A plethora of cultural and environmental sages predicted increasing poverty, pollution and pestilence. The last century was particularly pessimistic. He shows that such gloom-mongers have always been with us, and have always been proved wrong. Ridley's real target is those doomsayers who insist that everything is going from bad to worse and something must be done about it. The book's strength, however, does not lie in its economic analysis. This blanket suspicion of government is less convincing than Ridley's enthusiasm for trade. Attempts to control markets from the top down tend only to make things worse. In Ridley's view, things work better when individual economic actors construct solutions from the bottom up. Great civilisations are built when merchants find new markets, and decline when unproductive bureaucrats strangle their enterprise. Just as trade fosters prosperity, so excessive government stifles it. Sudden advances are often followed by long periods of stagnation. Of course the path of economic progress does not always run smooth. Far better to work at one thing and let the market supply the rest.

If you really had to make everything yourself, you would be back in the stone age, scrabbling around with hand axes. From this perspective, specialisation is the essence of humanity, and self-sufficiency a misguided myth. He takes us from the hunter-gatherers who first ventured out of Africa up to the modern moguls of Silicon Valley, and shows how humanity has built innovation on innovation in its never-ending search for new gizmos that people will want to buy. Ridley makes a strong case for this thesis. I make the hooks and you catch the fish – and together we achieve something that neither of us could manage on our own. Once we cottoned on to this trick, there was no stopping us. But they never saw the point of making things they could swap. Homo erectus had a large brain and probably a rudimentary language.

As he sees it, we owe the forward march of humankind to the benefits of barter. What makes us so different? Why have we come so far so quickly when our hominid predecessors were stuck in a rut for thousands of generations? Matt Ridley has a simple answer. Then we modern humans arrived, and within 100,000 years or so not only devised fish hooks and farming, but steam engines, cellophane and one-click buying. It never seemed to occur to our erectus ancestors that you could make a better hand axe. If you've seen one hand axe, you've seen them all. Once they started making axes, they stuck to the same design for more than a million years. We know this because they left crafted stone axes all over the globe. Homo erectus ape-men were avid tool users.

Matt ridley rational optimist