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When I was a student here in Oxford in the 1970s,

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the future of the world was bleak.

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The population explosion was unstoppable.

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Global famine was inevitable.

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A cancer epidemic caused by chemicals in the environment

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was going to shorten our lives.

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The acid rain was falling on the forests.

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The desert was advancing by a mile or two a year.

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The oil was running out.

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And a nuclear winter would finish us off.

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None of those things happened.

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(Laughter)

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And astonishingly, if you look at what actually happened in my lifetime,

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the average per-capita income

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of the average person on the planet,

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in real terms, adjusted for inflation,

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has tripled.

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Lifespan is up by 30 percent in my lifetime.

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Child mortality is down by two-thirds.

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Per-capita food production

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is up by a third.

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And all this at a time when the population has doubled.

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How did we achieve that -- whether you think it's a good thing or not --

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How did we achieve that?

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How did we become

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the only species

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that becomes more prosperous

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as it becomes more populous?

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The size of the blob in this graph represents the size of the population.

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And the level of the graph

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represents GDP per capita.

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I think to answer that question

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you need to understand

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how human beings bring together their brains

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and enable their ideas to combine and recombine,

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to meet and, indeed, to mate.

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In other words, you need to understand

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how ideas have sex.

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I want you to imagine

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how we got from making objects like this

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to making objects like this.

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These are both real objects.

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One is an Acheulean hand axe from half a million years ago

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of the kind made by Homo erectus.

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The other is obviously a computer mouse.

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They're both exactly the same size and shape to an uncanny degree.

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I've tried to work out which is bigger,

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and it's almost impossible.

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And that's because they're both designed to fit the human hand.

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They're both technologies. In the end, their similarity is not that interesting.

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It just tells you they were both designed to fit the human hand.

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The differences are what interest me.

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Because the one on the left was made to a pretty unvarying design

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for about a million years --

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from one-and-a-half million years ago to half a million years ago.

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Homo erectus made the same tool

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for 30,000 generations.

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Of course there were a few changes,

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but tools changed slower than skeletons in those days.

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There was no progress, no innovation.

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It's an extraordinary phenomenon, but it's true.

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Whereas the object on the right is obsolete after five years.

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And there's another difference too,

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which is the object on the left is made from one substance.

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The object on the right is made from

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a confection of different substances,

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from silicon and metal and plastic and so on.

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And more than that, it's a confection of different ideas,

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the idea of plastic, the idea of a laser,

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the idea of transistors.

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They've all been combined together in this technology.

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And it's this combination,

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this cumulative technology, that intrigues me.

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Because I think it's the secret to understanding

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what's happening in the world.

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My body's an accumulation of ideas too,

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the idea of skin cells, the idea of brain cells, the idea of liver cells.

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They've come together.

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How does evolution do cumulative, combinatorial things?

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Well, it uses sexual reproduction.

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In an asexual species, if you get two different mutations in different creatures,

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a green one and a red one,

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then one has to be better than the other.

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One goes extinct for the other to survive.

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But if you have a sexual species,

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then it's possible for an individual

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to inherit both mutations

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from different lineages.

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So what sex does is it enables the individual

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to draw upon

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the genetic innovations of the whole species.

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It's not confined to its own lineage.

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What's the process that's having the same effect

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in cultural evolution

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as sex is having in biological evolution?

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And I think the answer is exchange,

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the habit of exchanging one thing for another.

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It's a unique human feature.

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No other animal does it.

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You can teach them in the laboratory to do a little bit of exchange.

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And indeed there's reciprocity in other animals.

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But the exchange of one object for another never happens.

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As Adam Smith said, "No made ever saw a dog

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make a fair exchange of a bone with another dog."

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(Laughter)

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You can have culture without exchange.

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You can have, as it were, asexual culture.

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Chimpanzees, killer whales, these kinds of creatures, they have culture.

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They teach each other traditions

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which are handed down from parent to offspring.

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In this case, chimpanzees teaching each other

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how to crack nuts with rocks.

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But the difference is

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that these cultures never expand, never grow,

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never accumulate, never become combinatorial.

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And the reason is because

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there is no sex, as it were,

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there is no exchange of ideas.

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Chimpanzee troops have different cultures in different troops.

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There's no exchange of ideas between them.

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And why does exchange raise living standards?

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Well, the answer came from David Ricardo in 1817.

