Evolution and Psychology

Darwin - evolutionary biology

• Darwin theorised a gradual progression from nonhuman to human minds

• It provides a conceptual framework for understanding human traits as the outcome of natural selection during our evolutionary past (phylogenetic basis of human mind)

• The difference between non-humans and humans was one of degree, not of kind (Penn et al.)

  • HOWEVER, Penn et al. argues Darwin was wrong; behind the biological continuity there is an equal discontinuity between humans and non-humans

Difference between phylogeny and ontogeny

Phylogeny - the evolutionary history of a kind of organism

Ontogeny - the development or course of development of an individual organism

‘The Selfish Gene’ Richard Dawkins

• Gene-centered account of evolution

• Natural selection is most usefully understood as favouring genes that are good at getting themselves copied into future generations

• “Selfish” is a metaphor for selection, not a moral claim

• Evolution is the competition between replicating genes

Frameworks for theory and research – Sociobiology

• Branch of evolutionary biology

• Explains natural selection of particular traits as reproductive success

• E. O. Wilson’s book ‘Sociobiology: The New Synthesis’ triggered major controversy

  • Criticism: genetic determinism overlooks the roles of mind and culture and can’t account for the complexity of human behaviour

The demographic-economic paradox

• Evolutionary biology predicts that successful individuals would optimise their reproduction

• In human societies, there is widely demonstrated inverse relationship between income and fertility

Frameworks for theory and research – Game theory

• Branch of mathematics

• Analyses strategies for dealing with competitive situations where the outcome of a participant's choice depends on the actions of the other participants

• Evolutionary game theory: applied to Darwinian competitions in evolving populations and explain the evolution of cooperation

• E.g., the prisoner's dilemma or 2 sticklebacks approach predator together but both have the incentive to hang back to let the other take greater danger

Inclusive fitness

• W.D Hamilton’s idea aimed to explain how social traits, (like altruism) evolve in populations

• Natural selection favours animals who care for other animals that have a statistical likelihood of sharing the same genes

  • Direct fitness: your own offspring (50% shared)

  • Indirect fitness: your genetic relatives (< 50%)

Hamilton’s rule

Altruism can evolve when: rB > C

r = relatedness

B = benefit to recipient

C = cost to the actor

E.g. if survival is boosted - Belding’s ground squirrels: they give calls to the group when a predator is nearby

Hamilton’s rule when compared to humans:

• Humans are unusually cooperative compared to other animals cooperating with genetically unrelated strangers

• Charity is less explained by inclusive fitness, and more social payoffs (reputation), internal rewards (warm glow), and cultural institutions (norms)

• E.g., Fehr and Fischbacher (2003) argue human cooperation with strangers is often sustained by “strong reciprocity” and culturally transmitted norms, not by kin selection alone

On the other hand, comparative psychology:

The study of similarities and differences in organisms’ behaviour

Some psychologists differentiate ‘comparative cognition’ from ‘comparative psychology’:

• Abramson (2015)

  • Psychology is the science of behaviour

  • Textbook definitions restrict comparative psychologists to animals studies or to also include human behaviour

• Chiandetti & Gerbino (2015)

  • Psychology is the science of the mind

  • Animal behaviour is studied also by biologists; what makes it ‘psychology’ is the study of mental phenomena

Focuses of comparative psychologists:

• Cognitive traits that are uniquely human

• Inherited predispositions that are typical to human mind

• What can human minds do without certain types of direct experiences with one’s environment? (e.g. using distance estimation, maps)

• Animal behaviour and cognition are studied by biologists; it becomes ‘psychology’ when compared to humans

Human + non-human skills:

Both:

• Problem solving

• Using tools

• Cultural transmission = modifications over time, leads to ‘ratchet effect’ (Tomasello,

  Kruger and Ratner, 1993)

Humans:

• The ability to understand others as intentional beings: we learn the intentional significance of tools and symbols

Matsuzawa (2015): Sweet-potato washing revisited

Early example of cultural behaviour in macaque monkeys:
1. Emergence (‘Imo’ started doing it on her own)
2. Propagation (new behaviour spread through troop via relations)
3. Modification (washing first done in fresh water; a few generations later, started immersing in the sea for a salty taste)

Verbal behaviour – does language make us special?

B. F. Skinner: on verbal behaviour:

• We learn it through operant conditioning, e.g., verbal praise

  • Humans complicate behaviourist experiments: inferred meanings can override the reinforcement schedule

• Language is learnt the same way as any other behaviour

HOWEVER, Chomsky criticised Skinner, arguing human brains have the generative capacity to produce language independently of reinforcement

Origins of linguistic nativism

• In the 50s/60s, Chomsky’s “generative” programme reframed linguistics as explaining the internal knowledge that lets humans generate an open-ended set of sentences from finite means

  • This suggests learners start with an innate framework of grammar

  • Work in the same period argued language development shows “biological” features

• Chomsky’s claims had motivated attempts to teach chimps human language

  • E.g., 1960s: Allen and Beatrix Gardner taught Washoe American Sign Language

Does a chimpanzee have a theory of mind?

• Across multiple experimental paradigms, chimps understand others’ intentions, goals, and what others see and know

• HOWEVER, no evidence that chimps understand false beliefs (predicting behaviour based on what another mistakenly believes)

• Chimps appear to operate with a perception-goal psychology (acting because they perceive things and want outcomes) rather than human-like belief-desire psychology involving mental representations that can be false

Animal communication - bee:

• Karl von Frisch: they communicate flower locations using a waggle dance

• Unlike humans, bees cannot change how information is presented, elaborate, etc.

Difference of kind – communication:

Vervet monkeys have a proto-language: different calls for warning about snakes, eagles and leopards

In cognitive science, the symbol-grounding problem refers to how the human mind connects audio/visual stimuli to meanings

Sociological view - the significance of language (G. H. Mead, 1934)

• A ‘conversation’ of gestures – animals play fight without an explicit role

• The symbolic interaction – children take on a role, e.g., 'playing Indian', responding to stimuli

• Sociologist argue non-humans can’t have a sense of self, whereas biologist would argue they could

Konda et al. (2019) - the ‘rouge’ test (mirror recognition)

• Test for awareness of oneself as a separate entity

• They found a cleaner wrasse did recognise itself

The development of evolutionary psychology

• 80s/90s Cosmides and Tooby redefine ‘evolutionary psychology’ combining the principles of evolutionary biology with the information-processing framework of cognitive psychology

• Evolution reframes cognition as evolved computation; it regulates behaviour and physiology

• Core premise = the Massive Modularity Hypothesis (MMH)

MMH

The human mind consists of many innate, special-purpose information-processing systems (Darwinian modules) that were shaped by natural selection, each shaped to solve a specific ancestral problem

Critiques of MMH

• Central cognition is not plausibly “modular” (since 90s, cognitive science has moved away from modularity)

  • While some perceptual systems may be specialised, reasoning used in planning, explanation, etc. depends on information from many domains

• Ketelaar & Ellis (2000): The basic assumptions of evolutionary psychology can’t be tested by means of the scientific method

• ALTERNATIVE MODEL = Samuels (1998)

Samuels (1998): The ‘library model of cognition’ (alternative model)

• The mind contains relatively few specialised bodies of knowledge (mental schemas)

• Computational mechanisms are domain-general – the same mechanisms subserve a variety of purposes (e.g., reasoning, belief-fixation)

• Called the library model because a librarian’s operation of organisation is the same for any category