  Active nematics are conceptually the simplest orientationally ordered phase
of self-driven particles, but have proved to be a perennial source of
surprises. We show here through numerical solution of coarse-grained equations
for order parameter and density that the growth of the active nematic phase
from the isotropic phase is necessarily accompanied by a clumping of the
density. The growth kinetics of the density domains is shown to be faster than
the 1/3-law expected for variables governed by a conservation law. Other
results presented include the suppression of density fluctuations in the
stationary ordered nematic by the imposition of an orienting field. We close by
posing some open questions.
