This essay is based on the working paper “Prosperity in the Very Long Run” by Ian Morris.

There are many ways to define prosperity. For some, it is all about money in the bank; for others, it is about health, spiritual well-being, or happiness. But because humans are animals, all of these definitions in the end come down to the same thing: energy flows. Unless we each consume about two thousand kilocalories of energy each day from food, plus more for fuel and shelter, we will sicken and die. However, if we master bigger energy flows (by increasing the number of kilocalories we capture, the efficiency with which we use them, and/or the variety of ends to which we can apply them), we can invest them in other things, such as hospitals, churches, or Hoover Institutions. We become more prosperous. 

Energy flows are the central story of history. But when did this story begin, and how did it work? According to the Harvard astrophysicist Eric Chaisson, it is actually as old as time itself. Almost as soon as the universe was created, 13.8 billion years ago, the fundamental force of gravity began clumping subatomic particles into hydrogen and helium nuclei. After a billion years, the intense gravitational pressure at the center of vast gas clouds created nuclear reactors, fusing hydrogen and helium into heavier and more complex elements that, in turn, over billions more years, became stars and planets, some of the latter with atmospheres and at least one of them—our own—hosting life.

In principle, none of this should have happened, because the law of entropy means that every complex arrangement of matter is constantly decaying as energy leaks out of it. Eventually, the universe will reach thermodynamic equilibrium, an undifferentiated mush in which energy and matter are evenly distributed across time and space. The only reason this has not (yet) happened is that the existence of gravity and electromagnetism mean that complex clusters of matter can form, persist, and become even more complex by capturing free energy from their environments faster than entropy sucks it out of them. According to Chaisson’s calculations, atomic nuclei persist on energy budgets of less than 1/100th of an erg per second per gram of matter (erg/s/g), while a star like the sun needs about 10 erg/s/g, and even the simplest algae need 900 erg/s/g. When we get right down to it, the physicist Erwin Schrödinger believed, life is simply an efficient system for “continually sucking orderliness from its environment.” Most animals need at least 10,000 erg/s/g. The simplest human hunter-gatherer societies consumed 40,000 erg/s/g; ancient empires like the Romans got through 300,000 erg/s/g; and modern Americans use a whopping 2 million erg/s/g.

Yet, while humans’ exploding energy flows form part of a single story going back to the Big Bang, it would be odd to call subatomic particles, stars, or even algae “prosperous.” That is because prosperity is something that is deliberately created, and, so far as we know, humans are the only arrangements of matter in the universe able to deliberate about anything. Protons, neutrons, and electrons do not argue over whether to form atoms; gravity makes them do it. Humans, however, consciously debate whether to share ideas, adopt customs, and create institutions that will increase their energy flows. Anthropologists call this “cumulative cultural evolution,” by which they mean the ability not just to think of new ways of behaving—chimpanzees, crows, dolphins, and plenty of other kinds of animals do that—but to tweak and improve on older ideas and institutions in a ratchet effect, generating what the biologist Peter Richerson and anthropologist Robert Boyd describe as “the gradual, cumulative assembly of adaptations over many generations, adaptations that no single individual could evoke on his or her own.” No one could just invent a computer from scratch; it took the combined contributions of billions of minds spread across millions of generations.

Thanks to archaeology, we even have some idea of just how many generations are involved. African apes began walking upright 3.7 million years ago, freeing their front feet to evolve into hands and setting off neurophysiological feedback loops that rewarded the growth of bigger brains. By 3.4 million years ago, some apes had figured out that banging rocks together gave them sharp edges that could slice meat more efficiently off animal bones, providing the protein to feed their bigger brains; and 2.1 million years ago, their descendants spread all the way from Africa to China. 

Anthropologists argue over whether these increasing energy flows represent truly cumulative cultural evolution or just the biological evolution of bigger brains, but the case becomes stronger around 1.8 million years ago. By then, apes we call Homo ergaster (“working man”) looked somewhat like us, foraged in ways somewhat like those of modern hunter-gatherers, sometimes cooked their food, and may even have had something like speech. A million years ago, enough Homo ergaster managed to cross twelve miles of open water to establish a breeding population on the island of Flores in Indonesia; and by 500,000 years ago, they may have been tending to their sick and even creating crude art.

Here, too, experts debate whether we are seeing genuinely cumulative cultural evolution, but by 300,000 years ago, protohumans had learned to kindle fire at will and make highly efficient stone tools (some attached to wooden handles) and were making art much more often. The distinctive, domed skulls of our own sort of ape—Homo sapiens—also appear at this time, but other sorts of Homo, especially Neanderthals, were just as creative as us. It seems almost certain that cumulative cultural evolution and the deliberate pursuit of prosperity go back 300,000 years. But the pace of change remained glacially slow until about 45,000 years ago, probably because there were so few humans. DNA suggests that there were less than 15,000 Homo sapiens and even fewer Neanderthals in the world 150,000 years ago. Tiny, thinly scattered bands regularly died out before they could share their hard-won innovations with others; old ideas were lost almost as fast as new ones were being created.

Only around 100,000 years ago did much change, and not until 45,000 years ago did population growth and innovation become relentless. Cultural evolution remained shockingly slow by modern standards because populations remained small (global population did not reach one million until 25,000 years ago), communication technology remained simple, and innovators were building on a tiny stock of knowledge. But little by little, numbers, knowledge, and prosperity crept up. Villages of one hundred people were being formed by 25,000 bce (Dolní Věstonice in the Czech Republic), towns of one thousand by 7000 bce (Çatalhöyük in Turkey), cities of ten thousand by 3300 bce (Uruk in Iraq), supercities of one hundred thousand by 700 bce (Nineveh in Iraq), megacities of one million by 50 bce (Rome), and modern metropolises of ten million people only by the 1920s (New York). Throughout prehistory, most hunter-gatherers had a standard of living equivalent to $1.50 per day in modern terms, and none could read or write. By about 3000 bce, farmers might hope to live on the equivalent of $2–3 (in the World Bank’s terms, they had progressed from extreme poverty to just plain poverty), and a fraction of 1 percent of the population, living entirely in the Middle East, were literate. By 350 bce, ordinary Athenian citizens were earning a comparatively lavish $4-5 per day and maybe one man in four (and far fewer women) could read and write his own name. Not until the second millennium ce (and in most parts of the world, not until its very end) was this level of prosperity widely surpassed.

In a sense, human history is just one more chapter in the universal story of increasing energy flows, although the biological evolution of brains big enough for cumulative cultural evolution turned that story into one of rising prosperity. Evolutionists immodestly call our kind of ape Homo sapiens, “wise man,” but it might actually make more sense to call us Homo augens, “growing man.” Increasing prosperity, it seems, is just what we do.

However, there is one last twist in this otherwise happy tale. Evolution is an undirected process. Cumulative cultural evolution, like biological evolution, generates higher-energy systems only when they work better than lower-energy ones. Plenty of times in the past, environments have changed in ways that made entropy a sensible adaptation, and people responded by walking away from their cities, states, and systems of writing. In the best-known example, climate change, migrations, and political blunders left fifth-century ce elite Romans seeing little point in paying taxes to the center. As they stopped doing so, governments, trade routes, and law and order collapsed. The utility of maintaining decaying cities, roads, and schools declined, so people gave up on them, trading a golden age for a dark age.

What we don’t yet know is whether we will repeat this pattern in our own age.

Read the full working paper here.

Ian Morris is the Jean and Rebecca Willard Professor of Classics and senior fellow of the Stanford Archaeology Center at Stanford University, and a senior fellow of the IDEAS Institute at the London School of Economics.

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