Week 3 Flashcards
nature nurture debate
the influence of genetics and environment have on human development
why is it difficult to answer the nature-nurture debate
With humans, we can’t assign babies to parents at random, or select parents with certain behavioural characteristics to mate merely in the interest of science. In typical human families, children’s biological parents raise them, so it is very difficult to know whether children act like their parents due to genetics or environmental reasons
behavioural genetics
the empirical science of how genes and environments combine to generate behaviour
Easiest opportunity to observe behavioural genetics
adoption study
Adoption study
A behaviour genetic research method that involves comparison of the similarity of identical and fraternal twins
Monozygotic twins
Also called “identical” twins. Result from a single zygote and have the same DNA
Dizygotic twins
Also known as “fraternal” twins. Developed from two zygotes and share 50% of their DNA
nature nurture studies
We can do these studies on siblings and half siblings, cousins, twins who have been separated at birth and raised separately, or with entire extended families
Contentions about nature-nurture
Intensified because quantitative genetics produces a number called a heritability coefficient, varying from 0 to 1, that is meant to provide a single measure of genetics’ influence on a trait
Heritability coefficient
An easily misinterpreted statistical construct that purports to measure the role of genetics in the explanation of differences among individuals
Quantitative genetics
Developed in the 1920’s; DNA was discovered by Watson and Crick in the 1950s; the human genone was completely sequenced at the turn of the 21st century
What have we leanred about nature-nurture
The more genetically-related people are, the more similar they are for everything. Genetic influence on behaviour is a relatively recent study. The best predictors of an adopted child’rs personality or mental health are found in the biological parents he or she has never met, rather than in the adoptive parents who raised them. No behavioural traits are completely inherited, so you can’t leave environment or genes out alltogeher
Outcome of the nature nurture debate
Everything has turned out to be at least somewhat heritable, yet nothing has turned out to be absolutely heritable, and there hasn’t been much consistency as to which traits are more heritable and which are less heritable once other considerations are taken into account
Heritability of a trait
not simply a property of that trait, but a property of the trait in a particular context of relevant genes and environmental factors
Issue with the heritability coefficient
it divides traits’ determinants into two portions-genes and environment-which are then calculated together for the total variability
The way genes integrate
is complex. For many traits, genetic differences affect behaviour under some environmental circumstances but not others-a. phenomenon called gene-environmental interaction, or GxE
Effects of a behavioural trait
for most behavioural traits, the effects are so small and distributed across so many genes that we have not been able to catalog them in a meaningful way
one of the most important things modern genetics has taught us
Almost all human behaviour is complex to be nailed down even from the most complete genetic information, unless we’re looking at identical twins. The science of nature and nurture has demonstrated that genetic differences among people are vital to human moral equality, freedom, and self-determination, not opposed to them
Evolution
Change over time
Why do certain traits and behaviours develop over time
they are advantageous to our survival
when is physical survival important
only if it eventually contributes to successful reproduction
Reproductive success
the engine of evolution by natural selection
natural selection
Differential reproductive success as a consequence of differences in heritable attributes. In order for our genes to endure over time, we have inherited adaptive, psychological processes designed to ensure success
Adaptions
evolved solutions that historically contributed to reproductive success
First class of adaptions
Called survival adaptions
Survival adaptions
mechanisms that helped our ancestors handle the “hostile forces of nature”. For physical survival
Second class of adaptions
described in an evolutionary theory proposed by Charles Darwin, called sexual selection theory
sexual selection theory
the evolution of characteristics because of the mating advantage they give organisms
Intrasexual selection
a process of sexual selection by which members of one sex compete with each other, and the victors gain preferential mating access to members of the opposite sex. Whatever qualities lead to success in intrasexual competition are then passed on with greater frequency due to their association with greater mating success
Intersexual selection
A process of sexual selection by which evolution occurs as a consequence of the mate preferences of one sex exerting selection pressure on members of the opposite sex
Gene selection theory
Genes that are better able to encourage the organism to reproduce, and thus replicate themselves in the organism’s offspring, have an advantage over competing genes that are less able. Genes can influence the odds for survival and reproduction of the organism they are in
gene relatives
Genes can influence the organism to help other organisms who also likely contain those genes to survive ane reproduce
Evolutionary psychology
focuses primarily on psychological adaptions. Fundamentally an interactionist framework, or a theory that takes into account multiple factors when determining the outcome
psychological adaptions
mechanisms of the mind that have evolved to solve specific problems of survival or reproduction. Adaptions that occur in the body as a consequence of one’s environment
Physiological adaptions
mechanisms of the mind that evolved to solve specific problems of survival or reproduction; conceptualized as information processing devices. Developments or changes of a mechanism in the mind
how does culture have a major effect on psychological adaptions
Status within one’s group is important in all cultures for achieving reproductive success, because higher status makes someone more attractive to mates. Cultural norms that advise against premarital sex presuade people to ignore their own basic interests because they know that virginity will make them more attractive marriage partners
