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Appendix 2. Dietary decision-making: formal models and ethnographic Qualifications

(Summarized from Johnson, 1980)

  1. Devise a well-structured problem on an optimum diet: what combinations of foods provide a fully nutritious diet with the least caloric energy (work) expended in food production and processing?
  2. Determine by ethnographic observation: (1) food-production strategies (typical strategies might be gathering/hunting, fishing, gardening); (2) foods provided by means of these strategies (e.g. different species of game from hunting or wild fruits from gathering); (3) typical diets for men, women, and children of different ages.
  3. Use the data from step 2 to construct: (1) a cost vector (the labour cost in calories of work expended per kg of each food); (2) a food vector (the nutrient value of each food and combinations of foods); and (3) a nutritional requirement vector (the nutritional requirements for men, women, and children in this society).
  4. Calculate the labour costs per kg, and nutrient content of, each food and food strategy. Also calculate the total nutrient requirements per household per year.
  5. Set up a linear programming routine that can search through available foods to find a solution that meets the minimum requirements for nutrients (energy or, alternatively, other nutrient mix) at least cost, without further constraints.
  6. Examine the acceptability of that solution (i.e. a food basket selected by the programme in step 5). How does it compare with actual (observed) energy expenditures (in food strategies) and actual diet?

Crop proportions by weight (solution 2)

Crop category Model (%) Observed (%)
Maize 10 5
Root crops 53 (cocoyam) 76 (cocoyam, manioc, yams)
Banana/plantain 20 (plantain) 7 (banana, plantain)
Legumes 17 (pigeon 0.2 (pigeon peas, beans)
Other peas)


12 (sugar cane, papaya, pineapple, guava)
  1. Consider what nutritional or other qualities alternative food strategies and foods provide. Interview subjects about their criteria for food selection, evaluations of food qualities, and ideas of what constitutes an adequate and preferred diet (see further discussions in this chapter, and in the chapter by Goode, on dietary structure). Also interview subjects about their relative preference for or dissatisfaction with different patterns of work in food strategies. Use this information to describe the relative value or negative value on different patterns of allocating time in the food quest. Taking into account this ethnographic information, describe the relative preference for different foods and food strategies in terms of factors as taste, nutritional quality, and the perceived drudgery of different food strategies. (In his Machiguenga study, as a case in point, Johnson found that the "optimum" solution was for Machiguenga to allocate all their labour to gardens, but that was not, in fact, how they spent their time or selected their preferred diets. He calculated how gathered and hunted foods, while costly in terms of energy expenditure, provided nutritional balance and variety to the diet. People also enjoyed the work of searching for food in the forest compared with the drudgery of gardening. These understandings helped Johnson describe the "rationality" of the observed food strategies and their divergence from the optimum diet model.)
  2. Consider other ways to frame the problem; e.g. treat each food as separate, assigning it an average cost proportional to its share in the particular basket. Allow the linear programming routine to sort through the numbers of foods and to select any combination according to the new criteria.
  3. Compare this solution with the actual dietary behaviour.
  4. Describe how the actual behaviour still differs from predicted behaviour in the formal model, and use this information to further describe dietary decision-making.

Appendix 3. Bitter or astringent taste standards

Appendix 3. Bitter or astringent taste standards

The effect of varying concentrations of tannins and alkaloids on the amount of food eaten by Testudo gracca:

Quinine: -----
Hydrolysable tannin: - - - - - -
Condensed tannin: ...........

The rejection limit concentration is that at which < 80 per cent of the food is consumed.

  1. Vary the concentrations of quinine, tannin(s), etc., to a standard element of diet.
  2. In a free choice situation, compare the amount of a treated food eaten by a selected group with the amount of untreated food eaten by a control group.
  3. Replicate observations to determine precisely the concentrations of the various substances which, when added to the food, created particular degrees of aversions, and determine a "rejection limit" (Swain, 1976, pp. 11-12).

Appendix 4. A field test for estimating sweetness preferences to improve estimates of sucrose intakes in individuals

  1. Prepare six sugar/water/ solutions (see table A below)
  2. Present each of the solutions of each subject, one at a time, in irregular order. For each trial, ask the subject whether the sample is "the preferred sweetness," "not sweet enough," or "too sweet." Record responses.
  3. Present the subject with a sample of the household beverage, and repeat tasting of each solution until the subject reaches consensus that one sample matches the sweetness of the household beverage. Record responses.
  4. Carry out steps 2 and 3 with all household members to establish: (1) whether all perceive the "matches" equally; and (2) whether all share consensus on how sweet they like their beverages. Record which sample matches the household level of sweetness. As a check, calculate the sweetness by weighing the grams of sugar and litres of water plus flavouring used in the preparation of the household beverage.
  5. Ask each household member how much of the home beverage he/she consumes each day. Check by observation.
  6. Measure volumes of drinking vessels and sum the total volume of beverage intake per person per day.
  7. Calculate the quantity of sugar (in beverages) consumed per person per day by multiplying grams of sugar per litre beverage x litres of beverage consumed per individual.
  8. Calculate the contribution of this sugar to dietary calories by multiplying grams of sugar x 4 calories per gram.

