Sex-Typed Social Development in Lemur catta.

Strong chemical control of strepsirrhine mating behaviour when compared to haplorhines might suggest that strepsirrhine behavioural development, generally, is under stronger somatic control. A comparative lack of reported behavioural sex differences in immature strepsirrhines would seem to support this hypothesis, but the recent discovery of sex differences in juvenile foraging behaviour in Lemur catta suggests that this difference might be an artefact of undersampling in strepsirrhines. Here, I document in wild L. catta the temporal development of a wider repertoire of social behaviours than have been studied in captivity over a longer developmental duration than has been studied in the wild to identify which behaviours might be and which cannot be linked to puberty. Sex differences in proximity and agonism did not appear before 2 years, consistent with previous reports and suggestions that they are linked to somatic or social changes at puberty. Immature females exhibited adult female-typical interest in infants; immature males demonstrated elements of adult male scent-marking behaviour, and immature males demonstrated marked attraction to adult males - sex differences that cannot be dependent on gonadal maturation. Immature L. catta exhibited some sex differences common in immature haplorhines, which are thought to be strategic choices by immatures to increase their later reproductive success.