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Las alas del Diablo

The Ecology, Evolution and Genetics of Capsaicin in Chilies


Brett C. Couch
Departments of Botany and Zoology
University of British Columbia


Why are chilies so hot? This case study begins with a story about an undergraduate student who is inspired to learn about capsaicin production in chilies after losing a spicy chicken wing eating contest. The case was developed as an initial activity for an introductory biology course serving biology majors and non-majors. The case would also be appropriate for an introductory or non-majors course with an emphasis on evolution and could serve as a starting point for a unit on understanding adaptations in a second year evolution course. The case is designed with a large amount of flexibility in the depth of content coverage and can be used by instructors teaching in either flipped or lecture-based classes. In the flipped approach basic understanding of primary content is acquired by working through the handout and answering the questions and class time is devoted to discussion and interaction with the instructor. A PowerPoint presentation, available for download from the teaching notes, can be used to guide the in-class activity.


  • Read, describe and interpret graphical data, error bars and results of statistical tests.
  • Identify the importance of experimental controls.
  • Propose logical hypotheses for observations and identify when hypotheses can be discarded based on results of experiments.
  • Draw conclusions based on experimental data supported with relevant and appropriate details.
  • Use experimental evidence to determine if a trait could be considered an adaptation.
  • Describe the ecological, evolutionary and genetic factors resulting in an adaptation.
  • Identify the specific criteria required for a trait to be considered an adaptation.
  • Identify alternative hypotheses to a trait being an adaptation.


Chilies; chillies; capsaicin; capsaicinoids; evolution; adaptation; hypothesis testing; plant secondary metabolites;

Topical Areas

Scientific method

Educational Level

Undergraduate lower division



Type / Methods

Clicker, Flipped, Interrupted



Subject Headings

Biology (General)  |   Ecology  |   Evolutionary Biology  |  

Date Posted


Teaching Notes

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Supplemental Materials

Access to the PowerPoint presentation listed below is restricted to instructors only and requires a paid subscription.

  capsaicin.pptx (~2MB)

Answer Key

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The following video(s) are recommended for use in association with this case study.

  • The Agony and Ecstasy of Capsaicin
    This video features Dr. Marco Tizzano, a researcher in chemosensory sensation, who once believed he could develop a tolerance to the painful sensations from eating chilis; he now knows better. Watch him explain how capsaicin creates a chemical cascade inside the body. Running time: 5:04 min. Produced by Luke Groskin, Science Friday, 2016.