gcote at runet.edu
Thu Sep 9 07:54:22 EST 1999
At 09:02 AM 9/8/99 -0700, you wrote:
I know we're getting a bit off topic, but I had to comment on the XYY
males. There was a time when the hypothesis that they were aggressively
violent was all the rage. They also tend to be abnormally tall and
somewhat retarded. As I point out to students this fits in with the
stereotypes of males--big, dumb, and violent. However, one must not let
stereotypes drive scientific research. My understanding is that no one
ever proved these guys to be more violent, only more common in prison.
Given that they are big (so people remember them) and not too bright, it's
no surprise that the ones that do commit crimes wind up in prison. The
whole violence hypothesis has just evaporated--at least I never see it in
books or magazines any more.
Let's be very careful what we blame on people's genes.
>After doubling of the sex chromosomes meiotic separation of the gemini
>would yield only one type of gamete, even in the heterogametic partner,
>giving only one type of offspring e.g.
>XXXX diploid females yields XX gametes.
>XXYY diploid males yield XY gametes.
>producing XXXY offspring (male?, female?)
>These are variations that occur. Klinefelter males are xxy ( in fact any
excess in x chromosomes with a y is a klinefelter and male). Happens in
both cats and humans, but the males are sterile and in humans generally
retarded and show female secondary sex characteristics.
>Super males xyy are thought to be the cause of aggressive tendencies in
>Any excess (xxx) or lack (xo) is called a turners syndrome. These also
lead to sterility, retardation and other problems, the more copies the more
problems. It is thought that these people survive because the extra x's are
"turned off" in the form of a barr body.
Dr. Gary Coté
Department of Biology
Radford, VA 24142-6931
email: gcote at runet.edu
More information about the Plant-ed