They don’t need liquid water for the rest of their bodies to exist. They only need water to have an active metabolism.
So like tatrigrades who use that one substance when they go into hybernation-like state?
Tardigrades replace the water in their bodies with the CAHS8 protein which is like a gel. So one could argue that they are no longer a water based organism when they enter their tun state.
Radiation seems to be a bigger issue than the presence of water during the trip. Going to Mars takes 8 years and during that time the bacteria needs to be covered with a layer that is at least half a millimeter thick on all sides*.
There are 2 known species of bacteria that can survive (1)being ejected into space, (2)being in space assuming no radiation and (3)falling back to a planet. Tardigrade can survive being in space but not (1) and (3).
Panspermia should no longer be considered an unlikely theory. It should be treated like a fact. At least inside the solar system.
Mars and Venus had oceans when Earth had its great oxygenation? Therefore they must have also had a great oxygenation after Earth of before Earth, with time difference depending on how often they exchange microbes.
In fact, Mars still has some oxygen in its atmosphere (174 ppm). Venus doesn’t have any because volcanism supplies new gasses to be oxidized.
There is a very simple proof for panspermia that atheists don’t want you to know about. Doctors hate it. It should shatter the beliefs of all disbelievers.
What is the first thing that we learn in school about archaea? That they are extremophiles.
What does Venus have? Extreme conditions.
Q.E.D. drops mic
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This still means that one of our System’s planet’s still had to be the birthplace of life.
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If we assume that every square meter has the same probability of having an abiogenesis, then it would be proportional to the surface area of the planets, 46% chance that the first cell lived on Earth, 41% chance it lived on Venus and 13% chance it lived on Mars.
I don’t think we can discover where it happened. Earth lost most of its oldest rocks as plate tectonics recycles the crust.
I think Archaea came from Venus.
When two biotas come into contact, a biotic interchange takes place and the species in the two ecosystems homogenize. All of the oceans of Earth are connected, so we can consider the pelagic regions a single biogeographic realm. And we can consider the Earth-Venus-Mars trio different biogeographic realms that sometimes come into contact.
Biotic interchanges are asymmetric, the species in the larger biota outcompete the species in the smaller biota, and fill their niches. For example, when South America and North America collided, North America was connected to Eurasia and Africa at that point, so the more competitive placental mammals which occupied a larger region replaced the South American marsupials.
Larger biotas are called donator biotas and smaller biotas are called the recipients. When a biotic exchange happens between planets, the larger planet would be the donator, and the smaller planet would be the receiver.
Mars would send microbes more often than it receives because it has the weakest gravity, but Martian microbes would have less success in Earth and Venus. Martian species would have ancestors that evolved on Earth and Venus for a longer amount of time than in Mars.
Venus has more sulfur compounds, it has more volcanism and it is hotter since its closer to the sun. So its aquatic environments that have these extreme conditions have a larger area than similar locations on Earth such as hot springs and hydrothermal vents.
So my theory is as follows:
The common ancestor of Bacteria and Archaea evolved on Earth. Those that remained on Earth became the Bacteria and those that went to Venus became the Archaea. And this is why they are different.
Venus isn’t that habitable anymore, so slowly, all the Archea on Earth will go exctinct and be replaced by Bacteria, because when an Archea goes exctinct, since there are more Bacteria than Archea, there is a higher chance that its niche is filled by a Bacteria. The same is true for when a Bacteria goes exctinct[1]. After all Archea go exctinct, different subclades of Bacteria will start to go exctinct and the date for the last common ancestor of all living organisms will keep moving forward in time. And this effect was weaker when there were two planets that were seperated.
if there were infinitely many species, the percentage of bacteria and archea wouldn’t change, for the same reason that heads and tails would approach 50% if you did that infinitely many times, but since that isn’t the case, eventually one of them would replace the other, and the more common one is more likely to be the replacer ↩︎
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Ok, now where do you have hard proof that this did indeed happen?
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Cells can survive moving between planets.
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We would expect incoming species to be different
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There are different species on Earth.
Therefore some of them may be alien.
I don’t have any physical proofs for this that I can point to but there are ways to test this theory.
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Identify meteorites that came from another planet. Try to find ones that spent a short amount of time in space.
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Look at the microbe fossils before and after the meteorite lands. Try to extract DNA.
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Were there new species that appeared after a meteor crash? Are they more adapted to environments that are more common in other planets? Did adaptations to such environments speed up after meteor crashes? Are there any genes that look like they are horizontally transferred from a species that was isolated in another planet for some time?
