  Nearby starburst galaxies have consistently shown anomalous Ly-alpha/H-beta
ratios. By re-analysing the published IUE/optical observations, we show that
most starbursts present a normal Ly-alpha emission, consistent with case B
recombination theory, provided extinction laws appropriate to their
metallicities are used. This implies that extinction is more important than
multiple resonant scattering effects. The anomalous emission and absorption
lines present in a few remaining galaxies are simply explained if they are
observed in the post-burst phase, between about 10$^7$ and 10$^8$ yrs after the
start of the burst. We use updated stellar population synthesis models to show
that anomalous ratios are produced by the aging of stellar populations, since
the underlying stellar Ly-alpha line is important in the cooler massive stars.
The inferred low-duty cycle of massive star formation accounts naturally for
the failure to detect large numbers of Ly-alpha--emitting galaxies in deep
surveys and at high redshift. Some testable predictions of the proposed
scenario are also discussed.
