The secret of the kiss

When we kiss the body, we secrete certain chemicals that can control stress hormones in both sexes.

Chemicals related to stress state vary greatly when people kiss, but this change in men and women is not the same. That is the conclusion of Wendy Hill, a professor of neuroscience at Lafayette University (USA).

Wendy and her colleagues recruited several couples in love among Lafayette University students. Before conducting tests, experts took samples of volunteers' blood and saliva. They then asked the couples to listen to the music and kiss and take their saliva and blood again. The research team wanted to understand the changes in oxytocin and cortisol concentrations at the time before and after the couples kissed.

Oxytocin is a hormone that plays a decisive role in building and maintaining relationships in mammals. In humans, the pituitary gland is the producer of oxytocin. The concentration of oxytocin increases when women give birth, breastfeed and have sex. The higher the concentration of oxytocin is, the easier it is to trust other people.

Meanwhile cortisol is also called stress hormone because it affects the body's response to stress. Cortisol increases blood pressure and blood sugar levels, and reduces the immune response.

The results showed that cortisol levels in both men and women decreased after kissing, meaning that the level of stress decreased. Increased levels of oxytocin in male groups indicate that they are more interested in the act of kissing a partner, but the concentration of this chemical decreases in the female group. 'That surprised us,' Wendy said.

When the group of volunteers only held hands, the chemical changes in men and women were the same. Helen Fisher, a neurologist who also participated in the study, emphasized that more than 90% of the world's population performs kissing. She believes that every kiss represents three things: sex, love and cohesion.

Men tend to think that kissing is the beginning of lovemaking, Helen said. They like to use their tongue during kissing so chemicals, including testosterone (male sex hormones), can be transmitted to partners through saliva. Testosterone has the ability to stimulate sexual desire in both men and women.