What is the Environment of Evolutionary Adaptedness (EEA) and why is it important to evolutionary psychology?
A: The current environment in which natural selection is actively shaping human psychology today
B: The ancestral environment — roughly the Pleistocene African savanna — in which our psychological mechanisms were shaped by natural selection, and to which they remain primarily adapted
C: The ideal environment for human psychological flourishing, identified by cross-cultural psychologists
D: The range of environments across human history; evolutionary psychology predicts that behaviour adapts flexibly to any environment
Correct: The ancestral environment — roughly the Pleistocene African savanna — in which our psychological mechanisms were shaped by natural selection, and to which they remain primarily adapted
The EEA — a concept developed by John Bowlby and John Tooby and Leda Cosmides — refers to the ancestral conditions under which a psychological mechanism was selected. For humans, this broadly corresponds to small-group hunter-gatherer life during the Pleistocene (~2.6 million to ~11,700 years ago). Evolutionary psychology's core premise is that the human brain is a product of selection in that environment, not in the modern world. This creates the possibility of "mismatch" — psychological mechanisms that were adaptive in the EEA may be maladaptive today. Classic examples: a strong preference for calorie-dense foods (adaptive in feast-and-famine conditions, maladaptive with constant access to junk food); strong in-group/out-group bias (adaptive in small competing groups, potentially maladaptive in ethnically diverse modern societies); fear of snakes and heights (adaptive, even in people who have never encountered these dangers).
What is the difference between an adaptation, a byproduct, and noise in evolutionary psychology?
A: Adaptations increase fitness; byproducts decrease it; noise is neutral genetic variation
B: Adaptations are features that evolved because they directly enhanced reproductive fitness; byproducts are incidental structural consequences of adaptations (not selected for themselves); noise is random variation with no functional significance
C: Adaptations are universal; byproducts vary by culture; noise varies by individual
D: All three terms describe the same phenomenon at different levels of analysis — adaptation at species level, byproduct at population level, noise at individual level
Correct: Adaptations are features that evolved because they directly enhanced reproductive fitness; byproducts are incidental structural consequences of adaptations (not selected for themselves); noise is random variation with no functional significance
Tooby and Cosmides distinguish three sources of biological design: (1) Adaptations: features that exist because they were directly selected for — they solve a specific recurrent ancestral problem and bear the hallmarks of special design (complexity, efficiency, specificity, fit to the problem). Example: the eye is an adaptation for vision; the fear system for detecting and responding to threat. (2) Byproducts: features that exist because they are architecturally coupled to adaptations, not because they were selected directly. Example: the navel is a byproduct of the umbilical cord; the fact that blood is red is a byproduct of haemoglobin chemistry. The human capacity for music may be a byproduct of adaptations for language and rhythm processing. (3) Noise: random genetic variation with no adaptive significance. Distinguishing these categories requires careful reasoning about what selection pressures could have produced a feature.
William Hamilton's concept of inclusive fitness extended Darwin's notion of fitness. What does it propose?
A: Fitness is defined by an organism's direct offspring only; Hamilton showed that larger body size increases reproductive success
B: Natural selection can favour genes that increase fitness of genetic relatives, even at a cost to the individual — because shared genes are propagated either way; this is captured by Hamilton's rule: rB > C
C: Inclusive fitness means selecting traits that benefit the entire population, not just the individual; group selection is the primary mechanism
D: Fitness should include environmental sustainability; Hamilton proposed that evolution favours behaviours that preserve habitat for descendants
Correct: Natural selection can favour genes that increase fitness of genetic relatives, even at a cost to the individual — because shared genes are propagated either way; this is captured by Hamilton's rule: rB > C
William Hamilton (1964) resolved the puzzle of altruism — how could natural selection favour costly behaviour toward others? — by recognising that genes, not individuals, are the unit of selection. An individual shares 50% of their genes with a sibling, 25% with a niece/nephew, 12.5% with a cousin. Helping a genetic relative survive and reproduce propagates shared genes — indirectly but genetically equivalently to personal reproduction. Hamilton's rule formalises this: altruistic behaviour will evolve when rB > C, where r = coefficient of genetic relatedness between actor and recipient, B = reproductive benefit to the recipient, C = reproductive cost to the actor. This explains nepotism (stronger helping of kin than strangers), why parents sacrifice for children (r = 0.5), and why soldier behaviour may appear altruistic (in small cohesive groups, likely relatives). J.B.S. Haldane allegedly quipped he would "lay down my life for two brothers or eight cousins."
