By Kevin Davies
August 15, 2003 | The 24th human chromosome, writes Steve Jones in Y: The Descent of Men: Revealing the Mysteries of Maleness (Houghton Mifflin, 2003), “has a single redeeming feature. To half the human race, the Y is the prince of chromosomes, for it gives the embryo a testis. There resides the noblest of all genes, the sine qua non of maleness.”
That crucial scrap of DNA, SRY (which stands for sex-determining region of the Y), was discovered by British researchers in 1990 -- somewhat to the chagrin of David Page, a geneticist at the Whitehead Institute, who had prematurely (and, it turned out, erroneously) bestowed that honor on a neighboring gene a year earlier.
But Page’s interest in the Y chromosome did not wither, and for the past decade his group has produced a sublime series of papers on the structure and evolution of the chromosome, culminating in the complete sequencing of the Y (H. Skaletsky et al. “The male-specific region of the human Y chromosome is a mosaic of discrete sequence classes” Nature 423, 825-837; 2003).
The efforts of Page and Robert Waterston’s group (at Washington University in St Louis) were hailed by Francis Collins as a tour de force of genomic analysis. Including SRY, the Y has fewer than 80 protein-coding genes, many of which are involved, not surprisingly, in sperm production. The architecture of the Y chromosome is remarkable, featuring eight large palindromic (mirror-image) sequences. Page views the Y as the genetic equivalent of an archaeological dig -- peeling apart genetic rearrangements that, over hundreds of millions of years, transformed an anonymous ancestral chromosome into a pair of misfit sex chromosomes, X and Y.
Despite an exhaustive search using state-of-the-art bioinformatic algorithms, the newly revealed map of the Y chromosome has failed to identify the genes for many of the classical male behavioral traits predicted in this whimsical cartoon produced 10 years ago by University of California geneticist Jane Gitschier. So far, no gene for air guitar or inability to express affection over the phone -- although, most would agree, those traits appear to be part and parcel of owning a Y chromosome.