Lost in love

Is being in love a pathological condition? It certainly has some profound effects on our behaviour – and our physiology.

We've all heard someone being called 'hormonal' when they're in love – so it's no surprise to learn that a hormone may be involved in 'love' biology. Studies have shown that people who are in love have higher levels of a hormone known as oxytocin. Oxytocin also seems to generate trust in humans: using a trust-based investment game, scientists found that experimental subjects given an oxytocin nasal spray showed far greater trust than a control group.

Brain activity also changes when we are in love. Using a brain scanning technique called functional magnetic resonance imaging (fMRI), scientists have shown that certain parts of our brains become activated – and deactivated – when we are in love.

Brain activity has been studied in people claiming to be deeply in love, while they viewed pictures of friends or loved partners. People looking at their partner had increased activity in areas believed to have a high concentration of oxytocin receptors and to be associated with reward. Meanwhile, other studies showed that parts of the brain associated with social judgement were deactivated when in 'maternal' or 'romantic' love.

So when we are in love, we become less critical of others and feel rewarded for forming bonds. Unfortunately, perhaps, these effects seem to wear off after two or three years and our critical faculties are restored. By this point, though, partners may have bonded sufficiently that such mechanisms are no longer necessary.

So, although Einstein may have been right when he said: "You can't blame gravity for falling in love", it seems that there might still be a scientific basis for love.