HERMAPHRODITIC POLAR
BEARS FOLLOWING POLLUTION PRODUCED BY THE MAN.
By Renato Cocchi
In two preceding notes on the presence of
homosexuality in animals and on its possible origin, (see: <www.stress-cocchi.net/News7.htm> and <www.stress-cocchi.net/News21-it.htm>) I suggested that the stress, of any origin, could interfere
with the sexual differentiation in the embryo.
For the fishes of the polluted river Potomac, the fact could be still debatable because the fertilization happens outside their bodies, into the water (see:<www.stress-cocchi.net/News21-it.htm>).
For the polar bears, where wider recent
research printed in December 2005 on Environmental Science and Technology, the
pollution seems be the direct cause of an increasing of hermaphrodites. Since
this incidence is higher of what reported in past, the hypothesis of a
metabolic stress is becoming always more probable. The current rate of
polybrominated diphenyls attracted attention, since in the laboratory they can
act negatively even on the sexual glands of mice.
We can think that the sexual differentiation
happens for independent and parallel lines, for which the line that doesn't
become going to maturation could bring to different results on the sexual
behaviour of the so born animal.
Perhaps polybrominated diphenyls act then on
an exact line of this differentiation, either specifically, either by the
internal metabolic stress. So they give origin to a greater incidence of the
same defect of sexual development, which was known even in the past.
In the polar bears homosexual behaviour is
known, as reported in Bruce Bagemihl: Biological exuberance. Animal
homosexuality and natural diversity. St. Martin's Press 2000 (USA).
The hermaphrodite females' increasing is
however a new fact, and worrisome.
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