Ryu's Blog

The Economist features several articles on evolutionary theory to celebrate the 150^th anniversary of Darwin’s On the Origin of Species, using his theory to explain music, our shopping behavior, rape,
murder, racism, income inequality between men and women, and much more. It also has an article on how women choose perfume and partner based on scent. This Christmas issue is a treat for lovers of evolutionary theory and psychology.

I think evolutionary theory is by far the best way to explain human behavior.  Accepting the evolutionary view doesn’t mean we are determined to behave in a certain way or that we are all a signaling machine. Learning about our tendencies and origins of our motivations helps us to appreciate the differences we see in this world. And a lot of signaling behaviors are masked in sincere emotions. The Economist puts it well, “Perhaps, after a century and a half, it is time not just to recognise but also to understand that human beings are evolved creatures. To know thyself is, after all, the beginning of wisdom.”

Below are some bits from this issue, with much more in the full articles.

The food-of-love hypothesis of music:

Dr Miller starts with the observations that music is a human universal, that it is costly in terms of time and energy to produce, and that it is, at least in some sense, under genetic control. About
4% of the population has “amusia” of one sort or another, and at least some types of amusia are known to be heritable. Universality, costliness and genetic control all suggest that music has a clear function in survival or reproduction, and Dr Miller plumps for reproduction.

One reason for believing this is that musical productivity—at least among the recording artists who have exploited the phonograph and its successors over the past hundred years or so—seems to
match the course of an individual’s reproductive life…As is often the case with this sort of observation, it sounds unremarkable; obvious, even. But uniquely human activities associated with survival—cooking, say—do not show this pattern. People continue to cook at about the same rate from the moment that they have mastered the art until the moment they die or are too decrepit to continue. Moreover, the anecdotal evidence linking music to sexual success is strong.

Another reason to believe the food-of-love hypothesis is that music fulfils the main criterion of a sexually selected feature: it is an honest signal of underlying fitness. Just as unfit peacocks cannot grow splendid tails, so unfit people cannot sing well, dance well (for
singing and dancing go together, as it were, like a horse and carriage) or play music well. All of these activities require physical fitness and dexterity. Composing music requires creativity and mental agility. Put all of these things together and you have a desirable mate.

The science of supermarket placement (this reminds me of the book Why We Buy: The Science of Shopping by PacoUnderhill).

it takes a while for the mind to get into a shopping mode. This is why the area immediately inside the entrance of a supermarket is known as the “decompression zone”. People need to slow down and take stock of the surroundings, even if they are regulars. In sales terms this area is a bit of a
loss, so it tends to be used more for promotion. Immediately to the left in Sainsbury’s is another familiar sight: a “chill zone” for browsing magazines, books and DVDs, tempting impromptu purchases and slowing customers down. But those on a serious mission will keep walking ahead—and the first thing they come to is the fresh fruit and vegetables section.

For shoppers, this makes no sense. Fruit and vegetables can be easily damaged, so they should be bought at the end, not the beginning, of a shopping trip. But psychology is at work here: selecting good wholesome fresh food is an uplifting way to start shopping, and it makes people feel less guilty about reaching for the stodgy stuff later on. Shoppers already know that everyday items, like milk, are invariably placed towards the back of a store to provide more opportunity to tempt customers. This is why pharmacies are generally at the rear, even in “convenience” stores.

But supermarkets know shoppers know this, so they use other tricks, like placing popular items halfway along a section so that people have to walk all along the aisle looking for them. The idea is to boost “dwell time”: the length of time people spend in a store.

Why we seek status:

For a Darwinian, life is about two things: survival and reproduction. Of the two, the second is the more significant. To put it crudely, the only Darwinian point of survival is reproduction. As a consequence, much of daily existence is about showing off, subtly or starkly, in ways that attract members of the opposite sex and intimidate those of the same sex. In humans—unlike, say,
peafowl, where only the cocks have the flashy tails, or deer, where only the stags have the chunky antlers—both sexes engage in this. Men do it more than women, but you need look no further than Ascot race course on Gold Cup day to see that women do it too. Status and hierarchy matter. And in modern society, status is mediated by money.

Girls have always liked a rich man, of course. Darwinians used to think this was due to his ability to provide materially for their children. No doubt that is part of it. But the thinking among evolutionary biologists these days is that what is mainly going on is a competition for genes, not goods. High-status individuals are more likely to have genes that promote health and intelligence,
and members of the opposite sex have been honed by evolution to respond accordingly. A high-status man will get more opportunities to mate. A high-status woman can be more choosy about whom she mates with. For men, at least, this is demonstrably true. Evolutionary biologists are fond of quoting extreme examples to make the point, the most famous being Moulay Ismail the Bloodthirsty, a Moroccan ruler who fathered over 1,000 children. But kings have powers of coercion. Some better examples are provided by Joe Studwell, in his book “Asian Godfathers”, which dissects the lives of businessmen. Stanley Ho, a veteran operator in Hong Kong and Macau, has 17 children by several women. Oei Tiong Ham, a tycoon who died in 1924, had 18 concubines and 42 children. The relationship holds good further down the social ladder. Danile Nettle and Thomas Pollet, of NewcastleUniversity, recently showed that in Britain the number of children a man has fathered is, on average, related to his income, the spread of modern contraception notwithstanding.

