The Economist features several articles on
evolutionary theory to celebrate the 150th 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 Paco Underhill).
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 Newcastle University, 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.
