Borschtbeet wrote...
None of the aliens are actually related to each other in Mass Effect. The reason any of them look similar is due to convergent evolution.
Evolution favors certain characteristics like bipedal species, vocal cords, etc which is why most of the species in Mass Effect are humanoid.
Evolution doesnt favor anything, not really. Survival of the fittest, perhaps. Once we reached a certain complexity, based on the random divergences that took place before, it might be possible we finally reached a realm where only certain things were workable/possible for species as complex as humans. And all Earth life is alike because we are all from the same amino acid pool.
The funny thing about Mass Effect is how they treat humans as geneticly diverse. No, we arent. There is only a 1% difference between ALL humans geneticly. ALL genetic diversity was killed off during a natural disaster that almost wiped out mankind in our early years. Further, the same is true for life in general. Almost all life on Earth has been wiped out several times, only leaving a small amount of evolutionary path's left to move forward. This accounts for the huge genetic similiarities on Earth (And even then we still have some rediculously unique life on Earth if you look hard enough).
The likelyhood of life in space being anything even concievable to humans is so low it's not even funny. I doubt there's even much life at all in our half of the Galaxy. Dont get me wrong, i think there will be a lot of Earth-like planets. I just dont think anything will be living on them. So far, every near-Earth-sized planet found in the habitable zone has been uninhabitable. It's exactly the same as Earth in almost all respects, but plants never evolved so the oxygen was never converted into something liveable (these planets would be rediculously easy to terraform though).
I highly doubt Sex with aliens would be common, even if they have our shape. It wouldn't feel the same, and could even be extremely uncomfortable if not dangerous. What if the females produce some kind of acidic lubrication during sex, or the interior isnt layed out the same way. Dont get me wrong though, by dangerous i dont mean "STD's", Cross-species disease would be impossible, as far as i know. It's possible alien life wouldn't even HAVE DNA, but would be constructed of something completely unique (DNA is a product of amino acid's, and is inherently unique to Earth-based life). Viruses could enter their body, but not interact with the cells. You'd get a stuffy nose, but nothing more.
For quarians that aspect makes even less sense. If they have no immune system, then they, of ALL species, should have the LEAST reaction to alien bacteria. Because their body wouldn't have much that it deploys to fight foreign entities, they wouldn't feel anything at all, where as humans would get a stuffy nose and a sinus headache everytime something got inside. I am, however, curious as to if bacteria could adapt/evolve to make use of non-DNA based "Cells" inside of an alien. That's a questionf or a xenobiologist, but i doubt it....
...
...
But i digress.