5. Direct Benefits of Mate choice Core Flashcards Preview

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1
Q

What did Darwin say about sexual selection

A

• ‘depends, not on the struggle for existence, but on a struggle between the males for possession of the females; the result is not death of the unsuccessful competitor, but few or no offspring” Darwin 1959

2
Q

what was wrong with Darwin’s original view of sexual selection?

A

• Darwin’s original view of sexual selection was very sexist and was very much based upon his own perception of the world/ experiences/ outlook.

3
Q

what should we change about Darwin’s statement about sexual selection?

A

• If we remove males from Darwin’s wording and replace with ‘struggle within one sex for matings with the other’ it is a good premise. It is not a struggle for existence but struggle for offspring which is the critical driver.

4
Q

what are the three ways mating can occur?

A

1) Indiscriminate random mating
2) non-choosy harem accumulation
3) Choosiness

5
Q

Talk about indiscriminate/ random mating

A

o Could in theory spend a lot less time by mating indiscriminately where the only energy cost is the time spent physically searching. (finding anyone that you can mate with). When you are spending time and energy on something then you are not on something else there has to be a bonus for the cost.
o Only cost is mate searching.

6
Q

Talk about non-choosy harem accumulation.

A

o The cost of intra sexual competition can be incredibly high and there is no expenditure of energy for the females involved.
o Only cost= intra sexual competition

7
Q

talk about choosy mating

A

o Have to find time finding individuals you could mate with, then a selection process/ courting rituals, then if you don’t choose the first individual you have to repeat the process. Every time you reject someone you then spend more time looking for someone else.
o Is far more complex than mating randomly
o +selection cost +additional searching.

8
Q

relation of fruit flies to why humans are choosy

A

Edward & Chapman (2012) studied flies (drosophila melanogaster)
• Take with a degree of caution on how related to humans.
• They produce a large number of eggs but do engage in choice.
• Either randomly assigned females to mate with or allowed males to choose mates and fount that….“male mate choice increased fitness by an average of 1.59 eggs above the leel of male fitness that would be expected by chance” (1.5x as many eggs)
• Even fruit flies are able to use mate choice mechanisms to enhance their fitness by selecting higher quality/ more compatible mates

so if it works for flies this should in theory be same for humans

9
Q

who argued Paternal investment and what did they argue?

A

In an average lifespan in a fertile environment females could expect between 5-7 children through lifetime every child is a huge investment in parental output thus given this females ought to be more choosy because there is a far greater time and energy cost.

10
Q

what happens with choosiness in other species compared to humans?

A

Where you do get choosiness in species we tend to get males doing displaying and females choosing. Humans are different in the sense that we do not have males that make huge displays and plain females.

11
Q

why do humans not really make huge displays?

A

Where humans are polygynous, we can be very polygynous. But where we are monogamous we are extremely monogamous to the extent where female and male reproduction rates are the same. Reproductive output of male and female is the same and thus the males should be just as choosy as the female. Furthermore, even in the case of the fruit flies that mate all over the place even then being choosy is giving an advantage, so we might expect even polygamous males to be choosy to some extent, rather than acquiring as many females as possible

12
Q

overall why are men choosy and why are females choosy?

A

So females choosy because of huge time commitment and males choosy because of the same or because of the genetic benefit that arises from being choosy.

13
Q

who is choosing who in humans?

A

So humans have mutual mate choice where both partners are choosing to some degree, the argument has however been made that males and females looking for different traits

14
Q

how do humans attract/ be attractive?

A

Males and females pick up locally culturally ascribed cue to being attractive and using it to attract mates

15
Q

What are the two types of benefits that can be gained from mate choice?

A

Direct and indirect

16
Q

what are the direct benefits of mate choice (very generally)

A

-increase in own RS/ survival
o You have more children so you are more likely to survive
-mate is better so will provide better

17
Q

what are the indirect benefits of mate choice

A

o Increase in offspring RS/ survival

o Have more grandchildren and surviving children

18
Q

which is better direct or indirect benefits? IE. which type will we focus more on in mate selections.

A

Buss and Schmitt (1993) Sexual Strategies theory- would argue that it is completely dependant on what type of relationship you are in and who you are.
o Humans are very flexible on how they mate
o What we look for in a Short term mate is different to what we look for in a long term mate.
o And indeed within this what males and females look for in turn is different.
o Crucuially male and female interests in a long term mate become more aligned in a LT relationship.

