Family composition and menarcheal age: anti-inbreeding strategies.

R.L. Matchock & E.J. Susman, American Journal of Human Biology, v.18, n.4, 2006, pp.481-91.

This socioendocrinological study examines the relationship between family composition and sexual maturation in girls. A retrospective questionnaire requesting information on participants' estimated age of menarche, family composition, social environment (urban, suburban or rural) and demographics was completed by 1,938 female college students attending a university in the mid-Atlantic United States. While participants' mean menarcheal age was 12.79 years, father-absent girls' mean menarcheal age was approximately three months earlier than that of father-present girls. Growing up in an urban environment and the household presence of half- and step-brothers (but not stepfathers) was also associated with earlier menarche, while the presence of sisters, particularly older sisters, was associated with later menarche. This study adds weight to the theory that 'pheromonal cues modulate sexual maturity so as to enhance mating and prevent inbreeding' in humans, as has been found in rodents and non-human primates. However, an examination of measures of interpersonal stress within family compositions and its relationship to girls' pubertal timing is needed to test the veracity of the psychosocial acceleration theory.