As you leave childhood, your old brain expands its focus to a new task. It urges you to get excited about girls. It hopes that someday you will pass on copies of yourself in the form of babies. As odd as it may seem, this is the number one job for the old brain.News flash: Gay boys are a myth, like unicorns and actual faeries of the winged sort.
Your old brain prepares you for this future task by making you “hungry” for anything that is related to sex.
In fact, your old brain thinks sex is way more interesting than eating. That's why sexual feelings can be much more intense than hunger.
When you stumble upon something connected with making babies – like a website with naked women on it, or some other picture associated with sex – your old brain takes over. It releases chemicals into your brain that make you feel like true happiness is just around the corner. It is like the feeling you get when you're about to open your birthday presents. This feeling is the old brain's way of giving you a big “yes!” for focusing on sex. As one man said, “When I saw my first picture of a naked woman I thought, ‘This is just wonderful!”