biological approach: the relationship between genetics and behaviour Flashcards

1
Q

gene

A
  • the basic unit of heredity in a living organism
  • holds the information to build and maintain their cells and pass genetic traits to offspring
  • represents a segment of DNA, is located at a specific point on an organism’s chromosome
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2
Q

genotype

A

refers to all the genetic information held within the organism’s DNA

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3
Q

phenotype

A

the expression of the genotype, the observable physical and behavioural traits e.g. hair colour, physique, abilities, hormone levels
→ phenotype is also influenced by environmental factors e.g. geographical location, upbringing, education → this explains why monozygotic twins (identical) don’t have identical personalities/ abilities

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4
Q

alleles

A
  • different versions of the same gene e.g. allele for blue eyes, allele for brown eyes
  • Each allele in a pair is inherited directly from each parent
  • Alleles create diversity
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5
Q

what is the theory that is preferred over the idea that particular abilities or traits are governed by 1 single gene

A

seems that people inherit specific vulnerabilities or sensitivities which predispose them to certain conditions e.g. depression

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6
Q

monozygotic twins

A
  • identical
  • develop from one fertilised egg which splits and forms two embryos
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7
Q

dizygotic twins

A
  • fraternal
  • develop from two different fertilised eggs
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8
Q

concordance rate

A

the probability that the same trait will be present in both members of a pair of twins

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9
Q

adoption studies

A
  • Researcher investigate similarities between the adoptee and their biological & adoptive parents
  • Similarity with biological parent = potentially the result of genetic inheritance
  • Similarity with adoptive parent = more likely the result of environmental factors
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10
Q

kinship studies

A
  • Researcher traces a phenotype over several generations in a family tree
  • To determine the likelihood that a behaviour is inherited
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11
Q

twin studies

A
  • Researchers compare behavioural traits of MZ and DZ twins
  • To evaluate the degree of genetic and environmental influence on a specific trait
  • If there is a significantly higher concordance rate among identical twins, the specific trait is likely to be the result of genetic similarity.
  • If concordance rates between MZ and DZ twins are similar, the specific trait is likely to be the result of environmental factors.
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12
Q

5-HTT gene

A

plays a role in serotonin pathways that scientists believe are involved in controlling mood, emotions, aggression, sleep, anxiety

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13
Q

genetic inheritance: a biological theory of depression

A
  • Genetic inheritance is the theory that abnormal behaviour, in this case, depression, can be passed down through genes.
  • Diathesis-stress theories of depression predict that an individual’s reaction to stressful events depends on their genetic make-up.
  • If an individual has a specific genetic predisposition toward a disorder (genotype), then interaction with stressors in the environment may cause these genes to be expressed
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14
Q

study: Caspi et al (2003) AIM

A

to investigate the link between the alleles of the 5-HTT gene and depression

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15
Q

study: Caspi et al (2003) PARTICIPANTS + METHOD

A
  • He conducted the study on 847 New Zealand participants aged 26.
  • Participants were allocated to groups based on the length of the allele of their 5-HTT genes.
  • The groups were: 2 short alleles, 1 short and 1 long allele, or 2 long alleles.
  • Participants were evaluated for depression and asked to fill out a questionnaire detailing stressful life events.
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16
Q

study: Caspi et al (2003) RESULTS

A
  • more depression in response to stressful life events was reported from the participants who had the 2 short 5-HTT alleles compared to the other 2 groups.
  • the participants with 2 long alleles reported fewer depression symptoms overall.
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17
Q

study: Caspi et al (2003) CONCLUSION

A
  • there may be a relationship between short 5-HTT alleles and depression
  • Stressful life events are more likely to trigger depression in people with this genetic makeup.
  • Long 5-HTT alleles may provide protection against stress-induced depression
  • The onset of depression appears to be an interaction between environment (stressful events) and genetic make-up.
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18
Q

study: Caspi et al (2003) LINK

A
  • Caspi et al.’s (2003) study explains the effect of the 5-HTT on behaviour.
  • Participants with 2 short alleles of the gene were most at risk of developing depression after stressful life events compared to those with 2 long alleles.
  • Alleles are versions of genes, meaning that genes do affect behaviouR
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19
Q

