Yale Lecture - 'What Motivates Us: Sex'

I watched this lecture on Youtube: http://www.youtube.com/watch?v=RCNgknc7Qv8 and like a good student I took some notes. What better place to write up these notes than on my Psychology blog?

• Biological/Darwinian approaches argue that sex is for reproductive purposes. Does this mean other forms of sex e.g. homosexual, with contraception, are unnatural or wrong? This would be a very close-minded view, in my opinion.
• "Genetic does not mean inevitable, cultural does not mean easy to fix". I found this an interesting quote. The examples used were: genes determine bad eyesight but it is not inevitable that the individual must suffer from poor eyesight throughout their lives, due to glasses and contact lenses being invented. Whereas, opinion on obesity is cultural and, although these opinions vary between cultures, they are nearly impossible to change. 
• Female sex cells are bigger than males' however, males of most species are physically bigger and more aggressive - what is the reason for this? This is answered by Parental Investment theory. In most species, females have higher investment in the offspring. Whereas males compete for mates, females can easily find one so competition is less (although they do compete for the best mates). This explains why males are larger; they need to adapt to get the females' attention, while females can afford to be more 'choosy' so do not need such adaptions. In short: differences in sizes of sex cells lead to differences in parental investment, which explains how differences in psychological and physiological mechanisms evolved between males and females. The size or aggressiveness of a species can be predicted when level of parental investment is known. For example, in penguins the parental investment is equal, and sizes of males and females are also equal, in reflection of this.
• Mostly, humans are polygamists i.e. they have more than one sexual partner throughout their lives. Evolutionary, the fact that human males are bigger suggests competition and gives an indication of levels of Parental Investment in humans. On average, human males are more aggressive and violent than females, which can be explained by levels of testosterone. 
• Parental investment theory suggests males are more receptive to anonymous sex, whereas females are more 'picky' (bearing in mind these differences evolved before birth control). Due to the fact that males do not have to invest so much into offspring, they do not 'care' as much about their mate as females do and they more readily compete for whatever sex they can get.
• Prostitution is a near universal interest for males, which supports the above point. As does the fact that porn is universal for males (even monkeys have a form of porn!)
• Questionnaires showed that whilst women, on average, want less than 1 sexual partner in the next month, 1 in the next two years and 4-5 over their lifetime, men want 2, 8, then 18 respectively. Experiments have shown that when attractive actors approached strangers to ask them to 'go to bed' with them, no women agreed but 75% of men did! 
• It has been found that female homosexuals are more monogamous than male homosexuals. In theory, what gay men do, in terms of frequency and nature of sexual habits, is what heterosexuals would do if they had females who are as willing as them. This shows the differences in sexual 'choosiness' in human males and females.

Sexual Attractiveness/Mate preference:

• Cross cultural studies show that everyone values kindness and intelligence in potential partners.
• Females focus more on power and status and the male's interests in being a good father. Evolutionary, this makes sense; a male with these qualities will be able to protect the female and help her to raise the young.
• Males focus more on a female's ability to have children, therefore they care more age.
• Everyone likes physical beauty. This can be explained by the fact that beauty, e.g. large eyes, big lips, smooth skin, signals youth. Beauty also signals health e.g. absence of deformity, clear eyes, good skin and teeth. 
• If a lot of faces are morphed together, the result is a 'beautiful', and very average, face. It has been found that even babies prefer average faces, suggesting that a preference towards normality is hardwired rather than cultural. For those of us who aren't considered particularly attractive, this is quite a pleasant fact. Beautiful people are very average - how boring! 
• Males and females are treated differently by society i.e. there are different expectations of behaviour.
• Developmentally, gender self segregation from the ages of around 4-11, exaggerates and enhances these gender differences. 

Homosexuality

• Around 98% of women are sexually attracted to men and around 96% of men are sexually attracted to women. Why the differences?
• It has been both scientifically and logically proved that people do not choose their sexual orientation (I still get angry thinking about the ignorant guy in my Psychology class last year who was adamant that 'gays choose to be gay')
• There is reason to believe that gay and straight people are different long before puberty with regard to childhood fantasies and desires. 
• It is believed that there is a sort of genetic predisposition towards homosexuality. However, twin studies show 50% congruence in identical twins and although this is high odds, it would be 100% if homosexuality was entirely genetic. 
• It is somewhat an evolutionary mystery as to why some men do not want sex with women and vice verse. It would make sense that these genes would be eliminated by evolution since they do not lead to offspring. However, these genes remain, why is this?