Women Says: All Men Think about is Sex Without a doubt, men and women are biologically different in the sex department. These distinctions stem from gender-based differences in hormone levels. Hormones are the chemicals that are produced in one part of the body and race through our blood to other organs, causing changes in the delicate balances of our behavior__and our desire for sex. For men, it's testosterone that fuels that drive. Testosterone is produced in the testes (slang term "balls") and flows through the blood to affect the functioning of nearly every other organ system, from cholesterol levels to muscle strength to brain function. This hormone is the reason why your wife/girlfriend is right: You do think about sex far more often than she does__because you have ten to twenty times more testosterone flowing through your system than she does, causing you to have more thoughts of sex and a greater desire for sex (most of the time) than your wife/girlfriend. Although testosterone also contributes to an increase tendency to be competitive and even aggressive, and affects energy levels, motivation, and drive, evolutionary endocrinologists think that its influence on the sex drive is the most pronounced. They speculate that this has something to do with WHY married men, and other men in committed relationships, have a 20 percent drop in their testosterone levels___to help keep them from straying. There are a great many ways in which the brain and certain body chemicals influence the way men act and the way they see the world. In later chapters you'll see how higher testosterone levels make men more aggressive than women and less able to hold eye-to-eye contact. You'll learn that levels of other hormones are responsible for our strong need to bravely protect our homes and our mates (as well as our occasional desire to wander away from home) like going fishing and hunting! You'll learn about Oxytocin, a bonding hormone that surges when a man has an orgasm (dispelling the myth that men aren't looking for emotional connection in the sex department). You'll come to understand that men are different from women but that this does not make them incompetent husbands, fathers or lovers.