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

3. Dawkins… genes as “replicators”

4. 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.” 

5. Living organisms…
…“survival machines” (designed and built by genes)
…“gigantic lumbering robots” (controlled—indirectly—by genes)
…“vehicles” (used for genes for purposes of replication)

6. 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.

7. Some clarifications about what this logically implies:
Does NOT imply perfection or optimality.
(Constraints on how evolution “designs” things.)
Does NOT imply effectiveness over time.
(adapted ≠ adaptive)
Does NOT imply that each and every thing we do
actually serves the agenda of the genes that designed
and built us.

8. 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

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

10. Nature versus Nurture fallacy

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

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

13. “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”

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

15. “The brain is a physical system designed to generate behavior that is appropriate to one's environmental circumstances.”
Adaptive flexibility

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

17. 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.
“Nature”
(a person’s genes)
“Nurture”
(input from the environment)
Expression of genes during development
Cognition and behavior

18. Example: Regional differences in extraversion
Background:
Extraversion has some genetic basis.
Extraversion has many benefits.
Extraversion can also have costs: exposure to infection.
These costs are high in disease-y environments.
Implication:
It would have been adaptive if genes promoting extraversion were less likely to be expressed (and so less likely to produce extraverted people) in highly disease-y environments.
Testable hypothesis:
In geographical regions characterized by a high prevalence of infectious diseases, people are likely to be generally less extraverted.
Evidence:

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

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

21. Example: Temporary changes in extraversion
Background:
Extraversion has some genetic basis.
Extraversion has many benefits.
Extraversion can also have costs: exposure to infection.
These costs are high in disease-y environments.
Implication:
- It would have been adaptive if evolved mechanisms underlying interpersonal behavior were sensitive to perceptual information indicating infection risk, and inhibited extraverted responses when the threat of infection appeared to be especially high.
Testable hypothesis:
When the threat of infection is temporarily salient, people are likely to be temporarily less extraverted.
Evidence:

22. Across two experiments…
Empirical evidence:
(Mortensen, Becker, Ackerman, Neuberg, & Kenrick, 2010)
Across two experiments…
Manipulated temporary salience of infectious diseases.
Measured:
Self-reported extraversion.
Speed of movement toward and away from people.
Results: When disease was temporarily salient…
People report lower levels of extraversion.
People show more reluctant-to-interact movements.