Just say "No" to violence against testosterone

Say NO to violence against Testosterone!

Contemporary research shows that testosterone does not cause
aggression. At most testosterone can exaggerate the aggression that is
already there.

The implications of this ground-breaking research are major,
indicating that all previous social policies based on the idea of the
'biologically programmed to be more aggressive male' must be revoked
and looked at afresh. (the current ads for violence against women
being case in point).

The following is by a leading biological scientist:


THE TROUBLE WITH TESTOSTERONE by Robert M. Sapolsky

"Social conditioning can more than make up for the hormone"

What evidence links testosterone with aggression? Some pretty obvious
stuff. Males tend to have higher testosterone levels in their
circulation than do females (one wild exception will be discussed
later) and tend to be more aggressive. Times of life when males are
swimming in testosterone (for example, after reaching puberty)
correspond to when aggression peaks. Among numerous species, testes
are mothballed most of the year, kicking into action and pouring out
testosterone only during a very circumscribed mating season- precisely
the time when male aggression soars.
Impressive, but these are only correlative data, testosterone
repeatedly being on the scene with no alibi when some aggression has
occurred. The proof comes with the knife, the performance of what is
euphemistically known as a "subtraction" experiment. Remove the source
of testosterone in species after species and levels of aggression
typically plummet. Reinstate normal testosterone levels afterward with
injections of synthetic testosterone, and aggression returns.
To an endocrinologist, the subtraction and replacement paradigm
represents pretty damning proof: this hormone is involved. "Normal
testosterone levels appear to be a prerequisite for normative levels
of aggressive behavior" is the sort of catchy, hummable phrase that
the textbooks would use. That probably explains why you shouldn't mess
with a bull moose during rutting season. But that's not why a lot of
people want to understand this sliver of science. Does the action of
this hormone tell us anything about individual differences in levels
of aggression, anything about why some males, some human males, are
exceptionally violent? Among an array of males -human or otherwise-
are the highest testosterone levels found in the most aggressive
individuals?
Generate some extreme differences and that is precisely what you see.
Castrate some of the well-paid study subjects, inject others with
enough testosterone to quadruple the normal human levels, and the high-
testosterone males are overwhelmingly likely to be the more aggressive
ones. However, that doesn't tell us much about the real world. Now do
something more subtle by studying the normative variability in
testosterone -in other words, don't manipulate anything, just see what
everyone's natural levels are like- and high levels of testosterone
and high levels of aggression still tend to go together. This would
seem to seal the case -interindividual differences in levels of
aggression among normal individuals are probably driven by differences
in levels of testosterone. But this turns out to be wrong.
Okay, suppose you note a correlation between levels of aggression and
levels of testosterone among these normal males. This could be (a)
testosterone elevates aggression; (b) aggression elevates testosterone
secretion; (c) neither causes the other. There's a huge bias to assume
option a, while b is the answer! Study after study has shown that when
you examine testosterone levels when males are first placed together
in a social group, testosterone levels predict nothing about who is
going to be aggressive. The subsequent behavioral differences drive
the hormonal changes, rather than the other way around.
Because of a strong bias among certain scientists, it has taken
forever to convince them of this point. Behavioral endocrinologists
study what behavior and hormones have to do with each other. How do
you study behavior? You get yourself a notebook and a stopwatch and a
pair of binoculars. How do you measure the hormones? You need a
gazillion-dollar machine, you muck around with radiation and
chemicals, wear a lab coat, maybe even goggles- the whole nine yards.
Which toys would you rather get for Christmas? Which facet of science
are you going to believe in more? Because the endocrine aspects of the
business are more high-tech, more reductive, there is a bias to think
that it is somehow more scientific, more powerful. This is a classic
case of what is often called physics envy, the disease among
scientists where the behavioral biologists fear their discipline lacks
the rigor of physiology, the physiologists wish for the techniques of
the biochemists, the biochemists covet the clarity of the answers
revealed by molecular biologists, all the way down until you get to
the physicists, who confer only with God. Hormones seem to many to be
more real, more substantive, than the ephemera of behavior, so when a
correlation occurs, it must be because hormones regulate behavior, not
the other way around.
As I said, it takes a lot of work to cure people of that physics envy,
and to see that interindividual differences in testosterone levels
don't predict subsequent differences in aggressive behavior among
individuals. Similarly, fluctuations in testosterone levels within one
individual over time do not predict subsequent changes in the levels
of aggression in that one individual - get a hiccup in testosterone
secretion one afternoon and that's not when the guy goes postal.
Look at our confusing state: normal levels of testosterone are a
prerequisite for normal levels of aggression, yet changing the amount
of testosterone in someone's bloodstream within the normal range
doesn't alter his subsequent levels of aggressive behavior. This is
where, like clockwork, the students suddenly start coming to office
hours in a panic, asking whether they missed something in their
lecture notes.
Yes, its going to be on the final exam, and its one of the more subtle
points in endocrinology- what is referred to as a hormone having a
"permissive effect". Remove someone's testes and, as noted, the
frequency of aggressive behavior is likely to plummet. Reinstate
precastration levels of testosterone by injecting that hormone, and
precastration levels of aggression typically return. Fair enough. Now
this time, castrate an individual and restore testosterone levels to
only 20 percent of normal and ... amazingly, normal precastration levels
of aggression come back. Castrate and now generate twice the
testosterone levels from before castration- and the same level of
aggressive behavior returns. You need some testosterone around for
normal aggressive behavior - zero levels after castration, and down it
usually goes; quadruple it (the sort of range generated in weight
lifters abusing anabolic steroids), and aggression typically
increases. But anywhere from roughly 20 percent of normal to twice
normal and it's all the same; the brain can't distinguish among this
wide range of basically normal values.