Sexual strategies theory
based on sexual selection theory. Proposes that humans have evolved a list of different mating strategies, both short term and long term, that vary depending on culture, social context, parental influence, and personal mate value. Focuses on the differences between men and women in mating preferences and strategies. Predicts specific similarities and differences in. men and women’s mating preferences and strategies
Error management theory
Deals with the evolution of how we think, make decisions, and evalute uncertain situations-where there’s no clear answer to how we should behave. General evolutionary psychological theory that can be applied to many different domains of our lives
Visual descent illusion
States that people will overestimate the distance when looking down from a height so that people will be especially wary of falling from great heights
Auditory looming bias
People overestimate how close objects are when the sound is moving toward them compared tow hen it is moving away from them
What can EMT predict
adaptive biases in the domain of mating, that men have a sexual over perception bias
Social exchange theory
predicts our modern day behaviour and preferences
Heteronormativity
the idea that all people are or should be heterosexual. Involves the structures and beliefs that support that macro: marriage, micro: assuming that two women having dinner are simply friends rather than a couple
Epigenetics
The study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence. Epigentic marks include covalent DNA modifications and posttranslational histone modifications
Phenotype
the pattern of expression of the genotype or the magnitude or the extent to which it is observably expressed-an observable characteristic or trait of an organism, such as its morphology, development, biochemical or physiological
Epigenome
The genome-wide distribution of epigenetic marks
Environmental factors and epigenetics
Recent studies have provided insights into epigenetic regulation of development pathways in response to a range of external environmental factors. These environmental factors during early childhood and adolescence can cause changes in expression of genes conferring risk of mental health and chronic physical conditions
Nucleosome
The combination of DNA and histone proteins. Represents a structural solution for maintaining and accessing the tightly compacted genome.
Chromatin structure
a structural solution for maintaining and accessing the tightly compacted genome. These factors alter the likelihood that a gene will be expressed or silenced. Cellular functions such as gene expression, DNA replication, and the generation of specific cell types are therefore influenced by distinct patters of chromatin structure, involving covalent modification of both histones
Epigenetic variation
emerges across the lifespan. Although identical twins share a common genotype and are genetically identical and epigenetically similar when they are young, as they age they become more dissimilar in their epigenetic patterns and often display behavioural personality, or even physical differences, and have different risk levels for serious illness
DNA methylation
a chemical process that adds methyl groups to DNA, which can alter gene expression and affect a person’s risk of disease
Methylation of DNA in gene regulatory regions
Usually results in gene silencing and reduced gene expression. May broadly impact human brain development
Histone modification
a process that chemically alters histone proteins to regulate gene expression and chromatin structure
Histone acetyltransferase
Enzymes that transfer acetyl groups to specific positions on histone tails, promoting an “open” chromatin state and transcriptional activation
Histone decetyalases
Remove acetyl groups, resulting in a “closed” chromatin state and transcriptional repression
Mothers that exhibit increased levels of pup licking and grooming over the first week of life
Increased expression of the glucocorticoid receptor in the hippocampus (associated with stress responsivity and learning and memory)
Rat pups that received low levels of maternal licking and grooming during the first week of life
decreased histone acetylation and increased DNA methylation of a neuron-specific promoter of the glucocorticoid receptor gene. Expression of this gene is then reduced the number of glucocorticoid receptors in the brain is decreased, and the animals show a higher hormonal response to stress throughout their life
Effects of maternal care on stress hormone responses and behaviour in the offspring can be eliminated through
A pharmacological treatment, a dietary amino acid supplementation, treatments that influence histone acetylation, DNA methylation, and expression of the glucocorticoid receptor gene
How does the food you eat reflect your own personal development and risk for disease
nutrients can reverse or change DNA methylation and histone modifications, thereby modifying the expression of critical genes associated with physiologic and pathologic processes, including embryonic development, aging, and carcinogenics. Can influence the epigenone either by directly inhibiting enzymes that catalyze DNA methylation or histone modifications, or by altering the availability of substrates necessary for those enzymatic reactions
Epigenetic mechanisms influence genomic activities in the brain to
Produce long-term changes in synaptic signalling, organization, and morphology, which in turn support learning and memory
Changes in histone modifications
Can influence long-term memory formation by altering chromatin accessibility and the expression of genes relevant to learning and memory
Neuronal increase in histone deacetylase activity
Promotes gene silencing, results in reduced synaptic plasticity and impairs memory
misregulation of epigenetic modifications and their regulatory enzymes
capable of orchestrating prominent deficits in neuronal plasticity and cognitive function
Epigenetic events that alter chromatin structure to regulate programs of gene expression
Associated with depression-related behaviour and action of anti-depressant medications, with increasing evidence for similar mechanisms occurring in post-mortem brains of depressed individuals
Chronic social stress
found to decrease expression of genes implicated in normal emotion processing
The links between early environment and epigenetic modifications suggest
a mechanism underlying gene-environment and epigenetic modifications suggest a mechanism underlying gene-environment interactions
