The rat’s paw moves constantly, sometimes becoming a blur as it depresses the lever over and over. Once, twice, ten times, a hundred times, five thousand times in the space of an hour. With each push, an electrode sends a jolt of electricity coursing through its tiny rodent brain. The rat will push the lever for as long as 24 hours without stopping. It won’t eat, or sleep, or make any effort to leave the confines of its stainless steel cage. Unless the men in white lab coats cut off the current, it will stimulate itself to death.

It’s 1954, and science has just stumbled upon the brain’s pleasure center. Heady days! The excited researchers repeat the experiment on monkeys, and find, again, they can reach right into the hypothalamus and light it up like a Christmas tree, transforming their subjects into blissed-out automatons. The seminal paper concludes that these results could “very likely be generalized eventually to human beings—with modifications, of course”.

Of course…