Income difference between men and women

When outcomes are unequal in socially acceptable areas of behaviour, such as employment, it is often interpreted as a sign of discrimination. But people who draw this conclusion rarely consider that the discrimination in question might actually be being exercised by the supposedly disadvantaged women themselves.

A classic example is income. Women earn less than men. Or do they? In fact, younger women do not, or not much. A recent report by the Institute of Economic Affairs (IEA), a British think-tank, found that British women aged between 22 and 29 who were in full-time employment earned only 1% less than their male counterparts. This age group corresponds for many women to the period when they are single. Once they have found the best available mate, the calculation changes: a woman no longer needs to show off. In that context, it is less of a surprise that older women are out-earned by their male contemporaries. One reason is that they now care less about the size of their earnings. Of the top 25 ideal employers, as chosen by women, the IEA found that 12 were in the public or voluntary sectors—areas where salaries for equivalent work tend to be lower than in the private sector, though job security is higher and job satisfaction is often believed to be greater. For men, only four employers were in this category. The other reason, of course, is that women usually look after the children. Indeed, the study by Dr Nettle and Dr Pollet which found that reproductive success correlates with men’s income, also points out that with women the correlation is inverted. But the IEA study also found that it is women themselves who are taking the decisions about child care. It reports that two-thirds of the women who had not already had a “career break”, as it is euphemistically known, planned to take one at some point in the future. Less than an eighth of men had similar aspirations. That, too, would be predicted by a Darwinist.

Although there is a strong argument for making working conditions more sympathetic to the needs of parents of both sexes, the underlying point is that many women—and certainly many women with children—do not care as much about striving ahead in their careers as men do. Men, the report found, are more motivated by pay and less by job satisfaction than women are. If managers, they are more likely to work long hours. They also take more risks—or, at least, are
more frequently injured at work.

Why perfume does for men

They already knew that appropriate scents can improve the mood of those who wear them. What they discovered, though, as they will describe in a forthcoming edition of the International Journal of
Cosmetic Science, is that when a man changes his natural body odour it can alter his self-confidence to such an extent that it also changes how attractive women find him.

Over the course of several days, Dr Roberts’s team conducted a battery of psychological tests on both groups of volunteers. They found that those who had been given the commercial fragrance
showed an increase in self-confidence. Not that surprising, perhaps. What was surprising was that their self-confidence improved to such an extent that women who could watch them but not smell them noticed. The women in question were shown short, silent videos of the volunteers. They deemed the men wearing the deodorant more attractive. They were, however, unable to distinguish between the groups when shown only still photographs of the men, suggesting it was the men’s movement and bearing, rather than their physical appearance, that was making the difference.

The science of scent

The correlation is with the genes of what is known as the major histocompatibility complex (MHC). This region of the genome encodes part of the immune system. It turns out that one of the most important aspects of mate choice in mammals, humans included, is to make sure that your mate’s MHC is different from your own. Mixing up MHCs makes the immune system more effective. The MHC is also thought to act as a proxy for general outbreeding, with all the hybrid vigour that can bring. Fortunately, then, evolution has equipped mammals with the ability to detect by smell chemicals whose concentrations vary with differences in the MHC of the producer.

That means people are able to sniff out suitable MHC genomes in prospective partners. A woman, for instance, will prefer the smell of T-shirts that have been worn by men whose MHC genes are appropriately different from their own. Dr Milinski and Dr Wedekind also found an association between a woman’s MHC genes and some of her preferences for perfume.

Women, it seems, choose not the kind of smell they would like on a partner, or even one that might mask a nasty odour of their own, but rather something that matches their MHC. In other words, they are advertising their own scent.

There are many useful inferences that might be drawn from this research. One would be that a woman’s choice of perfume will resist the vagaries of fashion. This may explain why most innovation in the industry involves changes in packaging and marketing, producing all that fussy paraphernalia, rather than changing what is in the bottle.

Another implication, says Dr Roberts, is that it is probably best that people choose perfumes for themselves rather than for someone else—unless they happen to know what the recipient likes. If you have made a good genetic choice of partner (ie, someone with a significantly different MHC),
then the theory suggests that you should not be able to choose something that smells nice to them based on your own preferences. You might, though, have better luck choosing for a close relation, because she would probably have an MHC similar to your own.

I was discussing this with a friend the other day and a few days later saw Ben’s post on exactly the same topic. I agree with most of his views, perhaps because we share similar ideology (1). But I think it’s difficult to disentangle between what’s inherited versus conscious change in personality. It’s likely that people with certain traits are more likely and capable of changing or improving themselves than the others. I agree with my ‘particular’ friend that the essence of a person is hard to change. Not that it’s impossible, but the cognitive dissonance and the discomfort from deviating from our inherited tendency are generally large enough to counter our desire and determination to change. I think few people are willing to make the sacrifice for big change in their personality and identity. So I might have a more pessimistic view about change: I think it’s possible to improve and change oneself, but it’s much more probable for certain type of people.

(1) I follow the classical liberal (or modern libertarian) tradition of thoughts (J S Mill, Adam Smith, David Hume, F A Hayek, etc.) and am fascinated by evolutionary psychology. I also read Steven Pinker’s books. I like The Blank Slate a lot, How the Mind Works is also good but has less impact on me.