The Human Spectrum

The Human Spectrum Photo Credit: Clipart.com


In this lesson, you will explore how the sun’s intensity at different latitudes has contributed to variation in human skin color.


Your first activity is to explore the continuum of variation for human traits. Visit The Human Spectrum: Where Do You Draw the Line? As you move through this feature, work with a small group to answer the following questions. You can record your answers on The Human Spectrum student sheet. Be prepared to present your group’s responses to the class.

Slide 1

  • Short, medium, and tall is one way we categorize people. There are many others. For example: young, middle-aged, and old. What are some other ways people commonly categorize each other? What are the advantages and disadvantages of grouping people in the ways you have named?

Slide 6

  • “Skin tones overlap both within and between native peoples.” Give an example using the named peoples from the graph of native peoples. For example: Although Holy Island people as a whole are lighter-skinned than Sherpa people, some Sherpa individuals are lighter-skinned than some Holy Island individuals. What does it mean for the concept of race if the quoted sentence is true?
  • Do you think race is a good way to group people?

After you have discussed The Human Spectrum, read Only Skin Deep, also from the Race: Are We So Different? website. Be prepared to respond to the following questions. You can record your answers using The Human Spectrum student sheet.

  • What was the challenge for the human body when our early ancestors moved into hot, open places such as grassy savannahs, in search of food and water?
  • How did they evolve in response?
  • What was the challenge for the human body as it evolved away from body hair and more skin became exposed?
  • What is a benefit of ultraviolet radiation for the human body?
  • How does ultraviolet radiation challenge the human body?
  • Where is ultraviolet radiation the strongest?
  • How did natural selection work to bring about the trait of darker skin in people who live near the equator?
  • How did natural selection work to bring about the trait of lighter skin in people who live far from the equator?
  • Why is the threat of skin cancer from ultraviolet radiation not a plausible explanation for why dark skin evolved in peoples who lived near the equator?

As a follow-up project, you will be assigned to investigate one of the peoples named in the sixth slide of The Human Spectrum. Find some facts about the culture of your assigned people and locate the latitude at which that people has traditionally lived. Search the Internet to find and print a photograph of a representative member of that people. Use the Native Peoples, Skin Tones, and Latitudes student sheet to compile the information and photos.

This esheet is a part of the Sun, Natural Selection, and Skin Color lesson.

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