lecture 3
Evolutionary Theory
Introduction to Evolution and Development
Focus on evolutionary and genetics as main theories in child development.
The importance of evolutionary theory in understanding child development:
Theodosius Dobzhansky's famous quote: "Nothing in biology makes sense except in the light of evolutionary theory."
Evolutionary theory is crucial for explaining the behavior and diversity of living organisms, including humans.
Significant contributions from child psychologists and theorists with biological backgrounds:
Jean Piaget: initially studied animals.
B.F. Skinner: worked with animals in behavioral studies.
Harry Harlow: studied attachment in monkeys.
The Concept of Evolution
Definition: evolution is a theory that explains the diversity and functionality of all living organisms but does not address the origins of life.
Comparable to a force like gravity that operates once life exists.
Debates about the validity of evolution; however, the evidence supporting it is overwhelming and consistent with biological observations for over 200 years.
Factual evidence includes fossils, experimental studies, and genetic analysis supporting evolution.
Statistical confidence in evolution's truth is about 99.999…%.
Darwin's Contribution to Evolutionary Theory
Evolution is primarily associated with Charles Darwin, who articulated the concepts of natural and sexual selection.
Contrast with earlier evolutionary theories:
Lamarckianism: suggests traits acquired during a lifetime (e.g., muscle gain from exercise) can be passed to offspring (incorrect).
Importance of natural selection and sexual selection explained:
Natural selection: survival and reproduction.
Sexual selection: traits for attracting mates (e.g., peacock tails)
Key ideas about evolutionary biology and individual traits versus genetic predispositions, including gendered traits like facial hair in males.
Mechanisms of Natural Selection
Five steps of natural selection:
More offspring are produced than can survive.
Offspring exhibit variation in inherited traits.
Some traits increase the likelihood of reproduction (differential reproductive success).
Environmental changes can impact species, leading to new adaptations over generations (e.g., polar bears adapting to climate change).
The ultimate biological meaning of life: organisms exist to pass on genes, highlighting the role of survival and reproduction.
Common fallacies about evolution:
Survival of the fittest is often misinterpreted (fitness in evolutionary context relates to reproduction, not physical strength).
The belief that evolution promotes happiness and stability across species.
A misunderstanding that evolution is directed towards complexity.
Examples of Evolutionary Concepts
Cicadas: emerge in large numbers, mate, and die, illustrating reproductive strategy over individual fitness.
Discussion of variations in reproductive success through hypothetical scenarios comparing individuals focused on fitness versus reproduction.
Personal anecdotes encourage understanding biological fitness instead of gym fitness (importance of passing on genes).
Misconceptions about Evolution
Evolution does not aim to produce the strongest or complex individuals.
#1 Misconception: Survival of the fittest equates to physical strength.
#2 Misconception: Evolution promotes species stability or welfare.
#3 Misconception: Evolution has a predetermined direction.
Evolution's Role in Child Development
Evolutionary Psychology:
Influenced by researchers like Tobi and Cosmides, along with John Bowlby:
Specialized adaptations in human brain function (domain-specific adaptations) to tackle historical problems.
Example: universal preference for sugars in children due to past scarcity of calories.
Childhood as an Evolutionary Adaptation:
Childhood traits (curiosity, dependency) enhance survival and gene passing in adult life.
The extended childhood is an adaptation, supporting development and learning.
Children should not be viewed as broken adults, but as beings adapted for learning and survival.
Nature vs. Nurture Debate
Modern understanding emphasizes that it is both nature and nurture.
Key elements in development:
Genotype: genetic makeup.
Phenotype: observable traits influenced by genes and environment.
Environment: external conditions impacting expression.
Influence can go both ways (e.g., child's behavior can affect parental response).
Genetics and Development
Overview of Genetics:
Genetics focuses on DNA (deoxyribonucleic acid) and chromosomes.
Human total: 46 chromosomes or 23 pairs.
Gene function: sequences of DNA coding for proteins essential for bodily functions.
Genetic Expression
Process of how DNA translates into proteins involves messenger RNA (mRNA).
Changes to recipes can occur through mutations during copying of genes.
Inheritance of traits and alleles (dominant vs recessive).
Genetic Pitfalls and Understanding
Common Genetic Disorders:
Color blindness (sex-linked recessive), hemophilia, sickle cell anemia (provides malaria resistance in heterozygotes), cystic fibrosis (northern European context).
Impact of environment on gene expression and interactions leading to disorders.
Polygenic Traits:
Most behaviors and traits (e.g., intelligence, aggression) are influenced by multiple genes.
Example: PKU (phenylketonuria) showcases gene-environment interaction—diet can mitigate genetic effects.
Summary of Development Processes
Brain development stages: proliferating neurons, migration, synaptogenesis, apoptosis, and synaptic rearrangement.
Plasticity: Ability of the brain to adapt based on experience, maintaining flexibility over time but becoming more specialized as necessary.
Evidence: Experience-dependent changes like early exposure to language impact development, enhancing future learning capabilities.
Closing Implications
Significance of evolution and genetics for shaping children's behavior.
Need for understanding complex interactions influencing child development, using a multifactorial approach.
Experience-based Learning: Importance of allowing children to explore and engage with their environment to promote healthy development.