study: Caspi et al (2003) STRENGTHS

A
  • Researchers exerted control by restricting the measurement of stressful life events in their sample as falling between the ages 21-26 → ensures a degree of consistency across the measurement – increases reliability
  • Conducting 3 separate correlational analyses means that each measure is checked by the findings of the other measures → ensures internal validity
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20
Q

study: Caspi et al (2003) WEAKNESSES

A
  • The experience and aetiology of depression is complex and may be due to a number of factors (biological and non-biological) → makes the study reductionist as it provides an overly simplistic explanation
  • Using a self-report to collect data is prone to bias (social desirability and response) → reduces the validity of the findings
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21
Q

study: Kendler et al (2006) AIM

A

to determine the role that genetics plays in major depressive disorder

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22
Q

study: Kendler et al (2006) METHOD

A
  • 42,161 twins, 15,493 complete pairs from the Swedish national twin registry
  • Twins were interviewed to determine the level of heritability of depression
  • Interviewers assessed lifetime major depression by using modified DSM-IV criteria
  • They then evaluated the twin models
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23
Q

study: Kendler et al (2006) RESULTS

A
  • Concordance rates for MDD were significantly higher in women than men
  • Correlations were significantly higher in MZ twins than in DZ twins
  • No correlation between number of years that the twins had lived together and lifetime MDD
  • Estimated heritability of MDD was 0.38, in live with previous research
  • No significant differences seen in the roles of genetic and environmental factors in MDD
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24
Q

study: Kendler et al (2006) CONCLUSION

A

Suggests that the heritability of MDD is higher in woman than in men and that some genetic risk factors for MDD are sex-specific

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25
Q

study: Kendler et al (2006) STRENGTHS

A
  • Confirms previous research, strengthening reliability
  • The very large sample size taken from a single population helps to mediate some of the concerns
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26
Q

study: Kendler et al (2006) WEAKNESSES

A
  • The study is correlational, so no cause and effect relationship can be determined. No particular genes were isolated and tested in the study.
  • Information about life-events and depressive symptoms was self-reported. Differences could arise if men are less reliable in their reporting of lifetime major depression than women.
  • The interviewers did not officially diagnose the twins and they accepted the diagnoses made by clinicians when it was reported by the interviewee; as we know, clinical diagnoses are not highly reliable and making such a diagnosis by telephone may be considered of questionable validity.
27
Q

genes and behaviour critical thinking

A
  • No behaviour is the result of a single gene - we are still learning about the role of genes and how the interact both with the environment and with each other.
  • Genetics is a reductionist approach to behaviour.
  • Many of the studies have problems with construct validity - for example, how depression was operationalised for a study; twin, adoption and family studies only study genetics indirectly - only since the HGP have we been able to study specific genes.
28
Q

study: Weissmann et al (2005) AIM

A

to investigate the potential genetic nature of Major Depressive Disorder

29
Q

study: Weissmann et al (2005) METHOD

A
  • longitudinal kinship study
  • sample of 161 grandchildren and their parents and grandparents
  • took place over a twenty year period, looking at families at high and low risk for depression
  • original sample of depressed patients (now, the grandparents) was selected from an outpatient clinic with a specialisation in the treatment of mood disorders
  • the non-depressed participants were selected from the same local community
  • the original sample of parents and children were interviewed four times during this period
  • children were evaluated by two experienced clinicians - with one being a child psychiatrist and the other a psychologist
30
Q

study: Weissmann et al (2005) RESULTS

A
  • researchers found high rates of psychiatric disorders in the grandchildren with two generations of major depression
  • children had an increased risk of any disorder if depression was observed in both the grandparents and the parents, compared to children where their parents were not depressed
  • if a parent was depressed but there was no history of depression in the grandparents, there was no significant effect of parental depression on the grandchildren
31
Q

study: Weissmann et al (2005) CONCLUSION

A
  • A family history of mental illness for 2 or more generations leads to a higher risk of psychiatric disorder
  • Strong case for genetic component as children were more likely to show symptoms of psychiatric disorders when both grandparents and parents did
32
Q

study: Weissmann et al (2005) STRENGTHS

A
  • Longitudinal- increases reliability
  • Credibility- researcher triangulation was used
  • Sample- 161 children is large
  • Prospective data, rather than solely relying on family history
33
Q

