A nthropological Perspective on the Human Life Course

1. Anthropological Perspective on the Human Life Course • Fundamentals of Growth and Development • Nutritional Effects on Growth and Development • Early Evolution of Human Diet • Diets of Humans Before Agriculture • Human Diet Today • The Human Life Cycle

2. I. Growth and Development • Growth refers to an increase in mass or number of cells. An increase in cell number is referred to as hyperplasia. An increase in cell mass is referred to as hypertrophy. • Development refers to differentiation of cells into different types of tissues and their maturation. • The terms growth and development are often used interchangeably, but they are different processes involved in… • Stature and… • Brain growth.

3. I D. Stature • Stature is influenced by genetics, health and nutrition. • Children with good health and adequate nutrition are more likely to reach their genetic potential for height. • Children who are malnourished or experience prolong periods of poor health may not reach that potential. • Members of higher socioeconomic groups tend to be taller than members of lower socioeconomic classes, reflecting the impact of culture and economic status on the processes of growth and development.

4. I E. Brain Growth Human brain growth is unusual among mammals: • At birth the brain is about 25 % of its adult size. • Six months after birth it has doubled in size and reached 50% of its adult size. • By age 5, the brain has reached 90 % of its adult size. • By age 10 the brain is at 95 % of its adult size.

5. II. Human Nutrition • Nutrition has an impact on human growth and development at every stage of the life cycle. • There are five basic nutrients: • Proteins are composed of amino acids and are the major structural components of the body, but serve other purposes. • Carbohydrates are an important source of energy. • Lipids include fats and oils and protect as well as act to store. • Vitamins serve as enzymes, substances that speed up the chemical reactions necessary for running the body. • Minerals contribute to normal functioning and health, and act as catalysts or structural components as well.

6. III. Early Evolution of Human Diet • Our nutritional needs have evolved with the types of foods that were available to our evolutionary ancestors. • We have inherited the ability to digest animal protein from our mammalian forebears. • Early primates also evolved the ability to digest plants. • Immediate ape-like ancestors were primarily fruit-eaters and passed on their ability to process fruit to us. • Bottom line: Human needs for specific vitamins and minerals reflect ancestral nutritional adaptations. For instance…

7. Bottom Line: Essential Amino Acids • Adult humans lack the ability to synthesize 8 of the amino acids and must obtain these from the diet. • The amounts amino acids needed nutritionally parallel the amount present in animal protein. • This suggests that food from animal sources may have been an important component of ancestral hominid diets when nutritional needs were evolving. • So….

8. IV. Pre-agricultural Diet • The pre-agricultural diet was high in protein and complex carbohydrates and low in fats. • Many of our biological and behavioral characteristics contributed to our ancestors' adaptation, but may be maladaptive in our modern industrialized societies. e.g Today there is a relative abundance of foods in western nations. The formerly positive ability to store extra fat has now turned into a liability which leads to degenerative diseases. • The human population began to increase when people began to live in permanent settlements.

9. V. Human Diet Today • Undernutrition means an inadequate quantity of food. • It is estimated that between 16 and 63% of the world's population is undernourished. • Malnutrition refers to an inadequate amount of some key elements in the diet. • Malnutrition greatly affects reproduction and infant survival. • Malnourished mothers have more difficulties in producing healthy children. • Children born of malnourished mothers are behind in most aspects of physical development.

10. VI. The Human Life Cycle. • Humans have five phases to their life cycle. • Prenatal begins with conception and ends with birth. • Infancy is the period in which the baby nurses. • Childhood is the period from weaning to puberty. • Adolescence is the period from puberty to the end of growth. • Adulthood is marked by the completion of growth. • An extra period in females is menopause, recognized as one year after the last menstrual cycle.

11. Pregnancy, Birth and Infancy • Pregnancy • Almost every culture imposes dietary restrictions on pregnant women to keep them from ingesting toxins that could hurt the fetus. • Brain growth • The language centers of the brain develop during the first three years of life.

12. Childhood • Humans have an unusually long childhood reflecting the importance of learning for our species. • Childhood is the time between weaning and puberty when the brain is completing its growth.

13. Adolescence • Hormonal changes are the driving force behind physical changes during adolescence. • A number of factors affect the onset of puberty in humans: Genetics, gestational experience, nutrition, disease, activity levels, and stress. • In humans and other primates, females reach sexual maturity before males. • Menarche is a clear sign of puberty in girls and is usually the marker of the from childhood in cultures where this event is ritually celebrated.

14. Adulthood and Late Adulthood • Several theories address the long nonreproductive period in human females: • Child-rearing theory. - Women are biologically "programmed" to live 12 to 15 years beyond the birth of their last children. • Grandmother Theory - Women who live several years beyond the independence of their last child would be freed to provide food and other resources to their children and grandchildren. • Nonselection Theory - Menopause is an artifact of the extension of the human life span.

15. Aging/ Senescence • While "old age" tends to be regarded negatively in the united states, it means wealth, higher status, and new freedoms in other cultures. • One of the reasons that people are living longer is because they are not dying from infectious diseases. • While life span is unlikely to increase, human life expectancy at birth (the average length of life) has increased significantly in the last 100 years. • The final "phase" of the human life cycle is death.