BEHAVIORAL RETARDATION IN A MACAQUE WITH AUTOSOMAL TRISOMY AND AGING MOTHER

The social development of a female rhesus monkey (Macaca mulatta) was followed from the day of birth until her death, at age 32 months. The subject, born to an older mother, had an extra autosome (karyotype: 43 , XX, +18), an affliction that came about spontaneously. MRI scans rev ealed that she was also hydrocephalic. Compared to 23 female monkeys g rowing up under identical conditions, the subject showed serious motor deficiencies, a dramatic delay in the development of social behavior, poorly established dominance relationships, and greater than usual de pendency on mother and kin. The subject was well-integrated into the s ocial group, however.