What I have trouble believing, though, is that no parallel life forms ever originated other than what we know. I'm no molecular geneticist, but you mean to tell me that the molecules of DNA, RNA and 20 particular amino acids are the only possible molecular combination that can give rise to self-replication? Why only those 20 amino acids? Why only the L-isomers? There are many other macromolecules that can be generated with the existing quantities of C, N, O and H. In those 1-2 billion years before DNA/RNA/Protein based life-forms reached a critical mass, no other spontaneous generation events took place? Or they did, but they all went extinct? Leaving no trace at all? Even the most isolated, extremophile prokaryotes that have been discovered replicate with the same DNA/RNA/20 Amino acids mechanism.
There's actually a potentially really good reason for the dominance of one kind of life over the others, although there still remains the possibility that a
shadow biosphere(the term for this kind of radically different life from our own) exists somewhere in the interior of the Earth. In more recent times a microbe was discovered that could be major proof that Eukaryotes were challenged, in
Parakaryon, and plenty of microbial communities that have been sustained over tens to hundreds of millions of years have been found inside of various rocks. There is still much more to discover for Earth's ancient past and the microbial world.
The reason for the dominance of our form of life though, is that chirality and handedness of molecules matters a lot. A great example in humans is
thalidomide. One chirality worked perfectly as intended, the other caused extreme development problems and absolutely horrific birth defects, making it a teratogen. This doesn't just stop with human development though, as of course much of the processes our cells utilize are based on ion channels or enzymes with very specific shapes. Wrongly shaped molecules getting into these are usually either deadly poisons or our medicines. Just about any medication you can think of has some role with enzymes, receptors, ion channels and so on. Most infamously
sarin gas is one that is very deadly. For medicines any opioid that is used would be an example for a medication along the same lines.
Therefore it's very reasonable to assume that different types of life would be outright poisonous to one another. I remember there was some controversy with "
mirror life", which had artificially made new organisms with a different handed form of DNA. People were worried it'd be an existential threat, but more than likely we'd be a threat to its survival. I think our tree of life was just the one that rapidly took over the planet and choked out the other forms.
Beyond that though there's still a lot about deep time in the earlier portions of Earth's history that we don't know. The
Great Oxidation Event or "GOE" is one major point in Earth's distant past that is thought to have been one of the most deadly events for life on the planet. I personally don't think it was nearly as dire as many have claimed it to be, as many anaerobes will rapidly evolve tolerances to O2(on human timescales, not geological ones), it still would've been cataclysmic and not just because of the direct damage the O2 would've caused in killing life. The secondary and tertiary effects of just the GOE almost certainly caused a major shift in the ecology of most ecosystems of that time, due to the changes in redox potential. It is almost certain that there were other major extinction events in the past that could've contributed to the purging of other trees of life on our planet too.
One final thing is with
panspermia, which is the theory that life could've been seeded here from another planet or celestial body far, far away. It is very possible that Earth never truly had an abiogenesis event(or even the proper conditions for one), but instead was inoculated with life from elsewhere. All that it would need is for the contaminating comet or asteroid to have been occupied by only one kind of life and for it to take root before any other contaminated bodies would hit the Earth later. Any new trees of life would find themselves in an already colonized world whilst likely being very poorly adapted to it and having had a very taxing journey and entry. A world already inoculated is thusly a death sentence for them.
All of that being said though, there are organisms that use other amino acids. There are even some that utilize molecules that aren't proper amino acids, but instead similar compounds with one atom swapped out with a radical element. Here's a
paper(copy the DOI link into scihub to read the full thing for free, but the abstract says it all) going over a variety of organisms that were found to be substituting sulfur for tellurium in cystine, methionine and serine. The resultant proteins they made were far heavier than their sulfur counterparts. There is also
pyrrolysine which is used by some microbes too, which is a non-standard amino acid.
1. I could buy that some weird shit is going down in Antarctica, no idea what yet but there's weird history over there.
Russia at least was doing a lot of oil, gas and mineral exploration for resources under the guise of research. Here's an
article about it, but it's also very likely that Russia wasn't the only one to be doing this. Geological surveys by their very nature will reveal great deals of information about what resources can be expected if not present in an area. So while it may not be ayy lmaos in secret bases, it is certainly the case that the major countries funding research in Antarctica have been doing so in order to covertly understand what resources there are to exploit there. All whilst having signed a big agreement to not exploit the continent for said resources.
It seems in Russia's case the alarms were raised due to the more recent affairs in Europe.
Reminds me of the original
Mechanical Turk. It's like poetry, it rhymes. Also
>Indian call center scams have evolved
I just had an epiphany whilst still reading through this thread(already on page 128 ), in relation to a discussion about the cure for cancer:
What if pharmaceutical companies are purposefully making strains of bacteria that are immune to various antibiotics to which the patents/trademarks have run out and then releasing them? If they released the bacteria on the surface of something like the pills/pill bottles they know are going to a hospital then that'd be a great cover as of course hospitals are infamous for hosting "
superbugs" due to being nexuses of infected individuals and various antibiotics. Hospital staff would likely assume that the pills they get from a pharmaceutical company were clean. At the very least they'd be more lax with handling them. How would they ever even manage to try and track the source of the bacteria anyway? Hospitals are constantly cleaning surfaces in an effort to fight superbugs, so even if you could retrace its steps you'll be shit out of luck.
Beyond that it's trivially easy to selectively breed bacteria for antibiotics resistance. This documentary by Veritasium, that I'll link below, is great for showing it off but all you need to do is culture bacteria in petri dishes with antibiotic laden agar at ever increasing concentrations. Any pharmaceutical companies working on antibiotics would already be in regular contact with these generic antibiotics and bacteria as it's standard practice to use antibiotics to select for modified bacteria when doing genetic engineering. The idea being that only the modified bacteria with the genes for resistance you give them along with whatever other traits will survive whilst all the others die.
The Veritasium documentary also:
