Science 240

Biological determinism, cultural evolution, and sociobiology

Lectures #41 & #42: Friday, 11 December and Monday, 14 December

1. Nature versus nurture
   1. A longstanding problem in human behavior: To what extent is individual behavior determined by inherent biological properties rather than properties acquired through experience and training
   2. IQ and educational policy (claims of William Schockley and William Jensen, echoed in The Bell Curve)
      1. Extensive studies of IQ show marked differences in average IQ between Caucasians and African Americans
      2. IQ is highly heritable. 70% of variability accounted for by genetic factors.
      3. Therefore, remedial attempts to improve educational attainment are pointless: a waste of time, money, and effort
   3. General challenges to the analysis and conclusions
      1. IQ may not measure "general intelligence". It may not be anything we're particularly interested in.
      2. Average IQ scores may be different, but there is a broad overlap in scores. Race is a very poor predictor of IQ.
      3. IQ tests are culturally biased.
   4. Challenge to the thesis of biological determinism
      1. Genetic differences in populations of yarrow (a plant)
         1. Individuals collected from both high and low elevation populations.
         2. Each individual cloned.
         3. Grown in three different experimental gardens: low elevation, medium elevation, and high elevation.
      2. Results
         1. Individuals from different populations are recognizably distinct when grown in the same environment. Implies genetic differences between these individuals.
         2. Individuals from low elevation population tallest at low elevation. Individuals from high elevation population tallest at high elevation. No difference at medium elevation. Implies that phenotype produced by an organism depends on both its genotype and the environment in which it grows.
         3. Lack of difference at medium elevation indicates that the amount of variability that is caused by differences in genotype depends on the environment in which those differences are measured.
      3. Phnenylketonuria (PKU)
         1. Genetic disorder resulting from a metabolic deficiency. Individuals homozygous for PKU allele cannot metabolize phenylalanine, a component of many proteins.
         2. Result
            1. Severe mental retardation if they eat a normal diet.
            2. No retardation if they eat a special diet low in phenylalanine
      4. Reasonable to believe that everyone can benefit from increased investment in education
2. The dangers of anthropomorphism
   1. Extra-pair copulation in mallard ducks
      1. Male and female mallards normally pair for mating, rearing of offspring, elaborate mating ritual
      2. Males sometimes surprise a mated female and attempt to copulate immediately, to "steal" a mating, none of the usual mating ritual
      3. Females often attempt to escape, sometimes suffering injury in the process
   2. Evolutionary explanation for the origin of rape
      1. Extra-pair copulation increases reproductive success of males.
      2. As a result this behavior will be favored by natural selection.
   3. Challenges to the evolutionary explanation
      1. Is extra-pair copulation really an adaptation?
      2. If it is an adaptation, did it evolve for the same reasons in mallards and humans? Why would we expect so, since the social structures of our ancestors were so different from those of mallards?
      3. The description of the behavior may not be correct. Many psychologists think rape in humans is an aspect of violent or aggressive behavior, not an aspect of sexual behavior.
   4. Anthropomorphism: attributing human feelings/desires to animals
3. The naturalistic fallacy
   1. Name given by British philosopher David Hume to confusing "ought" with "is".
   2. Can we derive ethical principles from biological ones?
      1. Biological principles describe the way the world is.
      2. Ethical principles describe the way the world ought to be.