At a stroke, fire reduced significantly that existential threat. These benefits meant fire quickly became one of the first and most important examples of what economists would these days call a GPT – a General Purpose Technology.2 This is a technology that can be used 1 2  Dunbar (1993). Bresnahan and Trajtenberg (1995). 3  All speeches are available online at www.bankofengland.co.uk/speeches  3  across a wide variety of settings to a wide variety of tasks in a wide variety of places. Fire was the formative GPT for the human species, providing many of the everyday essentials of heat, light and protection. As with many GPTs, however, perhaps the greatest benefit of domesticating fire may have come indirectly and inadvertently. It was not a benefit primitive humans could remotely have foreseen at the time. Yet it was a benefit that, in time, would transform not just human bodies but human brains, not just human lives but human evolution. That elusive, transformational benefit was cooking. Fire transformed what humans ate. Cooking made edible the inedible, in particular protein-rich staples such as rice, wheat and potatoes. Cooking reduced the chances of illness from eating, by killing germs and parasites commonplace in foodstuffs. And cooking made it quicker and easier for human bodies to digest all foodstuffs, causing humans’ intestinal track (the part responsible for digestion) to shorten dramatically.3 Together, these had a transformative impact on the human body. Cooking meant far less of our bodies’ energies were devoted to gathering, eating and digesting food.

In each Industrial Revolution, a first imaginative step resulted in a great leap forward for societal living standards, a mass flourishing.18 In that sense the three industrial revolutions of the past three centuries fit the longer-run evolutionary arc of humankind. It is creativity and imagination, fuelled by big brains and nourished by cooked meals, that set humans on their jet-propelled evolutionary path. The rapid, ideas-fuelled, progress made by societies over recent centuries is a continuation of that ever-upward evolutionary arc. Except, that is, for one small detail. The evolutionary arc of humans has not been ever-upward. The historical path has not been a North-bound ascent. While human ingenuity and creativity have been ever-  17 18  Haldane (2018a). Mokyr (2011). 9  All speeches are available online at www.bankofengland.co.uk/speeches  9  present, economies and societies have in fact spent protracted periods crabbing sideways. Prior to the first Industrial Revolution, living standards appear to have been essentially static for several thousand years.19 Living standards in Glasgow in 1750 were little different than their ancestors constructing Hadrian’s Wall. Levels of poverty, nutrition, infant mortality, height and longevity would also have been indistinguishable. Prior to the Industrial Revolution, societies and economies stood still, financially and physiologically. There was flat-lining, not mass flourishing. Societal progress was far from being a social norm. What explains this great pause in living standards? It was not through lack of ideas and imagination. People did not suddenly make like monkeys for millennia.