Chapter 3: Genes, Environment and Behaviour Flashcards
What is the IMPLICIT MODEL? (3 major points)
- There are genes that cause a particular brain structure of function, which causes us to behave in a particular way
- Actions can be genetically predetermined.
- This effects how we treat people: Jail or Hospital (the brain problem nullifies the responsibility for the action)
GENETIC INFLUENCE ON BEHAVIOUR: who conducted experiments in 1860s on heredity?
Gregor Mendel (1860s) conducted experiments on heredity
Describe Genotype vs Phenotype:
- Genotype: the specific genetic makeup of an individual present from conception
- Phenotype: the individual’s observable characteristics can be affected by both genes and by the environment
- Genotype and phenotype are not identical because some genes are dominant and some are recessive
• Dominant and displayed: gene received from both mother and father
• Recessive and not displayed: gene received from only one parent
o E.g. brown eyes dominant over blue eyes
Describe Chromosomes vs Genes vs Alleles
- Chromosomes: double-‐stranded and tightly coiled molecule of deoxyribonucleic acid (DNA)
- Genes: biological units of heredity
- Alleles: alternative forms of a gene that produce different characteristics
Define Polygenic Transmission
• Polygenic transmission: a number of gene types combine their influence to create a single phenotype
Explain Nucleotide Bases: DNA: Gene: PROTEINS, No.s
• 1. All information of heredity is encoded in the combinations of four chemical bases – adenine, thymine, guanine and cytosine
– that occur throughout the chromosome
- The sequence of the four letters A, T, G, and C creates specific commands for every feature and function of your body.
- The DNA portion of the chromosome carries the genes, the biological units of heredity
- Each gene carries the ATGC codes for manufacturing specific proteins, as well as when and where in the body they will be made
- These proteins can take many forms and functions, and underlie every bodily structure and process
• 6. With one exception, every cell with a nucleus in the human body has 46 chromosomes.
o Exception is the sex cell (egg or sperm) which has only 23
o At conception 23 from the egg combine with the 23 from the sperm to form a zygote, containing 46 chromosomes
Define Behaviour Genetics
• Behaviour Genetics: How heredity, environmental and social factors influence psychological characteristics
o Also studies how these factors account for individual differences in behaviour
Explain the Basic Probabilities of GENETIC SHARING
• Basic probabilities of genetic sharing:
o You sharing a particular gene with one parent: 0.5
With one grandparent: 0.25
o You sharing the same gene with a sibling: 0.5
With a half-‐sibling: 0.25
o Identical twins have 1 probability of sharing a particular gene
Explain Family Studies:
• Family studies: researchers study relatives to determine if the genetic similarity is related to similarity in a particular trait
o Genetic contribution indicated by the similarity between those closely related
Explain Adoption Studies:
• Adoption studies: people who were adopted early in life are compared on some characteristic with both their biological parents, with whom they share genetic endowment, and with their adoptive parents, with whom they share no genes.
o If adoptive people are more similar to biological parent than adoptive parent, indicates a genetic influence on that trait. Inversely, this indicates environmental factors to be more important for that particular characteristic
Explain Twin Studies:
• Twin studies: compare trait similarities in identical and fraternal twins
o Monozygotic/identical twins are genetically identical twins – (1 in 250 births):
One sperm and egg; Zygote divides; Two zygotes with identical chromosomes
o Dizygotic twins (Fraternal twins-‐ 1 in 150 births):
share 50% genetic endowment like ordinary siblings
Two eggs and two sperms, two zygotes with different chromosomes
o Comparing the two twin types can determine whether genes or the environment determine behaviour – but this is hard to do as both types of twins are usually raised in the same environment anyway
o Separate rearing compared to rearing together shows both genes and the environment influence behaviour
Define HERITABILITY COEFFICIENT:
• Heritability coefficient: estimates the extent to which the differences or variation in a specific phenotypic characteristic within a group of people can be attributed to their differing genes.
What is Concordance rates?
• Concordance rates: trait similarity
What is Learning?
• Learning: is a process of personal adaptation
What Behaviourisim?
• Behaviorism: laws of learning that apply to virtually all organisms
Organism is initially a ‘blank slate’
What is ETHOLOGY?
Adaptive significance vs. Fixed action pattern
• Ethology: evolutional differences between species
Adaptive significance: behaviour influences chances of survival and reproduction
Fixed action pattern: instinctive behaviour automatically triggered by a particular stimulus
Explain FUNCTIONS OF BEHAVIOUR
• Functions of behaviour: adaptive significance – how behaviour influences an organism’s chances of survival and reproduction in its natural environment
Explain FIXED ACTION PATTERNS
• Fixed action patterns: an unlearned response automatically triggered by a particular stimulus
o Modified by experience
o In many cases what appears to be instinctive behaviour actually involves learning
Explain how the Environment shapes behaviour in two fundamental ways:
• Environment shapes behaviour in two fundamental ways:
- Species adaptation: influence from environment through natural selection
- Personal adaptation: our interactions with immediate and past environments
Explain SHARED vs UNSHARED enviroments
- SHARED environments: people who also reside in the environment experience many of their features in common (e.g. family)
- UNSHARED experiences that are unique to us (e.g. an individual member outside of family)
- To examine the influence of these two environments, twin studies are ideal
Explain HERITABILITY OF INTELLIGENCE:
- Intelligence has a strong genetic basis, with heritability coefficients in the 0.5-‐0.7 range. Shared family environment is also important, as are educational experiences
- Personality has strong genetic contribution, though a lower heritability coefficient than intelligence. Shared family environment is secondary to unshared family environment as an environmental determinant of personality
- Identical twins reared together have a high correlation of IQ scores (0.86)
- If you rear them separately the correlation drops down slightly (0.75)
- Siblings reared together (0.45)
- Siblings reared apart (0.21)
- Relates to Watson and behaviourism: he said he could rear any infant to become any profession, he failed to account for genetic similarity
- Heritability of intelligence: more common genes= more similarity in IQ scores
Explain ENVIROMENTAL DETERMINANTS of intelligence heritability.
• Heritability of intelligence: more common genes= more similarity in IQ scores
• Environmental determinants:
→ Shared family environment
→ Environmental enrichment and deprivation
→ Educational experiences
• •Heritability allows us to explain the variations between genes and people
GENE-ENVIROMENT INTERACTION: Genetic, enviromental and social factors interact (2)
• Genetic, environmental and social factors interact
Genetic factors influence how different people experience the same environment
The environment can influence how genes express themselves
How can genetic factors influence the enviroment in 3 ways.
• Genetic factors can influence the environment in 3 ways:
- Genes shared by parents and children may be expressed in how the parents behave and in the environment they create
- Genes may produce characteristics that influence how others respond to the person
- People self-‐select or create environments that are consistent with their genetic characteristics e.g. intelligent person seeks out intellectually stimulating situations
