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Chapter 2: Culture and Human Nature — Vocabulary Flashcards

Is Culture Unique to Humans?

  • Two definitions of culture discussed in the chapter:
    • Broad definition: culture = information acquired through social learning from members of one’s own species.
    • Narrow/symbolic definition: culture = symbolic coding (signals, icons, words) that many in a culture recognize.
    • Both definitions are explored to avoid circularity (e.g., defining culture as symbolic coding and then claiming culture is unique to humans).
  • Examples illustrating cultural learning across species:
    • Imo the Japanese macaque ( potato washing )
    • Imo invented washing sweet potatoes in water to remove sand.
    • Within ~3 months, her mother and playmates learned the behavior; ~40% of the troupe adopted it within ~3 years.
    • Demonstrates culture as information learned socially, spreading within a group.
    • Chimpanzees and termites:
    • Mt. Assirik chimps use tools to fish termites with twig tools; peel bark from twigs and use bark to fish out termites (Senegal).
    • Gombe chimps use bark similarly but differently; two distinct cultural repertoires (twig-fishers vs bark-fishers).
    • At least 39 specific culturally transmitted chimp behaviors identified across communities (body cleaning with leaves, branch-slapping to attract attention, etc.).
    • Dolphins and whales:
    • Bottlenose dolphins use marine sponges as foraging tools; different dialects in killer whales; dialects change over time.
    • Other taxa:
    • Pigeons learning food acquisition strategies; birds learning calls; guppies and octopuses show some social learning.
  • Major question: Are humans unique in culture? A nuanced view:
    • If culture is defined strictly as social learning within a species, humans are not the only species with culture; many animals show cultural learning.
    • If culture is tied to symbolic coding, humans may appear unique, but this definition is arguably circular.
  • Three core cognitive adaptations that support human cultural learning (as a package):
    • Mentalizing (perspective-taking): understanding others’ intentions, goals, and beliefs.
    • Language: sophisticated communication to encode, transmit, and refine ideas.
    • Sharing experiences/goals: motivation to coordinate, collaborate, and teach.
  • Modes of cultural learning in humans vs other primates:
    • Imitative learning: learners copy the model’s goals and actions (e.g., imitation of intentional actions).
    • Emulative learning: learners focus on environmental events/outcomes and figure out how to achieve them themselves (less emphasis on copying the exact actions).
    • Empirical comparison (Nagell, Olguin, Tomasello, 1993):
    • Children showed true imitative learning: copied the model’s precise actions to obtain a reward.
    • Chimps showed emulative learning: observed the effective method and adopted the most effective rake position (teeth up) to retrieve the reward, often ignoring the exact sequence they observed.
  • Overimitation and selective copying:
    • Humans (especially WEIRD samples) tend to imitate all observed actions, including irrelevant steps, more than chimpanzees.
    • Children overimitate even when instructed not to copy irrelevant actions; this tendency appears cross-culturally (e.g., Kalahari San and Australian Aboriginals show overimitation similar to WEIRD samples).
  • Language and communication as enablers of culture:
    • Language enables question, clarification, persuasion, description, instruction, and the transmission of beliefs and complex ideas.
    • No nonhuman species shows human-like grammar/syntax; whales’ language capabilities are impressive but not fully mapped; some animals have limited vocabularies (e.g., vervet monkeys calls) but not human-level grammar.
    • Reading a book as cultural learning illustrates language’s central role in transmitting culture.
  • Social learning biases that guide whom to imitate (distinctively human features):
    • Prestige bias: imitate those deemed prestigious (e.g., models with skills or social respect).
    • Similarity bias: imitate people who are similar to oneself (gender, ethnicity, language/accent).
    • Conformist transmission: copy behaviors that are more common in the group, especially when tasks are difficult, confidence is low, and multiple options exist.
    • These biases maximize the likelihood of acquiring effective cultural knowledge and are argued to be largely unique to humans (with some conflicting findings in other species).
  • Why these biases matter for cumulative culture:
    • Prestige, similarity, and conformist tendencies help identify reliable models to imitate and increase the efficiency of cultural learning.
    • They support the accumulation of culture by focusing on high-quality information and widely adopted practices.

