  The Hubbard Hamiltonian on a two-leg ladder is studied numerically using
quantum Monte Carlo and Exact Diagonalization techniques. A rung interaction,
$V$, is turned on such that the resulting model has an exact SO(5) symmetry
when $V=-U$. The evolution of the low energy excitation spectrum is presented
from the pure Hubbard ladder to the SO(5) ladder. It is shown that the low
energy excitations in the pure Hubbard ladder have an approximate SO(5)
symmetry.
