I mean, the first sentence of the preprint is "This paper characterizes the first protein to be discovered in a meteorite." The Significance section states that "[the preprint] is the first report of a protein from any extra-terrestrial source." And they claim that their evidence[0] that the protein is not a terrestrial contaminant is quite strong, so I would say that the confidence level of the researchers matches the title exactly.
[0] For example, from the conclusion: "The average molecular deuterium excess above terrestrial is (25,700 ± 3,500)%, or
a D/H ratio of (4.1 ± 0.5) x10^-3, comparable to cometary levels, interstellar levels and also equal to the highest prior report in micro-meteorites."
One of the cites at the link is a previous paper on similar investigations of one of the same meteorites plus one other, that was published in 2015 in Meteoritics & Planetary Science, a journal with a long publication history. That paper is cited by two other papers from different authors. [0]
At some level, these researchers seem to be doing basic chemistry. Maybe they're not characterizing the implications correctly or maybe they haven't controlled contamination, but if proper research discovered extraterrestrial protein it would probably generate papers that looked like these.
>> At some level, these researchers seem to be doing basic chemistry <<
what it looks like to me is that a couple just received a good research grant set up a laboratory in started putting it to good use. we need to find these polymers on samples that are still
off world, or we need to be able to demonstrate such polymerization in an environment mimmicking conditions off planet.
"Basic" is not meant to be derogatory. They're chemists; that's what they should be doing. It would be more troubling if their results came from "novel" chemistry.
I need to make time to ask someone to ELI5 to me how this research is done without contaminating the sample with terrestrial-originated protein. The meteorite was on Earth for some time, and bacteria are staggeringly invasive little bugs.
I believe they successfully avoid contamination, but I have no idea how.
the thing with structured peer review is that noone knows it all , and a team of specialists [review commitee] are much more powerful than a team of generalists, to the end of revealing any artefacts of procedure, or hair splitting levels of knowledge regarding metalo-organic chemistry that could explain abiotic process that would produce amino acid polymerization.
I read a comment on HN or Reddit a while back about how some molecules were found in a meteorite that were left-handed where every molecule on earth is right-handed or something to that extent.
If my memory serves it was as if molecules fit together like a lock and key except this molecule's key/lock combo was inverted.
Apologies if I'm bungling it up but it felt as though it was significant. As if the molecule found was unlike any molecule on earth due to its lock/key orientation.
"The origin of this homochirality in biology is the subject of much debate.[12] Most scientists believe that Earth life's "choice" of chirality was purely random, and that if carbon-based life forms exist elsewhere in the universe, their chemistry could theoretically have opposite chirality. However, there is some suggestion that early amino acids could have formed in comet dust. In this case, circularly polarised radiation (which makes up 17% of stellar radiation) could have caused the selective destruction of one chirality of amino acids, leading to a selection bias which ultimately resulted in all life on Earth being homochiral."
I've also heard some scientists say that parity breaking could explain the origin of homochirality. Personally, I'm happier with the "random chance" hypothesis.
You are talking about chirality. Biologically produced molecules are all of the same "handedness", but molecules produced by other means (normal chemical reactions) tend to have 50/50 chance to be either handedness (although selective reactions are possible).
So you'd expect to see both at a 50/50 ratio in a meteorite, if you see any at all. That's just chemistry.
Why 50/50? It should take on the statistics of causations of chirality. And based on that, one might be able to guess the exact location and orientation of the meteorite when these chemicals were formed
Interestingly, the protein described in the article is made out of glycine, the only amino acid that doesn't have handedness (i.e. it is achiral). So you can't tell if this protein is terrestrial or not based on its handedness.
To be perfectly honest, you’ve drawn my attention to an ambiguity I had never before noticed: does panspermia’s hypothesis that “life” came from space require that life arrive fully formed and functional, or does it advocate that complex organic chemicals arrived from space and assembled on earth into a working configuration?
I have always found the idea of panspermia to be a bit of a cop-out as it totally sidesteps the problem of abiogenesis: it’s all fine and well to say “life came from space” but you still need to explain how life arose in space to begin with.
I'm not an expert, but I think that there are different flavors of panspermia. Some would say that we got at least single-celled organisms from space; others would say that we just got complex chemicals.
It's only a cop-out if you try to use it to explain the origin of life in general, not just on Earth.
Life arose very quickly on Earth, almost as soon as it was capable of surviving, so it raises the interesting question: were we just lucky, or is it easy to spawn life, or did it come from elsewhere? The answer creates very different pictures for what Earth-like planets elsewhere in the galaxy actually look like.
I'm always confused by that. So there's only one form of life possible? Otherwise life may have arisen before, been wiped out when Earth changed, and life arose again. We may be just the latest in a long series of life forms.
Good point. It might be that the kind of life that arises on a planet depends on what it is bombarded with and which of those various candidate life-forms ‘takes’ on the specific environment.
theoretically possible but there is no evidence to suggest this. Weighing the various hypotheses, most people would suggest the "simpler" (fewer wipeout/arise events) hypothesis, given the assumption that life arising is considered very rare.
Because the earth remade itself several times. Any previous life would have surely been erased. The assertion was that life arose just once. That's hard to prove.
From what I've read there are people on both ends of the debate. Most people I've seen talking about the idea tend to lean towards amino acid and simple proteins making it down here - not fully functional lifeforms that are able to replicate.
