Lesson Overview

We are going to begin this course with a brief overview of an important topic in evolutionary theory—sexual selection. We will review some important theories that contribute to our understanding of why men and women differ in their sexual behaviors and use different mating strategies. For example, why are men typically more interested than women in one-night stands? Why are women generally choosier when it comes to sexual partners? Why are women usually more interested in commitment? Why are men more likely to be sexually jealous and women more likely to be emotionally jealous? Is there a difference in humans when it comes to parental investment? Which sex is typically more involved in childcare? Sexual selection theory helps us lay the foundation for understanding how some of these sex differences may have evolved throughout the animal kingdom. We will initially examine evidence from several nonhuman animal species and then look at evidence in humans.

Do you like watching nature shows? Go through the slide show below and see how many species you can identify. Click on the info icon on each image to see what species it is.

 

Now, go through the slides again and try to pick out a common theme that applies across all of these species. What differences do you notice between members of each species? And how is this relevant to our species? Could you tell which one is male and which is female?  If so, which sex is typically larger in each species? Which one is more brightly colored and more noticeable to predators?

A good example to illustrate the trend that can be seen across many different species throughout the animal kingdom is the peacock (male peafowl). The peacock is vividly colored with a beautiful, large tail that is put on full display when the peacock struts in front of a peahen (female peafowl). In contrast, the female is smaller and plainer and does not preen in front of the male.

Peacocks have this brilliant plumage even though it increases their risk of being seen by potential predators and decreases their chances of getting away from them. Why? What compensating advantage does this attention-drawing plumage give the male peacock? It turns out that the brightly colored feathers help the male obtain mating opportunities, in this case by attracting females. The same theme can be seen in other species—males are often larger, more brightly colored, have additional features like antlers or long tails, and so on. These traits are designed to attract females, and they are often considered to be sexual displays. Your assigned reading for this week also provides some good examples from other species.

View Video 1.1 to see a wonderful example of courtship behavior from the gorgeous bird of paradise. The male has striking plumage, which it shows off for the female while doing a little dance in front of her.

Lesson Objectives

Upon conclusion of this lesson, you should be able to do the following:

• Identify major tenets of evolutionary theory and key mechanisms of sexual selection.
• Define what is meant by the science of sex (i.e., focus on the empirical findings in the field of sexology).
• Identify key mechanisms of sexual selection.
• Identify parental investment differences between the sexes (i.e., the fast sex vs. the slow sex).

Lesson Readings & Activities

By the end of this lesson, make sure you have completed the readings and activities found in the Course Schedule.