" has recently been initiated to map the wiring of the human brain to more fully understand how activity centres function. Neuroimaging is expected to shed much light on why prurient urges are so potently compelling.

Of particular interest to researchers is the influence of watching pornography on the brain's sensory circuitry. Preliminary data indicates porn impacts on all the brain's reward centres.

Accumulating evidence shows that about 50 per cent of all married women, and 55 per cent of married men, engage in cuckoldry. Some 81 per cent of women and 86 per cent of men engage in flirting.

In birds and most mammals, infidelity is rampant and in perhaps a majority of instances, male parents rear offspring that they did not actually father. So far, research has not confirmed whether or not birds and mammals actually experience lustful urges or whether infidelity stems exclusively from innate genetic programming.

Robert Alison has a PhD in zoology and is based in Victoria, B.C.

Republished from the Winnipeg Free Press print edition August 23, 2009 A11