Human Mating Flashcards
What are WEIRD societies
What are the issues with studying these societies in evolutionary anthropology
• WEIRD – Western Educated Industrialised Rich Democratic
- Only small amount of variation encompassed
- Invariably the outlier when cross-subsistence data available
- Unlikely to inform us about evolutionary origins
What are the benefits of including small scale societies (not just WEIRD societies) in studies
- Universality cannot be assumed, but tested.
- Diversity better predicted by economy than geography.
- Opens up much broader range of subject areas e.g. kinship, marriage patterns etc.
- Natural fertility populations useful for testing fitness outcome
What is Human Behavioural Ecology concerned with
Concerned with understanding human behavioural diversity
(within and between societies) – focus on ethnographic work.
Employs core theory from behavioural ecology; adaptationist stance.
What is the adaptionist stance to behaviour
Behavioural flexibility produces adaptive responses to socioecological conditions:
- reaction norms
- phenotypic plasticity
What is the phenotypic gambit
the assumption genetic architecture does not constrain which phenotypes can evolve
What are modules in human psychology according to evolutionary psychology
Human psychology consists of mental modules which have been selected to deal with specific fitness related problems e.g. ‘cheater detection module’.
Modules evolved in response to pressures faced recurrently by our Pleistocene ancestors livings as HGs -in the EEA
What is the cheater detection module
This module is an adaptive algorithm in the brain that once activated causes individuals to automatically look for cheaters in social exchange
such modules are operate without conscious effort and are distinct from general cognitive resources
What do evolutionary psychologists believe about post-Neolithic psychology
In post-Neolithic transition populations cognition and behaviour is
maladaptive as natural selection is slow – mismatch!
• Behaviour is relatively inflexible and genetically determined.
• Human nature is universal; thus studying diversity and using
ethnographic methods is a low priority in EP; often survey based
or experimental
How did Trivers define parental investment
“any investment by the parent in an individual offspring that increases the offspring’s chance of surviving (and hence reproductive success) at the cost of the parent’s ability to invest in other offspring” (Trivers 1972)
What happens to the other sex when one sex invests considerably more in offspring
How does this relate to oogamy
members of the other sex will compete
for mating access to the investing sex
Female gamete requires more metabolic investment so male gametes compete with each other
What is oogamy
sexual reproduction involving a small motile male gamete and a large much less motile female gamete: occurs in all higher animals and some plants.
Other than oogamy, what increases maternal investment compared to paternal
What does this lead to
- internal gestation in mammals
- Breast feeding/ lactating
Females have a lower potential reproductive rate
What is Bateman’s principle
in most species, variability in reproductive success (or reproductive variance) is greater in males than in females
Thus, male fitness is closely tied to mating access – quantity over quality while females must b choosier
this is a simplification and just a general trend
Give criticisms of Bateman’s experiments
Birkhead argued that since Bateman’s experiments lasted only three to four days, the female fruit fly, Drosophila melanogaster, may not have needed to mate repeatedly, as it can store sperm for up to four days; if Bateman had used a species in which females had to copulate more often to fertilize their eggs, the results might have been different.
Snyder and Gowaty conducted the first in-depth analysis of the data in Bateman’s 1948 paper. They found sampling biases, mathematical errors, and selective presentation of data
Use bird data to show females are not destined to be chaste
Do the same for primates
Until recently, most bird species were believed to be sexually monogamous. DNA paternity testing, however, has shown that in nearly 90% of bird species, females copulate with multiple males during each breeding season Zuleyma (2016)
In many primate species, females solicit sex from males and may mate with more than one male in quick succession. (Drea, 2005)
Describe the results of the Clark and Hatfield (1989) experiment
Men are less choosy than women and more willing to engage in casual
sex…75% of men vs 0% of women agree to have sex with an attractive
stranger (Clark & Hatfield 1989).
What did Bateman say about male and females
‘There is nearly always a combination of an undiscriminating eagerness in the males and a discriminating passivity in the females,’ wrote Bateman
Saini (2018)
Give an example of Trivers’ work on the difference of sexual activity between sexes having an effect on popular culture
In August 1978, Playboy carried a story entitled
‘Do Men Need to Cheat on Their Women? A New Science Says Yes’
According to the Bateman hypothesis what should men and women be attracted to
- Human offspring are highly dependent so we expect women to care about willingness and ability to invest resources, not just genes.
- Men ought to be attracted to physical signals of reproductive value (youth and health) since women’s fecundity declines with age
What did Buss (1989) show
Give a further study that supports Buss’ conclusions
In a seminal EP study, Buss (1989) examined sex differences in mate choice in 37 populations.
• In all 37 populations men rated physical attractiveness as more important than women; and in 36/37 women rated financial prospects as more important than men.
• Experimental evidence for trends e.g. clothing (status cue) affects women’s preferences more
Women cared more about uniform then men (Townsend & Levy 1990b).
What is Zahavi’s handicap principle (1975
: For a signal to evolve it must be costly/difficult to fake
Only those with the best genes can afford display the signal
Give 2 examples of honest signals in humans
- High testosterone supresses the immune system and produces a strong jawline…only males with good genes can afford to display this signal.
- Symmetry – Ability to maintain stable development in spite of environmental pressures. Reflects genetic quality and immunocompetence
What did Rhodes show about attractiveness
Averageness - Features more close to population average/less extreme deviations. Reflects heterozygosity and correlated with health (Rhodes et al 2001).
