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Comment by jneal | Hacker News Reader

Okay, I'm no scientist but one part of the argument just kind of irks me:

[i]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.[/i]

UNLESS, Panspermia is correct and all life on earth came from space, in which case it would be completely in the realm of possibility that life from space that landed on earth had already landed here before, in the distance past.

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No. You exhibit a severe misunderstanding of evolution.

Imagine panspermia is true. Some kind of life exists in space. and some of it fell down to earth. Then life on earth would evolve down here, adapting to the particular circumstances of our planet, and the species in space would evolve, separately, to adapt to living in space. The result is that both strands would inevitably become very different.

If you brought down life from space, compared it to actual life on earth, and found they turned out to be the same, then necessarily it would mean that both strands, in completely different environments, evolved to become the same. This is not only improbable, but emphatically impossible.

You would have a point if they found living specimens in the meteorite. As it stands, they found organisms that have died a long time ago and that greatly resemble organisms that have died a long time ago. Dead things don't evolve, so placing their lives at the same chronological point is not a problem.

But according to the evolutionary biologist quoted in this article, neither the organisms in the photos nor the known species they look like have been dead a long time.

> "1) they are, for the most part, in great shape. There certainly is not any sign of this being fossilized material… There are no extinct taxa found, only ones we would find living today…"

Fair enough. I was basing my comment on the other article, which claimed the opposite.

No...

Because even if life on earth came from a far far away galaxy (Millions of years ago) the way they would evolve would dependend on the environment and I bet earth is not 100% equal to any other planet on every single variable that also is close enough for a contamination to happen.

It would be ok to find one or two specimens that maybe "look" close to earth ones , but a whole bunch of them is somewhat impossible.

That's true, makes sense. At first, I just felt like this guy was rebutting based on the common belief that life evolved on its own on earth. In the past I've seen evidence discounted and honest theories rejected simply because they contradict the norm, and what everyone is taught. I don't believe this is one of those situations now, but that's just how it felt to me at first.

>UNLESS, Panspermia is correct and all life on earth came from space, in which case it would be completely in the realm of possibility that life from space that landed on earth had already landed here before, in the distance past.

The earliest known life on earth is cyanobacteria from 3.5 billion years ago. The earliest diatoms we've found are from 185 million years ago, and they are believed to have arisen around 250 million years ago.

So even assuming that the earliest life on Earth included diatoms, that leaves over 3 billion years between the earliest specimens observed and these hypothetically original specimens. I don't think the odds are even worth considering that a species adapted for an extraterrestrial environment would be visually recognizable after 3 billion years of terrestrial evolution.

I don't think there is a lot of doubt that panspermia can work. There is nothing preventing it in principle, and the scenario becomes more probable the more we learn about extremophiles.

But, it's another thing to simply assert that life on Earth originated elsewhere. If anything, it's probably us who are spewing bio matter all over the solar system. There is simply no compelling evidence to suggest otherwise. We see all kinds of bio-like formations in space rocks, but they're always "fossilized" in a sense that they most likely arose from abiotic processes. This is not the first time dubious crystal formations have been declared as of biological origin.

We also discovered a lot of unexpectedly complex organic molecules floating around in outer space, so it's definitely possible to find familiar chemicals without a biosphere around to produce them.

It can be somewhat difficult to distinguish scientists who are expressing valid thoughts about panspermia from quacks who are pushing a philosophical agenda. In this case though there was not even a little bit of doubt that the data didn't agree with their conclusions.

Except this wasn't even a space rock..

What I find worrying about this whole affair is that first everyone jumped on them saying that the fossils aren't really fossiles but instead just simple rock formations and then afterwords that the fossils are earth life so that the fossils didn't form outside of the earth.

Certainly the JoC is insane, but the jumping to conclusions it's critics engaged in seems worrying to me.

EDIT "you" is generic, not you EthanHeilman!

When you have a rock and some things that look like fossils and you want to say that this is a space rock and these are space organisms then you have a responsibility to do all that kind of jumping to conclusions first, in order to rule each of them out. You should be attacking, as vigorously as possible, your theory because you know that's what other scientists are going to be doing and you can save them a bit of work if you show that you've tried to do this.

Otherwise you could actually have a space rock with space bugs but you'll be dismissed for longer because people don't have enough time and money to do your work for you.

Agreed, the burden of proof is on the person making the claim and clearly they did not carry this burden. Generally I don't worry about how crackpots do science because you know they are crackpots. I worry that the first response of the critics was a sadly uncritical rebuttal which turned out to be incorrect. Namely that the rock formations were not fossils and they the pictures were a 'Ink Blot' that someone was imagining fossils into. There really were fossiles. Lets do better next time.

It is correct to say that Perpetual Motion machines are impossible, but it is incorrect to say that Perpetual Motion machines are impossible because of the rotation direction of the earth.

Only if you assume that evolution hasn't affected earthbound diatoms in any way. That's a rather stronger assumption than "life comes from space".

They claimed there was no evolutionary differences, so either it started it's space journey at the same time our ancestor did, or it evolved in the exact same way...

However the stating of, "zero chance" is rather un scientific.

>However the stating of, "zero chance" is rather un scientific.

Not really. It's just rounding. Of course nothing has literally zero chance, but sometimes the chances are so low that the epsilon isn't worth mentioning.

He should have said "probability 0", which translates as "almost impossible". The word chance is the tricky one, here.

Well no, "probability 0" means "impossible". I'm not sure what difference you're seeing between "zero probability" and "zero chance", but they mean the same thing.

It's rather pedantic in this context, but "probability 0" and "impossible" actually aren't the same thing:

http://nolaymanleftbehind.wordpress.com/2011/07/13/the-diffe...

In mathematics, probability 0 means "almost impossible". Think about randomly choosing a number between [0,1]. Uh-oh, that set is actually infinite (cardinality aleph 1, technically). Suppose we consider only the numbers in it with 1 decimal digit, i.e. {0, 0.1, ... ,0.9,1}. Every one of them has 1/10 of probability of being chosen. Now, suppose we consider two decimal digits: 1/100 probability of being chosen. Repeat this process and consider no discretization (i.e. there exists arbitrarily small epsilon>0 such that the difference between two numbers in the set is < epsilon).

Then the probability is.. 0! (you see how we divide 1 by the number of elements which are in the set)

But in the end you are going to pick one number or another in that set, so it is not "impossible". Surprise surprise.

Yes, perhaps a just a poor choice of words.

But it's not just Earth-like life, it's known species. That's a totally different thing.

Imagine if a car was found in a meteorite. It looks sort of like Earth cars. One explanation is that it actually came from Earth. Another explanation would be that it really is from space, but it looks like Earth cars either due to convergent design, or a sharing of ideas in the past.

Now imagine if another car was found in a meteorite. But not just a car that looks like an Earth car. It is, in fact, a 2009 Toyota Prius. This obviously did not come from space. No amount of convergent design or sharing of ideas can explain that.

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