Sex is the key to changing the vole -

Over the years there has been a sea change in the hearts and minds of people about the vole.

Some put this down to the fact that really there are much worse things out there - things with a fruity flavour and those organisations which claim to do no evil but pay no taxes.

Now scientists have worked out why people are feeling a lot more positive about the vole and it is all down to brain chemistry and sex.

Researchers have confirmed that sex induces permanent chemical modifications in the chromosomes, affecting the expression of genes that regulate sexual and monogamous behaviour.

According to a study published in Nature Neuroscience, prairie voles mate for life. The voles' pair bonding, sharing of parental roles and egalitarian nest building in couples makes them a good model for understanding the biology of monogamy and mating in humans.

Neuroscientist Mohamed Kabbaj and his team at Florida State University in Tallahassee took voles which had been housed together for six hours but had not mated. The researchers injected drugs into the voles' brains near a region called the nucleus accumbens, which is closely associated with the reinforcement of reward and pleasure.

Animals that had been permitted to mate also had high levels of vasopressin and oxytocin receptors, confirming that sex activates this brain area which leads to partner preference.

It is not just the drug though. It takes a drug plus about six hours of living together for the Voles to think they have found their dream partner. This might explain why Steve Ballmer has stayed as Microsoft's CEO for so long.