What did Wedekind show
The Sweaty T-shirt Experiment
(Wedekind et al. 1995)
Women are attracted to the scent of men who have dissimilar MHC genes to
their own i.e. those with whom they will produce the healthiest offspring
Dissimilar smells also reminded them of previous sexual partners, suggesting this theory translated into real life actions – mated with individuals who are more genetically compatible with themselves
Why was Buss’ 1989 study not representative of all humans
Cultural group explains a larger proportion of variance in mate preferences than sex!
• “The samples obtained cannot be viewed as representative of the populations in each country. In general, rural, less-educated, and lower levels of socioeconomic status are underrepresented”
Subsistence mode is meant to be a very good indicator (more so than geography: hunter gatherers in 2 different countries will be more similar to each other than to populations living in the capital cities of those countries – selective pressures) – this is not represented here
In what populations would we expect physical attractiveness to be particularly important
What does this indicate
If physical attractiveness is indicative of ‘good genes’ we may expect its value to be higher in populations where parasite load is a stronger pressure.
A shift in priority from resource shopping to gene shopping.
What did Gangestad (1993) discover about mate choice
Human data from 29 cultures indicate that people in geographical areas carrying relatively greater prevalence of pathogens value a mate’s physical attractiveness more than people in areas with relatively little pathogen incidence
What did Little find about mate choice
Give a hypothesis for this
Little et al. 2007 found that preference for symmetry were more strongly expressed among Hadza hunter-gatherers than European populations.
• Ache hunter-gatherers found to place more emphasis on facial averageness than participants from industrialised societies
Follows predictions: Higher pathogen stess -> more consideration given to cues of heterozygosity and immunocompetence.
Why is evolutionary psychology obsessed with waist-hip ratio
often cited as a principal
determinant of male mate choice.
• 0.7 is the golden ratio and a signal of optimal health and
fecundity (Wass et al. 1997).
• WHR has stayed constant in over 40 years of playboy
centrefolds and Miss USA models (Singh 1993)
‘More feminine’ waist-hip ratio associated with greater extra-pair sex (Hughes, 2004)
Describe how attractiveness changes with BMI
body-mass index has an inverted-U relationship with
fecundity + in resource deprived areas, body mass is positively associated with health
Tovee et al. 2006 Contrasted British men, Zulu men living in S.Af, Zulu men who migrated to UK and Zulu men born in UK.
• Different cultural ideals of attractiveness based on local conditions rather than universal preferences.
• Intra-individual flexibility in preferences rather than genetic determinism.
Describe the findings of Tovee (2006)
In WEIRD societies where obesity is more of an issue lower ratio is preferred – opposite in non-WEIRD societies Tovee 2006 – British vs Zulu men
Native Zulu men living in SA had inverse opinions of British men
Native Zulu men who had migrated to UK had intermediate opinions when compared to native Zulu living in SA (not quite as negative correlation)
Zulu men born in UK virtually identical to opinions of British men
Preferences are updated with local conditions and not purely genetically determined – even if genetic heritage was very different conditions
What is the issue with EP explaining mate preference having evolved in the EEA
EP emphasises that mate preferences evolved based on the EEA yet ignores lack of storage and material wealth accumulation.
EPs suggest that women are attracted to rich men to provide BUT hunter gatherers don’t accumulate wealth
EP predictions of attractiveness do not hold up in Marlowe’s 2005 study . Explain
• Hunter-gatherer men place far more emphasis on women being hard-working than in US college
samples; and do not value good looks significantly more than women (Marlowe 2005).
• In industrialised societies financially independence predicts likelihood of women prioritising attractiveness over financial prospects.
How does the person choosing the mate differ between populations
In a vast number of cultures parents exercise
control over their children’s marital decision.
• Extensive education postpones marriage in
industrialised societies until an age of
independence.
What did Apostolou 2010 find about mate choice in agro-pastoralist societies
- skills required for subsistence are achieved at
an earlier age, thus marriage doesn’t need to be postponed. - production in based on private ownership and
thus dependence on parents is extremely high as is parental interest in partner choice (more
to lose)
Summarise the mate choice lecture (5)
- Females usually invest more in offspring + fitness not a function of number of mates unlike males -> females choosier.
- Female mate choice consider genetic and resource contribution of males. Given high PI required by human offspring, women concerned with resource access of males.
- Men place more emphasis on physical attractiveness which (honestly) signals reproductive value.
- Ecological conditions can vary the relative importance of characteristics (e.g. pathogen load and attractiveness); as well as actual preferences (e.g. resource abundance and body type). Preferences appear to be flexible.
- Labour and parenting roles vary within and between subsistence modes, which has knock on effects for partner choice.
What did Low claim was so interesting about human mating systems
“Human mating systems are particularly interesting. The extent of within-species variation is extraordinary. Most of the mating systems known in other species occur within the single species Homo sapiens.” (Low 2003)
Define the following
Polygyny
Polyandry
Polygynandry
Polygyny =
One man with many women
Polyandry =
One woman, many men
Polygynandry=
Many men, many women
Give an example of how social monogamy doesn’t necessarily match with social monogamy
90% of birds form monogamous unions but this doesn’t match with genetics – socially monogamous but not genetically monogamous – in some groups more than 50% of offspring can have a different genetic father to their social father
Often not got official definitions for 2 people as a mating pair
Which mating system is most common in humans
Polygyny is most common - >80% of all societies (some and general polygyny) – ‘some’ is tricky bc defined as 20% or fewer of men are polygynous – what if there was a society of 100 men and 100 women but 1 man married 100 women – this would be ‘some’ polygyny
What might be a better way to class proportion of people who are polygynous
Better to class polygyny as proportion of women who are polygynous
