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Chapter Sixteen

Chapter Sixteen. The Biology of Modern Homo Sapiens. Human Adaptability: Adjustments. One reason that the human species survives in a wide diversity of habitats is because of nongenetic changes termed adjustments.

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Chapter Sixteen

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  1. Chapter Sixteen The Biology of Modern Homo Sapiens

  2. Human Adaptability: Adjustments • One reason that the human species survives in a wide diversity of habitats is because of nongenetic changes termed adjustments. • Behavioral adjustments are cultural responses to environmental stresses. An example would be housing. • Acclimatory adjustments are reversible physiological changes to environmental stress. • Responses to an arctic habitat include shivering, vasocontriction, and a rise in the basal metabolic rate. • Responses to a desert habitat include conduction, radiation, evaporative sweating, and vasodilation. • Responses to high-altitude include hyperventilation, and an increase in the number of red blood cells and capillaries.

  3. Human Adaptation • Adaptations are the result of micro evolutionary change. Two examples are skin color and body build. • 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. • 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.

  4. Growth and Development • Growth is an increase in the size of an organism; development is a change from an undifferentiated to a highly organized, specialized state. • 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). • Bone age is the average chronological age at which events such as ossification (bone replacing cartilage) take place. The pattern of tooth formation and eruption can be used in a similar manner.

  5. Puberty • One aspect of puberty is the adolescent growth spurt, resulting in changes in body composition (e.g., amounts of fat and muscle). • Changes in the reproductive organs and secondary sexual characteristics are also included. • The nature and rates of growth and development are controlled by the complex interaction of many factors, including the endocrine glands, nutrition, and heredity. • Differences in patterns of growth and development in children growing up in stressful environments are known as developmental adjustments.

  6. The Secular Trend in Growth and Development • The secular trend is the tendency over the last hundred or so years for each succeeding generation to mature earlier and grow larger. • While no one knows for sure what causes this trend, some researchers believe that improvement in nutrition, better sanitation, improved health services and less tedious lifestyles are responsible.

  7. Forensic Anthropology • Forensic anthropology is the application of the specialized knowledge that anthropologists have about the human skeleton. • A common task is the identification of a skeleton. Sex and age determination are a part of this process.

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