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And here is a Stone Age version of his story,

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although he told it in terms of trade between countries.

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Adam takes four hours to make a spear and three hours to make an axe.

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Oz takes one hour to make a spear and two hours to make an axe.

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So Oz is better at both spears and axes than Adam.

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He doesn't need Adam.

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He can make his own spears and axes.

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Well no, because if you think about it,

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if Oz makes two spears and Adam make two axes,

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and then they trade,

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then they will each have saved an hour of work.

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And the more they do this, the more true it's going to be.

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Because the more they do this, the better Adam is going to get at making axes,

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and the better Oz is going to get at making spears.

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So the gains from trade are only going to grow.

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And this is one of the beauties of exchange,

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is it actually creates the momentum

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for more specialization,

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which creates the momentum for more exchange and so on.

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Adam and Oz both saved an hour of time.

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That is prosperity, the saving of time

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in satisfying your needs.

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Ask yourself how long you would have to work

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to provide for yourself

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an hour of reading light this evening to read a book by.

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If you had to start from scratch, let's say you go out into the countryside.

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You find a sheep. You kill it. You get the fat of of it.

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You render it down. You make a candle, etc. etc.

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How long is it going to take you? Quite a long time.

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How long do you actually have to work

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to earn an hour of reading light

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if you're on the average wage in Britain today?

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And the answer is about half a second.

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Back in 1950,

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you would have had to work for eight seconds on the average wage

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to acquire that much light.

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And that's seven and a half seconds of prosperity that you've gained.

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Since 1950, as it were.

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Because that's seven and a half seconds in which you can do something else.

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Or you can acquire another good or service.

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And back in 1880,

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it would have been 15 minutes

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to earn that amount of light from the average wage.

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Back in 1800,

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you'd have had to work six hours

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to earn a candle that could burn for an hour.

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In other words, the average person on the average wage

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could not afford a candle in 1800.

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Go back to this image of the axe and the mouse,

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and ask yourself: "Who made them and for who?"

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The stone axe was made by someone for himself.

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It was self-sufficiency. 

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We call that poverty these days.

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But the object on the right

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was made for me by other people.

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How many other people?

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Tens? Hundreds? Thousands?

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You know, I think it's probably millions.

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Because you've to include the man who grew the coffee,

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which was brewed for the man who was on the oil rig,

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who was drilling for oil, which was going to be made into the plastic, etc.

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They were all working for me,

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to make a mouse for me.

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And that's the way society works.

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That's what we've achieved as a species.

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In the old days, if you were rich,

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you literally had people working for you. 

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That's how you got to be rich; you employed them.

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Louis XIV had a lot of people working for him.

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They made his silly outfits, like this.

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(Laughter)

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And they did his silly hairstyles, or whatever.

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He had 498 people

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to prepare his dinner every night.

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But a modern tourist going around the palace of Versailles

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and looking at Louis XIV's pictures,

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he has 498 people doing his dinner tonight too.

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They're in bistros and cafes and restaurants

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and shops all over Paris.

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And they're all ready to serve you at an hour's notice with an excellent meal

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that's probably got higher quality 

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than Louis XIV even had.

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And that's what we've done, because we're all working for each other.

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We're able to draw upon specialization and exchange

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to raise each other's living standards.

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Now, you do get other animals working for each other too.

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Ants are a classic example; workers work for queens and queens work for workers.

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But there's a big difference,

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which is that it only happens within the colony.

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There's no working for each other across the colonies.

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And the reason for that is because there's a reproductive division of labor.

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That is to say, they specialize with respect to reproduction.

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The queen does it all.

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In our species, we don't like doing that.

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It's the one thing we insist on doing for ourselves, is reproduction.

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(Laughter)

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Even in England, we don't leave reproduction to the Queen.

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(Applause)

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So when did this habit start?

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And how long has it been going on? And what does it mean?

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Well, I think, probably, the oldest version of this

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is probably the sexual division of labor.

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But I've got no evidence for that.

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It just looks like the first thing we did

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was work male for female and female for male.

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In all hunter-gatherer societies today,

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there's a foraging division of labor

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between, on the whole, hunting males and gathering females.

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It isn't always quite that simple.

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But there's a distinction between

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specialized roles between males and females.

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And the beauty of this system

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is that it benefits both sides.

