  The high-temperature limit of Standard Model generated by the contractions of
gauge groups is discussed. Contraction parameters of gauge group $SU(2)$ of
Electroweak Model and gauge group $SU(3)$ of Quantum Chromodynamics are taken
identical and tending to zero when temperature increase. Properties of the
elementary particles change drastically at the infinite temperature limit: all
particles lose masses, all quarks are monochromatic. Electroweak interactions
become long-range and are mediated by the neutral currents. Particles of
different kind do not interact. It looks like some stratification with only one
sort of particles in each stratum. The Standard Model passes in this limit
through several stages, which are distinguished by the powers of contraction
parameter. For any stage the intermediate models are constructed and the exact
expressions for the respective Lagrangians are presented. The developed
approach describes the evolution of Standard Model in the early Universe from
the Big Bang up to the end of several nanoseconds.
