But we now know that hunter-gatherers like the Ju/’hoansi did not live constantly on the edge of starvation. Rather, they were usually well nourished; lived longer than people in most farming societies; rarely worked more than fifteen hours a week; and spent the bulk of their time at rest and leisure. We also know that they could do this because they did not routinely store food, cared little for accumulating wealth or status, and worked almost exclusively to meet only their short-term material needs. Where the economic problem insists that we are all cursed to live in the purgatory between our infinite desires and limited means, hunter-gatherers had few material desires, which could be satisfied with a few hours of effort. Their economic life was organized around the presumption of abundance rather than a preoccupation with scarcity. And this being so, there is good reason to believe that because our ancestors hunted and gathered for well over 95 percent of Homo sapiens’ 300,000-year-old history, the assumptions about human nature in the problem of scarcity and our attitudes to work have their roots in farming.

It is also clear, as the busy-building weavers remind us, that while success or failure in the energy quest will always shape the evolutionary trajectory of any species, many hard-to-explain animal traits and behaviors may well have been shaped by the seasonal overabundance of energy rather than the battle for scarce resources, and that in this may lie a clue as to why we, the most energy-profligate of all species, work so hard.

As farming societies grew more productive and captured more energy from their environments, energy appeared to be scarcer and people had to work harder to meet their basic needs. This was because, up until the Industrial Revolution, any gains in productivity farming peoples generated as a result of working harder, adopting new technologies, techniques, or crops, or acquiring new land were always soon gobbled up by populations that quickly grew to numbers that could not be sustained. As a result, while agricultural societies continued to expand, prosperity was usually only ever fleeting, and scarcity evolved from an occasional inconvenience that foragers stoically endured every once in a while to a near perennial problem. In many respects, the hundreds of generations of farmers who lived before the fossil-fuel revolution paid for our extended lifespans and expanded waistlines now by enduring lives that were mostly shorter, bleaker, and harder than ours, and almost certainly tougher than those of their foraging ancestors.

To foragers, change was immanent in the environment—it happened all the time, when the wind blew, the rain fell, or an elephant cleared a new path. But change was always constrained by a deeper sense of confidence in the continuity and predictability of the world around them. Every season was different from those that preceded it, yet these differences always fell within a range of predictable changes. Thus for the Ju/’hoansi, when they were still free to forage as their ancestors had, carrying the weight of history was as inconvenient as carrying a house around, and abandoning the deep past freed them to engage with the world around them unencumbered by ancient precedents or future ambitions.

Where foragers stoically accepted occasional hardships, farmers persuaded themselves that things could always be better if they worked a little harder. Farmers who put in the extra hours would, over time, usually do better than lazier ones who only ever made contingency for the one or two risks they considered to be the most likely. Thus among the Ju/’hoansi’s farming neighbors along the Kavango River the wealthiest ones were usually the most risk-averse—those who worked hardest to build good enclosures to protect their cattle and goats from predators at night; who spent long summer days diligently chasing birds, monkeys, and others drawn to their fields; who planted their seeds a little deeper; who went to the trouble of dragging bucketloads of water from the river to irrigate their crops just in case, as occasionally happened, the rains arrived late.