If you ignore for a second the constant forward-looking attention Internet news demands and stretch your mind back to the Mad Cow Disease scare of 2004, you might remember thinking "how strange that proteins can act as pathogens in the mammalian body!"

Mad Cow scares us because it's an enigma--a protein disease that acts like it has DNA. But now it's looking more familiar, as researchers prove it mutates very much like a DNA or RNA virus or bacteria.

In the most recent issue of Science, Li et. al. describe what looks like an evolving population of prions (infectious proteins taken from the brain of animals with Mad Cow Disease.) When grown in the lab, each identical prion colony becomes different; some out-compete others and grow a sizable population. This mirrors what happens when bacteria or viruses (with DNA) go through similar tests.

Could prion proteins be another form of heritability?

This hasn't always been a radical idea. If you've got a little extra time, pick up James Watson's "The Double Helix": a riveting tale that, among other things, faithfully describes the scientific attitudes towards heritability in the early 50's. Most big-name scientists (ahem-Linus Pauling) considered proteins not DNA the most important molecule associated with human inheritance. Once Watson and Crick proved DNA the culprit, the case was closed on proteins.

Perhaps if human minds allowed a more detailed memory, we wouldn't be so scared or amazed by prion disease. After all, it wasn't so long ago that proteins were at the center of the heritability research paradigm.

Despite the historical flip-floping, I don't think proteins will ever be proven more important than DNA. But I'll definitely stay tuned to see if other forms of inheritance might be uncovered in the future.