DNA analyses support the hypothesis that infanticide is adaptive in langurmonkeys

Although the killing of dependent infants by adult males is a widespread ph enomenon among primates, its causes and consequences still remain hotly deb ated. According to the sexual selection hypothesis, infanticidal males will gain a reproductive advantage provided that only unrelated infants are kil led and that the males increase their chances of siring the next infants. A lternatively the social pathology hypothesis interprets infanticide as a re sult of crowded living conditions and, thus, as not providing any advantage . Based on DNA analyses of wild Hanuman langurs (Presbytis entellus) we pre sent the first evidence that male attackers were not related to their infan t victims. Furthermore, in all cases the presumed killers were the likely f athers of the subsequent infants. Our data, therefore, strongly support the sexual selection hypothesis interpreting infanticide as an evolved, adapti ve male reproductive tactic.