Often referred to as casual sex without commitment or deep feelings. According to experts in the sex sciences, however, there is no such thing as “non-committal” sex. Human evolution has led to the emergence of three distinct brain systems associated with reproductive behavior. Each of these systems is directly related to only one or two hormonal neurotransmitters – the molecules that transmit information signals in the nervous system. The first system is that of the libido – it is responsible for sexual desire or drive. In men, as in women, libido is primarily controlled by the body’s testosterone levels. When sexual desire and readiness for sexual contact occur in every person, the diencephalo-pituitary structures, as well as parts of the limbic nervous system, are hyperactivated, which means that strong feelings are experienced and emotional and behavioral reactions are formed towards the partner – the brain adjusts to total change of bodily and psychological functions. The second system is the dopamine system. Whenever a person is overcome with romantic thoughts and strong feelings for their object of desire, their thoughts and actions are dictated by the released amounts of dopamine – one of the hormones of happiness. Its innumerable actions on the whole organism are directly related to enjoyment and the ability to experience pleasure, but can even lead to addiction. And addiction to a partner can only be interpreted as “falling in love”. NEWS_MORE_BOX The third system, which is responsible for emotional and physical attachment to the partner, is dictated by two hormones: oxytocin and vasopressin, the release of which in the brain leads to changes in behavior. For these reasons, “casual sex” simply does not exist. The brain is overwhelmed by the biochemical cocktails that are released during sex, so much so that the three systems responsible for sex – that of libido, dopamine and attachment – become interconnected and each of them activates the other two. This turns every desired and sought-after intimate contact into “love-making.”