Genetics and Violence
The publication in August in 'Science' magazine of the
first strong evidence linking a specific gene to violent behaviour
will come, in time, to be seen as a landmark in behavioural
genetics. It should also be a wake-up call to critics of behavioural
genetics: there is a desperate need to update and refresh arguments
which are looking increasingly dogmatic and rusty.
The paper,
by Caspi et al is
significant not only for its findings but also for its methodology.
Unlike previous studies, which have looked for direct links between
genes and behaviour, Caspi et
al looked at the interaction between their candidate gene, MAOA,
and an 'environmental' variable, experience of abuse in
childhood.The MAOA
gene codes for monoamine oxidase, which eliminates excess
neurotransmitters, such as norepinephrine, serotonin and dopamine,
which are known to affect mood. Prior evidence, including the
well-known study of a violent Dutch family with an MAOA mutation,
and the established link between childhood abuse and later violent
behaviour, made the search for interaction between these variables
logical.
The
study uses a group of New Zealand men and women that has been
tracked since childhood. The researchers genotyped 442 young men for
a MAOA variation which leads to low activity of the enzyme. They
found that while there was no link between MAOA genotype and
violence in the group as a whole, amongst men who had suffered abuse
in childhood, those with low MAOA activity were nearly four times as
likely to have been convicted of a violent crime by the age of
26. Similar results
were found with two other independent measures of antisocial
behavior, making it unlikely that the results are artefactual. 85% of
those with both risk factors, who were 12% of the total, developed
some form of antisocial behaviour.
These findings, if replicated,
are extremely significant. Although there is a long history of
failure to replicate in behavioural genetics, and indeed in current
attempts to identify genetic risk factors for common diseases, it
would be unwise to assume that this will happen in this case. Unlike
many behavioural genetics studies, the effect identified is large,
probably largely due to the improved methodology: in previous
studies the researchers attempted to identify genetic effects in the
whole sample population, in which many subjects did not share the
relevant environmental risk factor. Such studies generally find
small, barely statistically significant effects which are not
replicated. A similar problem is no doubt at the root of the failure
of many current studies to find clear, replicable, disease
susceptibility loci.
It seems
likely, then, that MAOA variations have a strong effect on
aggression in men who have suffered abuse. This will be hard to
swallow for many liberals who still, with various degrees of
sophistication, believe in a 'blank slate' model of human
development. But swallow it we must, and find a way to digest it,
too. Whilst many readers will not be too shocked by the idea that
genes can affect behaviour, many liberals tend to cling to a
comfortable scepticism about behavioural genetics. The most foolish
aspect of this is the assumption that the long term and ongoing
association of the field with eugenics and racism means that
behavioural genetics is bad science. This is obviously wrong. Liberal critics of
behavioural genetics also tend to have vague ideas about the
pitfalls of twin studies methodology and a feeling that IQ tests are
racially biased. But
whilst some critiques of twin studies are still valid, on the whole
our ideas about the scientific validity of behavioural genetics are
out of date. Over the past 20 years, behavioural genetics has become
much more sophisticated and has addressed many of the methodological
criticisms; the Caspi et
al study is the latest step in this process. A significant body of
evidence for genetic effects on behaviour now exists. This study should serve as a catalyst for us to re-examine
our critiques of behavioural genetics.
While it
is impossible here to do justice to what a refreshed critical
position on behavioural genetics would look like, the Caspi et al paper illustrates some key aspects of the problems raised by
behavioural genetics.In my
view, while the exploitation of behavioural genetics research by
reactionary and racist political forces remains a threat, these are
not its real driving forces.
Like the early 1990s Violence Initiative, this study was
funded by medical research funding agencies, not crime
prevention institutions.
Its most sinister aspect is its involvement in processes that
are often mistaken for 'progress' by liberals: the control of social
disorder through medicalisation. After all, what could be more
benign and sensible than to prevent violence and disorder by
'helping' those children unlucky enough to have both suffered abuse
and to carry a low activity MAOA allele, first by counselling and
later, no doubt, by pharmaceutical intervention? There can be no doubt that
this will be irresistible to both liberal and conservative
politicians.
In his 'The History of Sexuality', the French philosopher and sociologist
Michel Foucault describes the emergence in the 18th century of a new form of power, 'bio-power'. Bio-power controls
society through two intersecting approaches: the discipline and
normalisation of individual bodies and the regulation of the
population at large.
Its purpose is to control disorder and maximise the
productive forces of the population for capital accumulation.
Bio-power works through medicine, hygiene, manners and training on
the one hand, and through the sciences of epidemiology, demography,
sociology, and public health.
At the intersection of the population and individual arms of
biopower lies eugenics.
Bio-power is not repressive: on the contrary, it seems
benign, rational, progressive and sensible as it manages and
marshals the forces of life.
By 'measuring, appraising and hierarchising, it effects
distributions around the norm'.
Behavioural genetics, with its emblem of the normal or
Bell Curve, exemplifies bio-power and the work of Caspi et al, is a beautiful
example of how it works.
The individualising power of genetics is currently driving a
critical change in public health philosophy, away from the
one-size-fits-all approach towards an even greater focus on
identifying 'high-risk groups'. Again, this seems benign and
rational, a win-win situation for individuals and the state: why
waste resources on those who are at low risk and fail to make the
crucial preventive intervention on those who are high risk? This approach, which
encompasses both disease susceptibility and pharmacogenetics has
been described as rational medicine, and is widely predicted to
revolutionise the paradigm and structures of healthcare
delivery.
Yet, ironically, as a little reflection on Caspi et al will show, such a
strategy risks disastrously backfiring when applied in the area of
crime prevention. Even the most kind-hearted attempt to identify and 'help' those abused children with low activity MAOA alleles will
almost inevitably do damage to their own self-identity and lead to
their stigmatisation by others. To label and medicalise
these children can only give them the message that there is
something deeply and intrinsically wrong and bad about them, and
that everyone else thinks that they are the problem. This is precisely the
message they will have received from their abusers. Such medical
interventions are more likely to precipitate the kind of anti-social
behaviour the doctors are seeking to prevent than almost anything
else I can think of. In
turn, this will lead to a spiral of further interventions. Any fool can see this. Any
fool, that is, except a well-meaning scientist. For Caspi et al are not reactionaries.
Rather, this example illustrates beautifully the answer to the
perennial question of why scientists lend themselves so willingly
and easily to the purposes of capitalism. It is that combination of
naivety and arrogance in which we train our scientists that allows
them to overlook the obvious while believing they are doing
unchallengeable good for the world. Thus do the forces of bio-power and technocracy roll on.
For me,
the most frightening aspect of behavioural genetics, is the far
greater penetration that it gives to the powers of discipline, its
ability to identify the problematic or dangerous individual and its
opening of new, and commercially profitable, possibilities of
normalisation through biological interventions. The problem with behavioural
genetics is not that it is simply part of an old-fashioned right
wing agenda. We need a more realistic critique that questions its
role in medicalisation and other benign-seeming processes of social
control.
There
will no doubt be other studies of this kind, which will find strong
links between genes and behaviour. The lesson we should draw
from Caspi et al is that we must stop hoping that behavioural
genetics will fail, or that we can discredit it by linking it to
racism. I hope we can
take this opportunity to re-examine our arguments. If we
fail to do so, for fear of conceding ground to eugenicists, we are
likely to find ourselves increasingly irrelevant in the debate over
the social policy implications of genetics.
References
1. Caspi, A. et al 2002
Science No 297 ps 851-854.
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