https://www.cbc.ca/news/technology/hemimastigotes-supra-kingdom-1.4715823 https://www.nature.com/articles/s41586-018-0708-8 We've known about Hemimastigophora since the 19th century, but only recently have Canadian scientists come across them in a manner that allowed them to isolate them, breed them, and then sequence them. The molecular evidence shows that these little thingamajigs are more different from animals and fungi than either animals and fungi are from one another, thus putting into play a possible new supra-kingdom of life. A while back I came across an article concerning mimiviruses, another phenomenon that seems to be categorized in a rather "we don't know where else to put them yet" manner. Mimiviruses seem most like other things we call viruses, but they are orders of magnitude larger than other viruses and they have genomes that bear little resemblance to anything else on Earth. It's important to note when engaging that last thought, that you and a banana share a great deal of genetic blueprinting. https://phys.org/news/2018-03-newly-giant-viruses-apparatus-virosphere.html We barely know how life on our planet works, and we discover every day that our definitions and categories are only as valid as our understanding and discoveries of what can be and what can exist. I've always viewed the idea that a virus isn't "alive" as a rather arbitrary line, one steeped in eukaryotic prejudice. When we discover life elsewhere, will we recognize it? Will we acknowledge its aliveness if it doesn't answer to our small human definitions? Will we pass it over, as we search for things that look like things we understand and know? (these are all rhetorical questions) I wonder...
Thanks for sharing. I thought this video was relevant to your questions. The entire discussion is really interesting, so I'd recommend watching the whole thing if you're interested in the general subject of life, its origins, and its potential, but the main excerpt is just from 46:20-50:25 of the video.
"... why are you using Earth to constrain your capacity to think about what exists out there?" There it is in a nutshell, isn't it? It's also part of a phrase that forever makes me cringe when I hear it in both science and in science fiction: "Life as we know it" The Canadian scientists referenced above have proven that life that exists here on Earth is itself beyond the scope of "life as we know it". If nothing else, I'm glad that two minds like Richard and Neil can admit that we what we know is what we know, and what is is something different.
What? This part is glorious... VENKMAN: What do you mean "bad?" SPENGLER: It's hard to explain, but try to imagine all life as you know it stopping instantaneously and finding yourself confined forever in another dimension. VENKMAN: That's it! I'm taking charge. You guys are dangerous. I love this movie...
No, no, no... I'm hoping the universe is more creative than that phrase and that we discover life as we don't know it. I'm as jealous as a man can be with respect to the Canadian scientists who made this discovery, yet another branch of life on our planet, life as we did not know it up to now.
@Wreybies, Ok, I give you that. This phase is overrated. It is a coincidence that the apocalyptic sci-fi book I'm reading now talks about a lifeform based in RNA-pyranosal (instead of ADN) that it's quite different of us. But in the real world, the universe is bound to the four forces (if they don't change in a while) and life is constrained to a very small scope if you think about it. There are some mandatory conditions for life ("as we understand it": I consider that stars aren't alive, but are essential for life) to exist. This is a very interesting topic that could fill many cold afternoons in front of a fireplace.
There's another theory that states we would indeed recognize life on another planet, and it would be very much like life as we know it. That the processes of evolution are very narrow, that there are few avenues in which organic life can exist. On a genetic level, there's not a world of difference between you and a snail, or a grapefruit, or a magpie.
There is a book called Cross-Time Engineer by Leo Frankowski. It's a bit of an homage to A Connecticut Yankee in King Arthur's Court and it features a modern (Cold War-era) Polish engineer who gets sent back to the past by accident. I promise I'm in the right thread, btw. Anyway, one of the things he discovers the medieval (I don't remember the year, but go with me on this) Poles were not yet doing was beekeeping, so he has a word with the lord's carpenter and tries to show him how to build a beehive. The carpenter says it's impossible, it would take too much time to build any number of those, but he's got an idea that he'd like permission to try out. Over the next few weeks, the engineer notes a large number of sections of split log with small fires burning in the center portion of them near the carpenter's shop, but has no idea what they're for. Later, once the fires have done their work, the carpenter ties the halves back together, having created hollow logs that are suitable sites for beehives. The modern engineer thought only in terms of how to create things from boards and planks, but the pre-modern carpenter's though processes were on how to create things from trees. Our perceptions of how life can evolve and function are at present a result of our severely limited sample size of one planet. I'm not suggesting anything mystical out there, but I imagine if we ever do discover life with a non-common origin, there will be at least one moment of "Holy crap, is this data right? Nobody every thought of that angle before."
Life is typically defined as something that has defined boundaries (like a cell membrane), is capable of reproducing itself, is self-sustaining, and has its own metabolism. Maybe this could mean that we will miss out on some extraterrestrial stuff, but at the same time we're not limiting ourselves to water-based, carbon-based, DNA-based, etc. life. Doesn't matter what it looks like and what it's built from. That said, setting a definition of what is alive and what is not is very tricky, which is why no official definition actually exists. Here are a couple of examples that usually cause a mess in this debate: (Retro-)transposons: DNA fragments capable of moving and multiplying within a genome. When the host cell transcribes (and translates) these guys it produces machinery responsible for applying "copy-and-paste" or "cut-and-paste" on the transposon, which will move (or copy) the fragment to a new place within the genome. Should these DNA fragments (i.e. it's literally nothing but DNA), which form a majority of all DNA in the genomes of living organisms, be treated as living just because they reproduce (using someone else's machinery) and move around (by having someone else cut them out and then paste them back in)? Plasmids: Circular DNA fragments that are typically used by bacteria to transfer genes between one another (e.g. to propagate antibiotic resistance within a generation). However, there are some "rogue" plasmids that trick the bacteria they enter into producing copies of the plasmid (the bacteria transcribes and translates the plasmid, which leads to production of enzymes and stuff that induces replication of it), which are then sent outside the cell so they can enter other bacteria. Again, we're only talking about pure DNA fragments here, but they end up acting a bit like "naked" viruses. Should they be treated as living? Viruses: A virus is essentially a stolen shuttle containing, you guessed it, a DNA fragment (or RNA in retroviruses). These work similarly to plasmids, but also often have some machinery for avoiding immune systems and forcing themselves into host cells. While in the host cell, we are again talking about a DNA fragment inducing its own replication using the host cell's machinery (as well as production of the shuttle). None of these examples are capable of reproduction, self-sustain or metabolism on their own accord. Instead they all require a host of some kind to do everything for them (this is in contrast to parasites, which only use their hosts as habitats and not factories). And thus none of these are considered life by the definition above (which, again, isn't anything that is set in stone). EOTD, if we consider viruses to be living, then surely plasmids must fall into that category as well? And if plasmids are alive, then it's not that hard to see that transposons should also be (since they are essentially the same thing, but within organisms instead of between them). At that point we face the problem of separating "living" DNA from "inanimate" DNA, which will become a mess since we would have to base that definition on what these elements code for (RNA and/or enzymes for reproduction, or for triggering someone else to reproduce them) as opposed to what they are (DNA fragments). And that leads to the issue of now having a DNA-based definition of life, which ends up being much more narrow and Earth-centric than the current function-based definition.
The difference between this little doodad and other little anaerobic doodads is that this thing is 100% part of the animal kingdom, not bacteria or archaea. https://www.cbsnews.com/news/scientists-discover-first-ever-animal-that-doesnt-need-oxygen-to-breathe-2020-02-26/?fbclid=IwAR3DOAyWknP-0z66xF3NBYb4B_-0Zh-GdHTpjTCNqnz8CiUCINOedslQCs8
