Mazur Comm chambers

From: McNaught-Davis , Beth (bamnd195@psy.soton.ac.uk)
Date: Mon May 11 1998 - 17:01:55 BST


Target tissue sensitivity, testosterone and social environment
interactions, and lattice hierarchies

Kathleen C. Chambers

One must consider not only the levels of circulating hormone but the
target tissue upon which the hormone acts.
Increased testosterone levels alone do not account for differences in
displayed intermale aggression because testosterone and social
environment interact in complex ways to influence behavior.

This commentary is written from the vantage point of a researcher who
up until recently has used animal models exclusively to study
interactions between gonadal hormones and behavior. There are many
subtle and not so subtle differences in the nature of these
interactions among various species as well as among various strains of
a given species. Thus one would not expect that one animal model could
serve as a perfect model for the nature of the interactions in humans.

   Chambers acknowledges that animal studies that she has conducted
   often result in differing findings, this demonstrates that different
   species react differently to hormones. Chambers then goes on to use
   these studies to make inferences about the human species. Surely if
   there are differences between animal species in their reaction to
   hormones, it is highly likely thet human behaviour will also differ
   considerably. Perhaps Chambers should not make inferences about
   human behaviour based on findings from amimal studies.

The concept of 'tissue sensitivity' has been used to account for
individual, sex, and strain differences and for age-related changes in
the threshold amount of hormone needed to activate various behaviors
influenced by gonadal hormones

   I presume that this is refering to the amount of testosterone that
   is active in a persons body.

The specific mechanisms that determine tissue sensitivity remain
unknown but several possibilities have been suggested: decreases in
the availability of testosterone or the active metabolites of
testosterone at the receptor sites in the target tissues, decreases
in the total available cellular receptors, qualitative changes in the
properties of the receptor, such as a decrease in affinity of
receptor for the hormone or a change in hormone specificity, and
changes in the hormone-receptor-nuclear chromatin interaction.

   There appears to be no specific definition or measure of 'tissue
   sensitivity', several possible examples are given but there is no
   evidence which is given to back up any of the possibilities.

In those behaviors studied, differences in tissue sensitivity are
due to differences in the availability of testosterone during the
prenatal-early postnatal developmental period.

   How can this be claimed if the mechanism that determines tissue
   sensitivity is unknown? No explanation was given as to how the
   tissue sensitivity was measured?

Thus in human males, differences in aggression may be associated with
differences in testosterone availability during this developmental
period which then leads to differences in tissue sensitivity to
circulating testosterone in adulthood.

   The first problem with this statement is that it is based on animal
   studies and has been generalised to human males. Secondly, Chambers
   has found an association between aggression and high levels of
   testosterone which shouldn't occur, as many males with high
   testosterone are not aggressive (Chambers, herself has admitted that
   not all high testosterone males are aggressive).
   This association may have been found as a
   result of studying animals and not humans. This highlights the
   problem of generalising animal study results to humans. The third
   problem is that an explanation of the measure by which tissue
   sensitivity is determined, is not given.

There is evidence in other social animals that hormones and social
environment interact in complex ways to influence behavior. The
authors acknowledge this interaction when they discuss the reciprocal
linkage between hormones and behavior (Honor Subcultures, paragraph
10).

   Chambers seems to be agreeing that the histories and experiences of
   humans do influence their behaviour in the presence of
   testosterone. So, from initially saying that aggression and
   behaviour can be predicted from tissue sensitivity and testosterone
   levels, she is now suggesting that actually behaviour is also
   determined by past experiences. This in fact leaves no room for
   prediction whatsoever, as you will never know all of a persons
   history.

However, in animals, increased systemic testosterone levels alone do
not account for differences in displayed intermale aggression but the
combined interaction of sufficient testosterone, previous social
experience, and present social status do. For example, even though
two males may have high testosterone levels in the same situation,
whether they will display aggression is dependent on their prior
social histories.

   This distinction, can be made between animals because they can be
   observed and controlled throughout their lives, however this is not
   the case in humans, as it is not ethical and so testing such a
   theory is probably impossible.

If, as the authors suggest, testosterone is associated
with dominance behaviors in prosocial as well as antisocial men, then
one must still account for why, in the presence of sufficient
testosterone, some men direct their dominance in an antisocial
direction whereas others do so in a prosocial direction (Summary and
Conclusions).

   As always the answer could be that the behavioural reaction to
   testosterone is genetic or socially learned throughout life.
   Both of these explainations could be argued. The 'Honour Culture'
   could be taken as evidence that aggression in the presence of
   testosterone is a learnt association, brought about by the need to
   fight to protect yourself. However, it could also be suggested that
   it is genetically passed on through generations of the honour
   culture.



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