Trivers' (1972) parental investment theory predicts which sex will be more choosy about mates?
A: The sex that invests less in each offspring is more choosy; the higher-investing sex competes for access to the choosy sex
B: The sex that invests more in each offspring is more choosy about mate quality; the lower-investing sex competes for access to the choosier sex
C: Both sexes are equally choosy; investment level predicts aggression, not choosiness
D: Neither sex shows choosiness in monogamous species; choosiness only evolves in polygamous mating systems
Correct: The sex that invests more in each offspring is more choosy about mate quality; the lower-investing sex competes for access to the choosier sex
Robert Trivers's parental investment theory (1972) provides an elegant explanation for sex differences in mating behaviour. Parental investment is any investment in an offspring that increases its fitness at the cost of the parent's ability to invest in other offspring. The sex that invests more in each offspring (typically the one that produces large, costly gametes and bears gestation and nursing costs) has more to lose from a poor mating decision — so they should be more selective. The other sex, having lower per-offspring investment, benefits from maximising the number of matings. In humans: females invest enormously (9-month gestation, lactation, primary caregiving historically), predicting female choosiness. Males invest much less per sperm, predicting male competition and willingness to mate widely. However, male investment varies enormously across cultures and contexts, and Trivers' framework predicts that when males provide substantial paternal investment, they too become choosier.
Sexual selection is a specific form of natural selection. What are its two mechanisms?
A: Survival selection (traits that help survive predation) and reproductive selection (traits that help secure mates)
B: Intersexual selection (mate choice — one sex prefers certain traits in the other) and intrasexual selection (competition between members of the same sex for mating access)
C: Directional selection (traits pushed to extremes) and stabilising selection (traits toward the average)
D: Good-genes selection (choosing healthy mates) and runaway selection (arbitrary preference amplification); these are the only two mechanisms in Darwin's original account
Correct: Intersexual selection (mate choice — one sex prefers certain traits in the other) and intrasexual selection (competition between members of the same sex for mating access)
Darwin (1871) identified two mechanisms of sexual selection: (1) Intersexual selection (mate choice): one sex — typically female — preferentially mates with individuals possessing certain traits. This creates selection pressure on males to develop those traits, even if they reduce survival (e.g., the peacock's tail increases predation risk but females prefer large, elaborate tails — possibly as signals of underlying genetic quality or parasite resistance, per the "handicap principle"). (2) Intrasexual selection (same-sex competition): members of one sex — typically male — compete directly for access to the other sex. This selects for traits that enhance competitive ability (body size, weapons, dominance behaviour). Both mechanisms explain sex-typical traits: male physical ornaments (peacock, deer antlers, human facial hair) via intersexual; male–male fighting ability and risk-taking via intrasexual. In humans, both mechanisms operate but with substantial cultural modulation.
What is the "massive modularity" hypothesis (Tooby & Cosmides, Pinker) and what is the alternative view?
A: The mind consists of a single powerful general-purpose learning device (domain-general processor); massive modularity is the incorrect view that there are many specialised systems
B: The mind consists of many evolved, domain-specific information-processing mechanisms (modules) — each solving a specific ancestral problem; the alternative is domain-general learning (a few powerful general processors)
C: Modules are brain regions visible on neuroimaging; massive modularity proposes every cognitive function maps to one anatomical module
D: Massive modularity applies to sensory systems (vision, hearing) only; higher-order cognition is universally domain-general
Correct: The mind consists of many evolved, domain-specific information-processing mechanisms (modules) — each solving a specific ancestral problem; the alternative is domain-general learning (a few powerful general processors)
Tooby, Cosmides, and Pinker argue that the mind comprises a large number of evolved, specialised cognitive mechanisms — "modules" — each dedicated to solving a specific recurrent problem from ancestral life: a cheater-detection module, a face-recognition system, a theory of mind mechanism, a language acquisition device, a fear system tuned to ancestral threats. These modules are proposed to be domain-specific (triggered by relevant inputs), automatic, informationally encapsulated, and universal across cultures. The competing view is domain-generality: the brain has a few powerful general-purpose learning mechanisms (like reinforcement learning or Bayesian inference) that can acquire any cultural knowledge. The debate is partially empirical: findings of domain-specific deficits (prosopagnosia affecting face recognition while leaving object recognition intact; specific language impairment) support modularity; the flexibility of human learning and cultural variation support domain-generality. The current consensus involves some mixture: evolved specialisations that are less rigidly encapsulated than Fodor's original module concept.
