Dowd: Why the need for the Y anyway?


Even sitting in an MIT classroom made me feel smarter.

But I was still struggling with the difference between meiosis and parthenogenesis.

Dr. David Page, the zippy evolutionary biologist teaching a class Wednesday called "Are males really necessary?," had helpfully laid out some props to illustrate gene swapping — bananas, apples and heads of lettuce arranged on a table covered with a flowery white tablecloth.

"Since only females can give birth, why is it of any advantage to the species to have a second sex?" he asked. "Why should nature bother with males?" He told the packed classroom about the ingenious genetic feat of the Laredo striped whiptail lizards in the Rio Grande Valley in Texas and Mexico.

"This species is a Girls Only club, and the girls reproduce by cloning themselves," Page said. "In the species with males, life is pretty routine. The females produce eggs, the males produce sperm, fertilization occurs and the male-inclusive life cycle is completed. In species without males, life has a different texture. The females produce eggs, but the eggs do not need sperm.

That's parthenogenesis, which is a big word that means we understand absolutely nothing about how this works." He said old-fashioned fertilization (meiosis) beat cloning (parthenogenesis) because, as genes mutate, "males provide females with spare parts."

It had been eight years since I'd talked to Page, director of the Whitehead Institute for Biomedical Research, about doomsday predictions that we were hurtling toward a planet without men in a mere 100,000 to 10 million years.

The Y chromosome was shedding genes and wilting into a mere remnant of its once mighty structure. Y declinists were arguing that, from sperm count to social status, men were vanishing, Snapchat-style.

The Y had shrunk to a fraction of the size of its partner, the X chromosome. (Obviously, Stephen Colbert told Page, it had just gotten out of the pool.) The Y-sky-is-falling predictions mirrored Hanna Rosin's thesis in "The End of Men," showing that women are consolidating power — as graduates, breadwinners, single mothers, consumers.

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