I was walking around San Diego’s Balboa Park last night, and as one would expect, started musing on somatic markers. Somatic markers are, as you no doubt recall from a previous post, the physical sensations our bodies produce when prompted by a certain emotional state.

Why would our bodies and brains evolve this way? I wondered. As I started to think it through, it made a lot of sense. Let’s take sex as an example. After you blast a big load of man cream all over a Thai prostitute (or a picture of a Thai prostitute on your computer screen) you feel great. Your body rewards the process of ejaculation with pleasurable sensations (via “pleasure chemicals” which are introduced into your system.) This gives you a strong impetus to go out and have sex with more Thai prostitutes (or even regular women), thus increasing the odds that your DNA will be passed on to new generations.

Of course, both men and women have managed to find a workaround in the system: masturbation. By this method they get the pleasurable sensation without the hassle of having to go out and find a mate or Thai prostitute. Our bodies instantly reward the behavior — mating — not the result — having children, which is ultimately what continues our DNA. Frankly, if there was no pleasure involved, few people would have any interest in the process of creating screaming babies.

But sexual pleasure is easy to explain. Are there other activities, not involving Thai prostitutes, that earn pleasurable emotions? For me, one would be writing a song. Why would that be rewarded with a positive sensation? Well, songwriting is essentially problem-solving. And being good at problem-solving is rewarded by evolution. Throughout most of our history, the guy who could make fire, or ward off saber toothed tigers, was looking pretty good in terms of natural selection. And he was also quite appealing from the standpoint of sexual selection: chicks like dudes who can make fire or ward off saber toothed tigers. A brain that gives you a good feeling when you overcome a challenge is giving you an impetus to keep taking on challenges, which strengthens the odds of your genetic material surviving.