nature | Groups of humans have always slaughtered those who belong to other
groups. The twentieth century was shot through with numerous examples,
from the genocides of Armenians in Ottoman Turkey and of Jews in Nazi
Europe to the massacres of ethnic rivals in civil wars in Rwanda and
Bosnia during the 1990s. Today, the fundamentalist group ISIS is
spooking the world with its willingness to butcher others who do not
adhere to its extremist form of Islam.
Attempts to understand such events tend to focus on political
reasons. But a conference in Paris last month dared to ask a different
question: how, biologically speaking, do normally non-violent and
psychologically stable people overcome the instinctive human aversion to
killing when faced with circumstances of war or extremism? What drives
them to participate in acts of genocide? This is arguably the biggest
challenge for interdisciplinary dialogue across the fields that consider
brain and behaviour.
All human behaviours
originate in the brain, which computes cognitive and emotional
information to decide what to do. So what, precisely, happens in that
organ at the moment that a person’s natural abhorrence of harming others
is computed out of the equation?
The organizers of last month’s conference at the Paris Institute of Advanced Studies — ‘The Brains that Pull the Triggers’ — deserve
credit for even posing this question. It goes against another human
instinct: to consider evil in moral rather than biological terms, as if
identifying a biological signature in the brain might somehow be
exploited as an excuse to absolve a person of his or her responsibility.
Neuroscientists
have studied the abnormal condition of psychopathy in addition to
components of normal cognition — such as the recognition of emotions in
the faces of others — that may have a bearing on the problem. And
psychologists and sociologists have looked at the behaviour of ordinary
individuals who identify themselves with particular groups and align
their behaviour with that group.