study: Weissmann et al (2005) WEAKNESSES

A
  • Correlational- no cause-and-effect
  • Reliability- more research needed
  • Although kinship studies indicate a potential genetic link to behaviour, there is no actual genotype studied
  • Association between parental MDD and child diagnosis is moderated by grandparental MDD status. The amount of time a child spent with a health grandparent may be a confounding variable
34
Q

genetic similarities critical thinking

A
  • Family studies are often based on anecdotal data - asking family members about the behaviour of other members of the family. In some cases, behaviour may be documented, but this is often not the case, so reports may be based on family stories, rather than on actual data.
  • Twin studies allow researchers to look at the effect of genetic inheritance while keeping environmental variables relatively constant.
  • Twins do not represent the general population, so the research may not be generalizable
    E.g. there may be genetic factors that lead to higher rates of twins in some women
  • Most of the twin registry databases from which samples are drawn are from the developed world. The Sri Lankan Twin registry, established in 1996, is the only existing population-based Twin Registry in a low-income country.
  • Children that know that they are adopted are not representative of the general population.
  • A large amount of adoption research focuses on the behaviour of the birth mother, rather than on the father.
  • Adoption agencies tend to use selective placement when finding homes for children, trying to place children with families who are similar in as many ways as possible to the natural parents. Consequently, the effects of genetic inheritance may be difficult to separate from the influences of the environment.
35
Q

evolution

A

refers to the change in characteristics across successive generations

36
Q

what does Darwin’s theory of natural selection argue

A

that organisms that have the most desirable/useful traits are more likely to survive and reproduce, passing on the genes which caused them to have these traits as part of Natural Selection

37
Q

what have evolutionary explanations ben used to explain

A

a range of behaviours including mating, aggression, attachment and prosocial behaviours

38
Q

sexual selection

A
  • an evolutionary explanation for mating behaviour and of partner preferences
  • it proposes that characteristics which increase reproductive success are passed on to several generations of offspring
39
Q

Evolutionary psychologists attempt to explain human mating and sexual behaviour by the theory of natural selection, what does this theory argue

A

The theory argues that for men it is all about spreading one’s DNA and for women it is all about maximising the potential for survival for her fertilised egg.

40
Q

anisogamy

A

the difference between male and female sex cells

41
Q

what does the theory of anisogamy state

A
  • that females are more choosy than males when it comes to selecting sexual partners
  • Females tend to be choosier with their mate selection as their sex cells are less abundant compared to male sex cells
42
Q

inter-sexual selection

A

refers to the mating strategy in which females strive for quality over quantity when choosing a male mating partner and are more choosy

43
Q

intra-sexual selection

A

refers to the competition between males to mate with a female. It is a strategy involving quantity over quality.

44
Q

gametes

A
  • sex cells
  • females = egg cells
  • males = sperm cells
45
Q

female sex cells are…

A

considered a ‘rare’ resource. This is because they are only produced for a certain period of their life

46
Q

male sex cells are…

A

considered a ‘plentiful and abundant’ resource

47
Q

what do men seek for in females and why

A

males tend to seek fertile females, to increase chances of offspring production
Meaning looking for:
- Youth
- Neotenous features (baby face) e.g. small nose, big eyes
- Larger hip to waist ratio
(all signs of fertility)

48
Q

what do females tend to seek in males

A

tend to seek aggressive, bigger men who can protect both them and their offspring (traits that will benefit them), and to pass on desirable traits to their offspring

49
Q

The Sexy Sons Hypothesis, by Fisher (1930)

A
  • Female will mate with a male withe desirable characteristics e.g. tall, big, attractive
  • Resulting in this ‘sexy’ trait being inherited by her son
  • As the ‘sexy’ trait is inherited by the female’s son, this makes it more likely for successive generations of females to mate with her son
  • This is a reason for intersexual behaviours in females
50
Q

study: Clark and Hatfield (1989) AIM

A

to investigate the difference in choosiness shown by males and females when approached by a stranger offering sex

