Long Answer Q1. Infanticide

Using an example such as infanticide explain the similarities and differences between Evolutionary Psychology, Human Behavioural Ecology, Cultural Evolution and Gene-Culture Coevolution. If could choose only one theory to use in the field of Psychology, which one would you choose and why?

What is Evolutionary Psychology according to the slides?

• EP is a framework that explains behaviour using evolved psychological mechanisms—often called modules—that solved recurrent problems in ancestral environments. It follows a Standard Evolutionary Theory (SET), gene-centred logic and often assumes a universal human nature, though the slides note this assumption is challenged (Brown & Lala)

How would EP explain infanticide?

• Through evolved psychological mechanisms regulating parental investment.

• The slides use the Cinderella effect (Daly & Wilson 1988) to show that humans evolved mechanisms sensitive to genetic relatedness, leading to lower investment—and higher risk—toward stepchildren.

• Infanticide occurs when mechanisms favour maximizing genetic fitness by avoiding costly investment in unrelated offspring.

What slide content supports EP's interpretation of infanticide?

• Cinderella effect slide: risk to unrelated children due to evolved mechanisms sensitized to relatedness.

• EP’s emphasis on universal psychological modules (e.g., Cosmides & Tooby’s work referenced earlier in course).

• Critique: slides note Brown & Lala argue a universal human nature is problematic, which challenges EP’s strongest assumption.

What is Human Behavioural Ecology according to the slides?

• HBE views behaviour as adaptive and flexible, shaped by current ecological and economic conditions, not fixed modules. It emphasizes phenotypic plasticity and environment-specific decisions that maximize reproductive success under local constraints (e.g., Turkana vs. Aeta life-history differences)

How would HBE explain infanticide?

• As an adaptive strategy responding to ecological pressures such as resource scarcity, mortality risk, or life-history tradeoffs.

• Infanticide occurs when environmental costs of raising a child outweigh benefits, consistent with fast life-history strategies (e.g., earlier reproduction, less investment in each child when mortality is high).

What slide content supports HBE’s view?

• Fast vs. slow life-history strategies: environments with high mortality lead to early reproduction and lower investment.

• Chicago homicide ecology study (Wilson & Daly 1997): behaviour shifts with mortality expectations.

• Turkana vs. Aeta comparison: ecological conditions shape reproduction timing and investment.

• Gurven's “upside of flexibility” slide emphasizes the adaptability central to HBE.

What is Cultural Evolution according to the slides?

• A framework stating that behaviours spread and persist due to social learning (“cornerstone of cultural evolution”), transmission of ideas, norms, beliefs, and institutions. Culture evolves through variation, selection, and inheritance, similar to biological evolution, but the units are beliefs and practices, not genes.

How would Cultural Evolution explain infanticide?

• Infanticide is regulated by cultural norms, beliefs, taboos, and institutions that shape what behaviours are acceptable.

• Cultural systems—such as religion—evolve to stabilize cooperation and moral behaviour (e.g., moralizing gods promote prosociality in large groups).

• Norms can discourage, prohibit, or contextualize infanticide depending on the group’s cultural history.

What slide content supports this explanation?

• “Social learning” slide: cultural learning shapes behaviour instead of individual trial and error.

• Religion and cooperation slides: cultural systems provide moral frameworks that influence behaviour.

• Moralizing gods (Lang et al. 2019): beliefs make individuals more trustworthy and regulate behaviour even in large anonymous societies.

• The class theme: cultural evolution explains large-scale cooperation that biological reciprocity cannot.

What is Gene–Culture Coevolution according to the slides?

• GCC is a framework where genes and culture mutually influence each other. Cultural practices change ecological pressures, which then alter genetic selection, and biological predispositions influence which cultural traits emerge or spread. The slides position GCC as an integration of EP, HBE, and Cultural Evolution, not a replacement.

How would GCC explain infanticide?

• As the product of interactions between biological predispositions (e.g., investment biases) and cultural norms(e.g., family structure, alloparenting, expectations of siblings and fathers).

• Cultural norms about parenting (e.g., alloparenting, cooperative breeding) change the costs and benefits of investing in children, which reshapes biological selection pressures.

• Infanticide emerges only when both biological and cultural factors align to make it adaptive.

What slide content supports GCC?

