The Gene’s-Eye View of Life People as vehicles (for genes)   Three logical fallacies to avoid - Naturalistic fallacy - Nature vs. Nurture fallacy - Determinism fallacy Adaptive flexibility - “Phenotypic plasticity” - “Functional flexibility”

Dawkins (end of Chapter 2): “Replicators began not merely to exist, but to construct for themselves containers, vehicles for their continued existence. The replicators that survived were the ones that built survival machines for themselves to live in… “Now they swarm inside huge colonies, safe inside gigantic lumbering robots, sealed off from the outside world, communicating with it by tortuous indirect routes, manipulating it by remote control. They are in you and in me; they created us, body and mind; and their preservation is the ultimate rationale for our existence. They have come a long way, those replicators. Now they go by the name of genes, and we are their survival machines.” 

Broad implication for human psychology: Given that we are designed and built by genes to serve as “vehicles” for those genes, it means that the things comprising our psychology – our perceptions, our cognitive processes, our emotional reactions, our behavioral tendencies – are the products of underlying mechanisms that were designed and built by genes to serve as tools that facilitate the potential for genes to make copies of themselves.

  Some clarifications about what this logically implies: Does NOT imply perfection or optimality. (Constraints on how evolution “designs” things.) Does NOT imply evolved mechanisms are still useful today. (adapted ≠ adaptive) Does NOT imply that every thing we do actually serves the agenda of the genes that designed and built us. (Genes influence on behavior is indirect and overrule-able.)

  Three common fallacies: (Logically wrong conclusions that often follow from lazy thinking about evolution and human psychology) Naturalistic fallacy Nature versus Nurture fallacy Determinism fallacy

Naturalistic fallacy Tendency to assume that “what is” is the same as “what is right and/or good.”

Nature versus Nurture fallacy Tendency to assume some competition between gene-based and environment/learning-based explanations for psychological phenomena.

“Nurture” requires “Nature” “Nature” (evolutionary processes) Capacity to learn “Nurture” “Nurture” requires “Nature”

“Nature” interacts with “Nurture” (a person’s genes) “Nurture” (input from the environment) Expression of genes during development Cognition and behavior “Nature” interacts with “Nurture”

Determinism fallacy Tendency to assume that if some psychological tendency is rooted in genes/evolution, then it is unchangeable and inflexible.

“The brain is a physical system designed to generate behavior that is appropriate to one's environmental circumstances.” (Cosmides & Tooby) Adaptive flexibility Environmental inputs “Useful” behavioral outputs

Adaptive flexibility Two ways in which genes build organisms to be flexibly responsive to environments. - Developmental process (“phenotypic plasticity”) - Neurocognitive process (“functional flexibility”)

Developmental process (“phenotypic plasticity”) In response to input from the developmental environment, genotype (genetic makeup of an organism) produces phenotypic features (observable characteristics of the organism) that, historically, facilitated reproductive success within that kind of environment.

Example: Regional differences in extraversion Background: Extraversion has some genetic basis. Extraversion can have many benefits. Extraversion can also have costs: exposure to infection. These costs are high in disease-y environments. Implication: In environments that are generally highly disease-y, it could be beneficial to genes if the specific genes promoting extraversion were less likely to be expressed. (With the consequence that genes’ “survival machines” would generally be less extraverted). Evidence consistent with this implication: In countries that are generally highly disease-y, people are generally less extraverted.

r = -.51 (Schaller & Murray, 2008)

Neurocognitive process (“functional flexibility””) Evolved brain mechanisms are adaptively designed in such a way that, in response to input from immediate circumstances, these mechanisms temporarily produce cognitive, affective, and behavioral responses that, historically, facilitated reproductive success within those circumstances.

Example: Temporary changes in extraversion Background: Extraversion can have many benefits. Extraversion can also have costs: exposure to infection. These costs are temporarily higher when the risk of infection is temporarily higher. Implication: Beneficial to genes if psychological mechanisms were sensitive to temporary changes in risk of infection, and interpersonal behavior calibrated accordingly. (For example: temporarily reduced extraversion when risk of infection is perceived to be temporarily high). Evidence consistent with this implication: When the risk of infection is perceived to be temporarily high, people are temporarily less extraverted.

Across two experiments… Manipulated perceived risk of infection. Empirical evidence: (Mortensen, Becker, Ackerman, Neuberg, & Kenrick, 2010) Across two experiments… Manipulated perceived risk of infection. Measured: Self-reported extraversion. Speed of movement toward and away from people. Results: When risk of infection was perceived to be temporarily high… People reported lower levels of extraversion. People showed more reluctant-to-interact movements.

Next class: Good genes Reading: Dawkins, Chapter 3   Reading: Dawkins, Chapter 3 Reading: Gangestad, S. W., Thornhill, R. & Garver-Apgar, C. E. (2005). Adaptations to ovulation: Implications for sexual and social behavior. Current Directions in Psychological Science, 14, 312-316.