26 February 2008
Philosophy of
Biological and Cognitive Sciences
Matteo Mameli and
David Papineau
Tuesdays 12-1.30 Lecture Room KCL Dept of
Philosophy
KCL/LSE MSc in PHS
Paolo Mantovani
Cultural evolution 1: Evoked vs. Transmitted Culture
A premise and two broad questions
Cultural evolution (Fracchia and Lewontin):
Transformational theories vs Variational
theories (our focus)
(e.g., Spencer, Boas) (Memetics,
Co-evolution)
Intrinsic transformational mechanisms Extrinsic mechanism - environment
Directionality,
stages Variation, heritability,
differential reproduction
Model: organic development ‘Model’:
genetic evolution
(although things more complicated)
Two questions:
1)
Relationships between
cultural processes and genetic fitness (today)
2)
How to frame
cultural processes, particularly the suitability of selective models (next
week)
Question (1):
-
Superorganic
approach: traditional cultural
anthropology → autonomy of the cultural → biological constraints
are loose enough to justify a science entirely detached from biology (A.L. Kroeber, C. Geertz, M. Sahlins …)
-
Genocentric
approaches:
-
Sociobiology (E.O.
Wilson): culture ‘at the leash of our genes’ (ex. Incest taboo)
-
EP (Tooby and Cosmides): evoked culture vs
transmitted (or epidemiological) culture
-
Evoked → directly
produced by cognitive adaptations;
-
Transmitted
→ social learning (acquisition
of skills, dispositions, behaviours, ideas, etc.
through social interaction with conspecifics)
Cultural evolution theory,
particularly co-evolution, rejects both superorganicism
and the genocentric take on culture.
-
Against superorganicism: i) ‘natural origins’ argument ii) modularity and cognitive
biases
-
Against genocentrism:
cumulative effects of transmitted culture
Evoked culture (EC)
Notion emerges to contrast SSSM’s conception of culture:
culture → individual psychology. Through social learning.
EC: Evolved psychology +
environment → culture. No proper social learning. How?
-
Innate
(genetically encoded, adaptation, developmentally robust) universal content modules or biases: language, folk
biology, face recognition, ToM, animal detection,
cheater detection…
-
Each module is
activated by the appropriate environmental factor (domain-specificity of
cognitive modules)
-
Innate psychology
triggered by environmental factor A → cultural variant X, triggered
by environmental factor B → cultural variant Y…. (The jukebox metaphor:
same jukebox selects different records in different environments)
Examples:
Language: universal grammar + linguistic environment →
either Italian or Chinese or..
Religion (Boyer): ToM applied to
supernatural entities + ‘ghosts’ environment → concept of ghost; +
‘angels’ environment → concept of angels.
Cultural stability:
persistence of environment.
Cultural diversity:
changes in environment:
In sum, the theory of EC
substitutes social learning with the environmental triggering of innate
modules, which produces pre-ordered outcomes given the ‘right’ environment (the
‘records’ are all present innately in our cognitive jukebox). Most cultural information does not require learning:
you don’t have to learn from scratch
grammatical rules; you don’t have to learn that supernatural agents have properties such as beliefs
and desires, and perform goal-directed actions.
(Tooby
and Cosmides) Most
culture is EC. Phenomena of cultural transmission that are not directly
controlled by evolved modules (genes) have no evolutionary relevance. They get washed
out by natural selection acting on genes.
Note: Differences with
Problems with EC
1) Notion of environment in relation to the
explanation of inter-group cultural diversity (assuming that much
of it finds no account at the genetic level).
Environment must include
itself socio-cultural factors (‘natural’ environment underdetermines the behavioural hyper-variability among human groups). It is
for instance the radical change in the socio-cultural-technological environment
that explains why modern men and women often behave maladaptively
(Tooby and Cosmides): our
ancestral adaptations are not trained to cope with massive cities, medias, intense cultural horizontal transmission etc.
However how do these
changed socio-cultural environments come about? Relying on EC
renders these changes mysterious. The ‘explanation’ of cultural variation
through EC (modules + ‘environment’) is question-begging because it does not
provide tools to understand the key variable for the explanation, i.e. the
‘environment’.
(Additional problem:
distinguishing the innate from the ‘evoked’)
Alternative: population-level cumulative effects of transmitted
culture explain human inter-group behavioural
variation (Boyd and Richerson).