Table A. Six sugar/water solutions used to test perception of sweetness

Molar concentration Sucrose per litre Sucrose per 500 ml
0.032 M 10.94 g 5.47 g=1 tsp
0.056 M 19.15 g 9.58 g =13/4 tsp
0.1 M 34.2 g 17.1 g= 1 Tbsp+ 1/4 sp
0.18 M 61.56 g 30.78 g = 1/8 cup + 1 11/4 tsp
0.32 M 109.44 g 54.72 g= 1/4 cup + 1/2 tsp
0.56 M 191.50 g 95.76 g = 1/3 cup + 1/2 tsp

Sucrose 1 mole = 342.0 g/litre. These molar concentrations correspond to natural thresholds of sweetness taste perception. determined experimentally by Linda Bartoshuk and colleagues.

Appendix 5. Methods for describing staple food classifications

  1. Construct a classificatory tree diagram that describes by name the different types and varieties of staple grains (roots and tubers) available for daily consumption in the community. Labels should include: the species name (e.g. maize, rice, bean, potato) plus varietal descriptors such as colour (e.g. white maize, black beans,); size or shape of grain (e.g. thin (yellow) maize, thick (black) beans); type of seed (e.g. hybrid maize); and numbered variety (e.g. IRB rice bred and distributed by the International Rice Research Institute in the Philippines).
  2. Interview women (who prepare food for the household), farmers, shopkeepers, agronomists, nutritionists, and food planners about additional qualities of these different varieties of staple foods. Additional agronomic qualities might include: length and timing of growing season (e.g. three-, four-, five-, or six-month maize during the wet or dry seasons); yield potential (e.g. high-yield potential rice varieties); preferred environment (e.g. certain Mexican white maize does well in thick soils, but yellows in thin soils); and pest resistance (e.g. a particular rice or maize variety is resistant, or particularly vulnerable, to certain plagues during the growing season or in post-harvest storage). Additional cooking and eating qualities might include: preferred texture or cooking qualities (e.g. short-grain, sticky rices versus dry rices are preferred in different nations in Asia; white maize is preferred for softer whiter tortillas in many parts of Mexico); nutritional content (e.g. yellow maize in Mexican villages is said to be higher in vitamin A and more nutritious; certain varieties of maize, rice, and other staples have a measurably higher protein content); flavour; and healthfulness (see other sections in this chapter). Additional qualities might include: relative costs in time and money (e.g. availability and cost of seed, cultivation, processing). Compare attributes of typical grain varieties from the perspectives of local consumers and producers, agronomists, planners, and nutritionists.
  3. Construct a list of preferences for the different grain varieties for each group of respondents, and compare. Assess how varying classifications, perceptions of qualities and preferences for the different grain varieties affect consumption and nutrient intake.
  4. Determine the nutritional value of the basic staple, in raw and processed forms.
  5. Referring to the nutrient intake of the staple food, per person per day, calculate how choice of dietary grain/variety staple affects nutrient intake.


Appendix 6. Symbolic, folkloric, and medicinal factors

The best way to learn how cultural rules operate is through extended periods of participant observation in a culture. In this manner, one can observe what kinds of questions people ask in cases of illness, which cultural rules direct medicinal and nutritional dosing of the ill, and also, under ordinary circumstances, which rules direct preparation of diet.

Since this is usually not possible in short-term survey work:

  1. Carefully read the ethnographic/folkloric literature on the food habits of the locality or region.
  2. Carefully interview key informants to arrive at appropriate questions and categories for the particular culture under investigation. During these interviews (and later in the questionnaire):

Appendix 7. Gender factors

  1. During interviews with key informants, and also from existing folklore and socio-cultural literature, find out whether there are any foods particularly restricted to males or females (for example, meat for men, certain kinds of gruels, plantains for women).
  2. From the data of twenty-four hour dietary recall, observation, or a combination of dietary data, determine whether there is complete fit between the "food ideology" (the food rules) and the actual behaviour.
  3. Construct some typical diets for males and females in the same age and social categories from the combined dietary and food-ideology data:
  1. Examine whether there are other signs of sex differences in nutritional status:
  1. Summarize your findings, and return to key informants with questions relevant to your findings:

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