14: Human Variation and An Adaptive Significance Approach

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Learning Objectives

Describe how specific patterns of human adaptation are correlated to natural selection processes.
Summarize the role of solar radiation in variations of human skin tone. In your explanation, include information as to why reduced pigmentation leading to lighter skin colors is advantageous for populations indigenous to northern latitudes.
Compare and contrast the various genetic mutations present in Tibetan, Andean, and Ethiopian populations that allow them to survive at high altitudes.
Define the relationship between specific genetic mutations in some human populations and certain infectious diseases, such as the sickle-cell trait mutation and malarial infection.

Image: Asiatiska Folk by G. Mützel under Public Domain.

14.1: The Challenges of Change
In the previous chapters of this text, we explored the role of evolutionary forces in human evolution as well as the basics of genetic variation. Within this framework, we now shift our focus toward examining the numerous challenges our species has faced throughout its evolutionary odyssey as well as how we have met those trials.
14.2: Adaptations
The long-term, micro-evolutionary changes that occur within a population in response to an environmental stressor are referred to as an adaptation.The term “adaptation” refers to a phenotypic trait (i.e., physiological/morphological feature or behavior) that increase a species’ ability to survive and reproduce within a specific environment. Within the field of physiology, the term “adaptation” refers to traits that serve to restore homeostasis.
14.3: End of Chapter Review
Discussion questions and key term definitions.
14.4: Meet the Authors