Maternal cannibalism in two populations of wild chimpanzees

Pawel Fedurek,Catherine Crockford,Adriana E Lowe,Klaus Zuberbühler,Caroline Asiimwe,Liran Samuni,Catherine Hobaiter,Appolinaire Gnahe Dijrian,Patrick Tkaczynski,Roman M Wittig

doi:10.1007/s10329-019-00765-6

Abstract

Maternal cannibalism has been reported in several animal taxa, prompting speculations that the behavior may be part of an evolved strategy. In chimpanzees, however, maternal cannibalism has been conspicuously absent, despite high levels of infant mortality and reports of non-maternal cannibalism. The typical response of chimpanzee mothers is to abandon their deceased infant, sometimes after prolonged periods of carrying and grooming the corpse. Here, we report two anomalous observations of maternal cannibalism in communities of wild chimpanzees in Uganda and Ivory Coast and discuss the evolutionary implications. Both infants likely died under different circumstances; one apparently as a result of premature birth, the other possibly as a result of infanticide. In both cases, the mothers consumed parts of the corpse and participated in meat sharing with other group members. Neither female presented any apparent signs of ill health before or after the events. We concluded that, in both cases, cannibalizing the infant was unlikely due to health-related issues by the mothers. We discuss these observations against a background of chimpanzee mothers consistently refraining from maternal cannibalism, despite ample opportunities and nutritional advantages. We conclude that maternal cannibalism is extremely rare in this primate, likely due to early and strong mother–offspring bond formation, which may have been profoundly disrupted in the current cases.

Highlights

Filial cannibalism—a form of cannibalism in which a parent consumes its own offspring—is relatively common in some animal taxa (Polis 1981)
Primate maternal attachment can extend beyond an infant’s death to the extent that primate mothers have been observed to carry and groom the corpse of their infant for weeks or months after death (Biro et al 2010; Campbell et al 2016; Fashing et al 2011; Matsuzawa 1997; Sugiyama et al 2009; Watson et al 2015). Cannibalizing their own infants is, not something that would be expected from primate mothers, despite the nutritional gains and the apparent adaptive value of filial cannibalism observed in species with weak or absent mother–infant bonds (DeSantis and Schmaltz 1984; Polis 1981)
Infant mortality rates in chimpanzees are extraordinarily high for apes (Hill et al 2001; van Noordwijk et al 2018), with first-year infant mortality estimated at 20% across populations (Hill et al 2001)

Summary

Introduction

Filial cannibalism—a form of cannibalism in which a parent consumes its own offspring—is relatively common in some animal taxa (Polis 1981). In fish and reptile species with parental care, for example, eggs can be cannibalized when the costs of investing in the current clutch outweigh the benefits of future reproduction (Klug et al 2006; Lourdais et al 2005). Filial cannibalism exists in mammals (Polis 1981). Incidences of filial cannibalism, in particular by mothers (maternal cannibalism), are extremely rare, and it has been argued that this is due to the high costs of maternal gestation and, at the proximate level, strong mother–infant bonds (Hrdy 2000). If filial cannibalism occurs in primates, it is usually of already-deceased infants, which has been reported in baboons (Altmann 2001), thick-tailed bushbabies

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Conclusion