FOURTH PROPOSITION
IT IS SCIENTIFICALLY INCORRECT to say that humans have a "violent brain." While we do have the neural apparatus to act violently, it is not automatically activated by internal or external stimuli. Like higher primates and unlike other animals, our higher neural processes filter such stimuli before they can be acted upon. How we act is shaped by how we have been conditioned and socialized. There is nothing in our neurophysiology that compels us to react violently.
COMMENTARY
Among the scientists who drafted the Seville Statement, several are engaged in research on the brain. Brain research has investigated how the brain controls emotions like anger and fear and social skills like the ability to learn and the use of language.
Most of the research on the brain mechanisms of aggressive behavior has been done on laboratory rats and cats, as reviewed by Seville signatory David Adams. Even at the level of these animals, whose behavior is simpler than that of monkeys and humans, the brain mechanisms of aggression are not automatically elicited by stimuli, but are modulated in terms of the social context, for example, the extent to which the other animal is familiar.
In monkeys and apes, the situation is even more complicated. For example, José Delgado and his co-workers have shown that aggressive behavior evoked by electrical stimulation of the brain may be expressed by a monkey against a subordinate opponent, but would not be expressed against a dominant opponent. In a related experiment on apes, electrical stimulation of the brain of a gibbon produced aggressive behavior in the laboratory, but not when it was tested in a natural situation on a island.
The review concluded that "human aggressive behavior is far more complex than that of other vertebrates. It has been transformed by many cultural factors such as the development of institutions and economic systems and the elaboration of motor patterns with tools and language. Knowing this, we have a moral obligation to avoid oversimplified phylogenetic extrapolations which may be particularly provocative, and we should make it clear that such human phenomena as crime and war are not the inevitable results of neural circuitry."
