In my experience, Nature News summaries are generally more trustworthy than university press releases. Nature News can suffer from hype problems seen in all scientific journalism, but it's one of the least bad sources. On the other hand, university press releases are basically unbound by journalism best practices; they can be almost pure marketing and should not be considered more authoritative just because they are associated with the university.
We know that deep underground, and in vents in the ocean floor, there is still some life. Is it possible there are some extreme environments on Earth where this ancient life is still going?
I'm no expert, but my understanding is that past a certain point in history, the life that could thrive depended on an environment that no longer exists.
For example, the Great_Oxidation_Event (https://en.wikipedia.org/wiki/Great_Oxidation_Event) that killed off many anerobic organisms. So there are still pockets environments that can support such anaerobes, but they are rare.
Many Archaea (https://en.wikipedia.org/wiki/Archaea) are inhabitants of extreme environments - the extremophiles - but are they the same organisms as the ancient life here, or also relatives?
All life is equally ancient and the pressure of evolution has molded all life for equal amounts of time. (But not necessarily to equal extents as the ability to adapt is itself an evolutionary process.) What we may find is an ancient branch, with some features preserved we don't know about, but also some features adapted for the extreme environment.
1)
Probability of that is so miniscule as to be nonexistent. I’d suspect foul play at that point. As in someone just transporting the animal there. You can’t really get identical DNA on earth. It’s to be expected that it would be even harder if there are no common ancestors.
2)
Yes. In order to make that you need to basically fully understand the organism in question. All of it’s properties are the same and product of the same evolutionary history by the virtue of you just looking at the existing creature and making an 1:1 copy
Funnily enough, I have the opposite view: given the amount of stars and of earth like planets in the universe, probabilistically speaking there is bound to be a random chance where two instances of life have the same DNA without ever being in contact.
Disclaimer: I'm bad at maths and good at dreaming.
The bare simplest genomes are viral genomes about 1000 bases long. These can only operate in environments created by more complex genomes. But even taking them, the theoretical diversity in a genome 1000 bases long, using the 4 canonical nucleic acids, is 4^1000. The number of atoms in the entire universe is around 10^80 (https://educationblog.oup.com/secondary/maths/numbers-of-ato... ).
There's a lot of complexity here: other life may use other nucleotides; those atoms and bases are constantly being rearranged; many base changes are relatively silent - they don't materially matter; etcetera.
I don't know how to calculate all of the rest of these factors, but I think the odds are more than astronomical.
>> The number of atoms in the entire universe is around 10^80
This is incorrect. It's an unsolved question in modern physics if the universe is finite or infinite. Even if it's finite most theoretical physicists believe that visible universe (94 billion light years across) is only a small piece of a far larger universe - so there are probably far more atoms.
If the universe is infinite it may be that there are infinite number of copies of every living organism on Earth out there.
At that point aren't we getting into the idea of a multiverse, and not a universe anymore? We have no non-hypothetical knowledge of what exists beyond the limits of the universe as it descended from what we can still see of the radiation shortly after the Big Bang. However, from that radiation, can't we get a ballpark figure for the atomic limits of the Big-Bang-Universe?
No, the different multiverse hypotheses are something different. The size of "our" universe is unknown, we can can see a sphere with a diameter of 94 billion light years. How much is there beyond that sphere is a research topic. No light from beyond the sphere has reached us during the lifetime of the universe.
The number only seems small because we use notation to make it seem small.
Most combinations of nucleotides aren't functional, or even capable of being synthesized by natural processes. This limits what can be created quite a bit. The true odds are still extremely high, but not nearly as high as these calculations guess.
> You know your logarithm calculation rules, right? Right?!
Eh, at one point I did. I'll take your word for it. It seems familiar.
Now factor in number of rearrangements since the universe started. Or heck, let's keep it simple to the last 4.5 billion years.
I count about 30 atoms in a nucleotide, so X is a bit more than 10^523.
Let's say 2 rearrangements per day (this will vary dramatically, but I have to pull some number out of a hat). Over 4.5 billion years that's on the order of a bit more than 10^12. so X is around 10^511.
If it was truly identical, i.e. same anatomical and biological features, it would be proof that something had transported them there, and would therefore be a branch of life from Earth.
If it was truly an identical species and it was the simplest form of life possible, you're saying that it could only be transported from earth? That seems a bit shaky. You don't think the same factors that created the first lifeform on earth couldn't naturally be reproduced anywhere else to create that same lifeform?
Taking the premise rather literally, it would mean, for example, that the DNA of the organism would be typical for a member of its species on Earth. The odds of hundreds of millions of bits of genetic information coincidentally being the same are, if you'll pardon the expression, astronomical.
It's like saying a standard opener move in a boardgame is unlikely because there's a lot of other moves available. It's standard move because the game have an optimal set of opener move to achieve victory.
