Is it possible to distinguish a future murderer from a law-abiding person? It may not be possible with the naked eye, but with the help of a positron tomograph it’s easy. In any case, this is what psychologist Richard Davidson and his colleagues from the University of Wisconsin-Madison (USA) think. Having made tomograms of the brains of 500 people with a propensity for violence (convicted murderers, aggressive mental patients, etc.), and comparing them with the brains of normal people, they found clear differences in the same areas of the cortex and subcortical nuclei. According to Davidson, this not only allows for the early identification of potential criminals, but also opens the way to the development of treatments for excessive aggressiveness.