1. Legacies of Human Evolutionary
History: Effects on the Individual

2. Question:
Does the flexibility of human behavior pose problems for the species?

3. Evolved Biology and Contemporary Lifestyles—Is there a Mismatch?
Some aspects of modern human lives are disconnected from our evolved biology
In past 10,000 years, pace of cultural change has accelerated, changing the context of human evolution

4. Changing Contexts

5. Biocultural Evolution and the Life Course
Biological development occurs from embryo to old age
Cultural factors interact with genetically based characteristics

6. Human Growth and Development Today and in the Past
Human growth continues through late teens or early 20s
Three major spurts are typical, including first two trimesters in utero, first four years and the adolescent growth spurt

7. Adolescent Growth Spurt
Pronounced increase in growth rate at puberty, compared to fairly steady level maintained since about four years
Western teenagers typically grow around 4 inches per year
Followed by decline in rate of growth until adult stature is achieved by late teens

8. Human Brain Growth 25% of its adult size at birth 50% at six months
75% at 2.5 years
90% at 2 years
95% at 10 years

9. Human Brain Growth
Such a small amount of growth before birth is unusual for primates and mammals
Selective advantages of such an underdeveloped brain
Exit through narrow pelvis modified for bipedalism
Brain develops in stimulating, cultural context

10. Nutritional Requirements for Growth
Nutrients needed for growth, development, and body maintenance include: proteins, carbohydrates, fats, vitamins and minerals.
The amount we need of these nutrients coevolved with foods available to humans throughout evolutionary history.
Deficiencies during pregnancy can last a new child’s lifetime
The specific pattern of amino acids required in human nutrition (essential amino acids) reflects an ancestral diet high in animal protein.

11. Essential Amino Acids
The 9 (of 22) amino acids that must be obtained from the food we eat because they are not synthesized in the body in sufficient amounts.

12. Comparison of Diet (Table 13-1)
Total dietary energy (%)
Preagricultural
Diet
Contemporary
Recently
Recommended
Protein 33 12
Carbohydrate 46 58
Fat 21 42 30
Alcohol ~0
(7–10) —
Cholesterol (mg)
520
300–500
300

13. Total dietary energy (%)
Comparison of Diet
Total dietary energy (%)
Preagricultural
Diet
Contemporary
Recently
Recommended
Fiber (g)
100–150
19.7
30–60
Sodium (mg)
690
2,300–6,900
1,000–3,300
Calcium (mg)
1,500–2,000
740
800–1,500
Ascorbic acid (mg)
440 90 60

14. Preagricultural Diet Prior to 10,000 years ago
Typically high in animal protein, low in fats, particularly saturated fats
High in complex carbohydrates (including fiber), low in salt, and high in calcium
Human health declined in most parts of the world, beginning about 10,000 years ago
“Epidemological transition” marked by rise of malnutrition, drop in life expectancy

15. Once adaptive, now maladaptive
Ability to store fat, an advantage when food availability often alternated between abundance and scarcity
“Feast or famine” biology incompatible with context of constant feast
80% of new cases of type 2 diabetes appearing between now and 2025 will be in developing nations
Type 2 diabetes, linked to poor diet and inadequate exercise, occurring in children as young as 4
“Epidemiologoical collision” in countries where malnutrition and infectious diseases collide with obesity

17. Other Factors Influencing Growth and Development: Genes and Environment
Genetics – set the underlying limitations and potentials for growth and development
Environmental factors can influence growth and development, but an individual can not exceed their genetic potential.
Epigenome-Instructions that determine how genes are expressed in a cell
Epigenetics-Changes in phenotype that are not related to changes in underlying DNA and that may result from the interaction between the genotype and the environment

18. Other Factors Influencing Growth and Development: Genes and Environment
Hormones – produced by endocrine glands
Growth hormone has an impact on almost every cell in the body.
Cortisol, elevated during stress, suppresses normal immune function during high levels

19. Endocrine Glands
Glands responsible for secretion of hormones into the bloodstream, i.e. pituitary, thyroid, and adrenal glands, ovaries and testes