Cultural Learning: Mentalizing and Perspective Taking

  • Mentalizing (theory of mind):
    • The ability to infer others’ mental states (intentions, goals, beliefs) is evident in infants and develops fairly uniformly across diverse cultures.
    • This capacity is a foundational prerequisite for high-fidelity imitation and social learning.
    • Nonhuman primates have some mentalizing abilities but are markedly weaker than humans; chimpanzees show limitations relative to humans, particularly in perspective-taking.
  • Imitative vs. emulative learning revisited:
    • Imitative learning: internalizes the model’s goals and actions; more faithful replication of intended actions.
    • Emulative learning: focuses on outcomes and environmental changes; learner figures out the means to achieve the goal.
    • The distinction has consequences for cultural accumulation: imitation supports high-fidelity transmission and cumulative culture; emulation can be creative but may lead to slower accumulation due to missing intent-based cues.
  • The role of language in social learning:
    • Language supports the transfer of ideas, intentions, and complex plans; without language, many cultural concepts would be hard to transmit.
  • Collaborative learning and instructed learning:
    • Humans engage in collaborative learning (learning with others) and instructed learning (guided by teachers/models) to reproduce cultural behaviors accurately.
    • Scaffolding (guided participation) helps learners master complex tasks.
    • WEIRD vs non-WEIRD differences: explicit/instructed learning is more common in WEIRD societies; some small-scale societies emphasize patient, less direct instruction; East Asian cultures emphasize respect for adults.
  • The rarity of guided instruction among chimpanzees and other primates:
    • Chimps show little evidence of collaborative or instructed learning; humans show robust collaborative and guided learning, enabling rapid cultural progression.

Cumulative Cultural Evolution and the Ratchet Effect

  • Cumulative cultural evolution: cultural information builds on prior knowledge, allowing more complex and useful innovations over time.
  • Ratchet effect: once an idea is learned, it can be modified and improved by others, but the information does not easily slip backward to earlier, less advanced forms.
  • Prerequisites for cumulative culture:
    • High-fidelity social transmission (precise imitation, reliable copying) to preserve innovations across generations.
    • Sophisticated communication to share refined ideas and instructions.
  • Nonhuman cultures generally lack substantial cumulative cultural evolution due to limited fidelity and limited capacity to build on others’ discoveries; emulation dominates in many nonhuman species.
  • Example: hammer evolution (Figure 2.5 in the text):
    • The hammer did not evolve from scratch in a single leap; it emerged through a long series of incremental inventions, adaptations, and modifications built atop accumulated cultural ideas.
    • Our modern hammer results from millennia of culturally learned innovations, not a single genetic leap.
  • Consequences for human biology: culture and genes coevolve (gene–culture coevolution).

The Hammer, Cooking, and the Energetics of the Human Brain

  • Paleobiology of tool and cooking innovations:
    • The hammer’s history illustrates cumulative cultural evolution in toolmaking.
    • Cooking is a crucial cultural invention that transformed how we extract energy from food.
  • Cooking and energy budgets:
    • Cooking denatures proteins, gelatinizes starch, and softens food, reducing chewing effort and enabling more efficient digestion.
    • Cooking increases net energy available from food, allowing more energy to be allocated to the brain and reducing the need for a large gut.
  • Energetic costs and adaptations:
    • Brain energy use: about rac{E{brain}}{E{total}} \approx 0.16 (16% of total metabolic energy).
    • Brain weight relative to body weight: rac{W{brain}}{W{body}} \approx 0.02 (about 2%).
    • Encephalization quotient (EQ): ratio of actual brain weight to brain weight predicted for a similar-bodied animal; humans ≈ EQ \approx 4.6, the highest among mammals (except the tiny shrew).
    • Digestive tract (gut) size: humans have a gut that is about 60% smaller than expected for a primate of our body weight; this saves roughly 10 ext{%} of daily energy use, freeing energy for a larger brain.
  • Consequence: smaller gut and reduced muscle mass in humans free metabolic energy to support a larger brain.
  • Wrangham’s perspective on cooking and evolution:
    • Cooking allowed early humans to extract more energy from food, enabling a larger brain to develop while maintaining a smaller digestive tract and less bulky musculature.
  • Gene–culture coevolution:
    • Culture (cooking, tool use, etc.) and genetic evolution influence each other over long time scales.
    • Humans rely on culturally transmitted skills and genetically evolved capabilities to adapt to changing environments.

