Friday, December 3, 2010

New life? Not so fast.

Well, this is all very exciting, but having skimmed the actual paper, there is much less to this than there appears in the news. Despite breathless headline writers, this isn't "new life". This is a typically adaptable extremophile bacterium that does something that we know is theoretically possible: replaces phosphate PO4 with the chemically similar arsenate AsO4. In fact, that's part of the reason arsenic is toxic to most cells.

Bacteria of various types are remarkably adaptable to harsh environments--a sort of "if you can't beat it, defeat it." Think of the ones living on thermo vents on hydrogen sulfide, which is toxic as all get out to most life forms. There are acidophiles that live in conditions that would melt metal. Then there's D. radiodurans, which pays no attention to massive doses of radiation and is one of the most bizarre extremophiles out there. This doesn't "defeat Darwin" in any way. Rather, it is a prime example of evolutionary selection in action.

Bugs (slang for bacteria) do what they do to survive. They are adapatable, evolvable, and very good at it. Nothing here is challenging scientific principles, evolution, or our understanding of life.

In fact, it remains to be seen how complete the exchange is. They grew their bug under positive selection for arsenate incorporation, but it's almost impossible to eliminate trace phosphorous from all their reagents. There's a way to go before they prove arsenate has completely replaced phosphate in all aspects of metabolism.

Science works by adapting its hypotheses to available data. Hypotheses are tested by attempts to disprove them: that's what we do. Scientists love cool stuff that challenges the existing hypothesis and demands we refine it. Which is how we went from the central dogma in Molecular Biology (DNA makes RNA makes protein) to discover exceptions to the rule, like reverse transcriptase, RNA editing, and self-splicing proteins.

It's funny, but non-scientists seem to think we scientists are unreasonably rigid, that anything unexpected pulls the rug out. Not so: we just demand evidence. We keep it simple. Our mantra is Occam's razor:
entia non sunt multiplicanda praeter necessitatem (entities must not be multiplied beyond necessity)
So There's a lot of cool stuff out there, especially in microbes. Just ask any microbiologist why they do what they do!

In the meantime, this is a really cool example of a potentially adaptive response to an extreme environment. I will look forward to reading more of their work as they figure out how far it goes.

I must admit I don't see any theological component to this at all. I don't need to invoke a god to make it fit. I just need to adjust the model. The fact that there are still wonderful new things to discover in How Things Work continues to cheer me up.

Bug picture from Science Magazine. Mono Lake picture from IT's photo album


PseudoPiskie said...

I'm happy to read this, IT. I know just enough about genetics and evolution to be dangerous. I didn't find this adaptability especially extraordinary. Fascinating but hardly impossible or earth/faith shaking.

Göran Koch-Swahne said...

A word of Sanity, as can be expected ;-)

Paul (A.) said...

And here I had thought that The New York Times had journalistic standards. Quoting an astronomer on a biology story?

JCF said...

Heh: and I thought Occam's Razor was just "The Simplest Answer is Usually the Best"! ;-)

I wouldn't poo-poo this TOO much, IT: finding "something that we know is theoretically possible" is always notable. I think you would agree, science can't progress if theories aren't (either) confirmed/disproven?

As a native Californian, I do have strange pride that this was discovered in good ol' Mono Lake. WE always knew it was weird, seeing those bizarre tufa (?) towers . . . this arsenic "breathing" bug proves it! ;-p

IT said...

I'm not poo-pooing it, JCF. It's really really COOL, and I love the result. It's just not as earth-shattering as the media hyped it to be.

As I said, hypothesis testing is what it's all about.

it's margaret said...

Now I know why my mom wouldn't let me swim there.....!

Paul (A.) said...

Now all we need is a good press conference!

Paul (A.) said...

Another critical blog-post here. The comments are also incisive.

IT said...

Thank you Paul (A). The author of that post did a careful review of the paper, and it sounds like there is indeed much less to it than there appears. Indeed, they may have done not much more than show that the bugs can be selected to tolerate higher levels of arsenate, without showing it's truly incorporated. I'll look forward to see what happens next.