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6: FEB 4


  • Sapolsky, Chapter 10: The Evolution of Human Behavior 328-387 (59). For this class read only pages 354-387. Use notes above also for part two of this chapter.

Some lecture notes on Sapolsky, Chapter 10: The Evolution of Human Behavior 354-374

  • See previous class for reading notes on this chapter
  • How can cooperation get started and become stable? 353-
  • In other words, how does "tit for tat" survive among defectors? (example from Henrich of Inuits with meat sharing behaviors).
  • Effects of ind. selection, kin selection, and reciprocal altruism:
  • Tournament vs. Pair bonding - lots of traits and behavoirs follow from sexual dimorphism.
  • Parent-Offspring competition - in spite of kin selection, there are some "zero sum" situations bt parents and offspring. even metabolic conflict in utero.
  • Paternal "imprinted genes" promote fetal growth at expense of mom.
  • Multilevel Selection MLS
  • Remember the "bad" group selection from the beginning of the chapter? Group selection returns in the last few decades. (Tell story of visits with Bio prof friends over the years.)
  • Genotypic and Phenotypic levels of explanation - unibrows.
  • Organism (expressed individual) is a vehicle of the genome, but the genome has alot to say about how the organism turns out. Dawkins cake metaphor.
  • Two levels and counting.
  • Third level: neo-group selection - idea that some traits are maladaptive for individual but increase group fitness. Not altruism, but could look like it. Example: encouraging patriotism might lead you to enlist, taking a fitness risk that we benefit from. Jailing someone for their reproductive life is a serious fitness hit.
  • Where do we fit in? AND US?
  • Not quite pair-bonding, not quite tournament
  • Example of divorce: natural experiment when cultural taboos are lifted. Note that increased divorce rates are confined to the same percentage of population. Lift culture and you get to see who the "less pair-bonding" people are! Likewise with historically powerful (and not very romantic) rulers.
  • Kin selection still very powerful, but we can go to war against kin, and we give to strangers. (Stop to theorize this a minute. Does this mean we are not subject to kin selection or that there are other forces, such as culture, that can override kin preferences. What do your eyes tell you?) Biologists also want to find mechanisms. Animals recognize kin by MHC or imprinted genes. Story of Pavlik Morozov, 368.

Group Discussion on Group Selection

  • Let's try to deepen our understanding of the relationship between cultural or group selection pressures and our "fitness". How does kin selection still operate and affect our fitness? What are some of the non-kin based cultural and group selection pressures in our society? In addition to selection pressures, how do kin and culture offer resources for increasing our fitness? Where does morality come into this?
  • Weak vs. strong - pressures and resources for fitness
  • Kin vs. non-kin pressures and resources for fitness
  • Group selection structures specifically related to morality.