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The woman knows

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that, in the Hadzas' case here --

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digging roots to share with men in exchange for meat --

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she knows that all she has to do to get access to protein

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is to dig some extra roots and trade them for meat.

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And she doesn't have to go on an exhausting hunt

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and try and kill a warthog.

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And the man knows that he doesn't have to do any digging

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to get roots.

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All he has to do is make sure that when he kills a warthog

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it's big enough to share some.

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And so both sides raise each other's standards of living

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through the sexual division of labor.

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When did this happen? We don't know, but it's possible

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that neanderthals didn't do this.

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They were a highly cooperative species.

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They were a highly intelligent species.

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Their brains on average, by the end, were bigger than yours and mine

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in this room today.

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They were imaginative. They buried their dead.

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They had language probably,

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because we know they had the FOXP2 gene of the same kind as us,

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which was discovered here in Oxford.

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And it looks like they probably had linguistic skills.

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They were brilliant people. I'm not dissing the neanderthals.

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But there's no evidence

262
00:10:37,330 --> 00:10:39,330
of a sexual division of labor.

263
00:10:39,330 --> 00:10:42,330
There's no evidence of gathering behavior by females.

264
00:10:42,330 --> 00:10:45,330
It looks like the females were cooperative hunters with the men.

265
00:10:46,330 --> 00:10:48,330
And the other thing there's no evidence for

266
00:10:48,330 --> 00:10:50,330
is exchange between groups.

267
00:10:51,330 --> 00:10:54,330
Because the objects that you find in neanderthal remains,

268
00:10:54,330 --> 00:10:56,330
the tools they made,

269
00:10:56,330 --> 00:10:58,330
are always made from local materials.

270
00:10:58,330 --> 00:11:00,330
For example, in the Caucasus

271
00:11:00,330 --> 00:11:03,330
there's a site where you find local neanderthal tools.

272
00:11:03,330 --> 00:11:05,330
They're always made from local chert.

273
00:11:05,330 --> 00:11:07,330
In the same valley there are modern human remains

274
00:11:07,330 --> 00:11:09,330
from about the same date, 30,000 years ago.

275
00:11:09,330 --> 00:11:11,330
And some of those are from local chert,

276
00:11:11,330 --> 00:11:13,330
but more -- but many of them are made

277
00:11:13,330 --> 00:11:15,330
from obsidian from a long way away.

278
00:11:15,330 --> 00:11:17,330
And when human beings began

279
00:11:17,330 --> 00:11:19,330
moving objects around like this,

280
00:11:19,330 --> 00:11:22,330
it was evidence that they were exchanging between groups.

281
00:11:22,330 --> 00:11:25,330
Trade is 10 times as old as farming.

282
00:11:25,330 --> 00:11:28,330
People forget that. People think of trade as a modern thing.

283
00:11:28,330 --> 00:11:30,330
Exchange between groups has been going on

284
00:11:30,330 --> 00:11:33,330
for a hundred thousand years.

285
00:11:33,330 --> 00:11:35,330
And the early evidence for it crops up

286
00:11:35,330 --> 00:11:38,330
somewhere between 80 and 120,000 years ago in Africa,

287
00:11:38,330 --> 00:11:41,330
when you see obsidian and jasper and other things

288
00:11:41,330 --> 00:11:44,330
moving long distances in Ethiopia.

289
00:11:44,330 --> 00:11:46,330
You also see seashells --

290
00:11:46,330 --> 00:11:48,330
as discovered by a team here in Oxford --

291
00:11:48,330 --> 00:11:50,330
moving 125 miles inland

292
00:11:50,330 --> 00:11:53,330
from the Mediterranean in Algeria.

293
00:11:53,330 --> 00:11:55,330
And that's evidence that people

294
00:11:55,330 --> 00:11:57,330
have started exchanging between groups.

295
00:11:57,330 --> 00:11:59,330
And that will have led to specialization.

296
00:11:59,330 --> 00:12:01,330
How do you know that long-distance movement

297
00:12:01,330 --> 00:12:04,330
means trade rather than migration?

298
00:12:04,330 --> 00:12:06,330
Well, you look at modern hunter gatherers like aboriginals,

299
00:12:06,330 --> 00:12:09,330
who quarried for stone axes at a place called Mt. Isa,

300
00:12:09,330 --> 00:12:12,330
which was a quarry owned by the Kalkadoon tribe.

