Download Stein Ch 16, Biology of Modern Homo sapiens Adjustments

Stein Ch 16, Biology of Modern Homo sapiens
Adjustments, Adaptations and Acclimatization
*“Adaptation" however mostly refers to hereditary, genotypic traits, that have evolved through natural
selection. "Acclimation" refers to phenotypic traits, it is environmentally inducible, and mostly even
reversible.
Nongenetic changes are termed adjustments.
o Behavioral adjustments are cultural responses to environmental stresses (e.g., housing).
o Acclimatory adjustments are reversible physiological changes to environmental stress
(e.g., shivering in an arctic habitat, sweating in a desert habitat).
o Developmental adjustment is a variation in the pattern of growth and development that
provides a means of adjusting to environmental stress.
o Adaptations are the result of microevolutionary change.
o Human skin color is due primarily to the pigment melanin. In general, people living in equatorial
regions have darker skin, as a means of protecting the body from harmful UV radiation and to
regulate the production of vitamin D.
o People living in equatorial regions also tend to be tall and linear, a body build that maximizes
the efficiency of removing excess heat from the body.
o Gloger’s rule: within the same species, there is a tendency for more heavily pigmented
populations to be located toward the equator and lighter populations farther from it.
o Bergmann’s rule: within the same species, the average weight of the members of the
population increases and the surface area of the body decreases as the average
environmental temperature decreases.
o Allen’s rule: within the same species, the relative size of the protruding parts of the
body (e.g., arms and legs) increase as the average environmental temperature increases.
o Growth is an increase in the size of an organism.
o Growth occurs by hyperplasia (an increase in the number of cells), hypertrophy (an increase in
the size of cells) and accretion (an increase in the amount of intercellular material).
o Development is a change from an undifferentiated to a highly organized, specialized state.
o Secular Trend in Growth and Development:
o improvement in nutrition
o better sanitation
o improved health services
o less tedious lifestyles
* What is the difference between adaptation, acclimation and acclimatization?. Available from:
https://www.researchgate.net/post/What_is_the_difference_between_adaptation_acclimation_and_acclimatiza
tion2 [accessed Apr 18, 2017].