At least two species of rodents have already jettisoned their Y chromosomes
Also unknown is when the mammalian X and Y chromosomes
``When you think about the tail-male line,'' says Dr Matthew Binns, ``all that represents is the Y chromosome
For this reason, recent studies have attempted to utilize the paternally inherited Y chromosome
as well as biparentally inherited autosomal genetic markers to study the relatedness and histories of populations.
As a result, the Y chromosome
retains a largely undisturbed record of mutations.
Losing the Y chromosome
in blood cells may bring on cancer and shorten men's lives, new research suggests.
Deborah Charlesworth of the University of Edinburgh says, "It is not rash to call this a Y chromosome
or at least an evolving Y." The findings support the evolutionary theories of how sex chromosomes arise, she adds.
"The problem is to be sure that this is the personal Y chromosome
of Genghis Khan," adds Jaume Bertranpetit of the University of Pompeu Fabra in Barcelona.
The Y chromosome
segments in the new analysis exhibit much less variability than DNA regions that have been studied in other chromosomes.
Comparing the sex chromosomes of six species, Hoekstra found that the XY females have forms of the Y chromosome
unique to their species.
The male patient with the highest number of liver cells bearing the Y chromosome
also had the most dire disease--recurrent hepatitis C.
An egg fertilized by a sperm carrying a Y chromosome
becomes a boy.