The miniscule Y chromosome has been a longtime topic of debate in genetic research but its importance actually belies its size, according to new research.
Two recent studies have shed new light, revealing that the male Y chromosome comprises genes that are needed for the entire operation of the genome, The New York Times reported.
Scientists have long hypothesized that the Y chromosome lost hundreds of genes over time, making it substantially shorter than the X chromosome it is paired with.
The small Y chromosome is so difficult to unravel that it was left out during early attempts to sequence the human genome. But a research group headed by Henrik Kaessmann of the University of Lausanne in Switzerland found a faster way: comparing the X and Y chromosome DNA of different species and finding Y DNA by taking out anything they knew to be X.
Publishing their research in the journal Nature, the group estimates that the Y chromosome appeared around 181 million years ago, placing it where the platypus branched off from mammals.
In a separate study, Daniel W. Bellott and David C. Page of the Whitehead Institute in Cambridge, Mass., headed a group that decoded the Y DNA sequence of eight mammals. The sequences included that of humans as well as the sequence of the rhesus monkey, which has a Y chromosome with a number of genes similar to those found in the human Y chromosome.
Both of the research groups found evidence that the Y chromosome lost genes "almost immediately" and its remaining genes have stayed stable for millions of years.
The studies also highlighted the difference between male and female genes.
"Throughout human bodies the cells of males and females are biochemically different," said Page, as quoted by the Times.
Male and female tissues have a basic difference that is evident even before sex hormones affect the body.
"We are only beginning to understand the full extent of the differences in molecular biology of males and females," Andrew Clark, a geneticist at Cornell University, wrote in a commentary in Nature on the two reports.
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