Rats Pressing Levers

January 8, 2012 in The Commons by Rob Galbraith

In 1954, two biologists named Olds and Milner identified regions in the brain where, if stimulated in response to an action, animals would repeat that action as if they had been rewarded. It was an enormous breakthrough in understanding animal behavior, as Olds and Milner inferred that these are the brain areas that activate when an animal engaged in evolutionarily sound behavior – eating when hungry, for example, or drinking when thirsty, or reproducing. Olds and Milner studied rats.

Like our smaller mammalian brethren, humans also have centers in our brains that activate when engage in the behaviors naturally selected for over the millions of years of human evolution and billions of years of life on earth. It makes sense, too; if there was a trait by which the brain rewarded behaviors such as not eating or not reproducing, all the animals with that trait would die without passing it down to other generations. Olds and Milner found a shortcut around having to perform the behavior that is hardwired to the reward center, just activating the center itself with an electrical impulse.

Humans, in our seemingly endless ingenuity, have found similar shortcuts. Instead of hooking electrodes up to our brains (though in a way we do do this – it’s one way that cocaine and methamphetamine work), we have created incredibly ready access to all the food we could possibly eat. Granted, this is through no small amount of environmental, human, and other animal exploitation, but every time we bite into that El Nino Burrito, we are rewarded by our brain thanks to the circuitry deep within us that evolved because it kept us alive. Because we are rewarded in this fashion, however, all of the things that go into making that burrito are also rewarded: factory farmed beef, human slave labor picking tomatoes (are there tomatoes on an El Nino?), fossil fuel based pesticides that poison our water and put environmental pressures in place to create super-pests, the petroleum needed to ship all of these things all over the world and attendant pollution and global warning, and so on, and so forth. Because our brains reward us, we ignore big picture “externalities” in pursuit of the things that create the reward. We think of them as things that make life better or more comfortable, but we are killing ourselves in their pursuit. In countries with the readiest access to high-calorie food, there the highest rates of heart disease, diabetes, stroke, osteoporosis, and a host of other ailments. Americans and Chinese contribute the most greenhouse gases contributing to global climate change. We are pulling natural gas out of the ground through means that contaminate groundwater and create earthquakes. We have eaten almost all of the big fish in the ocean.

The rats in Olds and Milner’s study would activate their reward centers by pushing on a lever attached to the electrode in their brain. Later scientists found that rats would push the lever, self-stimulating to the point of exhaustion. Rats would run over shock grids and ignore warning signals of impending shock in order to self-stimulate and would even starve themselves to death, self-stimulating by pressing the lever instead of eating. Perhaps humans, in our seemingly endless ingenuity, can find a way to feed ourselves, reproduce, and live without taking such disastrous shortcuts.