19
Q

what are direct benefits? (list of)

A
  • phenotypic benefits
  • parental care
  • resource holding/ sharing
  • fertility and fecundity
20
Q

what are indirect benefits (list of)

A
  • Runaway/ ‘sexy son’
  • compatible genes
  • good genes
21
Q

Points to cover when talking about resource holding potential

A

-Emlen & Oring (1977) birds and two ways polygyny can work

in human examples:
-mormons & Kipsigis’ hed size (Borgerhoff & Mulder, 1988, 1990)

  • Buss 1990- women attracted to cues of resources
  • acquiring +monopolized resources can be turned into greater reproductive success.
22
Q

who outlined two ways polygyny can work in birds and what did they find?

A

• Emlen & Oring (1977) they looked at birds and they outlined two ways polygyny can work. 1) ‘Resource Defence Polygyny’ where a male bird can get a bit of territory and then keen other males away and then mates with multiple females that come to his territory (e.g. the resource of a fruit tree). The females are attracted to the resource that is the fruit tree as opposed to the male. Does involve female choice.

2) ‘Female Defence Polygyny’ where you might have a resource that is evenly distributed and females are distributed around that resource (e.g. grass) the male can not monopolise the resource so instead gathers a group of females and keeps them away from other males. Doesn’t actually involve any female choice.

23
Q

what human data can be used to show the effects of resource holding potential?

A

Mormon data as men become higher in status then they can acquire more wife’s higher status tends to have more money. Money and farm is monopolizeable and females are monopolizeable if you kick out other males. So both female defence and resource defence coming into play.

• Kipsigis’ herd size (Borgerhoff, Mulder, 1988, 1990)- the bigger a herd a man has the more wives he is able to accumulate. Need to pay bride price and also be able to support that family so bigger the herd the more women you can buy.

24
Q

what overall can be said about acquiring more monopolised resources?

A

• Acquiring more monopolised resources can be turned into greater reproductive success through greater mating.

25
Q

What was found about what women looked for? But what are potential issues in this?

A

• Buss 1989, 1990- thought that Women are attracted to cues of resources and drawn to those traits in the first place. Found that over multiple countries when you give questionnaires women tend to rank resource related traits as more important in a partner than men do. Intelligence, ambition, good financial/ social status this is found with large sample sizes.

but argued they could be overplaying this sex difference- ie. women rank intelligence at 5th most important whilst men rank it 6th. Normally it is a difference of one position and top 4 are exactly the same and in the same order.

1) mutual attraction and love 2) dependable 3) emotional stability and maturity 4) pleasing disposition

26
Q

Evidence that people do behave in a way still to show resources?

A

Lycett and Dunbar (2000) mobile phones were brick like and not many people so having a mobile phone was a cue to resources and that you had money. If they looked at people at a pub and looked at how many phones were out on tables the male to female ratio predicted the number of phones that men had out on the table. The more men to more women the more competition essentially there is so more need to show resources. These days we wouldn’t expect it to be phones out but maybe extent to showing fancy phones/ apple watch and showing status and resource markers.

27
Q

what has happened recently that may effect RHP?

A

• Male resource preference? Men are in a better place to acquire resources but whats been happening over last 50 yrs is that women have been able to enter the workplace more and monopolise resources more. If females can monopolise then do males begin to look for resources in a partner too? Pencavel (1998) If look back in 1940s e.g. whether the individual has been to uni or not it doesn’t matter the men are not marrying anyone with more education than them but doesn’t matter whether wives have been to uni or just school. 1960’s far more women going to uni and suddenly find that men who have been to uni are much more likely to marry someone who has been to uni than someone who has just been to high school. Women may be actively selecting partners who have the same level of education as them and males have a pool of women at uni so are more likely to end up with them. Availability of women at own educational level so that becomes more attractive.

28
Q

What do Buss and Schmitt argue in response to issues with their study about what people look for in a partner?

A

• It isn’t enough to have a partner that is well resourced, that partner must be willing to share their resources with you also. E.g. someone cant be a good hunter and not bring it back to you they need to be both- thus Buss and Schmitt (1993) argue that generosity is a key factor when searching for a LT partner. For so long women had so little influence over the marital money so were entirely dependant on how much the man was giving to them. –> so other factors are seen in line as these are vitally important but what happens post here is what narrows mate selection in terms of RHP for women.

29
Q

What paper clearly supports Evolutionary theory and shows that different cultural settings can result status being seen as different?

A

Yaffe et al., 2018

men look for youth women look for social dominance

30
Q

what are females when it comes to mate finding?

A

• Females as ‘limiting factors’- one of the most important things males can do when finding a mate is finding one that can conceive.

31
Q

what do animals do to show they are ready for conception?

A

Emery and Whiten (2003)- chimp females have big sexual swellings when in eustrus and become more swollen bottoms. The higher quality cycles (those which show clearest hormonal shifts) show the biggest and most red swellings. Shows which females are most fertile at any times.

o Kraak and Bakker (1998) found that male sticklebacks show a preference for bigger females- bigger females lay more eggs. Even simple species show these behavioural preferences for traits that are direct indicators of female fertility.

