Gene treatment for male monogamy
Gene treatment for male monogamy
June 18, 2004
YOU'VE just met the man of your dreams. But will he love you forever? Or will he love you and leave you? If only there were some sort of blood test to find out for sure...
Well, if one day a "fidelity test" for men does emerge, women may have the humble vole to thank, according to a study published Thursday in the British science journal Nature.
In a remarkable experiment in hormone chemistry, behavioural scientists implanted a single gene into promiscuous male voles, transforming them at a stroke into faithful, attentive and caring partners.
The rodent in question is the meadow vole, Microtus pennsylvanicus -- and he is the original love rat.
The male vole thinks nothing about mating with several females at one time and leaving them to rear his offspring while he wanders off in search of his next conquest.
In contrast, the meadow vole's cousin, the prairie vole (Microtus ochrogaster) is a model of fidelity.
After mating, the male prairie vole sticks close to his partner, protects her jealously and looks after the little ones after they are born.
This is such a rare thing in nature -- fewer than five per cent of all male mammals are monogamous -- that the prairie vole has become quite a celebrity in biology labs.
Previous studies have shown that its brain is studded with receptors for a hormone called vasopressin, which appears to encourage pair-bonding.
Intrigued by this, researchers led by Miranda Lim and Larry Young at Emory University in Atlanta, Georgia, implanted a gene for the V1a receptor in question in the brains of naughty meadow voles.
They tucked the gene into a harmless virus which then delivered the V1a gene to the ventral pallidum region of the voles' brains.
What happened next was dramatic. Once, the voles were Don Juans forever on the cruise. Now, they had a chosen partner, and would only ever mate with her.
Even when temptresses came by and flaunted their voley charms, the genetically-modified males only had eyes for that one partner.
The study theorises that when the modified meadow vole has sex, his brain release vasopressin, which is picked up by the V1a receptors.
They, in turn, unleash serotonin, a "feel-good" chemical, to flood the brain. Put together, it means the vole associates the feeling of reward when he has sex with this specific mate, and does not want to prejudice that sensation by having sex with others, according to this notion.
In a commentary, also published in Nature, US anthropologist Melvin Konner, says the work helps strengthens theories that an "organic subculture" -- our genes and the chemicals they produce -- lies at the root of the psychology of relationships.
That theory is bitterly contested by sociologists, who say social forces and environmental influences are the primary moulds which condition human bonds.
"We are a long way from a commitment pill, but perhaps closer to a neurology of romance," says Konner.
He adds: "We do not yet know if a similar system helps explain male attachment in non human primates, much less humans. But a medicine that might someday be offered to certain men is an interesting prospect."
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