301
00:12:12,330 --> 00:12:14,330
They traded them with their neighbors

302
00:12:14,330 --> 00:12:16,330
for things like stingray barbs.

303
00:12:16,330 --> 00:12:18,330
And the consequence was that stone axes

304
00:12:18,330 --> 00:12:20,330
ended up over a large part of Australia.

305
00:12:20,330 --> 00:12:22,330
So long-distance movement of tools

306
00:12:22,330 --> 00:12:25,330
is a sign of trade, not migration.

307
00:12:25,330 --> 00:12:28,330
What happens when you cut people off from exchange,

308
00:12:28,330 --> 00:12:31,330
from the ability to exchange and specialize?

309
00:12:31,330 --> 00:12:33,330
And the answer is that,

310
00:12:33,330 --> 00:12:35,330
not only do you slow down technological progress,

311
00:12:35,330 --> 00:12:38,330
you can actually throw it into reverse.

312
00:12:38,330 --> 00:12:40,330
An example is Tasmania.

313
00:12:40,330 --> 00:12:43,330
When the sea level rose, and Tasmania became an island 10,000 years ago,

314
00:12:43,330 --> 00:12:45,330
the people on it, not only experienced

315
00:12:45,330 --> 00:12:48,330
slower progress than people on the mainland,

316
00:12:48,330 --> 00:12:50,330
they actually experienced regress.

317
00:12:50,330 --> 00:12:52,330
They gave up the ability to make [bone] tools

318
00:12:52,330 --> 00:12:54,330
and fishing equipment and clothing

319
00:12:54,330 --> 00:12:57,330
because the population of about 4,000 people

320
00:12:57,330 --> 00:12:59,330
was simply not large enough

321
00:12:59,330 --> 00:13:01,330
to maintain the specialized skills

322
00:13:01,330 --> 00:13:04,330
necessary to keep the technology they had.

323
00:13:04,330 --> 00:13:06,330
It's as if the people in this room were plonked on a desert island.

324
00:13:06,330 --> 00:13:08,330
How many of the things in our pockets

325
00:13:08,330 --> 00:13:11,330
could we continue to make after 10,000 years?

326
00:13:12,330 --> 00:13:14,330
It didn't happen in Tierra del Fuego --

327
00:13:14,330 --> 00:13:16,330
similar island, similar people.

328
00:13:16,330 --> 00:13:18,330
The reason, because Tierra del Fuego

329
00:13:18,330 --> 00:13:21,330
is separated from South America by a much narrower straight.

330
00:13:21,330 --> 00:13:23,330
And there was trading contact across that straight

331
00:13:23,330 --> 00:13:25,330
throughout 10,000 years.

332
00:13:25,330 --> 00:13:28,330
The Tasmanians were isolated.

333
00:13:28,330 --> 00:13:30,330
Go back to this image again

334
00:13:30,330 --> 00:13:33,330
and ask yourself, not only who made it and for who,

335
00:13:33,330 --> 00:13:36,330
but who knew how to make it.

336
00:13:36,330 --> 00:13:39,330
In the case of the stone axe, the man who made it knew how to make it.

337
00:13:39,330 --> 00:13:42,330
But who knows how to make a computer mouse?

338
00:13:42,330 --> 00:13:45,330
Nobody, literally nobody.

339
00:13:45,330 --> 00:13:48,330
There is nobody on the planet who knows how to make a computer mouse.

340
00:13:48,330 --> 00:13:50,330
I mean this quite seriously.

341
00:13:50,330 --> 00:13:52,330
The president of the computer mouse company doesn't know.

342
00:13:52,330 --> 00:13:55,330
He just knows how to run a company.

343
00:13:55,330 --> 00:13:57,330
The person on the assembly line doesn't know

344
00:13:57,330 --> 00:13:59,330
because he doesn't know how to drill an oil well

345
00:13:59,330 --> 00:14:02,330
to get oil out to make plastic, and so on.

346
00:14:02,330 --> 00:14:05,330
We all know little bits, but none of us knows the whole.

347
00:14:05,330 --> 00:14:07,330
I am of course quoting from a famous essay

348
00:14:07,330 --> 00:14:10,330
by Leonard Read, the economist in the 1950s,

349
00:14:10,330 --> 00:14:12,330
called "I, Pencil"

350
00:14:12,330 --> 00:14:15,330
in which he wrote about how a pencil came to be made,

351
00:14:15,330 --> 00:14:18,330
and how nobody knows even how to make a pencil,

352
00:14:18,330 --> 00:14:21,330
because the people who assemble it don't know how to mine graphite.

