In barstool speculation on how long it’s possible for someone to survive without sex, the phrases “old fossil” and “a million years” certainly do turn up. However—meaning no disrespect to snubbed Homo sapiens—our species doesn’t even register in the scientific version of the debate. In this, there are genuine geologic fossils. And a million years? Forget it. The species attracting interest now look as if they may not have had sex for tens, or even hundreds, of millions of years.

Yes, there really is a scientific version of the barroom lament, and it’s a serious inquiry. Biologists have long held that asexuality is an evolutionary dead end because sex purges the genes of detrimental mutations, provides the genetic variation for coping with environmental change or both.

But new methods of genetic analysis are suggesting that certain groups of species have avoided sex and still have done quite well over the eons, thank you very much.

“The question of, ‘Why sex?’ is a very central one to biology,” says David Mark Welch of the Marine Biological Laboratory in Woods Hole, Mass.

Three years ago, Mark Welch and Matthew Meselson of Harvard University reported genetic evidence that an entire class of organisms, containing 360 species, seems to have evolved perfectly well without sex. This group of tiny water creatures, called bdelloid rotifers, is thriving in fresh water and soggy land worldwide despite, seemingly, no sex for at least 40 million years.

Since that publication, geneticists and paleontologists have been focusing their most advanced methods on questions of asexuality. The scientists are refining tests that detect sexuality and searching for other celibate lineages.

Sex signs

So far, biologists have found…

More here.