We seem to have figured out a couple of things by now. First, knowing
the differences in the levels of testosterone in the circulation of a
bunch of males will not help you much in figuring out who is going to
be aggressive. Second, the subtraction and reinstatement data seem to
indicate that, nevertheless, in a broad sort of way, testosterone
causes aggressive behavior. But that turns out not to be true either,
and the implications of this are lost on most people the first thirty
times you tell them about it. Which is why you'd better tell them
about it thirty-one times, because it is the most important point of
this piece.
Round up some male monkeys. Put them in a group together, and give
them plenty of time to sort out where they stand with each other-
affiliative friendships, grudges, and dislikes. Give them enough time
to form a dominance hierarchy, a linear ranking system of numbers 1
through 5. This is the hierarchical sort of system where number 3
monkey, for example, can pass his day throwing around his weight with
numbers 4 and 5, ripping off their monkey chow, forcing them to
relinquish the best spots to sit in, but, at the same time,
remembering to deal with numbers 1 and 2 with ***-eating
obsequiosness.
Hierarchy in place, it's time to do your experiment. Take that third
ranking monkey and give him some testosterone. None of this within-the-
normal-range stuff. Inject a ton of it into him, way higher than what
you normally see in a rhesus monkey; give him enough testosterone to
grow antlers and a beard on every neuron in his brain. And, no
surprise, when you then check the behavioral data, it turns out that
he will probably be participating in more aggressive interactions than
before.
So even though small fluctuations in the levels of the hormone don't
seem to matter much, testosterone still causes aggression. But that
would be a wrong conclusion. Check out number 3 more closely. Is he
now raining aggressive terror on any and all in the group, frothing in
an androgenic glaze of indiscriminate violence? Not at all. He's still
judiciously kowtowing to numbers 1 and 2, but has simply become a
total *** to numbers 4 and 5. This is critical: testosterone isn't
causing aggression, it's exaggerating the aggression that's already
there.
Another example just to show we're serious. There's a part of your
brain that probably has lots to do with aggression, a region called
the amygdala. Sitting right near it is the Grand Central Station of
emotion-related activity in your brain, the hypothalamus. The amygdala
communicates with the hypothalamus by way of a cable of neuronal
connections called stria terminalis. No more jargon, I promise. The
amygdala has its influence on aggression via that pathway, with bursts
of electrical excitation called action potentials that ripple down the
stria terminalis, putting the hypothalamus in a pissy mood.
Once again, do your hormonal intervention; flood the area with
testosterone. You can do that by injecting the hormone into the
bloodstream, where it eventually makes its way to this part of the
brain. Or you can be elegant and surgically microinject the stuff
directly into this brain region. Six of one, half a dozen of the
other. The key thing is what doesn't happen next. Does testosterone
now cause there to be action potentials surging down the stria
terminalis? Does it turn on that pathway? Not at all! If and only if
the amygdala is already sending an aggression-provoking volley of
action potentials down the stria terminalis, testosterone increases
the rate of such action potentials by shortening the resting time
between them. It's not turning on the pathway, it's increasing the
volume of signaling if it is already turned on. It's not causing
aggression, it's exaggerating the preexisting pattern of it,
exaggerating the response to environmental triggers of aggression.
This transcends issues of testosterone and aggression. In every
generation, it is the duty of behavioral biologists to try to teach
this critical point, one that seems a maddening chiche' once you get
it. You take that hoary old dichotomy between nature and nurture ,
between biological influences and environmental influences, between
intrinsic factors and extrinsic ones, and, the vast majority of the
time, regardless of which behavior you are thinking about and what
underlying biology you are studying, the dichotomy is a sham. No
biology. No environment. Just the interaction between the two.