What are the most significant scientific criticisms of evolutionary psychology?
A: Evolutionary psychology is not a science at all — it has no empirical methods and all its claims are philosophical
B: Key criticisms include: (1) just-so story risk — adaptationist explanations can be constructed post-hoc for almost any finding; (2) difficulty falsifying claims about the EEA; (3) neglect of developmental plasticity and cultural variation; (4) conflating current function with evolutionary origin
C: Evolutionary psychology is entirely correct at the group/species level but makes no predictions about individual differences
D: The only valid criticism is that the EEA cannot be precisely specified; all other aspects of the research programme are uncontroversial
Correct: Key criticisms include: (1) just-so story risk — adaptationist explanations can be constructed post-hoc for almost any finding; (2) difficulty falsifying claims about the EEA; (3) neglect of developmental plasticity and cultural variation; (4) conflating current function with evolutionary origin
Evolutionary psychology faces several legitimate methodological and theoretical criticisms: (1) The "just-so story" problem (from Gould & Lewontin, 1979): adaptationist explanations can be invoked for virtually any behaviour after the fact, without independent evidence. (2) Unfalsifiability: since we cannot observe the EEA directly, claims about ancestral selection pressures are difficult to test. (3) Neglect of plasticity: human behaviour is extraordinarily flexible and culturally variable — finding a cross-cultural universal doesn't establish evolutionary origin (literacy is nearly universal today but not evolved). (4) The naturalistic fallacy risk: the field is misused to justify present inequalities as "natural." (5) Gene-behaviour gap: no direct genetic evidence exists for most proposed psychological adaptations — the causal pathway from gene to specific psychological mechanism is rarely specified. Defenders respond that these are methodological challenges, not disqualifiers, and that multiple converging lines of evidence — cross-cultural universals, developmental timecourse, neural specificity, comparative data from other species — can constrain evolutionary hypotheses.
What is "preparedness" in learning theory (Seligman, 1971) and how does it support an evolutionary approach to phobias?
A: Preparedness means all stimuli are equally easy to condition — learning is "prepared" to occur with any CS-US pairing, demonstrating equipotentiality
B: Organisms are biologically "prepared" by evolution to acquire certain associations more easily than others — particularly fear associations to ancestral threats like snakes, spiders, and heights — even after minimal exposure and resistant to extinction
C: Preparedness refers to conscious readiness to learn; prepared learners acquire associations faster than unprepared ones regardless of stimulus content
D: Preparedness only applies to classical conditioning in non-human species; humans show true equipotentiality because cultural learning overrides biology
Correct: Organisms are biologically "prepared" by evolution to acquire certain associations more easily than others — particularly fear associations to ancestral threats like snakes, spiders, and heights — even after minimal exposure and resistant to extinction
Martin Seligman (1971) proposed preparedness as a revision of the behaviourist assumption of equipotentiality — that any CS can be equally conditioned to any US. Evolutionary logic: organisms that rapidly acquired fear of ancestral threats (snakes, spiders, heights, strangers) survived longer and reproduced more. Consequently, fear conditioning to these stimuli should be: (1) acquired with fewer trials; (2) more resistant to extinction; (3) present even after one-trial learning; (4) maintained even when the person "knows" the stimulus is safe. Öhman and colleagues provided experimental evidence: conditioned fear responses to snake and spider images were more resistant to extinction than fear responses to flowers and mushrooms, even when stimuli were presented subliminally (below conscious awareness). This explains why snake phobia is globally far more common than car phobia, despite cars killing vastly more people — the modern danger has not been evolutionarily calibrated.
Evolutionary Psychology
What is the Environment of Evolutionary Adaptedness (EEA) and why is it important to evolutionary psychology?
About this quiz
Evolutionary psychology asks why the human mind is the way it is — what selection pressures shaped our cognitive architecture, emotional systems, and social behaviour. By understanding the Environment of Evolutionary Adaptedness (EEA), we can make sense of everything from fear of snakes to parental love to the universality of certain facial expressions.
This quiz covers the core principles of evolutionary psychology: natural and sexual selection, adaptations and byproducts, inclusive fitness, parental investment theory, and the key criticisms of the field.