The Loom » Life Elsewhere

Life with a capital L? (Like Zimmer with a capital Z?)

Carl Zimmer — Wed, 11 Jan 2012 19:39:42 +0000

Over on Facebook, David Hillis, an evolutionary biologist at the University of Texas, took up my question as to whether anyone can define life in three words. His short answer was no, but his long answer, which I’ve stitched together here from a series of comments he wrote, was very interesting (links are mine):

Like all historical entities (including other biological taxa), it is only sensible to “define” Life ostensively (by pointing to it, noting when and where it began, and following its lineages from there) rather than intensionally (using a list of characteristics). This applies to the taxon we call Life (hence capitalized, as a formal name). You could define a class concept called life (not a formal taxon), but then that concept would clearly differ from person to person (whereas it is much less problematic to note examples of the taxon Life). So, I’d say that I can point to and circumscribe Life, and that it the appropriate way to “define” any biological taxon. A list of its unique characteristics is then a diagnosis, rather than a definition. So, I’d argue that any ...

Can you define life in three words?

Carl Zimmer — Wed, 11 Jan 2012 14:59:38 +0000

We are all sure we know what life is, but if you try to actually define it, things get tricky fast. I wrote a feature about the scientific struggle to define life in 2007 for Seed, and I’ve been keeping tabs on the evolution of this metaphysical quandary ever since. I was particularly intrigued to discover recently that one scientist thinks he can define life–and do so in just three words. I’ve written an essay about his short and sweet definition for the web magazine Txchnologist. Check it out.

Arsenic life and all that: My new book review for the Wall Street Journal

Carl Zimmer — Fri, 22 Apr 2011 22:06:53 +0000

The Wall Street Journal recently asked me to review a new book called First Contact: Scientific Breakthroughs in the Hunt for Life Beyond Earth. Astrobiology is a tricky subject to write about these days. It’s intensely exciting, despite the fact that its main object of study–life on other planets–has yet to be discovered.

I’ve given some thought to how we journalists should cover such a paradoxical science. We shouldn’t dismiss it outright, because astrobiologists have discovered fascinating things about life here on Earth, even if they have yet to find aliens. Yet we shouldn’t feel obligated to pump up every claim about the possibility of life elsewhere. We should be content to paint a portrait of the scientific process–including the intense debates–in all its gorey detail.

By this measure, I don’t think First Contact works. The author, Marc Kaufman, declares at the outset of the book that “before the end of this century, and perhaps much sooner than that, scientists will determine that life exists elsewhere in the universe.” Not whether life exists, mind you, but that it exists.

I don’t think he backed up that bold claim. Instead, he ...

Your daily dose of arsenic: On the Madeleine Brand Show on KPCC

Carl Zimmer — Thu, 09 Dec 2010 19:48:15 +0000

I just appeared this morning on the Madeleine Brand Show on KPCC in California to talk about arsenic life. Check it out.

Of arsenic and aliens: What the critics said

Carl Zimmer — Wed, 08 Dec 2010 21:57:21 +0000

A lot of people are interested in my Slate story yesterday on the arsenic aliens. It’s still the most-read story of the site at the moment, Slashdot and others have linked to it, and I’m doing some more radio and maybe other media (details to come).

I think that what has gotten so much attention to the story is just how many scientists had such critical things to say. The verdict was not unanimous, but the majority was large. I was only able to quote a tiny bit from just a few of the scientists I communicated with, so I thought, for those who’d like to delve more deeply into this, that I’d post a list of everyone I spoke to, and, when possible, post their reactions. A lot of scientists replied to me by email or even attached word files where they went on at length. I put together a similar dossier for another biological controversy–the search for soft tissue in dinosaur fossils–and I think (or at least hope) that this sort of exercise can help further discussion.

Of course, as I and others have reported, the authors of the new paper claim that all this is entirely ...

Talking on the radio Wednesday at noon about arsenic life

Carl Zimmer — Tue, 07 Dec 2010 21:49:52 +0000

Quick note: I’ll be on the public radio show Word of Mouth show just after noon eastern time tomorrow (Wednesday 12/8) to talk about NASA’s cookie full of arsenic. You can listen live here. [Update: the podcast is posted now.]

And the skeptics keep chiming in…George Cody on arsenic life

Carl Zimmer — Tue, 07 Dec 2010 17:38:10 +0000

One of the challenges of writing on deadline is that people are not waiting every moment of the day to answer your questions. My Slate piece on arsenic life was based on a dozen or so responses from an overwhelmingly skeptical group of experts. And now, an hour after my story went live, I got a reply from George Cody, a chemist at the Carnegie Institution who co-authored a major 2007 “weird life” report. Rather than let this thirteenth comment molder in my inbox, let me share it with you. It’s a bit technical but illuminating. I’ve condensed it for clarity (my clips marked by ellipses)–

I have been aware of the hypothesis of the possibility of substitution of arsenate for phosphate for some time…The issue that always comes up is the facility of hydrolysis of arseno ester bonds….The correct experiment to do would be mass spectrometry which would unambiguously determine whether an arsenate backbone was present or not in the DNA. I cannot accept this claim until such an experiment (easily done) is performed. ..