• Brown & Lala slides on integration of evolutionary subfields (EP, HBE, Cultural Evolution).

• Critiques of universal human nature showing need for an integrated framework.

• Family structure discussion: emphasis on alloparenting, cooperative families, and variation beyond WEIRD nuclear families shows culture-biological interaction.

• GCC slides highlight its ability to account for compatibility among subfields.

What is a major similarity across all four evolutionary approaches?

• All approaches see infanticide as linked to reproductive costs and benefits and parental investment, but differ in whether the cause is psychological (EP), ecological (HBE), cultural (CE), or interactive (GCC).

EP vs. HBE — what’s the key difference?

• EP: behaviour comes from evolved, universal psychological mechanisms.

• HBE: behaviour is flexible, shaped by current ecology and life-history tradeoffs.

Cultural Evolution vs. EP/HBE — what’s unique?

• CE sees behaviour as driven primarily by learned norms and practices, not inherent modules or ecological constraints.

Why is GCC different from all others?

• GCC uniquely views evolution as bidirectional and integrative, where culture shapes genetic evolution and genes shape cultural evolution, tying together insights from EP, HBE, and CE.

If you had to choose 1 field of Psychology, which one and why?

Gene–Culture Coevolution.

1. It explicitly integrates multiple evolutionary levels.
   The last slides highlight concerns about relying on a single, universal “human nature” and emphasize the need to integrate EP, HBE, and Cultural Evolution rather than choose between them.
   GCC is the only framework in the slides presented as fully integrative.

2. It captures both flexibility and constraints.

   • HBE explains flexibility.

   • EP explains evolved constraints.

   • Cultural Evolution explains institutions and norms.
     GCC unites these perspectives.

3. Brown & Lala emphasize that human nature is not fixed but shaped through dynamic evolutionary processes—precisely the point of gene–culture coevolution .

4. It aligns with the slide’s theme that multiple evolutionary subfields are compatible and should be integrated.
   The class concludes with integration questions and critiques of overly narrow models, implying that a broader metatheory is preferable.

GCC offers the most complete, flexible, and theoretically coherent framework for Psychology, given the content presented in these slides.

Q: How does Evolutionary Psychology explain infanticide, and what are its strengths and limitations

Explanation: EP interprets infanticide as the result of evolved psychological mechanisms shaped by ancestral selection pressures. It often focuses on reproductive conflict, such as males committing infanticide when doing so increases future mating opportunities.

• Strength: Provides clear, testable hypotheses about underlying psychological mechanisms.

• Limitation: Tends to treat behaviour as coming from species-typical internal mechanisms, which can underplay variation across societies and historical contexts.

How does Human Behavioural Ecology explain infanticide, and what are its strengths and limitations?

• Explanation: HBE sees infanticide as a conditional strategy that improves reproductive success in specific ecological contexts. It is shaped by cost–benefit trade-offs such as resource scarcity, parental condition, or offspring viability.

• Strength: Excellent at capturing within- and between-population variation in behaviour.

• Limitation: Focuses on outcomes rather than psychological mechanisms, often paying less attention to cognition.

Q: How does Cultural Evolution explain infanticide, and what are its strengths and limitations

• Explanation: Cultural Evolution emphasizes social learning and cultural norms. Infanticide practices persist when they are culturally transmitted, socially sanctioned, or symbolically meaningful—not only because they maximize fitness.

• Strength: Explains why infanticide can persist or disappear rapidly through shifting cultural norms.

• Limitation: Can underestimate biological constraints and evolved predispositions.

Q: How does Gene–Culture Coevolution explain infanticide, and what are its strengths and limitations?

• Explanation: GCC argues that genes and culture co-evolve. Cultural norms around infanticide can shift selection pressures, while evolved capacities for learning and moral reasoning shape which cultural practices endure.

• Strength: Captures feedback loops between biological and cultural evolution.

• Limitation: Methodologically complex and harder to test clearly.

Q: What similarities do EP, HBE, Cultural Evolution, and GCC share in explaining infanticide?

• All reject moral or individualistic explanations of infanticide.

• All view it as context-dependent, not random pathology or individual dysfunction.

• All rely on evolutionary logic, but differ in what they treat as the primary cause (psychological mechanisms, ecological pressures, cultural norms, or gene–culture interactions).