No, Diatoms Have Not Been Found in a Meteorite

By Phil Plait

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Posted Tuesday, Jan. 15, 2013, at 2:46 PM ET

If there’s a story practically guaranteed to go viral, it’s about evidence of life in space. And if you have pictures, why, that’s going to spread like, well, like a virus.

If only it were this easy...

So the moment I heard that a paper had been published saying that diatoms—a type of algae, microscopic plant life, that have hard outer shells made of silica and come in a variety of shapes and forms—had been found in a meteorite, I knew I’d get flooded with emails and tweets and Facebook messages because LIFE IN SPACE!

And so I did. People are really curious about this!

But then I read the actual paper, and guess what? Let me be delicate: It’s wrong. Really, really wrong. Way, way, way ridiculously oh-holy-wow-how-could-anyone-publish-this wrong.

[deep breath]

OK, let’s dive in, shall we?

That’s the JoC

The paper was published online on a site called The Journal of Cosmology. I’ll get back to that august publication in just a moment. The lead author is N. C. Wickramasinghe, and as soon as I saw his name alarm bells exploded in my head. Wickramasinghe is a proponent of the idea of panspermia: the notion that life originated in space and was brought to Earth via meteorites. It’s an interesting idea and not without some merits.

However, Wickramasinghe is fervent proponent of it. Like, really fervent. So much so that he attributes everything to life in space. He’s said that the flu comes from space. He’s said SARS comes from space. He’s claimed living cells found in the stratosphere come from space. (There is no evidence at all they do, and it’s far more likely they are terrestrial.) He’s said a weird red rain in India was from space (when it’s been shown conclusively that it isn’t). The list goes on and on. Wickramasinghe jumps on everything, with little or no evidence, and says it’s from outer space, so I think there's a case to be made for a bias on his part.

Now, you might accuse me of using an ad hominem, an argument that cast aspersions on the person making the claim, and not attacking the claim itself. I’ll get to the claim in a moment, but sometimes an ad hominem is warranted! If Sylvia Brown claims she can predict someone’s future, you would be right to doubt her based on her past, since she has continually failed in every attempt to do so. If Jenny McCarthy claimed botox cures autism, again, you might be forgiven for doubting it based on her previous anti-vaccine and other false claims. You still need to examine the claims on their own merits, of course, but: Fool me once, shame on you; fool me twice, shame on me.

So, to be polite about it, Wickramasinghe is something of a fringe scientist. Who would publish a paper by him?

The Journal of Cosmology is an online site that claims to be peer reviewed. However, the papers it publishes are not always of the highest quality. One paper they published a few years back claimed to have found fossils in meteorites, and it was roundly ridiculed by biologists familiar with the field—one even used the word “pathetic.” Ouch.

The journal also supports other fringe claims that have very little or no evidence to back them up. For an example in my own field, when some astronomers said they found circumstantial evidence for a previously unknown planet in the outer solar system, the JoC published a page with the headline, “Tyche: Rogue Planet Discovered in Oort Cloud,” which was dead wrong. And because I wrote an article on my blog saying the planet idea is interesting but not convincing, the editors of the JoC expressed their opinion of me:

The torches and pitchforks crowd, led by astronomer-wannabe Phil Plait claims its [sic] not so. But then, Plait's most famous discovery was finding one of his old socks when it went missing after a spin in his dryer.

Yeah. That’s professional.

So right away, I was not inclined to give a lot of weight to the idea that scientists found diatoms in a meteorite. But to be fair, we need to look at the evidence. So let’s take a look.

Diatomaceous Earth

The claim is as follows: A brilliant meteor was seen over Sri Lanka in December 2012. Meteorites from the fall were found and sent to a lab for analysis. When examined under a microscope, clear evidence of diatoms was found. They are fossilized, which means they aren’t ones from Earth that somehow got into the meteorite after it fell. Therefore, this is evidence of life in space.

One of the diatoms found in the speciman. The scale bar is 30 microns, about one-third the width of a human hair.
Image credit: N. C. Wickramasinghe et al.

The microphotographs in the paper are pretty interesting, I’ll admit. As you can see from the one above, there really is something that appears to be biological in the picture, and to my untrained eye it really does look like a diatom.

But I’m no expert! So I did what any good scientist should do. I contacted someone who is an expert. I sent an email with a link to the paper to Patrick Kociolek, a professor of ecology and evolutionary biology at the University of Colorado at Boulder, and director of the University of Colorado Museum of Natural History. He kindly replied, saying,

I should say up front, that most (not all) of the forms pointed out in the paper are indeed diatoms. While the authors may have not referred to some of the images correctly (labeling one as “filamentous” when it is just a fragment of a cell), they are indeed diatoms.

Huh! So they are diatoms! So does this mean life has been found in space?

Not so fast. Kociolek continues:

What is amazing about the forms illustrated is that 1) they are, for the most part, in great shape. There certainly is not any sign of this being fossilized material.

An example of a known terrestrial diatom, called Rossithidium pusillum. The vertical line represent a size of 10 microns, one-tenth the diameter of a human hair.
Image credit: Marina Potapova via Diatoms of the United States

Uh oh. That’s a strike against Wickramasinghe, since a big part of his claim is that the diatoms are fossilized and therefore must be native to the rock they found. But it gets worse:

In fact on page 8 of the journal, the authors indicate, “fossils [sic] diatoms were not present near the surface of the Earth to contaminate a new fall of meteorites.” What must have been near, however, was water, since the forms are all freshwater species…

In other words, all the diatoms shown in the paper are from known species on Earth. That makes it somewhat less likely they are native to space. And by somewhat, I mean completely. Like, zero chance they are from space.