32
Q

what can indicate fertility in humans?

A
  • oestrogen
  • body cues
  • youth
33
Q

why is oestrogen a good cue to fertility?

A

regulates the menstrual cycle is critical for female fertility

mice without oestrogen receptors become infertile (Lubahn et al., 1993)

• Sher & Rahman (2000) looked at women with and without fertility issues and found that essentially the women that were infertile were showing lower levels of oestrogen feedthrough. They gave women estriol and found that in control women more went through their system than in the infertile women suggesting that that was part of the problem in their infertility.

thus.. we should find indicators of oestrogen attractive

34
Q

what have studies shown about facial cues to oestrogen?

A

• Law Smith et al. (2006) biology students brought in urine samples each week and were tested for oestrogen metabolite. Got faces rated for attractiveness- +levels of oestrogen were rated +attractive and +feminine than those with low levels.

BUT
• Jones et al. 2018- women came in week after week for a few years using 5x as many women as previous study (250 compared to 50). Measured oestrogen and progesterone levels each week from saliva samples. Found no effect of current oestradiol nor progesterone so no within or between women effect going on. Nothing clear in human evolution that would explain this effect. In second study all women removed all makeup before photo. In first they just took out women with makeup which could also remove women who had bad skin/ potentially associated with being on the pill. So the second was a bigger and better controlled sample and effect found in the second wasn’t found in the first.
• So we are not sure about faces.

35
Q

What does a WHR indicate?

A

. Indicated fertility (little girls are straight and same post menopause). One first thing that changes when become pregnant means that waist disappears

36
Q

what was first argued about WHR? But what were issues with this?

A

• Singh (1993)- 0.7 waist hip ratio and ‘gynoid’ fat distribution. Essentially argues that a woman with a WHR of 0.7 is probably of the right age and probably is not pregnant currently. Found that in different samples men preferred 0.7 to 0.8/9/10 ect. But didn’t show them 0.6 why?? Came out still with saying that 0.7 was ideal if hed shown 0.6 and they preferred 0.7 to 0.6 there would be a greater claim to this. But study still shows that a narrower waist relative to hips is attractive.

37
Q

What is WHR associated with?

A

o Fertile phase of life- Bjorklund et al. (1996): WHR increased during the transition from cycling to post-menopause.
o Oestrogen levels (Jasienska et al. 2004) found that those with lower WHR had higher oestradiol levels than those with a high WHR.
o Conception rate (Zaadstra et al. 1993): conception rate across 12 cycles of IVF. Found that higher WHR (less curvy) then the lower chances of getting pregnant during a cycle of IVF.

38
Q

what did others argue WHR was being conflated with?

A

o Tovee et al. 2001- argued that Singh was conflating BMI and WHR- they’re not becoming curvier but becoming lighter- found that BMI predicted attractiveness. Very clear relationship (completely skinny not attractive skinny = attractive (20BMI) and then further then it drops again. For WHR there wasn’t at all a pattern 0.7 bodies were rated as really attractive and really unattractive if you had a WHR of over 8.5 then not rated as really attractive but having a low WHR isn’t enough to get high attractiveness. Cubic relationship between WHR and BMI 75% of variance in the model explained by BMI and 2% explained by WHR. WHR almost negligible for western women.

o Grillot et al. 2014 WHR doesn’t predict E2 (oestradiol) once BMI controlled.

39
Q

what are some more recent studies suggesting about BMI

A

o Zaadstra (1993)- Independent Effects on conception?  WRH and BMI there is a sig relationship for attractiveness. Those who are obese have a much lower chance of being pregnant those who are slightly overweight have slight less chance but not huge. When throw all of these in the regression together, WHR remained significant and BMI dropped to a trend and the pattern is the same thus being obese was limiting chances of becoming pregnant so might be independent things going in in some samples.

o Jones et al. 2018- WHR and oestrogen there was a significant correlation which was unrelated to BMI

40
Q

what overall can be said about the importance of WHR

A

o WHR might be linked to oestrogen and thus might be an indicator of fertility in females only caveat is that WHR itself isn’t always vastly important when males are trying to work out how attractive a woman is and varies to a large degree cross culturally. We’ve got an indicator it just doesn’t seem to be extremely used.

41
Q

what happens in attractiveness as age and why has this been argued to happen/ what supports this?

