how do you think the alien species physically mature? recently my brother brought up this point how dumb it is that humans can biologically have kids when they are still kids (not even teenaged). do you think this is a trait unique to humans in the galactic community? i always thought krogan are intellectually and physically close to adulthood before they hit puberty which is the final stage of development. in me2 when grunt hits puberty, he seems to be pretty adult like otherwise
Good question ! I think the relevant problem with humans is that we have a few unique biological problems (e.g. the usual obstetric problem of making the big baby head pass through the narrow pelvis) but which we must always balanced with human cultures (e.g. from what I understand, humans (especially girls) getting children before they had finished growing was extremely rare, even among the elite which had an incentive to do so and get married earlier, because people understood that having a baby too early was harmful and potentially deadly). So we need to distinguish the ability to procreate, biological maturity (no further biological development) and legal adulthood. Added to that is probably : does the culture have a concept of childhood, and what does it include ? Patriarch recalls that the pre-genophage krogan were encouraged to kill (each other) from the first second, and Okeer laments that krogan children post-genophage are coddled, so "murder" and "risk" were part of the krogan concept of childhood pre-genophage in a way they just aren't post-genophage.
I headcanon that krogan get their puberty (i.e. Grunt in ME2) around 6 (Earth) years old, which also officially makes them legal adults. However, it would take a few more years for him to lose his "baby" look and look like any other adult male krogan, so some growth remains. Overall, the evolutionary history of krogan leads me to expect they'd be independent (intellectually and physically) very fast, like you think ; the word we're looking for is "precocial offspring".
As for asari (see my recent onslaught of posts), I think Maidens can meld, but they won't be able to have children until they're Matrons, so that's the opposite of what you describe for us.
Salarians I don't know ; I usually halve biological adulthood hallmarks for humans, so I imagine reproductive ability would occur before the 10-year birthday, perhaps as low as 6 years old for a female's first reproduction — but if you headcanon external reproduction for salarians + childcare being done by males, I guess it's not that horrific.
Turians, no idea, but I expect they are biologically mature by 15 (Earth) years old, since that's when they get taken to boot camp. Interestingly, formal adulthood only seems to occur after they complete boot camp, become citizens and ascend to the third tier of merit, seemingly a year after they got into boot camp. So I suspect turians develop faster than humans and go into boot camp as full biological adults, but I think babies before boot camp (e.g. before they're legal adults) or even before the end of their stint of mandatory duty (at 30 years old) are unthinkable.
And I honestly have no idea for the other species. We can probably calculate some latest possible date for drell reproductive ability onset by calculating how old Thane was when he became a dad (so, around the late teens/early twenties, if we assume Kolyat is in his late teens/early twenties himself when we meet him ; all we know, canonically, is that Thane was born in 2146, and that Kolyat is at least ten years old, probably twice that). As for quarians, we know that Tali was born in 2161 and that she had clearly undergone at least some of her puberty, judging by her appearance, in 2183 at 22 years old when she set off on her Pilgrimage (i.e. a rite of passage that officially makes her an adult once completed).
