ARandomGod said:
They don't.
It's a typo. The books full of 'em, so don't sweat it too much.
They also live much, much longer than that.
Also, they do have a much longer period of neotency, but that doesn't mean that they aren't "mature"; they just have a different definition of mature.
Humans think sometimes that they take a lot longer to "mature", but they really never do according to the human definition of the word. They're a different species.
I have to disagree with the last statement here. Humans and elves cannot be seperate species, because (in D&D, at least) they can produce fertile offspring.
In the real world, we know that horses and donkeys are seperate species because although they can produce offspring together (mules), that offspring is in fact always sterile. In a world without genetic evaluation, that's really the only way to tell.
In contrast, we know that dogs are in fact all one species, even though there are hundreds of racial differences (even variance in longevity). Since any two dogs could produce fertile offspring, they are all one species. Humans and elves can produce fertile offspring (Half-elves), so despite racial differences, they are one species, as well.
In fact, IMC Orcs, Humans, and Elves ARE all one species. Orc/Elf children are rare, just as dachsund/Saint Bernard puppies are, but not impossible. The introduction of the idea in the world led to some backlash similar to the introduction of the idea of evolution throughout the 19th and 20th centuries. "My cousin is an Orc! No way!" That type of thing.
I keep the longevity differences in, ascribing elves longevity to clean livin'.