NASA Redefines Life

Update: NASA has officially confirmed the following; more at the bottom!

We always hold true that the building blocks for life as we know it are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur, but what if there are other materials and combinations?

Astrobiologists at NASA may be about to announce that they’ve discovered another building block and, indeed, at least one other recipe for life, previously theorized about but never seen. A finding that would radically change our understanding of biology and of what makes life possible here at home and elsewhere in the cosmos.

Earlier this week NASA issued a curious press release which stated:
NASA will hold a news conference at 2 p.m. EST on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life.

While only a few people know the specifics of NASA’s discovery, Gizmodo seems rather sure in its case that what has been discovered is a lifeform which consists of arsenic rather than phosphorous, the backbone of nucleic acid:

Every being, from the smallest amoeba to the largest whale, share the same life stream. Our DNA blocks are all the same. But not this one. This one is completely different. Discovered in the poisonous Mono Lake, California, this bacteria is made of arsenic.

My gut tells me not to buy into the hype prematurely, but it’s just not possible to not get excited about something like this. This would significantly widen the scope of what we look for in the search for life elsewhere in the universe.

The press conference will be streamed live on NASA TV at 2pm EST. Then we’ll know.

Update: Several independent news outlets are now backing up Gizmodo’s claim that a completely new lifeform made up of arsenic has been discovered in Mono Lake. From Nature News:

A bacterium found in the arsenic-filled waters of a Californian lake is poised to overturn scientists’ understanding of the biochemistry of living organisms. The microbe seems to be able to replace phosphorus with arsenic in some of its basic cellular processes — suggesting the possibility of a biochemistry very different from the one we know, which could be used by organisms in past or present extreme environments on Earth, or even on other planets.

Scientists have long thought that all living things need phosphorus to function, along with other elements such as hydrogen, oxygen, carbon, nitrogen and sulphur. The phosphate ion, PO43-, plays several essential roles in cells: it maintains the structure of DNA and RNA, combines with lipids to make cell membranes and transports energy within the cell through the molecule adenosine triphosphate (ATP).

But Felisa Wolfe-Simon, a geomicrobiologist and NASA Astrobiology Research Fellow based at the US Geological Survey in Menlo Park, California, and her colleagues report online today in Science that a member of the Halomonadaceae family of proteobacteria can use arsenic in place of phosphorus. The finding implies that “you can potentially cross phosphorus off the list of elements required for life”, says David Valentine, a geomicrobiologist at the University of California, Santa Barbara.

Update 2: The statements given at the press conference confirm that a new lifeform which has substituted phosphorous for arsenic has been discovered. You can find NASA’s official press release here.

It wasn’t hype after all. If it stands up to scrutiny the implications are enormous.

And, oh yeah, yesterday we discovered that there’s quite possibly three times as many stars in the universe as we thought. It’s been a good week.

Update 3: Rollercoaster. It wasn’t that amazing.