It can be reasonable supposed that the no: possible building blocks that can lead to life is finite.
This would mean that a set consisting of all possible combinations of said building blocks would also be finite. (Though huge in no:)
Ofcourse all possible option will not lead to viable living organisms. We can approximate life as a search algorithm that sweeps through this set and rejects all unviable combinations. If the requirement for life is highly specific and not easily met (as it’s reasonable to suppose), then this will give us a set of possible life forms.
If this set is very limited in no: due to the stringent demands for having life…
Then though possibility for life to emerge is itself improbable/impossible- it would be highly probably for all existing life to show convergence irrespective of where it arises.
Edit: Since the probability for life to arise naturally is extremely low… the probability of finding aliens similar to humans would be lower than that… i.e we are talking about miracles of chance.
I would conclude that there is some connection between us and the aliens. The connection could be one of many things.
In the Star Trek universe the connection was a race of superintelligent aliens that seeded the galaxy with programmed life with the intent of bringing forth compatible humanoid aliens. Frankly, I don’t think that scenario would work given how evolution works, but it works as a sci fi trope. In my view, if separate planets were seeded with simple life with the goal of arriving at intelligent humanoids with compatible genetics then it would take nearly generation to generation control of mutations and selection.
It is worth mentioning that chimps and humans are separated by 5-8 million years, and we don’t appear to be genetically compatible.
I actually produced such a scenario once. Is anyone here familiar with the role-playing game Traveller?
But the explanation there was simple: aliens took humans from earth, long ago, and dropped them on many planets. What’s the biota on the humanoids’ world look like in the scenario here? Earth species, or unrelated species?
unless there are a limited no: of standard “forms” that DNA based life always evolves into when introduced into a planet similar to early earth. (Perhaps because, the atmosphere and major parts of the environment would be “terraformed” into a small range by early life through photosynthesis/other biological processes over billions of years).In that case, Human evolution post seeding might be guaranteed given enough time. (this would be an extreme case of parallel evolution).
Or atleast something close to human would “arise”, which could then be directly modified to become human beings compatible to the Alien life forms.
Clearly, given the disparity of life on earth, that just can’t be true. And given the number of DNA sequences capable of giving rise to similar forms, even if by some bizarre chance an alien looked human, genetic compatibility would be even less likely.
Isn’t evolution all about bizzare chance events happening.
What’s the probability for the genetic compatibility to happen? Can you calculate it?
Is it similar to the probability of life emerging by chance?
If it has happened,the probability is 100%…
I find it difficult to believe that your questions are intended seriously.
One can get a rough idea by looking at the biota. Do you see any species separated by billions of years of evolution that have become genetically compatible? Would another planet increase that probability?
If you look at the biodiversity on Earth, there doesn’t seem to be much of a limit. I would say body symmetry is perhaps a driving force in most lineages, but there isn’t much beyond that.
That would probably require a complete rewrite of the entire genome.
It’s so improbable as to be ignored. Horses and donkeys share a relatively recent common ancestor, and yet their offspring are sterile. Once two populations are separated it doesn’t take that long (geologically speaking) for different mutations to accumulate in each lineage to the point where they are no longer compatible. If this can happen to two populations that share a recent common ancestor, imagine what it would be like for two populations that don’t share a common ancestor?
Except that pretty much every explanation of evolution involves improbable chance events…
Take the evolution of eukaryotes… it requires a series of events that has happened only once in 4.5 billion years with millions of types of prokaryotes existing all along.
Of course it does. That’s expected. We see extremely improbable events happen all of the time in biology. For example, you were born with around 50 single base substitution mutations. With a 6 billion base diploid genome, the chances of those 50 mutations happening at those precise locations is 1 in 6 billion to the 50th power, which is a rather large number. However, the very fact that people are born with around 50 mutations means that a highly improbable event must happen, and they do.
By the same logic eukaryotes should have evolved several times…
Chance + stochastic events is a beautiful thing. It can explain any observation.
There is no observation that can be ruled out as impossible to happen by chance.
Nearly everything that happens in your life is a matter of improbable chance events. But we still would be wrong to say that your life is all about bizarre chance events happening.
