ANT-309 Elements of Archaeology Lecture Outline, March 5, 2008

XII Foragers in Evolutionary Perspective (Human Behavioral Ecology) “Application of natural selection theory to the study of adaptation and biological design in an ecological setting.”

A Optimal Foraging or Microeconomic Theory

B Leading proponents

1 McArthur and Pianka 1966

2 John Beaton in California in the 1970s

3 James O'Connell and Kristen Hawke 1980-90s

C Types of Optimality Models

1 Evaluate human behavior versus predictions involving reproductive fitness, mating frequency, survival frequency, harvest rate,

2 Most common- dietary efficiency models

b Diet Breadth (prey choice) Model

c Patch choice

Diet Breadth Model

Designed to predict the food items the forager will attempt to exploit (handle) and those it will ignore in favor of continued search for more preferred foods.

Decision component: to search or handle (mutually exclusive activities) handling: all the time devoted to pursuing, capturing, processing, transporting, and eating the prey. Includes unsuccessful pursuits

Currency component: energy (calories)

Cost component: time or calories

Search: all the time spent getting to the place prey is encountered.

Handling: all the time devoted to pursuing, capturing, processing, transporting, and eating the prey. Includes unsuccessful pursuits.

Assumptions:

• Foragers will seek to maximize the long-term net rate of energy capture during foraging (kilocalories per hour)

• searching and handling are mutually exclusive

• prey resources are encountered sequentially and randomly in proportion to their abundance

• prey vary in net returns from type to type

• prey can be ranked according to their net return rates

Predictions of the Diet Breadth Model

• The prey type yielding the highest return rate on encounter should always be pursued (always take the highest ranked prey)

• Lower ranked prey should be added sequentially to the diet until the next most profitable resource yields a lower rate of return on encounter than could be obtained by continuing to search for and pursue more profitable items. This is the optimal diet.

• None of the items ranked lower in profitability should be pursued on encounter – they are out of the diet.

• Whether a forager takes a lower ranked prey depends on the abundance of all higher ranked prey

• Foragers should add or drop particular resources from the optimal diet in response to fluctuations in the abundance of higher ranked resources

Example: Mark Basgall and the economics of acorn exploitation in prehistoric California

D. Diet and Gender: Kristen Hawkes, The Ache and the notion of Costly signaling