  Recent studies of homogeneous anisotropic universe models in the brane world
scenario show that the cosmological singularity in this context is isotropic.
It has therefore been suggested that this may be a generic feature of
singularities on the brane, even in the inhomogeneous case. Using a
perturbative approach, we show that this is not the case. As in the GR case,
the presence of decaying modes in the perturbations signal the instability (in
the past) of the isotropic singularity. The brane universe is therefore not
born with isotropy built in: as in standard cosmology, the observed large-scale
isotropy and homogeneity remains to be explained.