353
00:14:21,330 --> 00:14:24,330
And they don't know how to fell trees and that kind of thing.

354
00:14:24,330 --> 00:14:26,330
And what we've done in human society,

355
00:14:26,330 --> 00:14:28,330
through exchange and specialization,

356
00:14:28,330 --> 00:14:30,330
is we've created

357
00:14:30,330 --> 00:14:33,330
the ability to do things that we don't even understand.

358
00:14:33,330 --> 00:14:35,330
It's not the same with language.

359
00:14:35,330 --> 00:14:37,330
With language we have to transfer ideas

360
00:14:37,330 --> 00:14:40,330
that we understand with each other.

361
00:14:40,330 --> 00:14:42,330
But with technology,

362
00:14:42,330 --> 00:14:44,330
we can actually do things that are beyond our capabilities.

363
00:14:44,330 --> 00:14:47,330
We've gone beyond the capacity of the human mind

364
00:14:47,330 --> 00:14:49,330
to an extraordinary degree.

365
00:14:49,330 --> 00:14:51,330
And by the way,

366
00:14:51,330 --> 00:14:54,330
that's one of the reasons that I'm not interested

367
00:14:54,330 --> 00:14:56,330
in the debate about I.Q.,

368
00:14:56,330 --> 00:14:59,330
about whether some groups have higher I.Q.s that other groups.

369
00:14:59,330 --> 00:15:01,330
It's completely irrelevant.

370
00:15:01,330 --> 00:15:04,330
What's relevant to a society

371
00:15:04,330 --> 00:15:07,330
is how well people are communicating their ideas,

372
00:15:07,330 --> 00:15:09,330
and how well they're cooperating,

373
00:15:09,330 --> 00:15:11,330
not how clever their individuals are.

374
00:15:11,330 --> 00:15:13,330
So we've created something called the collective brain.

375
00:15:13,330 --> 00:15:15,330
We're just the nodes in the network.

376
00:15:15,330 --> 00:15:18,330
We're the neurons in this brain.

377
00:15:18,330 --> 00:15:20,330
It's the interchange of ideas,

378
00:15:20,330 --> 00:15:22,330
the meeting and mating of ideas between them,

379
00:15:22,330 --> 00:15:25,330
that is causing technological progress,

380
00:15:25,330 --> 00:15:27,330
incrementally, bit by bit.

381
00:15:27,330 --> 00:15:29,330
However, bad things happen.

382
00:15:29,330 --> 00:15:32,330
And in the future, as we go forward,

383
00:15:32,330 --> 00:15:35,330
we will, of course experience terrible things.

384
00:15:35,330 --> 00:15:37,330
There will be wars; there will be depressions;

385
00:15:37,330 --> 00:15:39,330
there will be natural disasters.

386
00:15:39,330 --> 00:15:42,330
Awful things will happen in this century, I'm absolutely sure.

387
00:15:42,330 --> 00:15:45,330
But I'm also that, because of the connections people are making,

388
00:15:45,330 --> 00:15:47,330
and the ability of ideas

389
00:15:47,330 --> 00:15:49,330
to meet and to mate

390
00:15:49,330 --> 00:15:51,330
as never before.

391
00:15:51,330 --> 00:15:53,330
I'm also sure

392
00:15:53,330 --> 00:15:55,330
that technology will advance,

393
00:15:55,330 --> 00:15:57,330
and therefore living standards will advance.

394
00:15:57,330 --> 00:15:59,330
Because through the cloud, 

395
00:15:59,330 --> 00:16:01,330
through crowd sourcing,

396
00:16:01,330 --> 00:16:03,330
through the bottom-up world that we've created,

397
00:16:03,330 --> 00:16:06,330
where not just the elites, but everybody

398
00:16:06,330 --> 00:16:08,330
is able to have their ideas

399
00:16:08,330 --> 00:16:10,330
and make them meet and mate,

400
00:16:10,330 --> 00:16:13,330
we are surely accelerating the rate of innovation.

401
00:16:13,330 --> 00:16:15,330
Thank you.

402
00:16:15,330 --> 00:16:19,330
(Applause)