A
  • as women age they tend to be deemed less attractive compared to men when they age.
  • has been argued this is because youth is very important in female fertility and females are the limiting factor.
  • Zaadstra et al. (1993) fertility declines with age. Once past 31 up to 37 significant reduction in chances for getting pregnant for women.
42
Q

age and donor eggs to get pregnant

A

• For mid 20’s-mid 40’s using donor eggs to get pregnant via IVF has roughly the same success rate. If using your own eggs there is a dramatic decrease from around 31 onwards and by 40s chances are really low. Ovum eggs are formed during foetal development, as get older these eggs degrade and are far less likely to be viable. Thus, if you want a fertile female the best way to ensure that is to pick someone in their 20s.

43
Q

Study that supports men like younger partners but what does this assume?

A

• Men prefer younger partners (Buss, 1989) But Buss assumed men can dominate woman’s entire reproductive career- assumes long term monogamy/ long term pair bonding. Making certain cultural/ reproductive assumptions.

44
Q

what was found about facial and vocal cues?

A

• Facial &Vocal attractiveness also follows a similar pattern to fertility (Wheatley et al, 2014) using US and Hadza. Women in 20s most attractive.

45
Q

what are men highly averse to in terms of age

A

• Men are averse to signs of menopause in women:
o Coarse hair
o Grey hair
o Greater facial hair

46
Q

what can be said overall for youth?

A

• Is preference for ‘youth’…or for pre-menopausal woman. Might be a Slight bias to optimal fertility but is it really about just not looking menopausal? This ties into Zebrowitz and Montepare (2008) idea of overgeneralisation that really what were looking at is not a direct preference for age/ state but an aversion to its opposite and is an avoidance pattern

47
Q

what are phenotypic benefits of mate choice?

A
  • Contagion avoidance- is something that both men and women can directly benefit from we are really averse to things that could possibly make us become ill. An argument has been made that elaborate displays might be in place to show good health.
  • We are generally in favour of people who look healthy.
48
Q

Study on health preferences for healthy skin

A

Jones et al. (2004) attitudes to healthy skin. Took 3cm squares out of photos of peoples faces got them magnified and then got them rated for how healthy they looked. Found peoples whose skin was rated most healthy when looking at whole face their faces were rated as more attractive. So anyone whose skin was smoother, with fewer blemishes, more even skin tone and a bit pinker were rated as more attractive. We like healthy looking skin.

49
Q

who argues and what is the overgeneralisation hypothesis

A

Zebrowitz and Montepare (2008) looked at extent to which cues are valid indicators of the thought they are meant to imply. But didn’t just look at people in general looked at people in top versus bottom half of the distribution. Measured intelligence and got attraction rating of faces and looked then at perceived intelligence. What we find is whether looking at bottom or top of distribution the more attractive someone is at every stage of life, the more intelligent they are perceived to be so there’s a very clear halo effect of attractiveness, if you look attractive people assume you as more clever. But if you look at actual intelligence and measured facial attractiveness you find that in bottom half of the distribution those who are more intelligent are rated as more attractive but those at top half there is no difference. So essentially if you score very low on intelligence you’re likely to look more unattractive possibly due to some underlying genetic issue but above this there is no difference and the overall link between perceived and measured intelligence is quite weak.

50
Q

what may suggest that we just avoid the worst?

A
  • We are certainly as a culture extremely adverse to signs of menopause (greying, bigger waist)
  • And very averse to signs of illness e.g. acne cold sores.
  • On flip side- hunting data- people know very best and very worst but not good in middle.
  • Is it that we prefer or is it that we are avoiding ill health/ age/ the worst hunters seeing an overflow for a very basic bias against something that can only really be perceived at extremes.
51
Q

what evidence supports that we are adverse to signs of ill health as opposed to attraction?

A

• Nice evidence for this comes from Park et al (2012) who looked at the relationship between pathogen disgust and attractiveness ratings under the idea that we are attracted to healthy looking people because we want to avoid infection, they hypothesised that people who have high levels of pathogen disgust (people who are particularly sensitive to cues of infection) would show strong preference for attractiveness in others. Split the sample between 8 most and 8 least attractive faces in their set. For the attractive targets there is no difference in ratings of attractiveness for those with high or low pathogen disgust. For the low attractiveness there was a significant different between the ratings of those with low pathogen disgust to those with high pathogen disgust with those with high pathogen disgust rating them significantly less attractive. So what we are seeing is that pathogen disgust is triggering people to be more averse to those at the bottom end of the distribution but its not effecting those at the top, so its not driving them to have a stronger preference for cues of health its driving them to have a stronger aversion to cues of ill health. Suggesting that were seeing an overgeneralization of aversion rather than a direct preference for attraction.

52
Q

in terms of aversion they why may we think celebs are very attractive?

A

So potentially when we consider why people who are considered in cultures as attractive tend to look like each other. E.g. celebs They all look very healthy, no wrinkles, they’re all rich and well dressed and smart so maybe what’s going on is that they are free of the things we may be more adverse to.