The random model for simulation of the growth of small populations
  The probability of the survival of the population of individuals of both sexes of given mature age, procreation rate and structure stability has been searched in the numerical experiment. The populations with long period of reproduction and the high rate of procreation and without social mobility have the most chance to survive. The populations with the late mature age and high mobility dies out. The fertility rate of simple reconstruction of generations obtained in the model (2.8) is close to the value for a human being (2.1). 
Kazimierz Pater