Falling in love is similar to a drug addiction, a US study says.
Prairie voles develop monogamous relationships similar to humans
A Florida State University team found that the brain chemistry responsible for addiction plays a role in love.
Researchers said the messenger chemical dopamine, which stimulates the brain's reward centre, helps keep male Prairie voles monogamous.
Prairie voles are well known for forging long-lasting relationships, the Nature Neuroscience journal reported.
Dopamine plays a key role in attracting people back to sources of pleasure, such as good food.
It also acts to keep a drug addict hooked on heroin or cocaine.
The team decided to study Prairie voles because they, more than any other animal, show signs of falling in love in the way humans do.
Males and females bond after a single mating encounter.
After which male voles also show signs of aggression towards other females.
Researchers found that after mating, dopamine was released into the brains of males and affected an area of the brain known as nucleus accumbens, which is also present in humans.
The team then blocked the activity of a protein that is activated by dopamine in the vole's brain.
They found males lost their usual strong preference for their mate over other females.
Lead researcher Brandon Aragona said the bond which develops between voles was extremely strong.
He said the study was the first to illustrate the way the brain reacts to prompt monogamy.
And he added while humans would differ, the basic mechanisms would be similar.
Colin Wilson, of the British Psychological Society, said: "Love is a complex emotion. Undoubtedly there are changes in neurophysiology, but it not going to be down to one chemical alone."
And he also agreed human attraction would be different to that of voles.