Sexual selection in humans: a reflection of human mating and social systems
Think of a human trait you think evolved through sexual selection. This should be a trait that does not increase survival, and may even decrease survival, but does increase mating opportunities. Often sexually selected traits are sexually dimorphic (it differs somehow in males vs. females). Describe how your trait may have evolved through sexual selection. **
• Do you think your trait a result of intersexual selection, intrasexual selection, or both? Explain your reasoning.
• How did the trait enable better access to mates?
• How has the trait changed through time?
• How does this trait reflect human mating and social systems?
Essay 3 checklist/rubric:
• Essay is written in full, grammatically correct sentences (2 pts) _____
o Essay is properly cited
o Includes at least one in-text citation (2 pts) ____
o Includes a references section (2 pts) ____
o Essay is no longer than 800 words with a word count listed at the end, single spaced, 12 pt font (1 pt) _____
o Essay accurately addresses each aspect of the essay prompt:
o Identification of a trait that may have evolved through sexual selection and an explanation of how the trait increased mating opportunities (5 pts) ______
 Things to consider:
• Is this trait sexually dimorphic? If yes, how is this trait different in males vs. females? Describe the trait in each sex.
• How would this trait help increase reproductive success?
• Does this trait have any effect on survival? If so, is sexual selection really necessary to explain the evolution of this trait?
o Explain whether this sexually selected trait is the result of inter-sexual selection, intra-sexual selection, or both and the evidence that supports this classification (7 pts) ______
 Things to consider:
• Is the trait you are describing here an example of intersexual selection or intrasexual selection or both?
o Does the trait help individuals to attract mates?
o Or does the trait help individual gain or monopolize access to mates through physical competition?
o Explanation of how trait enabled (or may have enabled) better access to mates (5 pts) _______
 Things to consider:
• You will likely answer this question as part of your answers to one of the other questions.
o What is this trait like in closely-related and more distantly-related species and what does that tell you about how it has changed through time (7 pts) ______
 Things to consider:
• Do closely related species have similar but different versions of these traits? What might this trait have looked like in a common ancestor with a closely related species? What factors might have led to selection for this trait?
• How does the mating system differ between humans and closely related species?
• What was the likely mating system of recent common ancestors of humans and chimpanzees?
• How do different mating systems affect reproductive strategies across these closely related species?
o How does this trait reflect mating and social systems in humans? (6 pts) ______
 Things to consider:
• Under which mating system would this trait be selected for? (Monogamy, polygyny, polygamy, etc.?
• What group structure would have been present when this trait was initially selected for? (Monogamous family groups within a larger community, or something else?)