BIOS 5445: Human Ecology
Dr. Stephen Malcolm, Department of Biological Sciences
•  Week 10. Survivorship:
resources:
–  Lecture summary:
•  Resources.
•  Resource gathering.
•  Temporal resource
variation.
•  Spatial resource variation.
•  Group sizes.
•  Human responses.
•  There should be no more
people in a country than could
enjoy daily a glass of wine
and a piece of beef for dinner
–  Thomas Malthus (1798).
American Gothic by Grant Wood, 1930
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 1
2. Resources:
•  Kinds of resources:
–  Essential, Substitutable & Complementary resources
(sometimes antagonistic):
•  Necessary.
–  Key resources:
•  Scarce but valuable.
•  Supply of resources:
–  Density-dependent when limited.
–  Costs and benefits of gathering resources:
•  Economics (study of resource allocation) of:
–  Renewable resources.
–  Non-renewable resources.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 2
3. Resource gathering:
•  Technology increases efficiency of resource gathering.
•  Human subsistence patterns - food gathering:
–  Foraging, Pastoralism, Horticulture, Intensive Agriculture.
Spring turning by Grant Wood, 1936
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 3
4. Foraging:
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Hunter-gatherer life style.
Use of wild food resources.
<12,000 BP all humans were foragers.
Modern versions:
–  Inuit of Canadian Arctic
–  San of the Kalahari desert.
•  Small, mobile groups strongly influenced
by their environment:
–  Bands with high family kinship.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 4
5. Pastoralism:
•  Herding domestic animals as major food
& materials resource.
•  Mobile - seasonal movements.
•  Low population density.
•  Rudiments of social control over
behavior.
•  Basically egalitarian society.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 5
6. Horticulture:
•  Subsistence agriculture.
•  Use of simple tools to grow crop plants without
complex irrigation and fertilizer use.
•  Use of small garden plots and long fallow
periods.
•  Sustainable with increased population
densities.
•  Examples:
–  Floodwater farming
–  Swidden or slash-and-burn agriculture, such as
milpa.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 6
7. Milpa agriculture:
•  Dominant throughout
mesoamerica:
–  Traditionally, a "milpa"
plot (from the Nahuatl
word for "corn field") is
planted with maize,
beans, and squash and
might include a variety
of other plants. These
plots are planted for two
or three years and then
allowed to lie fallow for
some years in order to
restore the fertility of the
soil.
•
Dr. S. Malcolm
Milpa plots are found from
Chihuahua to Central
America. This one is in
Oaxaca, Mexico. Squashes
are being grown between
the rows of maize.
Photo: Joey Hipolito
http://en.citizendium.org/wiki/
Milpa_agriculture
Harvesting beans from a
mountainside milpa in
Chiapas, Mexico.
Photo: Lorena Pajares
BIOS 5445: Human Ecology
Week 10: Slide - 7
8. Domestication:
•  Means controlling reproduction of selected
plants and animals:
–  Domestication is probably the single greatest
technical achievement in the human record, more
important than the internal combustion engine or
nuclear energy. It was, from the beginning and long
before these other triumphs, a remarkable way to
capture energy.
•  Hirschoff & Kotler (1989) p 115-116.
•  Mutualisms with food plants and animals:
–  Despite consumption of crops and livestock
harvested species benefit from the interaction with
humans.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 8
9. Intensive Agriculture:
•  Technology & labor used to create artificial agroecosystems to
grow crops and raise livestock.
•  Intensive use of fertilizers and irrigation systems and large-scale
monocultures.
•  Two major types:
–  Labor-intensive agriculture:
•  Use of human muscular effort.
–  Subsidized agriculture:
•  Use of fossil fuels for energy - not sustainable indefinitely.
•  Supports very high population density & urbanization:
–  Swidden rice = 12 people/Km2, intensive rice = 386 people/Km2.
•  People work longer & harder:
–  Population increase drives intensification, or,
–  Political pressure drives intensification, or,
–  Intensification drives population increase?
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 9
10. Modern 4-crop rotation to sustain soil
nutrient balance (Fig. 15.12, Bush 2002).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 10
11. Population and agricultural
intensification (Fig. 3.6, Livi-Bacci, 1997):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 11
12. Seasonal variation in resources:
•  Almost all resources on Earth are derived from the fixation of solar
energy by plants.
•  Solar energy varies systematically by location and time (Fig. 11-11).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 12
13. Non-seasonal variation in
resources through time:
•  Succession:
–  the non-seasonal, directional and
continuous pattern of colonization and
extinction on a site by species populations.
(Begon et al. 2006).
•  Successional changes allow for crop
rotations.
•  Many crops are early successional,
annuals, or mid-successional
perennials.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 13
14. Hypothetical succession by pioneer (pi), midsuccessional (mi) and climax (ci) species.
(Fig. 16.16, Begon et al. 2006).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 14
15. Spatial variation in resources patchiness
•  Group size is affected by spatial
distribution of resources - patchiness.
–  In North American Indians group size was
related to resource characteristics:
•  Amount, mobility, predictability and distribution.
–  Large group size = resources mobile, unpredictable &
clumped.
–  Small group size = resources stable & evenly distributed
•  Human behavior also influences group
size.
–  E.g. cooperative hunting with nets vs bowand-arrow hunting in Mbuti pygmies.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 15
16. Human responses to seasonal
resource change:
•  Movement or migration:
–  Common among foragers & pastoralists but
not agriculturalists.
–  Examples:
•  Nomadism - the entire social group moves
•  Transhumance - part of the social group moves to
follow herds.
•  Migrant farm workers - seasonal work availability.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 16
17. Annual cycle of Karimojong cattle
herders in East Africa (Fig. 11-13):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 17
18. Annual cycle of Quechua Indians
in Peruvian altiplano (Fig. 11-14):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 18
19. References:
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Begon, M., C.R. Townsend, & J.L. Harper. 2006. Ecology: From
individuals to ecosystems. 4th edition. Blackwell Science, Oxford, 738
pp.
Bush, M.B. 2002. Ecology of a changing planet. Prentice Hall, NJ.
Cohen, J.E. 1995. How many people can the Earth support? W,W. Norton
& Co. New York, 532 pages.
Hirschoff, P.M., & N.G. Kotler. 1989 (eds.). Completing the food chain:
Strategies for combating hunger and malnutrition.
Smithsonian Institution Press, Washington, DC.
Hobhouse, H. 1985. Seeds of change. Five plants that transformed
mankind. Harper Row, New York.
Kormondy, E.J., & D.E. Brown. 1998. Fundamentals of Human Ecology.
Prentice Hall.
Livi-Bacci, M. 1997. A concise history of world population. 2nd edition.
Blackwell, Oxford.
Milpa agriculture: http://en.citizendium.org/wiki/Milpa_agriculture
–  Citizendium, the Citizen s Compendium.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Week 10: Slide - 19