-
The idea of
content biases in transmission is central for understanding cultural processes →
co-evolution and cognitive anthropology (Sperber, Atran, Boyer, next week!). However
this does not rule out the possibility that multi-generational transmission
creates cumulative effects at population level, i.e., environments of
evolutionary novel cultural contents (again, how to explain the modern
cultural environment?) which we de facto
entertain with without having cognitive adaptations for them. (In fact individual-level biases have big
population-level differences)
-
What is the explanatory role of EC? Is EC a rhetorical notion
accommodating, somehow, cultural variation in a framework (EP) that does not
seem to provide the tools for this explanation? EP → the universal cognitive architecture (in
contrast with
2)
Transmitted culture seems powerfully adaptive → cumulative
multi-generational refinement of techniques → colonization of all
environments.
- If
you find yourself in a hostile environment (desert, Artic…), you are probably
better off learning survival tricks from locals rather than waiting for evolved
modules to evoke the appropriate cultural/behavioural
trait. Locals have constructed a culture, generation after generation, that deals with their
environment. Foraging techniques or building an igloo involve
complex skills: no lifetime individual learning, but cumulative,
multi-generational refinement.
-
Selection for cumulative
transmitted culture and the abilities that render it possible (Boyd and Richerson). The central tenet of gene/culture
co-evolutionary theory: human social learning puts into motion a cultural
evolutionary process that is (relatively) autonomous from genetic evolution and
has important feedbacks on genetic selection itself. Challenge to any unilateral gene-eye-view
where highly cultural organisms are concerned.
Transmitted culture as an adaptation
How can there initially be
selection for social learning?
-
Boyd and Richerson’s
solution of Rogers’ dilemma highlights the fact that it is cumulative culture that is an adaptation (the
possibility of learning individually starting from an already available
knowledge) and that it is cumulative culture that distinguishes human culture
from forms of proto-cultural traditions in the animal kingdom (Boyd and Richerson, ‘culture makes us odd’).
-
Still cumulative
culture requires costly cognitive structures (e.g., accurate imitation, ToM, memory, cooperative dispositions, language, also
domain-general cognitive abilities?) → evolutionary
bottleneck, needs peculiar conditions and extraordinary selective pressures
(this explains why proper cumulative culture is not widespread in nature).
-
One condition: heavy relying on social learning is adaptive when
environment changes slowly (if not individual learning is better) but not too
slowly (if not genetic selection will do the adjusting job) and when individual
learning is particularly costly → The climatic changes hypothesis (Boyd
and Richerson).
-
When conditions
are right → selection for whole range of individual-level cognitive
biases for figuring when and how to rely on social learning (conformist
bias, prestige bias.. these biases represent a big
part of the causal structure of co-evolutionary theory).
In conclusion: cumulative culture is, overall, a powerful adaptation. However, it has the power to
create evolutionarily new cultural environments, i.e., the conditions for the
spread of fitness neutral and maladaptive
cultural traits (contraception, suicide bombing, religious celibate, career
obsessions…). This view renders possible to see and possibly solve problems
that are not visible neither in EC nor in the superorganic perspective.
Issues:
-
What are,
precisely, the cognitive adaptations for cumulative culture and what is the
evolutionary hierarchy among them, if there is a clear hierarchy (e.g., basic
cooperation → imitation → ToM →
language …)?
-
Selection for a
mechanism evaluating the suitability of individual vs
social learning? Origins of cognitive flexibility/domain-general abilities?
Literature
Richerson P. J. and Boyd R. (2005), Not by Genes
Alone: How Culture Transformed Human
Evolution,
Tooby J. and Cosmides L.
(1992), ‘The Psychological Foundations of Culture’, in Barkow
J.
H, Cosmides L., and Tooby J
(Ed), The Adapted Mind: Evolutionary Psychology and the
Generation of Culture, Oxford University Press, New York, pp. 19-136.
Enrich J. and McElreath R. (2003), ‘The Evolution of
Cultural Evolution’, in Evolutionary
Anthropology 12, pp. 123-135.
http://www.psych.ubc.ca/~henrich/Website/Papers/Henrich%20McElreathCultural%20Evo.pdf
pp.819-831.
http://www.anthro.utah.edu/~rogers/pubs/Rogers-AA-90-819.pdf
Laland N. L. & Brown G. R. (2002), Sense
and Nonsense. Evolutionary perspectives on human behaviour, Oxford
UP, chapters 6,7.
Boyer P. (2001), Religion explained, Vintage,
Fracchia J. and Lewontin R.C.
(1999), ‘Does Culture Evolve?’, in Conceptual Issues in Evolutionary Biology,
MIT Press,