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Matt Ridley and the human revolution

24 Oct, 2012

Matt RidleyMatt Ridley stood before me wearing a geekily appropriate DNA-patterned tie. “As a writer I tell stories,” he said. More often than not, they’re big stories about genes.

The author of Nature via Nurture, The Red Queen and Genome, Ridley has won numerous awards for his books and been shortlisted twice for the Samuel Johnson Prize for non-fiction. More importantly for me, Genome got me through my undergraduate finals, revealing in 300 pages the bigger story of genetics that I’d spent three years studying in isolated units.

A fitting choice of speaker then for the 2012 Sanger Lecture. “The fact that we can read genes is the most extraordinary thing,” he said. “We are so fortunate to live in time when we can read not just ours but the genomes of other living creatures, and figure out what it means.”

Yet the story he told was one not entirely of genes, but of humanity (one of the threads in his latest book The Rational Optimist).

Around 200,000 years ago, our brains suddenly got larger. We evolved and developed a society and culture that allowed us to subsequently dominate the world. But what kick-started it all?

Trigger

Scientists, said Ridley, often talk about a ‘genetic trigger’, as simple perhaps as a single gene mutation granting us the brain capacity to think up wonderful things.

Not so, according to Ridley. To follow his argument in Nature via Nurture, it is not a case of one thing (genes) or another (environment), but a combination of both, with one influencing the other. Perhaps, he said, we’re thinking of things the wrong way round: instead of something in our biology triggering culture, what if it’s also our culture that changed our biology? And he had a case.

Exhibit 1: Milk. The LCT gene, found on chromosome 2, produces the enzyme required for us to digest milk. In most mammals, the gene is switched off following weaning, but not in us. Perhaps, said Ridley, our cultural take-up of milk drinking, as well as a penchant for cheese and other dairy produce, kept up the selective pressure for the gene to stay on? There is evidence of differences in LCT gene expression in African and Asian communities where milk-drinking never became a cultural norm.

Exhibit 2: Eye colour. “I sometimes get annoyed with Darwin,” said Ridley. “The secret of genetics (mendelianism) was staring him straight in the face.” He was referring to Darwin’s own eye colour (“a pair of such expressive, sparkling blue eyes,” according to the Austrian writer Ernst von Hesse-Wartegg), the cause of which is a mutation in the gene OCA2, found on chromosome 15. Darwin thought individual differences such as eye colour were the result of sexual selection (see The Descent of Man) – the peacock’s tail expresses individualism to attract a mate, for example (“a case of not survival of the fittest, but survival of the sexiest,” as Ridley put it).

But he was wrong (Darwin was wrong!). Sure, some blue-eyed beauties may well get more than their fair share, but the evidence doesn’t quite pan out – the blueness of one’s eyes does not generally lead to more copulations. So what’s the deal? Ridley has a theory. A 2008 study mapped the percentage of light eye colour around Europe. And an earlier, 2002 study on the paleoetiology of human skin tone speculated that the spread of agriculture may have had a role:

“Only one spot on the globe enables economically competitive grain production above the 55th parallel. Only circum-Baltic farmers could switch to a grain diet devoid of vitamin D, in a place where sunlight also lacked UV. And so, the extreme of the paleness adaptation is found only within 600 miles of this unique spot on earth.”

So Ridley’s logic is thus:

Ridley eye colour

Finally, Exhibit 3: Language. The FOXP2 gene is well known as the ‘language’ gene, based on the studies of Professor Simon Fisher (of the Wellcome Trust Centre for Human Genetics) and others. In Fisher’s famous study, a family whose members had a mutation in the gene developed speech and language problems. Subsequent experiments in mice and birds revealed that loss of the same gene led to loss of vocal communication.

So FOXP2 is synonymous in different species, but it’s also very different between them. A chimpanzee’s FOX2P protein is more similar to a mouse’s than a human’s. Clearly, there’s some genetic change that enables us to be better at language. But was this cause or effect? Was it the genes that enabled language skill, or language necessity that selected genes enabling better language?

Collective intelligence

So if not genes, then what? Appropriately for Ridley, it’s thinking big.

He showed us two similarly-sized objects from his desk: a stone ‘hand axe’ and a computer mouse. “How did we come to make sophisticated things?” he asked. As an answer, ‘culture’ is too vague – animals have been shown to have some form of culture. So what makes us so special? “Collective intelligence.”

As with biological evolution, there’s lots of trial and error in technology. There were many designs for the tail fins of planes before we settled on the most efficient one. But this trial and error does not have to be as fully random as biology to work, as long as there is some randomness in it.

The crucial thing, said Ridley, is recombination. Sex is one way to do this. Without sex, adaption is not cumulative – one form must go extinct for the other to survive. Sex means you can draw on genetic innovation wherever it appears in your species. But sex is not the only way to achieve recombination – horizontal gene transfer can allow bacteria to swap new genes. And it’s that word, ‘swap’, that’s interesting for Ridley’s theory.

Perhaps what kick-started the rise of humanity was swapping. (To be clear, we’re not talking about reciprocal actions generally, but exchanging things/favours at the same time.) Swapping different objects at the same time is a peculiarly human trait and one that’s hard to teach other species. Chimps can be taught to some extent, but won’t hand over food they like for food they like more. To quote the philosopher Adam Smith:

“No man ever saw a dog make fair and deliberate exchange of a bone with another dog.”

It’s the law of comparative advantage, said Ridley. We get better at something the more we specialise and we can all gain by trading with one another as long as each of us is more efficient at different things. To use Ridley’s example, one person might be better at making spears and another axes. Rather than make one good thing and another of poorer quality, if one person makes 2 really good spears and the other 2 really good axes, they can trade and both win.

This is what Ridley believes has sped human evolution. It’s a theory, but his case is compelling. Ridley showed a graph of the labour cost of electrically provided light (per 1200 lumen) vs. the average US wage. In 1800 it was 6 hours of work to earn an hour of light. Today it’s 0.5 seconds. We’ve been able to make such strides because we’ve spread specialism and labour, got other people to do things for us, while we do something else for them.

How did this start? Ridley thinks that the sexual division of labour may have been the beginning. All existing hunters gatherer communities segregate into males hunting and females gathering – it’s more efficient.

For Ridley, collective intelligence is the story of the last 2500 years. Who knows how to make a computer mouse? Or even a pencil? Nobody. But each person in the system knows how to make their contribution – gather the wood, mine graphite, press the parts together and then ship the pencils out to stores all over the world. “We are doing things technologically way beyond our individual brains,” said Ridley, “We are using the cloud before the term was even coined – the Internet is just an acceleration of it.”

Matt Ridley, thinking big, yet again.

Image credits: Wellcome Library, London and Matt Ridley
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