1School of Anthropology, University of Arizona, 2Centre ValBio, Ranomafana, Madagascar, 3Interdepartmental Program in Anthropological Sciences, Stony Brook University, 4Department of Anatomy, Midwestern University
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Allomaternal care (AC) of infants is hypothesized to benefit mothers and offspring by increasing infant survival and reproductive output. For primates, comparative analyses testing these hypotheses have mostly focused on anthropoids because studies of prosimian AC are rare. This research has shown that AC is associated with increased postnatal growth rates and decreased interbirth intervals (IBI). Recently, detailed studies of Malagasy primates have provided an opportunity to examine this question in non-anthropoid primates. We used these data to test the hypothesis that, like anthropoids, lemuriform mothers benefit from AC. We used comparative analyses controlling for the influences of body size, phylogeny, and diet, and collected data from the published literature and Duke Lemur Center on 23 taxa for three dependent variables: IBI, prenatal growth rate, postnatal growth rate. We conducted phylogenetic generalized linear models to test the relationship between the dependent variables and five predictor variables related to different aspects of infant care: nest, park, AC, allomaternal nurse, and carry by caregiver. Nesting and parking were significantly and positively related to prenatal and postnatal growth rates, and the presence of nesting was negatively related to IBI. No significant relationship was found between the remaining predictor variables and our dependent variables. In particular, the presence of AC does not translate into more rapid infant growth, nor higher reproductive output, in lemuriforms. Parking and/or nesting infants, which may indicate babysitting, benefitted mothers and infants. The ever-increasing availability of detailed data is sure to provide insights into the evolution of AC in lemuriforms.