Q: In Biology of Violence, you examine 20
years of research on the brain and on violence.
What are the major conclusions you’ve found?
A: The biggest lesson we have learned from
brain research is that violence, like all complex
human behaviors, is the result of a developmental process, a lifelong interaction between the
brain and the environment.
The way the brain
keeps track of our experiences is through the language of chemistry. It’s an
organic historian. These experiences get recorded as changes in the chemistry and the
hormones of the nervous system and particularly the circuitry for emotion and our responses to
When we come to
a new interaction with a new person, we bring to that a neuro-chemical
profile that is based on answers to some very important questions we’ve answered over a
period of years: Is the world safe? Are people generally trustworthy? What do I know about
this person from looking at her/him? What might I know from other sources?
That sets off some
emotional reactions within us and that emotion, the chemistry of those
feelings, is translated into our responses. Then that person reacts to us, and our emotional
response to their reaction also changes brain chemistry a little bit. So after every interaction, we
update our neuro-chemical profile of the world and of that relationship.
Q: So how does the interaction between brain
and environment begin?
A: The amazing thing about the human brain
is that it is so flexible, and it is very adaptable.
We are born with some things. We don’t come with a blank slate. We have a human brain
architecture; we have the desire to be social; we have the ability to use tools like language; and
we have a basic way of interacting with the world. Some babies are very excitable, some are
very laid back. And those differences in activity level, reactivity, and sensitivity are the basics
temperament. It’s what we bring to the situation. Then the way those characteristics fit with
particular environment goes on to shape that temperament and our behavior.
The most important
programming goes on in the circuitry that governs emotion and response to
the challenges of life, the stress. Our ability to shape those neuro-systems to fit our own
particular environment helps us to adapt to a particular situation. So, if we find ourselves in an
unsafe environment, we can adapt our behavior to survive. In comfortable, accommodating
circumstances, our behavior changes in a different way.
Q: And do we have conscious control over changing that template?
A: As adults, with some outside help, we
can look at our patterns of behavior and we can use
conscious means to change and control some of those emotional responses. Children less so,
because those systems are among the slowest in the brain to develop.
Q: By what age do those systems tend to
be fully developed?
A:The parts of the brain that we like to
think of as being rational or reasoning – able to work
with ideas rather than simply react to the environment –take a good 20 years to develop. The
prefrontal cortex, which is one of the best developed areas in human beings, is really important
to representational thinking or the ability to manipulate ideas and thoughts. Those functions of
the brain aren’t completely mature until early adulthood.
Q:And how does that relate to violence?
A:Well, that circuitry is overlaid and connected
to the circuitry of emotions. So the two work
hand in hand. Aggression, the ability to use force, is a natural part of the behavior repertoire of
living things. Aggression is important. If we couldn’t be aggressive, we couldn’t defend
ourselves, or our children. We wouldn’t be able to compete for jobs or compete in sports. But
when that normal behavior becomes inappropriate, when it is directed toward the wrong
person, in the wrong place, at the wrong time, and with the wrong intensity, then it becomes
violent and it becomes unacceptable.
When that happens,
there is a change in the person’s ability to accurately determine whether
something is a real threat. Either they are overreacting to benign stimuli, or they are not reacting
to very real threats, like the threat of punishment. Something has gotten out of whack in their
ability to understand and react correctly to their environment. The frontal cortex plays a big role
in providing additional information to our emotional reactions, to clarifying those reactions by
saying, “Wait a minute, that’s not really the way things are working. Step back and take
minute to think.”
If a person has
come to believe that the world is against them, and they are overreacting to
every little provocation, these violent reactions get beyond their ability to control because they
are in survival mode.