"Junk" DNA? Not so fast, there . . .

Ronald Bailey rounds up some new findings on what we've been dismissively calling "junk DNA":

Decoding the human genome found that only about 10 percent of the 3 billion or so base pairs of the DNA in the human genome consists of genes that code for proteins. The remaining 90 percent didn't have any obvious function, so researchers called it "junk DNA."

[. . .] In other words, these apparently long boring stretches of repeat DNA base pairs are central to determining which genes turn on when and by how much. In addition, some of these DNA repeats jump around inside genomes changing the expression of genes and the course of a species' evolution.

Interesting, but this part is definitely scary:

Even more amazingly, biologist Cedric Feschotte and his colleagues at the University of Texas in Arlington have found that some DNA repeats have actually jumped between mammalian and other tetrapod species including African clawed frogs, anole lizards, South American opposums, brown bats, mice and rats. This kind of horizontal interspecies DNA exchange happens among single-celled organisms all the time, but biologists find it very surprising that it can happen between large multicellular species. The repeat sequences have been dubbed "SPace INvaders" or SPIN transposons and may have been carried into these animal genomes by a virus 45 to 15 million years ago.

And this SPace INvasion may have been responsible for a mass mammalian extinction.