So if another planet with similar environment exist, the range of solutions for self preservation goal might be a tiny subset out of the hundreds of millions of bits of genetic information.
And the answer gave such certainty to what ancient life would be like that my hypotheticals should be able to be answered (in the same context) with just as much certainty.
It's trivial to apply my hypotheticals to models in which life didn't all descend from a common ancestor.
You're invoking god and magic (i.e. sufficiently implausible coincidence and sufficiently advanced technology). Yes, god and magic can render most descriptions of how the universe operates inadequate.
I am absolutely not. There are lines I didn't draw for the sake of time. Re: think about how you could translate my hypotheticals into how nature could do that on its own (obviously over a much longer course of time and fortuitous conditions).
1) I presumed that the person you originally replied to was speaking of terrestrial life when they wrote "all life".
2) There are thoughts that life on Earth, presuming it started on Earth and wasn't seeded from meteorites, may have started from multiple populations. But it's presumed that if it did so those multiple populations were either out-competed by one population, or sufficiently alike that they effectively merged in their descendants.
At any rate, at this point, all life that we have so far detected shares similar enough features to presume a common origin. This includes incredibly separate lineages such as the bacteria and archaea.
Would you consider modern computers to be descended from IBM mainframes? Someone building a duplicate lifeform from parts based on existing knowledge and existing lifeforms does not negate that those existing lifeforms evolved into form since the beginning of terrestrial life. Your work is standing on preexisting evolutionary knowledge, processes, and a chain of life, even if it technically replaces biological reproduction with a human engineer.
From a dialectical point of view you're effectively invoking god to nitpick. If you believe you aren't you're going to have to spell it out for me.
I don't think you understand what I'm saying. You can arbitrarily create models of earth life that didn't have a common ancestor via "my" hypotheticals which are just as valid as univeral common ancestor (which predominantly features: there is something common in all life, so all life must have came from the same place; obviously this is a gross oversimplification but that's what we're dealing with in the answer)
it may not share common ancestor, but from your comment I assume it could reproduce with earth based counterpart. Thus it would be considered by the most popular definition to be the same species.
We already know there are some extreme environments with ancient life!
The Movile cave [1] has been sealed off from the atmosphere for 5.5 million years, and it's filled with very unique creatures. They survive off of chemosynthesis, rather than photosynthesis. It's an extremely low-oxygen environment!
Yes, but it’s relatively unlikely to go back a billion years given how geologically active our planet is and how fast microbes can mutate.
The oldest I can think of are the Movile Cave [1] which was isolated for 5.5 million years before it was discovered and Lake Vostok [2] which has been isolated for tens of millions of years.
Seems like the real surprise here isn't the chemistry itself (which matches modern forms), it's that evidence for eukaryotic life from this era is scarce. Eukaryotes apparently hid for a billion years in an ecosystem completely dominated by prokaryote life. Which I guess is surprising since in theory they're supposed to be more complex and adaptable.
I wonder if the "hiding" phase was pre-mitochondrial. We can get a long history of stem-eukaryotes (?), starting to build up these diagnostic chemicals, but they don't take over until mitochondria give them a bunch of energy.
My naive thought - complexity kills all things. Eukaryotic cell is bigger, has more metabolic processes, can have specialized life cycle, etc. All of which means that it is slower growing and could be out-competed by the faster-growing, but less optimal organism. Natural selection only picks those who survived, not "the best".
Maybe we're already launching them - getting rid of all the microbes in a complex machine, like a Mars rover is almost impossible (without destroying electronics and other vulnerable parts on board).
“Professor Jochen Brocks inspecting the 1.6-billion-year-old rocks in Australia’s Northern Territory. The rocks contained a primordial chemical structure that hinted at the existence of the Protosterol Biota.”
Not sure where this sentiment is coming from… Considering it’s fat traces of a primordial species that is a common ancestor of all complex life on earth, which went extinct over 800 million years ago, and is found in ancient rocks around waterways literally all over the world; I think we are fine to touch it.
Finds like this are great because they can possibly shed light on the problem of abiogenesis. Many people, including myself, think there were possibly several generations of life that preceded the RNA/DNA driven stuff we have today. It was probably much simpler and simply consumed by later generations, and lost. If and when we send probes to water bearing places in our solar system, we may find these structures. This, in turn, will support the hypothesis that life is common in the universe. Which will, in turn, support the hypothesis that civs that can muster enough energy to expand beyond the initial star will instead use that power to destroy itself. Which will, in turn, help shape human civilization, if we choose to heed the warning.
Interesting. I depart towards one of your last steps. It's embarrassing to admit. But hundreds (or thousands) of these UFO reports are real and aliens have been visiting us since the beginning of human life. I said it. Please don't revoke my university degrees :) Actually, you can, they didn't really do anything for me anyway.
