Orgasms may have evolved as a bartering tool to keep sexual partners coming back for more.

A new study has shed light on the evolutionary purposes of intense sexual pleasure, revealing how these feelings act as positive reinforcement between partners and can, in turn, motivate our behavior.

These 'rewards' may have arisen as a way to maintain control in a relationship and even ensure reproductive success, preventing men from seeking other mating opportunities and keeping women from abandoning the father of her children.

And as women experience orgasms with far less consistency than men, the researchers say female pleasure may be a much stronger form of reinforcement.

A new study has shed light on the evolutionary purposes of intense sexual pleasure, revealing how these feelings act as positive reinforcement between partners and can, in turn, motivate our behavior

THE 'CURRENCY' OF SEX According to a new study, published in Socioaffective Neuroscience and Psychology, orgasms and intense sexual pleasure may be a form of 'currency' in relationships. These things act as positive reinforcement, or rewards,' between partners and can, in turn, motivate our behavior and help us maintain control. As the human sex drive isn't strongly linked to fertility, orgasms instead may be a way of reinforcing the bonds between two people. This type of reward could signal devotion to a partner, and improve the bond between parents, the researcher explains. And, it could even help ensure reproductive success. These 'rewards' could prevent men from seeking other mating opportunities, and keep women from abandoning the father of her children. And as women experience orgasms with far less consistency than men, the researchers say female pleasure may be a much stronger form of reinforcement. Advertisement

According to Dr Diana Fleischman, a psychologist at the University of Portsmouth, orgasms and intense sexual pleasure may have evolved as a type of 'sexual currency.'

'All animals engage in behavior that has positive consequences and learn to associate reward with the stimuli that go with it, eventually finding those stimuli rewarding in their own right,' said Dr Fleischman.

'Orgasm and sexual pleasure are intensely fulfilling and when people experience sexual pleasure with another person they start to be rewarded by that person, their form, their smell, their voice, etc.

'Their partner becomes a reward in their own right and ultimately this gives people leverage in relationships.'

A reward system, the researcher explains, is far more effective at shaping human behavior than punishments.

And, withholding these rewards – with the silent treatment, or a curt attitude – will have a heavier impact.

'When it's in our interest, such as making up after a fight, we are rewarding again,' Dr Fleischman said.

'Think about how we often use tasty, high calorie food as a reward.

'Food, warmth, sleep, and sexual pleasure are all examples of physical rewards that give us pleasure, make us feel good and can cause behavioral changes.

'Sex is incredibly powerful – when it comes to physical pleasure it doesn't get much better than an orgasm.'

The researcher also says these rewards are more pleasurable when they fulfill a need.

As the human sex drive isn't strongly linked to fertility, orgasms instead may be a way of reinforcing the bonds between two people.

This type of reward could signal devotion to a partner, and improve the bond between parents, the researcher explains.

In turn, this could help to ensure reproductive success.

'Rewarding someone with sexual pleasure or orgasm and having someone like you more, could help build a foundation for people in relationships caring for children,' Dr Fleischman said.

'Feelings of pleasure and well-being could lead to more positive associations and would make them more likely to forgive one another for errors or indiscretions that would, in the case of a less reinforced pair bond, cause one or both to abandon the relationship.

'A man's pleasure at sexual contact with the mother of his children may prevent him from allocating his effort or resources to other mating opportunities or other children, and for a woman, continued sexual pleasure with the father of her children could prevent her from abandoning a relationship that is provisioning and securing her offspring and could act as a reassuring signal of paternity to her mate.'

These 'rewards' may have arisen as a way to maintain control in a relationship and even ensure reproductive success, preventing men from seeking other mating opportunities and keeping women from abandoning the father of her children

According to the researcher, this could also help to explain why women have less consistent orgasms than men, suggesting there may be fewer biological drivers.

And as orgasm isn't a necessary element of conception, it could act as a way to reinforce the relationship.

'For men, sexual behavior has low potential costs compared with great potential reproductive benefits,' Dr Fleischman said.

'However, women can reproduce only once a year, and their parental investment is higher as they carry a child for nine months. We should expect evolution to be more selective about the sort of sexual behavior that should be reinforced with extreme pleasure.