Gleitman, Gross, & Reisberg define natural selection as “the mechanism that drives biological evolution”. This mechanism is a process that takes place over generations, as organisms who were able to successfully reproduce pass on traits that helped them survive to that point. Structural traits are physical attributes like hair. One of the examples provided was in regards to sticklebacks of Lake Washington. As murky water that had provided them cover from predators began to clear, sticklebacks with heavier armor became more likely to survive predator attacks and were more likely to reproduce. After fifty years of parents passing this trait down to offspring, the more heavily armored fish became dominant in the lake. Behavioral traits are not physical but rather are things that are done by an organism like being protective of your young, such as certain species of bird in which a mother bird flies from the nest and feigns injury to draw a predator from her offspring. This is more than simply a single extremely maternal bird because the behavior is seen in many female birds across many species of bird.
Our biology plays an important role in our behavior because our hormones and nervous system play a significant role in how we react to stimulus, and damage to our brain or nervous system can have a drastic impact on our behavior. Someone with higher than normal levels of testosterone is likely to be more aggressive than other people, and therefore more prone to angry outbursts or violence. It’s important to understand how biology affects our behavior because it means we can research ways to treat behavioral abnormalities through biological means – such as attempting to raise or lower hormone levels or affect the actions of neurotransmitters to alter or control behavior.
Biology is not the end all in understanding behavior, though, as there are other aspects that can influence it such as experience and learning. When confronting a new situation someone will behave a certain way, and if they have a positive experience they are likely to behave that way again but if they have a negative experience then they may attempt a different approach if they confront a similar situation in the future. This is an area where the ability to be flexible can play an important role, because if you are unable or unwilling to alter your behavior in the face of negative results than you are unlikely to find success.
Gleitman, H., Gross, J., & Reisberg, D. (2011). Psychology. (8th ed.). New York, NY: W. W. Norton & Company, Inc.