Environment and Testosterone:

Do you want to know how important environment and experience are in
understanding testosterone and aggression? Look back at how the
effects of castration were discussed earlier. There were statements
like "Remove the source of testosterone in species after species and
levels of aggression typically plummet." Not "Remove the source ... and
aggression always goes to zero." On average it declines, but rarely to
zero, and not at all in some individuals. And the more social
experience an individual had being aggressive prior to castration, the
more likely that behavior persists sans cojones. Social conditioning
can more than make up for the hormone.
Another example, one from one of the stranger corners of the animal
kingdom: If you want your assumptions about the nature of boy beasts
and girl beasts challenged, check out the spotted hyena. These animals
are fast becoming the darlings of endocrinologists, sociobiologists,
gynecologists, and tabloid writers. Why? Because they have a wild sex-
reversal system- females are more muscular and more aggressive than
males and are socially dominant over them, rare traits in the
mammalian world. And get this: females secrete more of certain
testosterone-related hormones than males do, producing the muscles,
the aggression (and, as a reason for much of the gawking interest in
these animals, wildly masculinized private parts that make it
supremely difficult to tell the sex of the hyena). So this appears to
be a strong vote for the causative powers of high androgen levels in
aggression and social dominance. But that's not the whole answer. High
up in the hills above the University of California at Berkley is the
world's largest colony of spotted hyenas, massive bone-crunching
beasts who fight with each other for the chance to have their ears
scratched by Laurence Frank, the zoologist who brought them over as
infants from Kenya. Various scientists are studying their sex-reversal
system. The female hyenas are bigger and more muscular than the males
and have the same weirdo genitals ands elevated androgen levels that
their female cousins do back in the savannah. Everything is in place
except ... the social system is completely different from that in the
wild. Despite being stoked on androgens, there is a very significant
delay in the time it takes for the females to begin socially
dominating the males- they're growing up without the established
social system to learn from.
When people first grasp the extent to which biology has something to
do with behavior, even subtle, complex, human behavior, there is often
an initial evengelical enthusiasm of the convert, a massive placing of
faith in the biological components of the story. And this enthusiasm
is typically of a fairly reductive type- because of physics envy,
because reductionism is so impressive, because it would be so nice if
there were a single gene or hormone or neurotransmitter or part of the
brain that was it, the cause, the explanation of everything. And the
trouble with testosterone is that people tend to think this way in an
arena that really matters.
This is no mere academic concern. We are a fine species with some
potential. Yet we are racked with sickening amounts of violence.
Unless we are hermits, we feel the threat of it, often as a daily
shadow. And regardless of where we hide, should our leaders push the
button, we will all be lost in a final global violence. But as we try
to understand and wrestle with this feature of our sociality, it is
critical to remember the limits of biology. Testosterone is never
going to tell us much about the suburban teenager who, in his after-
school chess club, has developed a particularly aggressive style with
his bishops. And it certainly isn't going to tell us much about the
teenager in some inner-city hellhole who has taken to mugging people.
"Testosterone equals aggression" is inadequate for those who would
offer a simple excuse: Boys will be boys and certain things in nature
are inevitable. Violence is more complex than a single hormone. This
is endocrinology for the bleeding heart liberal - our behavioral
biology is usually meaningless outside the context of social factors
and environment in which is occurs.

Robert M. Sapolsky is professor of biology and neuroscience at
Stanford University. He is a regular contributor to Discover and The
Sciences. In 1987, Sapolsky was awarded a MacAuthur Foundation "genius
grant".

This essay 'The Trouble With Testosterone' was first published in a
1998 Touchstone book edition with the same title, pages 147-159.
Citations from the end of this essay are: 'For a good general review
of the subject, see E. Monaghan and S. Glickman, "Hormones and
Aggressive Behavior," in J. Becker, M. Breedlove, and D. Crews, eds.,
Behavioral Endocrinology (Cambridge, Mass.: MIT Press, 1992), 261.
This also has an overview of the hyena social system, as Glickman
heads the study of the Berkley hyenas. For technical papers on the
acquisition of the female dominance in hyenas, see S. Jenks, M.
Weldele, L. Frank, and S. Glickman, "Acquisition of Matrilineal Rank
in Captive Spotted Hyenas: Emergence of a National Social System in
Peer-Reared Animals and Their Offspring," Animal Behavior 50 (1995):
893; and L. Frank, S. Glickman, and C. Zabel, "Ontogeny of Female
Dominance in the Spotted Hyena: Perspectives from Nature and
Captivity," in P. Jewell and G. Maloiy, eds., "The Biology of Large
African Mammals in Their Environment," symposium of the Zoological
Society of London 61 (1989): 127.
I have emphasized that while testosterone levels in the normal range
do not have much to do with aggression, a massive elevation of
exposure, as would be seen in anabolic steroid abusers, does usually
increase aggression. For a recent study in which even elevating into
that range (approximately five times normal level) still had no effect
on mood or behavior, see S. Bhasin, T. Storer, N. Berman, and
colleagues, "The Effects of Supra-physiologic Doses of Testosterone on
Muscle Size and Strength in Normal Men," New England Journal of
Medicine 335 (1996): 127.
The study showing that raising testosterone levels in the middle-
ranking monkey exaggerates preexisting patterns of aggression can be
found in A. Dixon and J. Herbert, "Testosterone, Aggressive Behavior
and Dominance Rank in Captive Adult Male Talapoin Monkeys (Miopithecus
talapoin), " Physiology and Behavior 18 (1977): 539. For the
demonstration that testosterone shortens the resting period between
action potentials in neurons, see K. Kendrick and R. Drewett,
"Testosterone Reduces Refractory Period of Stria Terminalis Neurons in
the Rat Brain," Science 204 (1979): 877.

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