Human genetic variation

Question 1

Selecting human participants and recording demographics for research

Answer 1

Biological categories:
1. age, developmental stage, reproductive stage
2. health, ability, addiction, physiological state
3. sex, gender, sexual orientation
4. race and ethnicity
Not biological:
1. occupation, leadership, work status
2. socio-economic status, immigration status
3. education, family
4. political views, religion

Question 2

reproductive binary and sex chromosomes

Answer 2

1. reproductive binary - XX and XY define sex at birth
2. traditionally, a deterministic view of sexual differentiation in humans is with reproductive binary, and this categorisation of participants can cause challenges and bias in research and knowledge
3. sex chromosome anomalies have various symptoms - klinefelter (XXY) syndrome and triple X syndrome, turner syndrome (no X or part of X missing)
4. intersex individuals -mild to severe anomalies in the development of organs in newborns
5. environmental variations - during development and adult life, many social/physical/pre birth physiological environmental factors, shaping gender identity, sexual preferences and behvaiours not captured by reproductive binary

Question 3

reproductive binary and intelligence

Answer 3

biological:
1. IQ tests devised over 100 years ago and are repeatedly revised
2. high statistical reliability but limited validity
3. subjects can increase IQ scores with training on test tasks
4. alternative theories - dynamic assessment testing proximal development of children, multiple intelligence theory
5. IQ studies select a range of tasks, correlate scores to calculate G factor that is then correlated with reproductive binary
6. infers that such correlations reflect differences in biological mechanisms that underpin cognition and brain function
7. gender similarity hypothesis - despite considerable biological differences, the brains, psychological traits and behaviour are also very similar between men and women
8. meta analyses and effect sizes show that environment, parent education and school type explain most of the variance in attainment between boys and girls

Question 4

how we conduct studies is influenced by research norms and biases

Answer 4

Categories of participants:
1. IV in planned comparisons
2. DV in multivariate analysis, structural equation modelling, path analysis
3. demographic information to check for biases in selection of subjects, contextualisation of findings or post-hoc comparisons
4. contemporary ethics guidelines and research norms impose that consent from participants is obtained for collecting, storing, sharing and analysing their personal data

Question 5

why decolonise psychology

Answer 5

1. most of mainstream psychology uses WEIRD population - inability to create world-view understanding of human behaviour
2. BAME and female underrepresentation means minority groups cannot identify
3. subcultural areas not represented can lead to discrimination

Question 6

from traits and biometry to PCR and genomics

Answer 6

1. 1980-21st century - PCR test invented, age of genomics
2. 20th century - quantitative genetics, emergence of molecular genetics
3. 19th century - theory of evolution, Mendel

Question 7

mystery of shrinking body heights during industrial revolution

Answer 7

1. downward phase started in 1830
2. discovery of previously known cyclic changes in human body height in Europe and N. America
3. despite growing economies, body sizes were shrinking
4. shortage of workers as labour itensified resulted in economic incentives for research that investigated the biological causes of height variations, such as inheritance, nutritionq

Question 8

quantitative genetics - measuring correlations

Answer 8

1. measuring the body and perceived differences amongst human beings
2. anthropometry - measuring variations in body, head, face
3. correlation with racial categories, intelligence, behavioural and psychological traits
4. human body height is highly heritable trait, genomic research reveals the high complexity of genetic interactions and roles of biologically relevant genes and non coding DNA

Question 9

heritability of human behaviour: use and misuse of pedigrees

Answer 9

1. broad population surveys and case studies show trace differences in mental, emotional, personality and behavioural traits through IQ tests, genealogy or statistical surveys of mental and other illness
2. Francis Galton coined the term eugenics, concluded from studying pedigrees of rich families in Britain that superior intelligence and abilities are heritable

Question 10

Misconceptions and politicisation of Darwin’s theory of evolution

Answer 10

1. misplaced morality and social darwinism - wrong in claiming that evolution is survival of the fittest
2. Darwin’s theory of evolution explains the diversity of species on earth and how species with differences in traits and adaptations appear and disappear over evolutionary time scales
3. misinterpretation when equalling evolutionary selection with selective breeding
4. evolutionary selection is goal oriented, does not optimise traits and results in progress, does not remove variation or prevent individua;s from reproducting

Question 11

eugenics and scientific racism

Answer 11

1. scientific racism has its roots in eugenics
2. nazi germany - forced sterilisation, ethnic cleansing
3. deep impact on society of 20th and until now
4. crimes against humanity and genocide deploy simplified wrong claims about natural selection and biological superiority in particular groups or types of humans
5. rise of pseudoscience - seemingly objective justification for colonisation, slavery and social policies that control and limit life, opportunities and rights of humans considered inferior

