Chapter Study Outline
1. The Agricultural Revolution: New Foods and New Adaptations
a. Began 10,000 years ago; the shift took place over many centuries and in several locations around the world.
b. Although researchers largely agree on when and where the shift took place, they don’t agree on the cause.
i. Environmental change to cooler conditions
ii. Increase in human populations
c. Population Pressure
i. Increased the need for larger and more stable food resources
d. Regional variation
i. Plant domestication occurred in at least 10–11 regions around the world.
ii. Levant, in Asia
(1) End of the Pleistocene saw intense harvesting of wheat and barley’s ancestors.
(2) Manipulation of plant growth cycles began about 11,500 yBP.
(3) In the Jordan valley, agriculture spread across the Fertile Crescent by 8,000 yBP.
(4) Some of these villages developed into cities: Jericho.
(1) Domestication of rice and millet dates to 10,000 yBP.
iv. Other regions as well
(1) Mexico (10,000 yBP)
(2) New Guinea (7,000 yBP)
(3) South America (5,250 yBP)
(4) Africa (4,500 yBP)
e. Survival and Growth
i. Animals domesticated, starting with the dog, around 15,000 yBP.
2. Agriculture: An Adaptive Tradeoff
a. Population Growth
i. Domestication fueled human population growth and formed the basis for complex societies and technologies.
ii. Plants were sources of both food and drink.
iii. European explorers and colonists in the Americas affected domesticated plants consumed by the world’s populations as food resources were transported around the world.
iv. Today, two thirds of humans’ necessary calorie and protein intake comes from key cereal grains domesticated in the earlier Holocene.
b. Environmental Degradation
i. Cultural and technological changes also caused negative changes.
ii. Population has increased from 2 million to 6 billion in the last 10,000 years.
iii. Competition for resources strains the global environment.
iv. Environmental degradation is well documented and began 10,000 yBP.
v. Processes of domesticating and raising plants and animals affected ecology, including world biodiversity.
vi. Unchecked population growth could lead to food crisis.
3. How Did Agriculture Affect Human Biological Change?
a. Humanity’s Changing Face
i. Human evolution has continued to the present.
ii. Changes can be linked to agricultural revolution.
iii. Diet influences human physical appearance.
iv. Changes in food relate to changes in facial structure.
v. Face and jaw size smaller than those of early hominids
vi. Two Hypotheses
(1) Early explanation focused on racial differences.
(2) Masticatory-functional hypothesis states that changes in skull form are a response to decreased demands on the chewing muscles.
vii. Changes in the face affect the teeth.
viii. Many more individuals today suffer from crowded jaws.
ix. Tooth size has decreased, but at a pace different from those of skull and jaw decreases.
b. Building a New Physique: Agriculture’s Changes to Workload/Activity
i. Changes in workload and activity have also affected human physical appearance.
ii. Bone responds to stresses on it over the course of a lifetime.
iii. How hard someone works affects the skeleton.
iv. Studies of the strength of bones in different populations illustrate the response to changing workloads.
v. The general evolutionary trend in humans is to a smaller, more gracile skeleton.
c. Health and the Agricultural Revolution
i. Population Crowding and Infectious Disease
(1) Increased population size and density caused the spread of more infectious illnesses; diet was also affected.
(2) Bones can reveal the presence of infectious illnesses even after hundreds of years.
(3) Studies suggest treponematoses affected many populations around the world.
(4) Tuberculosis also was found early around the world.
ii. The Consequences of Declining Nutrition: Tooth Decay
(1) Dental caries, or cavities, increased after certain plants (corn) were introduced.
iii. Nutritional Consequences Due to Missing Nutrients: Reduced Growth and Abnormal Development
(1) Lack of essential nutrients leads to smaller body size and developmental abnormalities.
(2) Bones and teeth provide excellent ways of assessing dietary changes and nutritional deficits.
iv. Nutritional Consequences of Iron Deficiency
(1) Iron deficiency (some argue other stress factors) causes anemia and is seen in the skull (porotic hyperostosis) and eye orbits (cribra orbitalia).
v. Nutritional Consequences: Heights on the Decline
(1) Across the world, increases in adult height have stopped and heights have decreased through times.
(2) This is not an adaptive response to poor food resources.
4. If It Is So Bad for You, Why Farm?
a. Agricultural practices increased human fertility.
b. More calories per land unit and more food resources for population increases