Are we more influenced by nature or nurture? Or is human behavior "a magnificent, fascinating, nuanced interaction between nature and nurture"? What can evolutionary biology and genetics tell us about human behavior? What can biology tell us about how we behave the way we do? These are the kinds of questions we will explore in this discussion.
This topic is inspired by six engaging, easy to follow, mostly jargon-free, entertaining, introductory lectures by Robert Sapolsky from his free, on-line video course "Human Behavioral Biology":
- Behavioral Evolution I (96 minute video): This video explores how to deduce various qualities of (human) social behavior from the principles of evolutionary theory. That is, it's a basic introduction to sociobiology and evolutionary psychology. Topics discussed include the foundations of evolutionary theory as initiated by Alfred Russel Wallace and Charles Darwin in the 1800s, the principles of natural selection, game theory of cooperation including the Prisoner's Dilemma, problems with group selction, the biology of reciprocal altruism, and the distinction between tournament and pair-bonded species and where humans fit on that spectrum. The following summaries of the lecture may also be perused:
- Behavioral Evolution II (96 minute video) This video builds on the previous one by applying the principles of sociobiology to "understand" infanticide, kidnapping, polyandry, the battle of the sexes, rape, murder, intra-group conflict and inter-group warfaring. The stories explain kin selection and reciprocal altruism. Then Sapolsky discusses multi-level selection and how group selection has some limited validity after all. He concludes with a big warning about sociobiology and critiques three assumptions to this approach to understanding human behavior. The following summaries of the lecture may also be perused:
- Molecular Genetics I (96 minute video) This video starts exploring molecular biology from a conceptual point of view. We learn that the central dogma of biology (DNA->RNA->Protein->biological tools) is wrong! Epigenetics is the regulatory system which controls gene expression and we learn about its mechanisms and its impact. Several fascinating examples are discussed: phenylketonuria (PKU), testicular-feminizing syndrome, the FOXP2 gene and language. Most of the lecture explains the mechanisms of molecular genetics which are critical to an understanding of behavior from a genetic perspective. The following summaries of the lecture may also be perused:
- Molecular Genetics II (74 minute video) More mechanisms of molecular biology are discussed including the microevolution / macroevolution distinction, jumping genes, and copy number variants. Examples include vasopressin and the social affiliative behavior of males and some effects of steroid hormones like estrogen, testosterone, and glucocorticoids. Sapolsky weighs the evidence between evolutionary gradualism and punctuated equilibrium and discovers evidence supporting both views. The following summaries of the lecture may also be perused:
- Behavioral Genetics I (98 minute video) As Sapolsky explains each of the ever improving approaches to behavioral genetics he exposes serious doubts about their validity. Twin studies and even studies of identical twins separated at birth are criticized strongly. We learn of influential studies whose methodologies and conclusions have been significantly questioned such as Benbow & Stanley's 1980 report "Sex differences in mathematical ability: Fact or artifact?" and Seymour Kety's adoption study of schizophrenia. We learn about behaviors that require no learning, those influenced by pre-natal effects, indirect genetic effects, and "non-Mendelian inheritance of traits" or Lamarckian inheritance (whose ideas have been vindicated in part!). The following summaries of the lecture may also be perused:
- Behavioral Genetics II (92 minute video) Here Sapolsky describes the modern approach to behavioral genetics which he characterizes with the mantra "go and find the genes". He introduces the third leg in the dichotomy between nature vs. nurture: chance. He overviews the techniques used to find the genes and emphasizes their complexity and statistical nature. With genetic diseases success is achieved. He explains why more complex behaviors have been less amenable to finding the genes. He explains what heritability means (not what you think!) and the importance of the gene-environment interaction and why this means that the science is so often "wrong". The following summaries of the lecture may also be perused:
If you manage to watch all six videos, you may want to watch the first 30 minutes of the next lecture in Sapolsky's course which provides an succinct review of heritability and provides a wonderful exercise in how to interpret scientific studies. Finally, although none of the content in the introductory lecture for Sapolsky's course will be important for our discussion, you may find the overview interesting. Sapolsky is brilliant, I hope you'll enjoy the lectures and maybe you'll join me and watch the whole course.
Subjects include sociobiology, behavioral ecology, evolutionary psychology, molecular genetics including the prominent role of epigenetics, and behavioral genetics.
Due to strong interest in this topic, it will be repeated on Saturday 27 July. Please RSVP to the meeting that works best for you.