The chapter explains juvenile dyschrony and sexual dimorphism in different periods of hominin life. Dyschrony is a discrepancy between different structures and functions of the organism in terms of their development during life. Sexual dimorphism includes differences in anatomical, psychophysiological, and mental structures between males and females. High libido in boys who experience premature sexual maturation reflects ancient stages of human evolution, when adolescence wasn’t a distinct age group. This trait, although dysfunctional, has survived because of the close relationship between male sexuality and aggressiveness. Increased aggressiveness and character instability of adolescent boys have their roots in intra-sexual rivalry and in ancient orders of initiation of young men into the community of full-fledged male hunters, when the rudiments of known initiation rites appeared. In girls, the first ovulation and menstruation occur several years before they are even anatomically capable of normal reproduction. The sped up braincase of the late H. erectus and H. heidelbergensis resulted in growth of the fetal skull and, accordingly, numerous birth traumas for both the fetus and the young women in labor. As a result, rod branch hominin groups protected girls from early sex. Girls had to reach maturity, as measured by the development of their mammary glands and hips. This arrangement shifted males’ erotic attention to young girls whose relationships were under the control of parents or powerful coalitions, such as tight-knit groups of male hunters. The author emphasizes the role of intergroup transitions of girls as potential birth mothers in group selection on criteria of coordination and development of normativity. The timing of the emergence of adolescence in anthropogenesis and the corresponding delayed maturation is supported by special analyzes of hominin tooth enamel. The emergence of adolescents with several years of active assimilation of cultural experience led to significant shifts in social orders, advances in technology, and the further development of language and cognitive abilities. Mature women who continued to bear children late in life also faced health risks, attrition, and social stigma. As a result, mothers of adult children withdrew from the “erotic market” and their behavior and hormonal processes shifted toward a steady decline of the reproductive system. Groups and populations with grandmothers won the competition against groups and populations without such a norm of (self-)cutting off mature women from sex and without the order of grandmothers’ guardianship of grandchildren. Selection over hundreds and thousands of generations led to the emergence of menopause. Stages of formation of protomonogamy corresponded with the role of verbalization and remote control in sexual relations of late hominins and early sapiens. In conclusion, the author formulates theoretical hypotheses for indirect testing of the explanations.