How does natural selection affect behavior?

Individuals within a population exhibit varying behaviors. In the majority of scientific experiments, individuals are classified into two groups: timid and courageous.

Both of these have benefits and drawbacks. For example, bold people typically have easier access to resources and partners, but they are also more susceptible to predators (shy people have the opposite problem).

A fast growing individual would tend to be bolder because it needs to acquire more energy to sustain its metabolism, according to some studies (this one, for example) that suggest behavior is related to growth and metabolism.

This also suggests that behavior is heritable through metabolism. In fact, if a selective pressure favors individuals with high metabolisms, such as those who are bold, it will favor those with high metabolisms, increasing the likelihood that both the trait and the associated behavior will be passed down.

For those who wish to delve a little deeper, check out this publication and its references, which discuss how fish behavior is affected by human selection (angling), with essentially the same mechanisms as those found in natural selection.

Additionally, individuals have the ability to learn and adapt their behavior in order to evade the selective pressure. For instance, research has shown that red deer adjust how they use their habitat at the beginning of the hunting season in order to avoid the pressure from hunters (see here).

Natural selection affects behavior by favoring traits and behaviors that increase an organism's chances of survival and reproduction in a given environment. Behaviors that contribute to finding food, avoiding predators, attracting mates, and caring for offspring are more likely to be passed on to future generations. Over time, these behaviors can become ingrained in a population, shaping its overall behavior patterns.