What Determines a Male?
Country: United States
Date: August 2005
When did science actually find out about the male determining
the sex of the child?
May be of help.
Yes, normally the Y chromosome from the male will dictate a male
child. However, it is more important to understand the sry gene that
actually determines maleness. Females carry this gene too. There
are males who are XX and have no Y chromosome; and their are females
with Y chromosomes. For the most part males determine the sex of the
individual, but it is not that simple in every case.
What year? About 50 years ago when it was shown conclusively, but it
was guessed about over 150 years ago when Mendel did his work and
when Morgan (circa 1905) worked with fruit flies.
The Y chromosome was discovered in fruit flies by Thomas Hunt Morgan circa
1910. Up until 1956, the number of chromosomes in humans was thought to be
48, but improved methods of observing chromosomes microscopically revealed
that there were actually only 46 chromosomes in humans. I wasn't able to
determine the exact year in which human females carry 2 X xhromosomes and
males only one plus a Y chromosome.
Ron Baker, Ph.D
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Update: June 2012