For Western humans, choral music is arranged with higher-pitched voices and lower-pitched voices singing different parts.
Even non-Western music is often listed as being arranged for the standard SATB (soprano, alto, tenor, bass -- with sopranos and altos being women or children, and tenors generally and basses always being men.)
Throat-singing, the most different style I know of, has compositions for men and compositions for women.
But what if people generally change gender, often more than once, at some point during their lives, and don't want to also change their choral role assignments? How can you arrange choral music where each section of the choir has a mix of both higher and lower voices?
(The experience of transgender humans will not be be completely applicable, as my choir members are close to but not entirely like the analogues of humans in their world, who themselves are not entirely like humans on Earth.)
My first thought was syncopated music, where some people sing fast and some people sing slow, but I can't find any good examples for voice online.
I'm most interested in the amateur/high school level, if it makes a difference.