PLB143 - Lecture 04

Why did agriculture start?

© Paul Gepts 2006

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Readings

Required:

Harlan JR (1992) Chapter 2: Views on Agricultural Origins. pp. 36-48 UC Davis access only (Kerberos password)

Additional readings:

Anderson E (1954) Plants, man, and life. Melrose, London.
Armelagos GJ (1991) The origins of agriculture: population growth during a period of declining health. Popul. Environm. 13:9-22.
Black JN (1971) Energy relations in crop production - a preliminary survey. Ann. Appl. Biol. 67:272-278.
Boserup E (1965) The conditions of agricultural growth. Allen & Unwin, London.
Childe VG (1952) New light on the most ancient east. Routledge & Paul, London
Cohen M (1977) The food crisis in prehistory. Yale Univ. Press, New Haven, CT
Evans LT (1975) Crop physiology: some case histories. Cambridge Univ. Press, Cambridge, UK
Flannery KV (1965) The ecology of early food production in Mesopotamia. Science 147:1247-1256
Kates RW (1994) Sustaining life on the Earth. Sci. Amer. 271(October): 114-122.
McCorriston J, Hole F (1991) Ecology of seasonal stress and the origins of agriculture in the Near East. Amer. Anthrop. 93:46-69.
McGuire RH (1984) In: Fish SK, Fish PR (eds) Prehistoric agricultural strategies in the Southwest. Arizona State Univ, Anthrop. Res. Papers No. 33: pp. 327-334
Peake H, Fleure HJ (1927) Peasants and potters. Cambridge Univ. Press, Cambridge, UK
Pimentel D (1974) Energy in world food production. Env. Biol. Rept. 74-1. Cornell Univ., Ithaca, NY
Sauer CO (1952) Agricultural origins and dispersals. MIT Press, Cambridge, MA
–Gepts P (2004) Crop domestication as a long-term selection experiment. Plant Breed Rev 24 (Part 2): 1-44.
–Richerson P, Boyd R, Bettinger R (2001) Was agriculture impossible during the Pleistocene but mandatory during the Holocene? Amer Antiq 66:387-411
–Coppa A, Bondioli L, Cucina A, Frayer DW, Jarrige C, Jarrige J-F, Quivron G, Rossi M, Vidale M, Macchiarelli R (2006) Palaeontology: early Neolithic tradition of dentistry 440:755-756

Presentation slides

Pdf format (you need to download Adobe Acrobat Reader, if you have not already done so)

Gordon Childe (1920s-1950s)

Agriculture arose as a Consequence of Climate Change (Environmental Determinist)

Sequence of events:

After end of Pleistocene (last glaciation), progressive desiccation
Withdrawal of humans, animals, and plants to banks of permanent rivers and oases ("oasis theory")
Close contact between humans, plants, and animals leads to domestication ("propinquity theory")
Associated with domestication was the "Neolithic revolution": sedentary village life, expanding population, use of ground-stone tools, development of ceramics, and emergence of a new type of social organization

Testable hypothesis: climate change vs. cultural change

Some related sites of interest

Pleistocene
- The Pleistocene, 1.8 million to ~ 10,000 years ago

Late pleistocene extinctions

Carl Sauer (1952) "Agricultural Origins and Dispersal"

Where did Agriculture Originate? In Two Areas

Six suppositions:

Agriculture did not originate from a lack of food
Hearths of domestication are to be sought in areas of marked diversity of plants and animals
Primitive cultivators could not establish themselves in large river valleys subject to lengthy floods and requiring dams, drainage, etc.
Agriculture began in wooded areas: easier to clear than grasslands
Inventors of agriculture had previously acquired special skills in other directions: predisposition to agricultural experiments
Founders of agriculture: sedentary, fishing tribes near fresh water ==> Old World: Southeast Asia; New World: N.W. South America

Mesoamerica: agriculture by (partially) nomadic people; Near East: center of origin without heavy reliance on aquatic resources

