Why did the wearing of hats become almost universal in Western society, and then almost die out? Why have cannibalism, excarnation, burial and cremation all waxed and waned as ways of disposing of bodies? Where did stockings come from? Why do some nations bother with monarchies? Why do nurses have more friends than lawyers? Well, on this site you will find an answer to all of these things, but first we must tackle a much more intractable problem... Why are our heads so large?
The human brain is about three times as heavy, relative to body mass, as that of any other ape. That differential has come about extremely rapidly, certainly during the last two and a half million years, but at first glance it’s hard to see why. Our huge brains use up about 20 watts (about the same as a dim light bulb), which means we have to consume more than 500 calories a day just to keep our brains ticking over. The size of the head needed to contain that brain leads to a great deal of pain and increased chances of death during childbirth, and the relative helplessness of babies ties parents down for years until children learn survival skills that other animals are born with. If there were not some evolutionary advantage to big brains, then large-headed people would have been selected out long before now.
An evolutionary argument, beautifully advanced by Sue Blackmore in The Meme Machine (1999), goes something like this: at some time in the past, a mutation gave an ape the ability to imitate others. The lucky proto-human would have observed others with skills that he could acquire himself, meaning that he had access to his own repertoire of skills, plus everyone else’s. Some of these skills would enhance his chance of survival by increasing foraging skills or by being more adaptable. He would get more food and therefore more mates, and so the genes for imitation were passed on. After a few millennia, those who could not imitate their peers would not survive long enough to breed. With this skill at imitation comes the need for more processing power and greater memory.
Although this argument is (of course) entirely speculation, it makes sense to me. The most useful skill for a gathering species is memory, and it’s pretty widely shared in the animal kingdom – think of a squirrel remembering the dozens of places it has stored food. Memory is vital for a foraging species: if some berries are nutritious while others are poisonous, then without memory each meal is a game of Russian roulette. The next most useful skill is learning through observation: our proto-human would learn survival skills by identifying that he ate the red berries and survived while she ate the white berries and died.
The next step up in the survival scramble is teaching your offspring: ‘Hey! Don’t eat the white berries!’. We don’t need language for this, but spoken commands transmit information more effectively than visual means because they don’t require recipients to be looking at you. And ‘Hey! Don’t eat the white berries!’ conveys a lot more survival value than a series of undifferentiated grunts and gestures. Complex language structures increase the chances of survival for recipients because it allows for transmission of more complex memes such as ‘Hey! Don’t eat the red berries if the days are getting shorter’.
So our foraging apes learned from each other – they created, absorbed and followed memes, and as language developed they found they could transmit more complex memes. Assuming that more complex memes enhanced the chances of survival, which seems reasonable, then a harsh environment would select for larger brains and more sophisticated vocal equipment, which then allowed the apes to develop and transfer more complex and more useful memes, and so on. Wrapping language up in more memorable structures such as dance, ritual, stories, songs etc makes it more memorable, and therefore more likely to be transmitted. So you could say that the ability to imitate – to create and use memes – drove human evolution.
Nature vs nurture
I said that a meme is more likely to thrive if it supports our genetic drives to eat, to reproduce, to hunt and to find shelter. Sometimes, memetic and genetic urges can contradict each other, which raises interesting questions about which predominate.
Consider the phrase ‘Good girls don’t have sex before marriage’. It’s a beautifully simple example of a memeplex containing two memes: the first being the concept of good and particularly a good girl, and the second being chastity. This is a memeplex because the concepts are self-reinforcing - I must be a good girl because I’m not having sex before marriage, and I must not have sex before marriage because I’m a good girl.
Young women in most societies in history have been exposed to this vertically-transmitted memeplex from a young age. The same reinforcing characteristic is true of the opposing memeplex - ‘if you love someone it is OK to have sex’ - but the community spreading this meme is smaller (mainly young men, I suspect), it is horizontally transmitted, and the girls encounter it much later in their lives.
The ‘abstinence’ movement arising from this vertical transmission has been particularly strong in the USA, where the Guardian newspaper reported that more than one billion dollars of taxpayers’ money had been spend promoting abstinence memes between 1998 and 2007. With that sort of advertising budget, we should expect to see a strong shift in behaviour. But we didn't.
A survey by Mathematica Inc. in April 2007 on behalf of the US Congress found that those who had been exposed to abstinence-only sex education lost their virginity at (on average) 14.9 years of age whereas in the group that had received conventional sex education it was…. 14.9. The proportion of people in each group who had had sex was about 45%, and the proportion who had had sex with multiple partners was also roughly the same (around 25%).
So abstinence memes, despite being heavily promoted, seem to have no constructive effect on behaviour. The reason is, of course, that we are genetically programmed to have sex and the genetic imperative is deeper and stronger than the memetic one. So not only is abstinence-only sex education dangerous (in that it excludes a lot of useful advice on contraception and avoiding sexually-transmitted diseases), it doesn’t work. And if you want to wear a ring to show people you are not having sex, get married like the rest of us.
So you might think that things which run counter to our biological drives will struggle to be absorbed and transmitted. That’s partly true, but there are plenty of examples when memetic conditioning overrides our biological urges:
- celibacy in clergy (where the person ‘chooses’ to devote all their time to spreading the religion), or arguably the modern equivalent of deciding to concentrate on your career rather than start a family;
- vegetarianism: We evolved as omnivores: deliberately eating less nutritious food in order to prevent the death of animals may be worthy, but kindness to animals conveys no biological advantage to us;
- raising other people’s children. If Dawkins is right about selfish genes, then childless people should be strongly motivated only to help raise their siblings’ children. Blackmore points out that the strength of the urge to spread your memes explains adoption and step-parenting, as the biological origin of the child is irrelevant as far as vertical memetic transition is concerned;
- contraception (a society-changing invention, to be sure, but definitely not in the gene’s interest); and
- creating this website when I should be earning money to feed my family.