  A cosmological scenario which explains the values of the parameters of the
standard models of elementary particle physics and cosmology is discussed. In
this scenario these parameters are set by a process analogous to natural
selection which follows naturally from the assumption that the singularities in
black holes are removed by quantum effects leading to the creation of new
expanding regions of the universe. The suggestion of J. A. Wheeler that the
parameters change randomly at such events leads naturally to the conjecture
that the parameters have been selected for values that extremize the production
of black holes. This leads directly to a prediction, which is that small
changes in any of the parameters should lead to a decrease in the number of
black holes produced by the universe. On plausible astrophysical assumptions it
is found that changes in many of the parameters do lead to a decrease in the
number of black holes produced by spiral galaxies. These include the masses of
the proton,neutron, electron and neutrino and the weak, strong and
electromagnetic coupling constants. Finally,this scenario predicts a natural
time scale for cosmology equal to the time over which spiral galaxies maintain
appreciable rates of star formation, which is compatible with current
observations that $\Omega = .1-.2$.
