Evolution is one of the features scored by the judges. Alas
have to fill out the whole samba runway, without leaving any blank
spaces. Passistas, as members of a wing are
called, may only march forward (going backwards is a no-no).
They must sing along the whole time, or the school may be
penalized, losing points in harmony. Larger alas may have as many
as 400 passistas, but most have between 100-250.