  We have explored the possibility that the universe at very early stage was
dominated by (macroscopic) heterotic strings. We have found that the
dimensionless parameter $G\mu$ for the heterotic strings varies from $10^{-2}$
to $10^{-4}$ as the universe evolve from the matter dominance to radiation
dominance. This led to the interesting consequence of epoch dependent gauge
coupling constant. The gauge coupling constant at early times was found to be
much stronger than the present strong interaction.
