We may be human because we figured out how to use more energy than the 100 W that burns within us from the food we eat. Certainly, we hadn’t been human for very long before we learned to benefit from extra outside energy, with some of the wealthier of us now using more than 10,000 W apiece.
The switch from a hunter-gatherer lifestyle to agriculture gave us more food, but we have remained hunter-gatherers of external energy, collecting and burning wood, whales, or whatever we could get. We have always burned more of these than nature could supply. Even with Ben Franklin’s amazing stove, trees didn’t grow fast enough to fuel his fellow citizens of Pennsylvania. Burning whales for light was wiping them out when there were far fewer people than now, and when many of those people were illuminating with other, cheaper sources.
Earth spent a few hundred million ...
