
Originally Posted by
Ryllharu
They explain it partially in the intro sequence before the OP. The events were all chronicled in the original Macross series. The "elves" are the Zentradi, the race of giants that humanity was nearly wiped out by when they attacked Earth. They were created by and enslaved to another race to act as warriors and not allowed culture of any kind. Humanity developed the first variable fighters to combat them and their weapons suits (now seen here as the mechs, before they were more like giant, armored spacesuits). They eventually heard songs from the original Miss Macross, Minmay. I don't know all the details because I haven't seen most of the original, but sooner or later the Zentradi rebelled and joined the humans against their masters.
Humans and Zentradi can interbreed because they are "genetically equivalent." Thus half-breeds like Mikael and quarters like Ranka. Zentradi are originally giants (as far as I know) and they can be micronized, where they change into more human-sized bodies, but maintaining their proportions. This is also how they interbreed with humans.
That's why it's funny that Klan Klein (Kuran Kuran, whatever) turns into a loli from a genetic abnormality. Her proportions don't stay right and she turns into a kid.
That should cover all the questions, either directly addressed or buried in one of those paragraphs.