Question 12

long lasting impact of half a century of eugenics and race science

Answer 12

1. already from the early 20th century there is opposition to eugenics and race science amongst scientists and society - disputing theory and methods
2. numbers and visibility of opponents amongst scientists started to increase after 1925 but eugenics ideas persisted widely in society
3. supremacy ideas persist to date, and some scientist claim to show modern evidence

Question 13

what’s in the genome

Answer 13

2% genes, 98% non coding DNA which is still functionally important as it contributes to complex genetic architectures in which genes are embedded

Question 14

genome is all of the DNA that is present in each cell of the body

Answer 14

1. gene architectures
2. polymorphisms and mutations in the genome
3. non coding dna
4. physical and social environment
5. somatic cells - gene environment interactions, determine all body and cell functions in every moment of an individual’s life
6. germline cells - reproduction and inheritance of traits, gene environment interactions influence the development of an individual’s offspring

Question 15

gene environment interactions

Answer 15

1. fallacy of nature-nurture dichotomies: activity of a gene cannot be separated from its environment
2. the nature nurture debate is now considered to be a “conceptually deficient and biologically implausible dichotomy that oversimplifies the dynamics of behaviour and development”

Question 16

measuring genetic variation

Answer 16

1. biometry and quantitative genetics measure observable traits in the whole organisms
2. genomics searches all DNA for markers at many hundreds genetic loci in chromosomes and mitochondria, including genes and non-coding dna
3. markers - short dna sequences, repeated sequences in dna sequences, single base pairs of the dna sequence that are sites of single nucleotide polymorphisms
4. now cheap to extract genomic sequences but complicated to analyse

Question 17

causes of genetic variation in humans and animals

Answer 17

1. across life parental dna changes spontaneously in any cells that can affect parent and their offspring
2. different environmental conditions, diseases across lifetime also causes mutations in parental dna
3. dna in germline cells is typically recombined during egg and sperm production
   Causes of variation within and between populations:
4. multiple variants occur in different frequencies within and between populations
5. genetic admixture between populations change the distribution of alleles and polymorphisms in a population over time

Question 18

race is real, but social construct

Answer 18

1. race is not a biological category
2. it is scientifically evidenced that concepts of so though biologically distinct human races are obsolete
3. genomics research showed that using the term race in relationship to human genetic variation is dangerous as it easily misleads
4. race constructs were historically used to establish social hierarchies

Question 19

human genome project 1984-2004

Answer 19

1. international, collaborative research that aimed to completely map all the genes of human beings
2. ethical concerns - indigenous populations societally most disadvantaged but stand the least to benefit from resulting novel scientific discoveries and healthcare improvements

Question 20

race as a mechanism of discrimination and social segregation

Answer 20

1. first appearance of term race in english language in late 16th century
2. pseudoscientific biological concepts cemented social barriers after abolition of slavery in the 19th century: inter ethnic mixture was considered medically pathological and unnatural

Question 21

small differences in traits, yet complex inheritance

Answer 21

1. modern genomics show that most human trait variations are polygenic
2. skin is visible, human skin colour is highly variable and complex trait
3. complex tangled relationship between genes determining polygenic inheritance, some genes have several alleles
4. 15 genes regulate the amount of melanin in the melanocytes of the skin

Question 22

evidence from mitochondrial dna: human migration in and out of Africa

Answer 22

1. early and modern human species dispersed and migrated overcoming geographical isolation
2. there are no physiological reproductive barriers that prevent admixture in homosapiens
3. mixed diet, cognitive functions and cultural innovations enabled modern humans to survive in many different environments

Question 23

only few human local genetic adaptations in geographic clusters

Answer 23

1. when humans within a geographical region are sufficiently isolated and had more frequent contact and admixture than with distant populations

Question 24

understanding human genetic variation for better health and aging

Answer 24

1. migration exposes groups of humans to new diseases and parasites, in addition to environmental challenges
2. understanding genetic variation and epigenetic processes under different environmental conditions and with different genetic admixtures in human populations can help to explain patterns of susceptibility to human pathologies and to identify risks
3. health conditions impact on capacity of individuals to respond to health threats that arise from fastly evolving microorganisms and viruses

Question 25

genotyping - genome wide association studies

Answer 25

1. complex analysis of SNP data identifies with GWAS variants that are highly associated with disease or disease risks 2. ethical challenges in research and applications - which parts of population are represented, which traits are defined as healthy, prediction errors, risks 3. benefits - relies on huge number of single nucleotides which are the smallest possible changes in dna sequence, looks at whole genome of many individuals, associations with polygenic traits more likely to be uncovered to understand variation and for applications in health and social care 4. limitations - requires fully sequenced genomes of hundreds to thousands of individuals and their relatives, hundreds and thousands of loci means chance of detecting associations that don't really matter