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And the simplest (to verify) option: Go to Venus and try to find some Archaea. Dig up rocks in Mars and look for fossils. See if they similar to Bacteria and Archea.
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Most fossils at that planet were probably destroyed by now.
And there is pretty much no chance of anything living here. The “Habitable” parts of the atmosphere lack the kind of water which could be easily consumable by anything.
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Are you… serious? Genuinely curious.
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Also, why is your plant picture still upside down? It’s been almost 2 months since april fools now…
Oh thank god, I thought you were some rampant conspiracy theorist
Edit: Why did you change your response
Occam’s razor says that given parity of evidence between two theories, we must prefer the one that makes the least amount of unfounded assumptions:
Your theory assumes that organisms billions of years ago were similiar to modern organisms, that they somehow escaped their planet, that they somehow survived reentry to another planet, and that they managed to arrive in an enviroment of the planet that allowed them to survive and reproduce.
In addition, “There are different species on Earth” is not evidence for panspermia, as evolution and speciation exists.
Panspermia is also a fringe theory in the scientific community, which further indicates that it is unlikely to be right.
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Bacillus subtilis is the most studied gram positive bacteria, so the fact that not many space faring bacteria have been discovered may be due to survivor bias. You keep studying the same bacteria rather than a new one every single time and only discover the capabilities of that bacteria.
What makes bacillus subtilis survive a space trip is its ability to form endospores. Many other species can also form endospores. According to chat gpt, endospores evolved before the great oxygenation.
Wheres for the other one, Chroococcidiopsis, wikipedia doesn’t give an explanation for its polyextremophility, other than saying that in nature it lived under dry drocks and did photosynthesis under those translucent rocks.
Lets talk about another bacteria that has a longer wikipedia page. Deinococcus radiodurans can survive being ejected to space and being in space, but not reentry. It has various adaptations such as high amounts of antioxidants, nitric oxide, and the LEA proteins that tardigrades also use.
If we assume that life first appeared on early tidal pools, then the evolutionary pressure for resisting desiccation would be there from the start.
Does it really mean that we’d have those extreme bacteria with the needed predispositions? You don’t need that to survive in a less moist environment.
Panspermiability is a side effect of desication. At least for some species.
It’s still going to be extremely rare.
It’s more likely that Archaeas evolved here on Earth in it’s own extreme places.
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i now regret reviving this thread.
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I guess that is because of the solar system panspermia theory presented by 50gens?
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There is no reason to have bad feelings about this thread. Just look at the evidence. Its a great theory.
- There a branch of life that lives in Venus-like extreme environments that is different than bacteria.
I was also going to mention the oxygen in Mars but it turns out the current oxygen is caused by the photolysis of carbon dioxide and water.(1)
The presented counter arguments are as follows
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“There are different species on Earth is not evidence for panspermia, as evolution and speciation exists." It can be a weak evidence.
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Panspermia is a fringe theory among scientists. So what? They are just being overly cautious in their public statements.
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How could we know that ancient microbes were similar enough to modern microbes? They had the same evolutionary pressures as today and they may have come up with similar solutions for them that caused the same effects. The dry soil away that is from the puddles is just as inhospitable for microbes as space.
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The occam’s razor defense presupposes that no panspermia is more likely than panspermia. But there is no reason to assume that. There is a weak evidence for it. And also there are no contradicting observations that have been mentioned so far. I can’t think of any. So my hypothesis makes more explanations than the null hypothesis.
I noticed that not only should microbes be able to hitch a hike, but the hikes should also be frequant enough and take a sufficiently short route between Earth and Mars or Earth and Venus. Is that the case? Yes it is. For example, Allan Hills 84001 leaved Mars 17 million years ago and landed on Earth 13 thousand years ago(2). Based on this one data point, we can assume that a martian arrives on Earth once every 17 million years on average.
And this number would have been shorter during the late heavy bombardment.
Can microbes hibernate for 17 million years? Yes, endospores are known to survive for that long
I saw this on my news feed today
The biologic source of the methane on Earth’s atmosphere is methanogenesis, which is the breakup of glucose into carbon dioxide and methane. Why should Mars, a planet with no volcanism and an oxygen containing atmosphere, have methane at all? Methane would react with oxygen and it would deplete, unless it is constantly being replenished.
Having said that, I looked it up and Mars does have volcanism. But I don’t think volcanism is the source of the observed methane.
Why should there be any methane in the soil, if methanogen microbes weren’t living in it? The Gale crater formed 3.5 to 3.8 billion years ago due to a meteor impact(7), it isn’t a volcanic crater. And it had a lake. Perfect place for life.
I have a feeling that a major argument is about to begin in this thread…
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