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The Interactionist Approach
• Neither genes nor environment can do it on
their own.
• Behaviors are not either-or.
“Heritability” Reflects This
• Heritability indices show the strength of the
relationship between genotype and
phenotype
• Can also be estimated with twin studies
• Parent-offspring (adoption) studies
Heritability
• Dawkin’s gene’s-eye-view is an important
framework, but environment is easily
overlooked
• Consider niche construction
• “Cake-baking” example
Instincts
• Are newborn “instincts” a reflection of
inevitable determinism?
• Consider Imprinting
– Konrad Lorentz (1903-1989)
– Nobel Prize with Timbergen (1973)
– Ethology (naturalistic animal behavior)
Instincts
• Imprinting
• Is this instinct or learning?
• What do you learn before you’re born?
– Voices
– Flavors
– Moro Reflex
• Birth is not a magic time to spot instincts!
Motherese and Social Smiles
• Motherese: A Human Universal, but how does
it emerge?
• Social Smiling and the Myelination of the
Basal Ganglia
• The importance of the social loop (Autism)
Language Acquisition
• Is language an instinct if it doesn’t develop
without others?
• The search for a “Language Instinct” can be
informed by looking for universals.
• The modular nature of language suggests that
we are “wired for it.” (Broca’s area, Wernicke’s
area)
Life Without a Left Hemisphere
• Is the brain “modular” or “plastic?”
– Modular = deterministic
– Plastic = flexible
• Hemispherectomy
• Neuroplasticity