chadachada123 said:
DracoSuave said:
Singularly Datarific said:
If we can produce viable, fertile offspring with them they are technically of the same species. I'd call them humans.
That might also disprove evolution theory in one fell swoop.
I wouldn't say so. Out of trillions upon trillions of planets out there, and with each planet with life on it presumably having hundreds of millions of different species like Earth has/has had, there's a real non-zero chance that two planets will end up sharing a species with really similar DNA (assuming DNA is standard amongst planets with life).
Plus, there's a larger chance that these humans were either planted there by some advanced alien species or something.
The odds of us having evolved simultaneously like that is extremely small, and it'd be something that we'd have to confer with the new-humans about, but it wouldn't be any real nails in the coffin of evolution.
If they have mapped their own evolution like we have ours, then we'd be able to see how their evolution ended up converging into a species just like ours. More than likely, though, it would just be aliens planting humans on random planets.
DNA anaylsis would have to be used, but the thing is... okay.
Humans come from Apes come from Primates come from Therapsids come from Vertibrates come from Chordates come from.... you get the picture. But each is the result of environmental pressures that are specific to the species involved. So, for example, the Cambrian Explosion was a result of the overoxygenation of the atmosphere and the resultant mass extinction event that followed. But that overoxygenation was the result of blue-green algae. On a planet that never evolved blue-green algae, there would not necessarily be overoxygenation, which in turn would not select for the sorts of evolution that take that poisonous gas and use it as a means to burn fuel.
So if you're presented with a bipedal, four-limbed, chordate, deuteronome, with a digestive tract, and primate features that developed independantly of earth... then you've shown evidence that life might not be naturally selected, because evolution predicts that only the various environments of our ancestor species could have lead to our current development. Even populations going through similiar environments but through different geographic locations diverge into different species. Evolution predicts it goes one way and one way only--divergence. There has never been a single instance of two species converging into one because there's no way to natural select for that at all.
To give you an idea of the chances of that happening... look at two pieces of dissimiliar DNA, humans and chimps. They share a lot the same, but are different enough to make this idea work.
Our DNA has these vestiges of viral infections called endogenous retroviruses, or ERVs. essentially a virus came in, inserted its code into a sperm or egg, and that sperm or egg made a baby, which copied that code to all its cells. And so on. It's useless and harmless dna, but it's obviously viral in origin. Now, the chances of two organisms sharing ERVs in the same location AND not having common ancestors is extremely low. Not impossible, but low.
Humans and chimps share over a dozen of these pairs, which has a chance--if common ancestry isn't true--of being less likely than you and I selecting the same atom at random from the entire universe of atoms, then you going out winning the lottery every day for a week, each day getting into a plane crash and surviving... and then a meteor hitting the earth on the last day, killing everyone BUT you. THAT is more likely than us not sharing common ancestry.
So when you talk about the likelihood of genetic similiarity in the vastness of the cosmos, remember that to be geneticly compatible there has to be a LOT more than some common features... most of it has to be absolutely identical. The probability of that happening without common ancestry is larger than all the particles in the universe. The 'vastness of space' isn't big enough to hold THAT level of coincidence at all.
