Abstract # 96:

Scheduled for Thursday, August 17, 2006 07:00 PM-09:00 PM: Session 8 (Regency West 1/3 ) Poster Presentation


J. R. Raper1, S. B. Stephens1 and K. Wallen1,2
1Yerkes National Primate Center Field Station , 2409 Taylor Lane, Lawrenceville, GA 30043, USA, 2Department of Psychology, Emory University, Atlanta, GA USA
     Rhesus macaques are a female dominated matrilineal society in which sudden replacement of the dominant matriline by a lower-ranking matriline occurs infrequently and seemingly spontaneously. These matrilineal power shifts are little studied and their causes are poorly understood. We describe the social and demographic conditions surrounding two attempted and two successful matrilineal power shifts in long-term social groups with 7 and 8 matrilines each. Behavioral observations and matrilineal records at the time of these power shifts support the opportunistic nature of these shifts as they seemed triggered by a reduced number of adult breeding females in the alpha matriline as a result of temporary experimental or clinical treatments. In all four cases the aggressing matriline had more adult females than did the alpha matriline at the time of the actual or attempted power shift. The two successful matrilineal power shifts occurred within 1 to 4 days with no observers present and were not presaged by increased conflict. The two attempted matrilineal power shifts were observed and were evidenced by increased aggression between the alpha matriline and a lower ranking matriline. Removal of adult females from the lower ranking matriline such that the alpha matriline had a greater number of adult females resulted in immediate cessation of aggression. These matrilineal power shifts suggest that rhesus monkeys possibly use numerosity in assessing relative matrilineal social power.