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The Development of Children
Sixth Edition
Cynthia Lightfoot
Michael Cole
Sheila R. Cole
Part I: In the Beginning
Chapter 2:
Biocultural Foundations
PSYC 206
Lifespan Development
Bilge Yagmurlu
I. Inheriting Culture
• Culture:
– The use of material and
symbolic tools that
accumulate over time,
are passed on through
social processes, and
provide resources for
the developing child.
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The Tools of Culture
• Material tools:
– Includes physical
manufactured
objects and
observable
patterns of
behavior
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Tools of Culture
• Symbolic tools:
– More abstract, including systems of
knowledge, beliefs, and values.
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Process of Cultural Inheritance
Culture is inherited through social processes
Use of culture’s tools
– Social enhancement: most basic way of social
learning.
– Imitation
– Explicit instruction
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Process of Cultural Inheritance
Culture is inherited through social processes.
Use of symbolic communication
•
•
Unique to humans
Learning about things not immediately present
and about abstractions
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Complexity of Culture
• Cumulative Cultural Evolution
– Cultures continue to evolve because they are
complex, with individuals producing variations in
the material and symbolic cultural tools they use.
• Examples of Variations in tool usage
– Material Tools
– Symbolic Tools
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Biological Evolution
• Heredity
– Transmission of biological characteristics
from one generation to the next
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Biological Evolution
• Genes:
– Contains instructions that guide the formation of
the individual’s traits
• Genotype:
– The exact genetic makeup
• Phenotype:
– The observable trait, behavior, and psychological
traits
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Natural Selection
The process whereby individuals with
phenotypes well adapted to the local
environment survive and reproduce to a
greater extent than individuals with less welladapted phenotypes, preferentially passing
on the genotypes associated with the betteradapted phenotypes.
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Natural Selection
Examples: Genotypic variations contribute
to phenotypic contributions
- Genotypes favoring shorter pregnancies
evolved as part of changes related to
bipedalism, larger brain and skull size.
- Baby-talk
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Heritability
The proportion of phenotypic (observed)
variance in a given population that is due to
genetic variance.
H of 20 = 20% GV and 80% Environmental
Example: Individual differences in drinking habits show
evidence of heritability
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Plasticity of the Trait
• Phenotypic plasticity
– The degree to which the phenotype is open to
influence by the environment, rather than by
genotype.
• Traits with high plasticity
• Traits with little plasticity
• Example: intellectual skills vs. eye color
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Plasticity of the Trait
• Phenotypic canalization
– A trait is called “canalized” when it follows a strictly
defined path, regardless of most environmental and
genetic variations.
Example: language acquisition
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Plasticity of the Trait
• Phenotypic canalization
– “auto-regulatory mechanism”
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Heritability
• Assessed through kinship studies: Behavioral
Genetics Methods
• Family Studies
• Twin Studies
• Adoption Studies
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Genetic Inheritance
• Chromosome
– Ovum contains 23
– Sperm contains 23
– Zygote contains 46 or 23 pairs
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Genetic Inheritance
Chromosomes containing
DNA (deoxyribonucleic
acid) are situated in the
nucleus of a cell.
Genes are functional units
of heredity which are
composed of DNA.
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Human Genome Project
• Genome is the set of complete instructions for making
an organism, containing all the genes in that organism
• Completed in 2003, the HGP was a 13-year project
coordinated by the U.S. with contributions from UK,
Japan, France, Germany, China, etc.
Some goals:
• identify all the approximately 20,000-25,000 genes in
human DNA
• transfer related technologies to the private sector
• address the ethical, legal, and social issues (ELSI)
that may arise
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Heritability
• Assessed through kinship studies:
– Family Studies: Studies that correlate degree of
genetic overlap among family members with degree
of similarity in developmental outcomes
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Heritability
Family Studies
– Example: a disorder might be described as “running in a
family” if more than one person in the family has the
condition
– Example: “Anxiety disorders run in families”:
– role of inheritance and environment
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Heritability: Twin Studies
Identical
twins
Same
sex only
Fraternal
twins
Same or
opposite sex
• Identical Twins
 develop from a single
fertilized egg that splits in
two, creating two
genetically identical
organisms
• Fraternal Twins
 develop from separate
eggs
 genetically no closer than
brothers and sisters
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Heritability
Twin Studies:
 Monozygotic Twins (100% shared genes)

Dizygotic Twins (50% shared genes)
If identical twins are more alike than fraternal twins,
then the increased similarity can be due to genetic
influences
 Relies on the “equal environments assumption”
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Heritability
Twin Studies:
Equal environments assumption
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• Phenomena of Niche Construction:
– Refers to how behaviors, activities, and
choices of individuals actively shape and
modify the environment in which they live
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Heritability
Adoption Studies:
Examine the correlations between adopted children
and their adoptive parents, or adopted children and
their genetic parents
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Adopted / Separated Twins
• Investigators have also studied identical
twins who were separated early in life
and reared apart.
– Any similarities in traits between them
should be primarily genetic and should
permit a direct estimate of heritability.
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III. The Coevolution of Culture and Biology
• Coevolution:
– the process that emerges from the interaction of
biological evolution and cultural evolution.
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III. The Coevolution of Culture and Biology
Example
The skeletal structure of humans and other primates
are highly similar. But there are two main
differences that might have caused early humans to
develop high technology:
1) bipedalism
2) using thumb in opposition with the other four
fingers
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Apply – Connect - Discuss
• In human beings, language is a highly
canalized trait, whereas intelligence appears
to have greater plasticity. Why does this
make
sense
from
an
evolutionary
standpoint?
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