Edgar Anderson: Plants, Man, and Life (1954)

Genetic Aspects of Domesticates and Domestication

Weeds as potential domesticates

disturbed habitats
"dump heap" theory

Disturbed habitat would increase the chances of hybridization and therefore the production of new gene combinations subject to selection

Peake H, Fleure HJ: Peasants and potters (1927)

"Natural habitat zone" hypothesis: Geographic prerequisites for food production

Alternation of rainy and dry season
Restricted area to avoid migration as an alternative to agricultural intensification

topography
territoriality

Not heavily forested
Meeting of people with different traditions
Climatic change
Presence of wild relatives

"=> "> Southwestern Asia = Near East

Robert Braidwood (1950s-1970s)

Field experiment on natural habitat zone hypothesis

Jarmo, Kurdish foothills in Iraq

"Fertile Crescent": upper piedmont and intermontane valleys from Judea, Lebanon, Syria, Turkey, Iraq, Iran; 650-1000m
Mixed oak woodland and grassland
Abundant rainfall
Presence of domesticable, wild species: wild barley, wheat, sheep, goat, pig, and cattle

Did not observe marked environmental change: challenges "propinquity" theory

Additional links of interest

Did the thirst for beer lead to domestication? Or, did beer come before bread? A hypothesis of J. Sauer and R. Braidwood, reviewed by Solomon Katz and Fritz Maytag (the latter of the Anchor Steam Co.)
Evidence of ancient beer

Ester Boserup: The Conditions of Agricultural Growth (1965)

Population Increase --> Increased Cropping Frequency --> Increased Labor (Energy) Input --> Decreased Output per Amount of Labor (Energy) Input into System

Population growth:

Independent variable (>< Malthus)
Major cause of change in land use (frequency of cropping), agricultural technology (hoes, plows), land tenure (private ownership), and settlement patterns (sedentism)

Critique (McGuire 1984):

Three major sources of increased demand for subsistence products: population pressure, social production (ritual, dowry, status and prestige), exchange
Means to meet demand:

craft specialization
emigration
population control
subsistence intensification:

wild
cultivated: increased cropping, labor, or capital

Energy Input-Output in Food Procurement Systems

Black (1971), Pimentel (1974), Evans (1975)

System	Example	kcal produced/kcal invested
Gathering	Wild wheat harvest, Turkey	40-50
Agriculture: Hand labor	Cassava, Zaire	37.5
	Cassava Tonga	26.9
	Sorghum Sudan	14.1
	Maize Mexico	10.1
Agriculture: Draft animals	Rice Philippines	3.3
	Maize Mexico	3.4
	Wheat India	-0.5
	Sorghum Nigeria	-0.1
Mechanized	Maize USA	2.5
	Rice USA	1.4
	Wheat USA	1.8
	Potato USA	2.3

Mark Cohen: The Food Crisis in Prehistory (1977)

Increases in Population and concurrently Depletion of Foraging Ranges led to Agriculture

Argument in favor: Depletion of local resources:

Change in diet from preferred foods to less-preferred foods
Exploitation of resources not used in earlier times and coming from greater distances

Arguments against:

Population levels of current hunter-gatherers < carrying capacity
Paleopathology:

no decline in health before agriculture: taller, excellent health, no evidence of endemic disease
early farmers were not as healthy; progressive decline from 5,500 BC until 500 BC

Human Population and Technological Innovation

(Kates 1994)

Human population increase as a fuction of technological innovation

Body Height and Technological Change

Body height as a function of technological innovation (© Scientific American Library)
(

another graphic of the same results)

Population Levels and Paleopathology (I)

Armelagos et al. (1991)

Population growth during Paleolithic

Very low: average: 0.015/1,000/yr for 1,000,000 yrs
8,000,000 people on the Earth around 8,000 BC
moderate fertility maintained by cultural practices + high mortality during reproductive age

