12.1 Chapter Objectives

   Learning Objectives

By the end of your reading and our in-class discussion, you should be able to meet the following objectives:

  • Define sexual orientation, heterosexuality, homosexuality, asexuality, bisexuality, and pansexuality.
  • Explain what scientists mean when they say “sexual orientation is not binary.”
  • Defend, using examples, the statement: “homosexuality is widespread in nature.”
  • Cite evidence for a genetic basis of homosexuality, as well as evidence that homosexuality is environmentally influenced.
  • Explain why some biologists call homosexuality “an evolutionary problem.”
  • Explain why many biologists think that homosexuality is an adaptation that has been selected forg. describe a few of the hypotheses for the evolution of homosexuality.
  • Explain how homophobia could be an adaptation (how could homophobia increase an individual’s fitness?)

In the following  discussion, our goals are for you to:

  • Realize that sexual orientation governs many observable natural phenomena, that themselves can be studied scientifically.
  • Understand that homosexuality is widespread in nature – in human and non-human animals.
  • Realize that homosexuality and homophobia may have arisen as a result of natural selection.
  • Appreciate that our understanding of same-sex sexual preferences is part of an emerging field of study, thus, many of the scientific studies we will mention are relatively recent and, like all science, subject to revision


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The Evolution and Biology of Sex by Sehoya Cotner and Deena Wassenberg is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.