Population Size and Interconnection: Why Culture Accumulates Faster in Larger, Connected Groups

  • Empirical findings on group size and cultural evolution:
    • Derex, Beugin, Godelle, & Raymond (2013): larger groups reproduce more successful nets in a design task; copying and innovations are more likely with more models to copy.
    • Group size experiment: nets were shown to participants; after 15 trials, groups of 16 nearly all reproduced the net, with some innovations arising in large groups that improved on the original.
    • Conclusion: bigger groups facilitate faster cultural evolution because of more models to copy and more innovations.
  • Historical cross-cultural data:
    • Large island populations at first contact with Westerners (e.g., Hawaii) had more diverse technologies than smaller-population islands (e.g., Malekula).
    • The pattern supports the idea that larger populations support greater cultural complexity.
  • Interconnectedness matters:
    • A group’s interconnectedness enhances cultural learning; groups with more interactions reproduce and transmit complex skills more effectively.
    • Experiments show that when interactions are limited (one member only) learning is slower; when interactions involve all members, learning and transmission improve.
  • The internet and globalization: connectivity accelerates cultural evolution by exposing individuals to more models and ideas.
  • The Tasmanian example: cultural knowledge can slip or be lost when population size and interconnectedness shrink; Tasmanians had simpler technologies in the 18th century after isolation from larger networks, illustrating how ratchets slip without enough high-quality models to copy.
  • Population size and rate of innovations:
    • Across prehistory, the rate of technological innovations accelerated dramatically with agricultural societies and increasing population density.
    • Moore’s law (computing) as a modern example of rapid cumulative improvement: data density doubles roughly every 1.5 ext{ years}, so a computer today is much more powerful than 30 years ago.
  • Conclusion: population size and interconnection are key drivers of cumulative cultural evolution; large, connected populations sustain higher fidelity transmission and more innovations.

Humans Live in Cultural Worlds

  • Cultural worlds vs. physical environments:
    • Humans inhabit cultural worlds that include schools, markets, governments, legal systems, family structures, and global information networks.
    • These cultural infrastructures guide daily behavior and decision-making beyond the immediate physical environment.
  • Examples of entrenched cultural information:
    • Education systems, legal frameworks, military and governmental organizations, monogamous nuclear families, mechanized transportation, and access to distant information via books, TV, and the Internet.
    • These cultural patterns shape everyday behavior and thought processes, beyond biological inheritance alone.
  • Implications for studying human behavior:
    • To understand human behavior and thought, we must study the cultural information that people encounter in daily life as well as biological predispositions.

The Costs and Benefits of Multiculturalism and WEIRD Biases

  • WEIRD samples: Western, Educated, Industrialized, Rich, Democratic populations are not representative of humans globally; relying on WEIRD samples can bias conclusions about human psychology and culture.
  • Benefits of multicultural perspective:
    • Broadens understanding of how culture shapes cognition, behavior, and social learning across diverse populations.
    • Highlights the variability in teaching styles, norms, and values across cultures.
  • Costs and challenges of multicultural perspective:
    • Requires careful methodological control to compare across cultures; potential for misinterpretation when cultural practices differ in context.
  • Color-blind vs multicultural perspectives:
    • Color-blind perspectives may overlook meaningful cultural differences; multicultural perspectives acknowledge and study differences to understand learning, behavior, and adaptation.

The Other Side: Ethics, Morality, and Cultural Relativism

  • Ethical implications of cultural practices (e.g., Sambian initiation rituals):
    • Some practices that are culturally meaningful in one society may be morally controversial or illegal in other cultures.
    • The question arises: should psychologists judge practices by universal norms or by local cultural meanings?
  • Relativism vs universal ethics:
    • The text invites reflection on whether to evaluate practices based on external norms or internal cultural logic and meaning.
  • Implications for practice:
    • Researchers should avoid ethnocentric judgments and seek to understand local norms and meanings while considering universal human rights concerns.

