A separate study of more than 8,500 men with cancer and more than 5,300 healthy men also found that Y chromosome
loss increases with age.
The UC Berkeley researchers demonstrated that if fewer males were the only cause of the low variability, it would mean that fewer than 1 in 4 males throughout history had passed on their Y chromosome
SRY is the gene on the mammalian Y chromosome
that determines that the organism will be male.
He was determined to prove, through variation in the Y chromosome
, that more than three stallions - the Byerley Turk, Darley Arabian and Godolphin Arabian - founded the breed.
Using estimates of the mutation rate of microsatellite DNA, the investigators conclude that the first man to have this particular form of the Y chromosome
lived in Mongolia roughly 1,000 years ago.
Members of his lab have dealt their fatal blow by sequencing the Y chromosome
of the rhesus macaque-an Old World monkey whose evolutionary path diverged from that of humans some 25 million years ago-and comparing it with the sequences of the human and chimpanzee Y chromosomes
In contrast, the human Y chromosome
dates from 200 million to 320 million years ago.
A unique aspect of the Y chromosome
that lends itself to this sort of research is that the Y does not swap stretches of DNA with other chromosomes.
Underhill studies pairs of mutations on the Y chromosome
in current populations.
He speculates that the palindromes enable the human Y chromosome
to constantly repair mutations, staving off its own degradation.
The Y chromosome
data support several other DNA studies indicating that modern humans arose from a small number of Africans who lived from 100,000 to 200,000 years ago, Harpending says.
Just what might have happened to the Y chromosome
in XY females also interests Jennifer A.
Over the course of evolution, the mammalian Y chromosome
has degenerated so much that it now shares few genes with its more robust counterpart, the X chromosome.
An egg fertilized by a sperm carrying a Y chromosome
becomes a boy.
The Y chromosome
passes solely from father to son, exactly like the cohen status.