WEEK 7 Discussion Forum--Anthropology 1( need high quality assignment!! And due on time !!!)
Legacies of Human Evolutionary History: Effects on the Individual
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
◦ Our bodies are meant to be in motion, not sedentary, our dietary needs are no longer being met
Biological development occurs from embryo to old age
Cultural factors interact with genetically based characteristics
◦ The food we eat is culturally based, and can affect growth, development and evolution
◦ Our social status affects access to resources
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
Cultivation most likely based on simple observation and chance
◦ People had begun living in small seasonal settlements for part of the year in areas where there was abundant wild grain (wheat and barley). Remaining hunter gathers for the rest of the year
◦ Grain accidently spilled or discarded in refuse piles would sprout, showing the seeds became new plants
◦ Easy to figure out the plants could be “grown” in areas convenient to human exploitation, i.e. near temporary settlements in areas protected from animals
The conversion of wild plants and animals into a form that humans can utilize, care for, or cultivate
Selective breeding begins to produce more desirable traits, such as bigger grains
This process is NOT the same as modern GMO techniques
Archaeological evidence suggests that humans were beginning to domesticate plant life by 11,500 ya.
This period is known as the Neolithic, it begins in the late Pleistocene and extends into the Early Holocene
Farming began in Turkey around 10,500 ya, and was highly advanced in China by 8,000 ya indicating a much earlier start
Diffusion spread the technology until every continent had adopted farming by 4,500 ya, except Australia
By 8,000 ya settled, permanent agricultural communities had sprung up all across the Fertile Crescent
Large concentrated populations were able to be supported by growing agriculture practices, the birth of the city
Humans “crave” fat and sugar, food sources that would have been high in caloric value during evolutionary processes, i.e. ripe fruit, meat, bone marrow
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
Modern food abundance has lead to rampant obesity which is spreading to much of the world through globalization
Food inequality has now taken precedent over food scarcity ◦ Some have food abundance, some starve, only a few
have access to truly nutritious, balanced diet
Humans are now dependent on a narrow food base that leads to malnutrition and other medical concerns ◦ Rampant iron deficiency in corn based diets
Since 2006 there are now more overweight people alive than malnourished
Type 2 diabetes, linked to poor diet and inadequate exercise
Used to occur in aging populations in the developed world, now occurring in children as young as 4
80% of new cases of type 2 diabetes appearing between now and 2025 will be in developing nations
Spreading due to globalization of sedentary lifestyle as well as poor nutritional value of modern food
“epidemiologoical collision” in countries where malnutrition and infectious diseases collide with obesity
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, turn them on or off, often due to environmental factors
◦ 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
The incidence of dental malocclusion (misaligned teeth or bite) began with the agricultural revolution
Changes in food density affected the development of jaw bone (environmental impact)
Smaller jaws no longer had room for teeth that are genetically determined (biologically determined)
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
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 and more
The specific pattern of amino acids required in human nutrition (essential amino acids) reflects an ancestral diet providing animal proteins.
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.
◦ phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine
Glands are responsible for secretion of hormones into the bloodstream, i.e. pituitary, thyroid, and adrenal glands, ovaries and testes
Hormones – produced by endocrine glands
◦ Growth hormone has an impact on almost every cell in the body. Can be inpacted by
◦ Cortisol, elevated during stress, suppresses normal immune function during high levels and can impact health and growth of children living in stress
1. Prenatal begins with conception and ends with birth.
2. Infancy is period of nursing.
3. Childhood, or juvenile phase, is period from weaning to sexual maturity (puberty in humans.)
4. Adolescence is from puberty to the end of growth.
5. Adulthood is the completion of growth.
6. Menopause beginning one full year after the last menstrual cycle
Cultural and social factor shape infant’s development in utero ◦ Especially important for female infants because future
reproduction it determined partially in utero
Birth is dangerous event and often surrounded by ritual significance
“Underdeveloped” human infant brains adapted to developing in cultural environments
25% of its adult size at birth
50% at six months
75% at 2.5 years
90% at 5 years
95% at 10 years
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, primarily language which the control centers for are developed in the brain by age 3
Most anthropologists suggest three to four years of nursing was norm for humans in our evolutionary past
Agriculture produced more options for supplemental foods and could quicken weaning ◦ How can lessening access to the food nature intended us
to have and replacing it with other sources affect us long term?
Nursing can act as birth control
Between weaning and puberty
Humans have unusually long childhoods, which illustrates importance of learning for human adaptation
Humans might be unique in practice of provisioning for juveniles ◦ Strategy for reproductive success
Marked by rapid growth which is unique among primates and the onset of puberty
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
Sexual maturity is reached by the end of the adolescent period ◦ Historically a females first pregnancy would have occurred
quickly after menarche
Women in our evolutionary past likely experienced fewer menstrual cycles throughout life, perhaps as few as 60, ◦ Most women were more often pregnant or nursing
Many links have been made to increased menstruation and cancer of the reproductive organs
Advantages of extended non-reproductive life span
◦ “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
Attitude towards old age is culturally determined ◦ The U.S.A.s negative views toward the elderly are in vast contrast
to much of the world
Top 5 causes of death in the US are heart disease, cancer, stroke, accidents, and chronic obstructive lung disease ◦ All “diseases of civilization”, caused by factors not in existence
during evolutionary processes i.e. pollution, poor nutrition, cars
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
Genes that have more than one effect.
Genes that have different effects at different times in the life cycle. ◦ Genes that support reproduction can potentially
have a negative impact later in life
May help to explain evolutionary reasons for aging, but do not explain the causes of senescence
Mitochondrial Theory ◦ Free radicals (highly reactive molecules) damage cells
◦ Free radicals produced by mitochondria diminish efficiency of cellular energy production
◦ Ultimately leads mitochondrial failure, which equals organ failure
Teleomere Hypothesis ◦ Repeated sequences of DNA at end of chromosomes
◦ Get shorter with each cell division (as organisms age)
◦ Eventually too short to continue healthy cell division
Our brains coevolved with technology and language development ◦ Is technology affecting social skills if human contact is
no longer needed for information gathering/survival?
Contemporary technological change may be much more rapid than evolution can keep up with
Brains are being developmentally modified by using new technologies
Socioeconomic and political concerns have powerful effect on our species today Where you live, your access to food, medical care, a
safe living environment, or lack there of greatly impact your survival and reproductive rate
Human gene frequencies are changing from generation to generation based on these survival rates
There is little doubt that the human species will continue to evolve or become extinct