Diseases prior to agriculture

Abundant resources: few nutritional deficiencies
Low impact of infectious diseases

hunter-gatherer bands: 25-50 persons/group at a density of 0.1-0.2/square mile (below density needed to retain infectious pathogens)

Disease of hunter-gatherers:

head and body lice, pinworms, yaws (Treponema), malaria, protozoans
salmonella, typhus, staphylococcus
zoonoses: sleeping sickness (Trypanosoma), tetanus, trichinosis, leptospirosis, schistosomiasis; greatest impact on producers (20-40)

Population Levels and Paleopathology (II)

Armelagos et al. (1991)

Diseases in agricultural society

Increase in population size and density

Increase in infectious diseases: malaria, measles, mumps, chicken pox, smallpox
Increase in zoonoses: anthrax, brucellosis, tuberculosis
Increase in disease associated with human waste, contaminated water: cholera, typhus, plague

Nutritional status: lean years: limited range of resources: ==> starvation
Expansion into new areas: new diseases; low immunity
Industrialization: toxic wastes, slums

Population growth in agricultural societies

Greatest potential for disease-related mortality: very old, very young; surviving individuals have immunity and maintain full reproductive potential
Child death: reduce birth spacing
Agricultural society: earlier weaning

= > continued population growth; little effect from catastrophic epidemics

Cultural ecology: Interaction between culture and environment (natural, social) (I)

Kent Flannery (1965)

Biological obstacles to early food production:

brittle rachis (inflorescence axis)
grains covered by husks or glumes
adaptation to hillsides and slopes and not floodplains ==> mutants

Human effects on plants:

Moved them to ecological niches were they were not adapted
Removed certain pressures from natural selection, which allowed more variants to survive
Eventually selected for characters not beneficial under conditions of natural selection

Cultural ecology: Interaction between culture and environment (natural, social) (II)

Kent Flannery (1965)

After 20,000 BP, "broad spectrum revolution":

predominant hunting ==> increased utilization of small game, waterfowl, fish, wild cereals, etc.
preadaptations to cultivation: grinding tools, storage pits, etc.
greater food security when faced with microclimatic fluctuations

Shift to agriculture:

population growth leads to population levels above the carrying capacity
around margins of optimum habitats: population expansion, fewer resources
2 regions in Near East:

Oak-pistachio woodland of Mesopotamia: wild barley, sheep, goats, einkorn wheat
Mixed-oak woodland of the Levant: wild emmer wheat

Cultural ecology: Interaction between culture and environment (natural, social) (III)

Kent Flannery (1965)

Testable hypotheses:

Population increase prior to domestication: YES
Earliest evidence for domesticates at margins:

Levant: YES
Zagros-Taurus: NO

Material culture of domesticators similar to that of inhabitants of optimal zone: YES
No single center of domestication: YES

Role of Seasonal Stress

McCorriston & Hole (1991)

Foods of high quality are abundant and can be stored
Severe seasonal availability of these foods; seasonality is exacerbated by change in climate: cold winter-hot summer ==> warm winter-hot summer + lengthened dry season ==> storage of food and sedentism
Territory is such that people cannot override seasonality through transhumance
Territory can be modified by humans to increase their yield

No-Model Model

Harlan (1992)

Although agriculture started more or less simultaneously (8,000-6,000 BC) in several parts of the world, circumstances were probably quite different. Therefore, a single model will not be satisfactory.
Most conspicuous difference between hunting-gathering economies and agricultural ones:

size of human populations: farming takes more work, but it can feed more people

In agricultural economies, children are an economic asset:

labor, wealth (dowries, bride-prices), security for the aged

Vicious circle: more people ==> more food ==> more work ==> more children
Agriculture produces more food than is necessary for subsistence ==> division of labor and specialization.

Current status: 2 farmers/100 individuals

How to summarize this lecture??

Identify the various 1) factors and 2) stages that have been proposed by the various authors for the transition from hunting-gathering to agriculture

Think of analogous situations in which humans in an apparently favorable situation were led to adopt a new culture or technology that may have been (initially at least) detrimental.

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