Kociolek makes this even more clear:

2) the diversity present in the images represent a wide range of evolutionary history, such that the “source” of the diatoms from outer space, must have gone through the same evolutionary events as here on earth. There are no extinct taxa found, only ones we would find living today…for me it is a clear case of contamination with freshwater.

I find it curious indeed that Wickramasinghe and his co-authors didn’t talk to diatom experts outisde their group about this. I can’t say anything about their own expertise on diatoms, except to note that, as Kociolek points out, they made some really basic errors in identification and didn’t recognize these specimens as Earth diatoms (they compare them to known species, but they should have gone out of their way to try to identify them specifically against known Earth species). That doesn’t speak very well for their scholarship here.

So, there you go. These aren’t evidence of life from space, they’re evidence of life on Earth. I hate to break it to you, but we already knew about that.

Meteorwrong

So much for the diatoms. But it turns out I was pretty sure the claim of life in space was wrong even before I heard back from Kociolek, though. And that’s because of the meteorite itself.

Or, I should say, “meteorite.” The evidence presented for that is pretty fishy as well.

First, the claim of a bright shooting star over Sri Lanka in December, 2012 is fine. And we do sometimes find meteorites—the actual solid bits of space rock and/or metal—after such a sighting. I love meteorites, and I’m fascinated by them. I own several myself.

But the story presented in Wickramasinghe’s paper gets a little sketchy at this point. They claim that one of the authors found a meteorite from the event and sent it to Wickramasinghe for analysis. However, there are no details whatsoever of the find itself. Where did they find it, exactly? What kind of environment did it fall in? Was it on a street, in a riverbed, on the roof of a building, or what? And how did they handle it? What precautions were taken to prevent contamination? Why are there no photographs of it in situ? The fact that none of this information is in the paper is irregular, to say the least.

And here’s the million dollar question: How do they know it was from that meteor sighting? There is not a single shred of evidence to back up this claim. Nothing. It could simply be a bit of black rock they found somewhere. They do present a chemical analysis and claim it’s a carbonaceous chondrite meteorite, a specific type of space rock with clear structures and composition. However, the analysis they present doesn’t prove it’s a carbonaceous chondrite, let alone a meteorite. For example, the chemicals (carbon, olivine, and so on) they found are also readily found in Earth rocks. Olivine is everywhere, like in beach sand. So right from the start, there’s no reason to trust that what they have is a meteorite.

Then they show a picture of it:

The specimen found by Wickramasinghe's team. It's not terribly meteorite-like.
Image credit: N. C. Wickramasinghe, et al.

Here’s the thing: In my opinion, it doesn’t look like a meteorite. At all. It isn’t rounded, it looks too friable (crumbly), and the structure is wrong. Carbonaceous chondrites look very much like small stones, more solid, compact, and with an entirely different structure. In fact, chondrules are small, generally spherical grains inside this type of meteorite—hence the name—and in the pictures presented in the paper, there are clearly no chondrules. Here’s what actual carbonaceous chondrites look like:

Two carbonaceous chondrite meteorites: the Murchison meteorite (left) and the Allende meteorite (right).
Image credit: Murchison: Art Bromage on Flickr via wikipedia; Allende: Shiny Things on Flickr

Those are very different beasts from the rock shown in the paper.

And again, as presented in their own write-up, the procedure they followed for this seems pretty sloppy. They didn’t even send a piece of this rock to an experienced meteoritics lab for independent confirmation! That's the very least they should have done.

I’ll be frank: I don’t think what they found was even a meteorite at all, let alone from the meteor event seen in December. And given that it was embedded with a bunch of identifiable fresh-water diatoms found on Earth, I’m guessing this rock is nothing more than some rock from a river bed or other similar location.

Conclusion

So we have a journal with an, um, unusual publishing record, a man who claims with little or no evidence that everything we see comes from space, a rock that is almost certainly from Earth and not space, and a bunch of diatoms inside it (the one claim they get right) that clearly evolved on Earth and are identifiable as native in fresh-water sites.

That does not fill me with confidence that this claim of life in space has any basis in reality whatsoever. Let me be clear: In my opinion, the claim that they have found diatoms in a meteorite is almost certainly incorrect, and just as certainly not something they can state so unequivocally in their paper. The evidence they present simply comes nowhere close to supporting their conclusion.

Having said that, I do think there is life in space, or at least that’s the way to bet. We know there are billions of planets in our galaxy, and we know life on Earth arose almost as soon as conditions on our newly-formed planet were right for it. So I’m confident that, statistically speaking, there is life on other planets, at the very least “primitive” life such as one-celled plants.

It’s even possible life arose on Mars before it did on Earth and was carried here via meteorite. It’s an interesting idea. But it’s one with a lot of holes in it, the biggest being we have zero evidence of life on Mars. Getting it here is not that big a problem, but then having it live long and prosper is another issue altogether.

So to me, panspermia is an interesting idea but has no evidence to support it. There are a host of other problems with it as well, but I think the biggest black eye it has right now is the support it gets from both pseudoscience and sloppy science.

In the end, the idea of life in space is a scientific one, and must be solved with scientific processes. Careful scientific processes. After all, this is one of the biggest and most fundamental questions we have. Flamboyant articles with grand conclusions based on questionably-conducted research and incomplete reporting are not the right way to go about this.