Title: Human Variation: An Adaptive Significance Approach – Explorations
Headings: 14
Human Variation: An Adaptive Significance Approach

14 Human Variation: An Adaptive Significance Approach
STRESS AND HOMEOSTASIS
ADJUSTMENTS AND ADAPTATIONS
Adjustments
Behavioral Adjustments
Acclimatory Adjustments: Thermal Stressors
Acclimatory Adjustments: Altitudinal Stressors
Developmental Adjustments
Adaptations
Adaptation: Altitudinal Adaptation
Adaptation: Skin Tone Basics
SPECIAL TOPIC: SKIN TONE GENETIC REGULATION
Adaptation: Melanogenesis
Adaptation: Evolutionary Basis for Skin Tone Variation
Adaptation: Shape and Size Variations
Adaptation: Infectious Disease
Adaptation: Lactase Persistence
Human Variation: Our Story Continues
Key Terms
About the Author
Leslie Fitzpatrick, Ph.D.
References
Figure Attributions

Content: In many developing countries, the use of refrigeration for the storage of perishable food products is uncommon; therefore, individuals within these cultures have developed a variety of behavioral adjustment strategies related to food preparation to address the possibility of food spoilage. Through a cross-cultural analysis of spice use in recipes, Sherman and Billing (1999) determined that cultures closest to the equator, where temperatures are hotter, tend to use both a greater number and a wider variety of plant-based spices with bacteria-inhibiting phytochemical properties (e.g., garlic and onion) in their recipes than cultures located further from the equator. The antimicrobial properties of the spices permits the consumption of foods, particularly animal-based protein sources, for a period of time beyond that which would be considered safe. There are some acclimatory adjustment benefits to the use of some pungent spices as well, which are explored in the following section. Acclimatory Adjustments: Thermal Stressors
Acclimatory adjustments
are temporary, reversible changes in an organism’s physiology in response to environmental stressors. Although they are regarded as non-genetic in nature, the range of acclimatory adjustments an organism is capable of producing to accommodate a given stressor is linked to its underlying phenotypic plasticity and duration and severity of the stressor. Figure 14.2 Various thermodynamic mechanisms related to heat gain and loss in the human body. Before we discuss how varying ambient temperatures affect the human body, we must detail the thermodynamic mechanisms through which heat may be gained or lost.