20. Variation in Growth Hormones

21. The Human Life Cycle
Prenatal begins with conception and ends with birth.
Infancy is period of nursing.
Childhood, or juvenile phase, is period from weaning to sexual maturity (puberty in humans.)
Adolescence is from puberty to the end of growth.
Adulthood is the completion of growth.
Menopause beginning one full year after the last menstrual cycle

22. Life History Theory
Typical developmental patterns shaped by natural selection
Entire life course thought of as a series of trade- offs among various life history traits

23. Life Cycle Stages for Various Animal Species

24. Pregnancy, Birth and Infancy
Cultural and social factor shape infant’s development in utero
Birth is dangerous event and often surrounded by ritual significance
“Underdeveloped” human infant brains adapted to developing in cultural environments

25. Diameter of Birth Canal and Head Length and Breadth of Newborns

26. Nursing
Most anthropologists suggest three to four years of nursing was the norm for humans in our evolutionary past
Agriculture produced more options for supplemental foods and could quicken weaning
Nursing can act as birth control

27. Childhood
Humans have unusually long childhoods, which illustrates importance of learning for human adaptation
Humans might be unique in practice of provisioning for juveniles

28. Providing for Juveniles
Percent Who Survive
Weaning
Adolescence
Lion 28 15
Baboon 45 33
Macaque 42 13
Chimpanzee 48 38
Human Populations
!Kung 80 58
Yanomamo 73 50
Paleoindian 86

29. Adolescence
Rapid growth seen during adolescent growth spurt unique among primates

30. Adulthood
Women in our evolutionary past likely experienced fewer menstrual cycles throughout life
Most were more often pregnant or nursing

31. Menopause
Advantages
“programmed” to live 12 to 15 years beyond birth of last child since human parenting involves years of post-partum care
Grandmother hypothesis
Women freed to provide high-quality care to grandchildren

32. The Trend in Age at Menarche in Europe

33. Aging and Longevity Attitude towards old age is culturally determined
Top 5 causes of death in the US are heart disease, cancer, stroke, accidents, and chronic obstructive lung disease (no longer in this order)
Senescence, the process of physiological decline in all systems of the body occurring toward the end of the life course
The decline is gradual throughout adulthood

34. Approximate Maximum Life Span (in years)
Life Spans (Table 13-4)
Organism
Approximate Maximum Life Span (in years)
Bristlecone pine
5,000
Tortoise
170
Human
120
Blue whale 80
Indian elephant 70
Gorilla 39
Domestic dog 34
Rabbit 13
Rat 5

35. Pleiotropic Genes Genes that have more than one effect.
Genes that have different effects at different times in the life cycle.
May help to explain evolutionary reasons for aging, but do not explain the causes of senescence

36. Mitochondrial Theory
Free radicals produced by mitochondria diminish efficiency of cellular energy production
Ultimately leads to organ failure

37. Teleomere Hypothesis Repeated sequences of DNA at end of chromosomes
Get shorter as organisms age
Ultimately, impairs healthy cell division

38. Changes in Life Expectancy Due to AIDS in Seven African Nations

39. Effects of Technology on the Brain
Our brains coevolved with technology and language development
Contemporary technological change may be much more rapid than evolution can keep up with
But, brains may be developmentally modified by using new technologies

40. Are We Still Evolving?
Socioeconomic and political concerns have powerful effect on our species today
Anthropologists can not predict whether humans will eventually become a different species or become extinct
There is little doubt that the human species will continue to evolve or become extinct

41. Why It Matters
The “small but healthy hypothesis” states that small adult stature under circumstances of low resource availability is adaptive in that small adults would need fewer resources and would fare better under chronically stressful conditions.

42. Why It Matters
Anthropological and evolutionary perspectives reveal that small body size also means small organs, less ability to perform work, and lower reproductive success.
Even if a baby whose mother was malnourished during pregnancy is well nourished from birth on, the child’s growth, health, and, for females, future pregnancies appear to be compromised.
This has clear implications for public health efforts that attempt to provide adequate nutritional support to pregnant women.