  We investigate the late-time behavior of a universe containing a supergravity
gas and wrapped 2-branes in the context of M-theory compactified on T^10. The
supergravity gas tends to drive uniform expansion, while the branes impede the
expansion of the directions about which they are wrapped. Assuming spatial
homogeneity, we study the dynamics both numerically and analytically. At late
times the radii obey power laws which are determined by the brane wrapping
numbers, leading to interesting hierarchies of scale between the wrapped and
unwrapped dimensions. The biggest hierarchy that could evolve from an initial
thermal fluctuation produces three large unwrapped dimensions. We also study
configurations corresponding to string winding, in which the M2-branes are all
wrapped around the (small) 11th dimension, and show that this recovers the
scenario discussed by Brandenberger and Vafa.
