  In this work we develop a microscopic physical model of early evolution,
where phenotype,organism life expectancy, is directly related to genotype, the
stability of its proteins in their native conformations which can be determined
exactly in the model. Simulating the model on a computer, we consistently
observe the Big Bang scenario whereby exponential population growth ensues as
soon as favorable sequence-structure combinations (precursors of stable
proteins) are discovered. Upon that, random diversity of the structural space
abruptly collapses into a small set of preferred proteins. We observe that
protein folds remain stable and abundant in the population at time scales much
greater than mutation or organism lifetime, and the distribution of the
lifetimes of dominant folds in a population approximately follows a power law.
The separation of evolutionary time scales between discovery of new folds and
generation of new sequences gives rise to emergence of protein families and
superfamilies whose sizes are power-law distributed, closely matching the same
distributions for real proteins. On the population level we observe emergence
of species, subpopulations which carry similar genomes. Further we present a
simple theory that relates stability of evolving proteins to the sizes of
emerging genomes. Together, these results provide a microscopic first
principles picture of how first gene families developed in the course of early
evolution
