The results of research of characteristics of behavior under stress, depending on the individual level of testosterone and sex composition of the group are presented in the article. Study was an experiment with natural biological model of a small social group. The laboratory mice were used as model animals. The living conditions in the modern city were modeled in experiment. The influence of external factors to the level of testosterone in the animals blood, both males, and females, are demonstrated. A correlation between the characteristics of the individuals behaviour in the group and the concentrations of testosterone was detected out. For the males the nature of this relation was not dependent on the number of stress factors: the dominant male-mouse has had the highest rate of male sex hormone in the blood. The females of the control group had the opposite trends: most active female-mouse had testosterone levels below the average. In stress the feedback watched for females became similar to trends specific for males. The same-sex groups had feature consisted in higher concentrations of testosterone in the blood of the test mice compared with animals that belong to bisexual group, as well as the more aggressive nature of relationships in group and the lack of a dominant individual. The parallels between the obtained results and data of the researches of social processes are considered.
Keywords: biosocial human nature, social behavior, life experience, biological model, testosterone, gender