While everyone's always waxing like Lord Tennyson about nature being "red in tooth and claw," neuroscience and psychology are quietly telling us that we may be innately nicer than we think. Sure, we're not cuddly little bunny rabbits, but many lines of evidence over the past few decades have pointed toward some distinctly physical underpinning of basic morality and aversion to violence, implying that humans (and probably many other animals, too) have a strong built-in "try-not-to-punch-that-dude" mechanism.
A recent study published in the journal Emotion, by psychologists Fiery Cushman, Allison Gaffey, Kurt Gray, and Wendy Mendes, provides some further evidence for the link, as the authors put it, "between the body and moral decision-making processes."
This may be the first paper to have experimental subjects simulate murder with a real gun (it's certainly the first one I've ever read). Essentially, the experimenters wanted to show that it is the physical act of potentially doing harm, rather than the viewing or hearing about such acts, that really turns your stomach. Subjects performed three kinds of actions: simulating direct harm (i.e. pulling the trigger of an unloaded gun pointed at one of the scientist's face), watching someone else simulate direct harm, and performing a neutral motor action (i.e. slicing bread). Subjects' physical responses were measured via blood pressure and heart rate, which are known to have a central role in reactions of disgust, aversion, and stress.
OK, I can't help pasting this image from the paper below showing the harmful vs. non-harmful actions, if for no other reason than to give you a nice peek into the art of "baby smacking."
The results, as predicted, were that the heart rates and blood pressures of subjects during and after the performance of harmful tasks were the highest by far: "These simulated harmful actions increased peripheral vasoconstriction significantly more than did witnessing pretend harmful actions or to performing metabolically matched non-harmful actions," they wrote. "This suggests that the aversion to harmful actions extends beyond empathic concern for victim harm."
The implications of this seemingly obvious result are really interesting. The idea of physically harming someone right in front of you is considered to be the most potent moral circumstance. Sarah McLaughlin talking about dog adoption behind sappy music might make you change the channel, but kicking a stray dog in the face will seriously mess with your conscience. How about a better example. Take the following moral dilemma:
A runaway trolley is about to run over and kill five people, but a bystander who is standing on a footbridge can shove a man in front of the train, saving the five people but killing the man. Is it permissible to shove the man?
Across cultures, genders, ages, and races, the result is essentially the same and has been replicated countless times: over 90% of respondents consider this act impermissible. People just don't want to have to do the pushing themselves. When a "lever" is added to the problem, and the person questioned can now drop the bystander onto the tracks without physically touching him, the result is flipped and 95% of people find it permissible.
It makes sense that this is how basic human morality evolved. Our species didn't evolve with any long range weapons or fancy bystander-killing levers. Decisions about violence were always made face to face. And because our species thrived from cooperation, it's no wonder that we're programmed to avoid directly harming others. We're less "red in tooth and claw," and more "soft in hands and face." Of course, humans commit violence all of the time and it is a central part of society. But the fact that we take it so seriously shows how much of a psychological transgression we find it to be. Violence is, and always will be, extreme.
To leave you on a dark, disturbing note, Cushman et al. wisely mention the connection between modern warfare (where our weapons don't demand face to face contact) and the quaint physical moral sense described above:
The action aversion model also suggests a darker side: When banal or novel actions lack motoric and perceptual properties associated with harm, they may fail to trigger an aversive response. Signing one's name to a torture order or pressing the button that releases a bomb each have real, known consequences for other people, but as actions they lack salient properties reliably associated with victim distress. A notable parallel is evident in moral judgment: People consider it morally worse to cause harm through direct physical engagement than at a distance.
So, for example, is this why people are okay with a Middle Eastern drone war? Well, it's tough to tell, but with pilots exhausted and suffering post-traumatic stress, perhaps our physical moral sense isn't totally distance-dependent.