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What did Darwin say about sexual selection

• ‘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


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

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


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

• 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.


what are the three ways mating can occur?

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


Talk about indiscriminate/ random mating

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.


Talk about non-choosy harem accumulation.

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


talk about choosy mating

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.


relation of fruit flies to why humans are choosy

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


who argued Paternal investment and what did they argue?

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.


what happens with choosiness in other species compared to humans?

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.


why do humans not really make huge displays?

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


overall why are men choosy and why are females choosy?

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.


who is choosing who in humans?

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


how do humans attract/ be attractive?

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


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

Direct and indirect


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

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


what are the indirect benefits of mate choice

o Increase in offspring RS/ survival
o Have more grandchildren and surviving children


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

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.


what are direct benefits? (list of)

-phenotypic benefits
-parental care
-resource holding/ sharing
-fertility and fecundity


what are indirect benefits (list of)

-Runaway/ 'sexy son'
-compatible genes
-good genes


Points to cover when talking about resource holding potential

-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.


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

• 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.


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

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.


what overall can be said about acquiring more monopolised resources?

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


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

• 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


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

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.


what has happened recently that may effect RHP?

• 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.


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

• 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.


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

Yaffe et al., 2018

men look for youth women look for social dominance


what are females when it comes to mate finding?

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