51
Q

study: Clark and Hatfield (1989) METHOD

A
  • 48 males and 48 female students
  • PPS approached by an average attractive person of the opposite sex
  • Person said “I’ve been watching you around campus, I find you very attractive, would you go to bed with me tonight?”
52
Q

study: Clark and Hatfield (1989) RESULTS

A
  • Not a single female agrees
  • 75% of men agreed
53
Q

study: Clark and Hatfield (1989) CONCLUSION

A
  • Men are more eager for sex with strangers than women
  • Women are more choosy
  • Supporting sexual selection as an explanation for mating behaviour
54
Q

study: Clark and Hatfield (1989) STRENGTHS

A
  • The 1982 replication obtained the same results as the original study, indicating that the results may be reliable
  • The study had high ecological validity because it was done under naturalistic conditions
55
Q

study: Clark and Hatfield (1989) WEAKNESSES

A
  • Deception was used, which is an ethical concern
  • It is possible that a society with different social norms would have different results. It could also be that women have more concerns about safety when asked for casual sex by a stranger. Men may be more confident in their ability to deal with any type of entrapment or physical assault than women.
  • The study was also done prior to the AIDS epidemic and to the sexual revolution of the early 2000s. Therefore, the study may lack temporal validity. However, modern replications in the US have yielded similar results.
  • Evolutionary theories are based on the assumption that behaviours are inherited. As we know from our study of genetics, it is difficult to know the extent to which certain behaviours are, in fact, genetically inherited.
56
Q

study: Buss (1989) AIM

A

to investigate the partner preference of males and females

57
Q

study: Buss (1989) METHOD

A

Conducted a survey of 10,000 adults across 33 countries, 37 cultures

58
Q

study: Buss (1989) RESULTS

A
  • Female respondents placed greater value on resource-related characteristics, maturity and higher social status e.g. good financial prospects
  • Males valued reproductive capacity and youth was highly important
59
Q

study: Buss (1989) CONCLUSION

A
  • Men want to maximise the potential for fertilisation, which can come from younger women
  • Women want to ensure the likelihood of reproduction and having a healthy offspring through financial help and resources that can come from a higher social status
  • Results explain the human mating behaviour as looking for the most optimal mating partner to reproduce a healthy offspring, which can be said to be sexual selection
60
Q

study: Buss (1989) STRENGTHS

A
  • Large sample of 10,000- ensures reliability
  • Cross cultural
  • Anonymity, consent, no deceptions
61
Q

study: Buss (1989) WEAKNESSES

A
  • Questionnaire- demand characteristics to look better to the researchers
  • Construct validity
  • Self-report, social desirability bias and demand characteristics- low validity
  • Rural, less educated and poorer areas were not included, decreasing generalisability
  • Lacks ecological validity- were given questionnaires, is more what the person thinks they would do, not their actual behaviour
62
Q

evolutionary explanation critical thinking limitations

A
  • Lack temporal validity, outdated, inapplicable to modern society
  • Doesn’t explain homosexual relationships
  • Reductionist (simplest) way of explaining partner preference and it encourages stereotyping and sexism
  • Some men prefer older women, may women can provide for themselves and their family, some men don’t want children
  • Can’t get evidence to support the theory as it is based on inferences drawn from observations of behaviours
  • Unable to explain why certain traits/behaviours are not universal, or why there are cultural differences in behaviour. Learning approaches e.g. SCT is better able to explain these cultural differences
  • Difficult to test the assumptions of evolutionary explanations
  • Can’t predict heterosexual relationships who are infertile/don’t want children
  • Can’t explain the mating behaviour of everyone
  • Based on the assumption that behaviours are genetically inherited, it is difficult to know the extent to which certain behaviours are, in fact, genetically inherited
  • Hard to test human mating behaviour → cultural influences or different ways human have learned to find mates
  • Assumes that a sexual partner is found for the sole reason of reproducing
  • Evolutionary arguments often underestimate the role of cultural influences in shaping behaviour
  • Much of the research to test evolutionary theories is highly artificial and lacks ecological validity
  • Little is known about the behaviour of early humans, so statements about how humans “used to be” are hypothetical.
63
Q

evolutionary explanation critical thinking strength

A

Generalisability- studies show that is is clear that the sexual evolution argument can explain human behaviour as humans look for mates that will allow for reproduction and healthy offsprings