A panspermia theory that involved non-living chemicals coming to Earth would be pretty useless. There's no real doubt that it's possible to generate those chemicals on Earth, and AFAIK it's still believed to be easier to make them on Earth than in space. Organic chemicals from space would just mix with all the ones that were already here.
>> it's still believed to be easier to make them on Earth than in space
I don't mean to be glib, but space is very large and time before our planet was formed is very long.
I assume that if it was easy here in those first few hundred million years, it had already been even easier in many elsewhere places. Any one, or multiples of which could have seeded us with as yet locally unavailable precursors and possibly even life.
I think a complex molecule could accepted. We don't know why our biological systems settled on their chirality, but maybe it was from a massive bump of molecules with all the same chirality from an extra-solar source.
While I have no objection to panspermia being possible, if it were true, it would be a significant hurtle added to the search for the origins of life. We would know how life on Earth started, but until we expand out into the galaxy, understanding the origins of the life that seeded Earth would be essentially unknowable.
At the same time, it's pretty clear we need to get out there (ultimately much beyond the galaxy itself) if we are to solve certain questions.
And there's a general idea that a purpose of life may be to "spread" through the universe — like, why die here on this planet instead of settling the universe... given the actual choice, there's no solution but to leave eventually, when your star dies (if only locally to "fix" it by adding more fuel in it, e.g. hydrogen).
So this, if true, is really just one more reason on top of an already high pile as I see it.
Assuming panspermia is correct, we could just continue to improve sampling of stuff coming here. Also sampling earth-originated organic materials from some distance away. This could give us some pretty good data on variety, density, duration.
Under this assumption I'd most like to estimate the number of discrete seeders in our vicinity and their interconnectedness.
At the best of times, what exactly does peer review add? I'll buy that it catches glaring flaws in their methodology or conclusions drawn from data. But it's not going to catch little mistakes or unlikely events that might have contaminated the sample.
For the purposes of a site like this, peer review filters out the cranks. Cranks can be rather a burden on people: they rarely accept criticism well, and effort spent explaining the problems to their defenders is a drain without a lot of upside.
So when somebody can say "It has been peer reviewed", it at least helps get past the crank filter. And conversely, "It hasn't been peer reviewed" can be a shortcut for "I'm not going to put a lot of effort into this without better reason than I've heard so far."
It's not so much an argument as a way of shortcutting an argument. Though note that doesn't really apply to a top-level comment on HN, where nobody has really advanced an argument yet and simply ignoring it might be a more useful strategy.
there has to be independently reproducable results from independent research over time until the variation of outcomes is known, for some sciences this can be a very long process for very unscientific reasons.
one thing not addressed is that the isotopic elements of the meteoric fragment may have been incorporated by a terrestrial biological or chemical process
whenever the methodologies of a scientific experiment are repeated the underlying principle is preserved if there is no signifigant deviation of observed results from expected results.
for example PCR has a lot of credit, the central dogma of molecular genetics has a lot of credit, but there are exceptions being found in very niche cases such as reverse transcriptase and the HIV virus.
those experimental protocols that have been reviewed and found to be non deficient at the time of review are often repeated in principle as they are used for a common tool.
The impact of a collision is so devastating that any life surviving it is unlikely. Unless such life can endure such extreme conditions, in which case, it would exist on such inhospitable conditions as on Venus
So far sugars, and amino acids have been found in both comets & gas clouds. BUT to find this protein is the slam-dunk, holy-shit they were right, proof that Panspermia is how we got here, and there _MUST_ be life in other parts of the universe.
I agree with the last part: it probably shows that there’s life out there.
It could show that life travelled here on meteorites etc. But it also could mean: life arises elsewhere, life commonly arises in the universe and may have also arisen here (and many places) independently.
Before we even get into the role of expert peer reviewers, does the article pass basic tests of authenticity, let alone extraordinary claims requiring extraordinary proof?
Could be a student... but do a search for
Malcolm. W. McGeoch, Sergei Dikler, Julie E. M. McGeoch from
Plex Corporation, Bruker Scientific LLC and Harvard University
and you will start to wonder if these people even know their names have been used in this article. Shame on phys.org for not calling the author for a quote or doing any other legwork to convince me this is anything other than a UFO hoax or the output of a paper-writing AI. It could be, but ...journalist please.
Some cursory search shows papers published by Julie E. M. McGeoch on related topics over the last 30 years, many of which are also co-authored by Malcom McGeoch of Plex Corporation, who I assume is of some relation (significant other or relative). I admittedly don't know a ton about academic publishing, but from my outside position, it seems unlikely that this report is fraudulently attributed—though it's certainly possible that I'm missing something.
You don't think it would be interesting to discover non-Earth proteins within our solar system? At the very least, this finding would be a pretty good indicator that proteins occur naturally outside of our solar system as well.
It's a potentially pretty big deal for understanding extraterrestrial chemical processes and estimating the likelihood of life, but to be clear this isn't anything like actual evidence of alien life.
It's a bit of a stretch to call this a "protein" TBH. The protein part is composed of only glycine, so there's really no information (e.g. DNA) required to synthesize it, just glycine and a chemical environment that would cause it to polymerize. The caps at either end are not protein components at all, as the article mentions, and protein backbones on Earth are never cyclic afaik.
But, it's still a very complex organic molecule ofc, which is very significant on its own, and its similarity to protein is evidence that protein-based life could be more common.
there is a mismatch between the title of that article and the level of confidence these researchers were expressing.
the preprint is here:
https://arxiv.org/abs/2002.11688