  The Serber force has relative orbital parity symmetry and requires vanishing
NN interactions in partial waves with odd angular momentum. We illustrate how
this property is well fulfilled for spin triplet states with odd angular
momentum and violated for odd singlet states for realistic potentials but fails
for chiral potentials. We analyze how Serber symmetry can be accommodated
within a large Nc perspective when interpreted as a long distance symmetry. A
prerequisite for this is the numerical similarity of the scalar and vector
meson resonance masses. The conditions under which the resonance exchange
potential can be approximated by a Yukawa form are also discussed. While these
masses arise as poles on the Second Riemann in pi-pi scattering, we find that
within the large Nc expansion the corresponding Yukawa masses correspond
instead to a well defined large Nc approximation to the pole which cannot be
distinguished from their location as Breit-Wigner resonances.