The Big Picture: What Makes Humans Distinct in Culture and Cognition

  • Summary of key differences between humans and nonhuman primates:
    • Humans have advanced mentalizing, language, and a motivation to share experiences/goals, enabling collaborative and instructed learning.
    • Humans imitate others with high fidelity and can build upon others’ ideas to create cumulative cultural evolution (the ratchet effect).
    • Nonhuman primates tend toward emulative learning and show less capacity for collaborative or instructed learning; they imitate less selectively and do not demonstrate substantial cumulative culture.
  • The cognitive toolkit that supports cultural learning:
    • Mentalizing (perspective-taking) + language + sharing experiences/goals → enables precise, scalable cultural learning.
    • These components coevolved and are central to human adaptability and innovation.
  • Brain size, energy, and biology:
    • Humans have the largest brain among primates (high encephalization quotient) but pay a high energy cost.
    • Evolution favored traits that reduced energetic demands for the brain (smaller muscles, smaller gut) and increased energy availability through cooking and other cultural practices.
  • The social brain hypothesis (Dunbar) and neocortex ratio:
    • Species living in larger social groups tend to have larger neocortex ratios, suggesting social complexity drives brain expansion.
    • Humans surpass the expected neocortex-group size relationship, reflecting ultra-sociality and the heavy reliance on social learning.
  • The theory of cumulative culture as a defining feature of humanity:
    • Unlike other species, humans accumulate cultural knowledge across generations, leading to rapid and exponential growth in cultural complexity.
    • This cumulative culture is supported by high-fidelity transmission, language, mentalizing, and shared goals.
  • Practical implications for understanding human nature:
    • Culture and biology are deeply intertwined through gene–culture coevolution.
    • To understand human behavior, we must study cultural environments, social learning mechanisms, and the brain’s role in supporting these processes.

Historical and Educational Takeaways from the Chapter

  • Tasmanian case study:
    • Tasmanians in the 18th century had far simpler technological repertoires than earlier periods or other Aboriginal Australians, likely due to isolation and lack of copying models. This illustrates how small or isolated populations are at risk for ratchet slip and cultural loss.
  • Cross-species comparisons and policy implications:
    • Recognizing the variability in cultural learning across species informs educational approaches, highlighting the importance of targeted modeling, imitation strategies, and social immersion in human learning contexts.
  • Final takeaway:
    • Culture is a central, if not the central, ingredient of human evolution and daily life; our genes and brains have evolved in tandem with culturally transmitted knowledge, enabling the remarkable phenomenon of cumulative culture.

Key Formulas and Numerical References (LaTeX)

  • Encephalization quotient (EQ):
    • ext{EQ} = rac{W{ ext{brain}}}{W{ ext{brain, expected}}} \approx 4.6
  • Brain energy share:
    • rac{E{ ext{brain}}}{E{ ext{total}}} \approx 0.16
  • Brain-to-body weight proportion:
    • rac{W{ ext{brain}}}{W{ ext{body}}} \approx 0.02 \
  • Digestive tract size reduction:
    • V{ ext{gut}} \approx 0.4 \, V{ ext{gut, expected}}
  • Group size (Dunbar’s estimate for ancestral populations): ~150
    • \text{Typical ancestral group size} \approx 150\
  • Neocortex ratio vs. group size (conceptual relation)
    • Not expressed as a simple formula in the text, but described as a positive association: larger groups -> larger neocortex ratios; humans exceed the pattern.
  • Moore’s law (computing):
    • Number of transistors doubles every 1.5\\text{ years}:
    • Nt = N0 \, 2^{t/1.5} where t is in years.
  • Innovations over time (illustrative rates per thousand years):
    • ~0.0015 per thousand years (before 100k years ago) → 0.05 per thousand years (around 40k years ago) → 0.55 per thousand years (12k years ago) → 5.2 per thousand years (9k years ago, with agriculture).

Shortlist of Key Takeaways

  • Humans rely on a unique combination of mentalizing, language, and the motivation to share experiences/goals to enable high-fidelity social learning and cumulative culture.
  • Cultural learning biases (prestige, similarity, conformist transmission) help target who to imitate and what to adopt, driving efficient learning and cultural evolution.
  • Emulative vs imitative learning show that humans tend to imitate more precisely, supporting cultural accumulation; chimpanzees often rely on emulation, which can be creative but limits cumulative progress.
  • Cooking and other cultural innovations dramatically altered human biology and energy budgets, enabling a larger brain through gene–culture coevolution.
  • Population size and interconnection strongly influence the speed and extent of cultural evolution; larger, more connected populations sustain more complex culture.
  • Humans inhabit cultural worlds—institutions and technologies that shape daily life and cognition, beyond the strictly biological world.
  • There are ethical and practical implications about evaluating cultural practices; researchers must balance cultural relativism with universal human rights concerns.