I recall a summer intern in my laboratory accidently culturing up a bacterial biofilm ...

Arsenic life: My take on the backlash at Slate

Carl Zimmer — Tue, 07 Dec 2010 16:33:08 +0000

Slate asked me to take a look at the scientific reactions emerging to last week’s big news about arsenic-based life. I got in touch with a dozen experts, and let’s just say, the results weren’t pretty. Check it out.

[Image of Mono Lake by .Bala via Flickr, under Creative Commons License]

Of Arsenic and Aliens

Carl Zimmer — Thu, 02 Dec 2010 19:00:15 +0000

Rumors have been swirling this week about a press conference NASA is starting right now. Some people have speculated that they’re going to announce evidence for life on another planet.

Well, not quite. Scientists have found a form of life that they claim bends the rules for life as we know it. But they didn’t need to go to another planet to find it. They just had to go to California.

The search for alien life has long been plagued by a philosophical question: what is life? Why is this so vexing? Well, let’s say that you’re hunting for change under your couch so that your four-year-old son can buy an ice cream cone from a truck that’s pulled up outside your house. Your son offers to help.

“What is change?” he asks.

“It’s…” You trail off, realizing that you’re about to get into a full-blown discussion of economics with a sugar-crazed four-year-old. So, instead, you open up your hand and show him a penny, a nickel, a dime. “It’s things like this.”

“Oh–okay!” your son says. He digs away happily. The two of you find lots of interesting things–paper clips, doll shoes, some sort ...

A Glint From Across The Solar System

Carl Zimmer — Thu, 17 Dec 2009 21:44:25 +0000

I know that this is Bad Astronomy‘s usual bailiwick, but I had to post this. It’s a glint of sunlight reflecting off the surface of a lake of liquid hydrocarbons on Titan, a moon of Saturn. When I look at it, I wonder what diesel-fueled creatures might be swimming below. More details here.

Alternative Landscapes

Carl Zimmer — Fri, 06 Nov 2009 20:47:14 +0000

Leave it to the Boston Globe’s Big Picture to pick out a staggering portfolio of pictures of Mars.

The 2009 John Wesley Powell Memorial Lecture: “What Is Life?”

Carl Zimmer — Sat, 07 Mar 2009 15:08:16 +0000

I’m honored to report that I’ve been asked to deliver this year’s John Wesley Powell Memorial Lecture.

Here is a description of the lecture series from its organizers, the Southwestern and Rocky Mountain Division of the American Association for the Advancement of Science:

The John Wesley Powell Memorial Lectures were inaugurated in 1929 in honor of the distinguished geologist and leader of the first expedition down the Colorado River through the Grand Canyon. Each year since then, with the exception of the years during WWII when the Division did not hold meetings, SWARM has invited a distinguished scholar to deliver a lecture at the Annual Meeting on a subject ...

Bad Astronomy on Bad Mars Reporting (Or Just Bad Mars Headlines)?

Carl Zimmer — Mon, 19 Jan 2009 15:47:57 +0000

Over at Bad Astronomy, Phil Plait reveals some of the astonishingly bad coverage last week about methane on Mars, giving people the impression that we’ve got proof-positive of life on the Red Planet. But I think Carol Collins Petersen raises an important point: it’s the headlines that were truly noxious. If you stripped the headlines off of the articles Phil lambastes, they’d range from acceptable to mediocre. At least, that’s my non-scientific analysis. Unfortunately, headline writers are harder to track down than reporters (who don’t write headlines and rarely get to vet them).

Live Blogging The Mars Methane Mystery: Aliens At Last?

Carl Zimmer — Thu, 15 Jan 2009 19:00:27 +0000

Frankly, if I were Michael Mumma, I’d be going nuts right now. The NASA scientist and his colleagues have either found evidence of life on Mars, or are getting fooled by some weird geochemistry.

The researchers today today are reporting that in 2003 and 2006, they recorded plumes of methane rising from the surface of the Red Planet. Working back from their measurements of methane in the air, the researchers pinpointed some particular spots on Mars where the methane came from. And it’s a lot of methane they’re talking about–19,000 metric tons of the stuff in one plume. It’s coming out of Mars at the same rate seen at methane-producing spots on Earth.

Those places on Earth happen to be places where microbes are churning the gas out. There might be other ways of getting plumes of methane into the air–generating it from magma, for example. But in a paper published today by Science, Mumma and his colleagues point to the possibility that microbes buried a mile or two under the surface of Mars might be responsible. There are certainly analogs here on Earth–or here under Earth. On our planet, scientists can study these deep ...