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... number on decreases in maternal aggression could involve increases in levels of either prolactin or opioids in the dams. Placentophagia elevates both prolactin (Blank and Friesen, 1980) and opioids (=-=Kristal, 1991-=-) in the dams and an increased number of pups could provide additional placenta for consumption. An increased number of fetuses could elevate prolactin in the dams during pregnancy. Levels of prolacti...

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...measures were available, they also reflect this range (Table II). Although some mothers do physically manipulate and inspect their neonate without concurrent licking, Mama handled her neonate considerably more than the other females we observed and more than others reported in the literature (although this variable is rarely quantified). After the emergence of the placenta, most macaque mothers reduce their focus on the infant; however, a macaque mother’s behavior toward the placenta ranges from ignoring it to the avid and rapid consumption often described in the literature on placentophagia (Kristal 1991). The avid consumption of the placenta, often while ignoring the neonate, appears to be a common behavior among macaque females (Gouzoules 1974; Hammerschmidt and Ansorge 1989; Kemps and Timmermans 1982; Negayama et al. 1986), particularly multiparous females (Timmermans and Vossen 1996 and Table II). Placentophagia is a very common behavior in nearly all terrestrial mammals, and evidence suggests that placentophagia enhances opioidmediated analgesia, in addition to providing protection from predators by removing the smell, and providing nutrition to the mother (Kristal 1991). However, not all...

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...54 2 7 Fe br ua ry 2 01 3 94 J. Selander et al. behavior, none is able to explain its benefit across mammalian species (for a review, see Kristal 1980). The effects of placentophagy on lactation have been investigated using both human (Soyková-Pachnerová et al. 1954) and animal models (Blank and Friesen 1980), however, these studies are not without limitations and the benefit to lactation remains unclear. One evidence-based benefit of placentophagy is the enhancement of opioidmediated analgesia (increased pain tolerance through opioid pathways) in postpartum rodents (DiPirro and Kristal 2004; Kristal 1991), which suggests there may be similar mechanisms operating in other mammalian species. Despite these findings, the ultimate adaptive benefit of placentophagy for mammalian mothers remains unknown. Although placentophagy is absent in the cross-cultural ethnographic record, accounts of the behavior emerged in the professional literature in the early 1970s (Ober 1973) and is currently promoted among a small number of women, primarily in the United States and Mexico, that claim therapeutic benefits (Bastien 2004; Field 1984; Janszen 1980; Selander 2009; Young and Benyshek 2010). While the frequenc...

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...198 D ow nl oa de d by [ D an ie l B en ys he k] a t 0 7: 49 3 0 M ay 2 01 2 The Fire Hypothesis 199 review). Different species’ biologies and ecologies have evoked different explanations, and as a consequence, none of the existing hypotheses can fully account for the behavior across species (Kristal 1980). Some research has been conducted to understand the benefits of placentophagy among animals. Data from multiple rodent studies strongly support the hypothesis that placental tissue consumption enhances analgesic effects through a specific endogenous opioid pathway (DiPirro and Kristal 2004; Kristal 1991), and similar hypotheses have been proposed for possible comparable effects in human mothers if they were to engage in the behavior (Apari and Rózsa 2006). While the analgesic enhancing effect of placentophagy has been well studied in rodent models, and is currently the best established benefit of placentophagy supported by rigorous empirical research, other studies have focused on alternative potential benefits of the maternal behavior, including its effects on lactation. Research on postpartum hormonal changes in female rodents allowed to eat the placenta, compared to those in which placento...

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...id-induced hypoalgesia (Kristal et al., 1990a, 1990b; Robinson-Vanderwerf et al., 1997), and (c) it does not produce hypoalgesia by itself (without the existence of an underlying opioid hypoalgesia) (=-=Kristal, 1991-=-, 1998). Furthermore, ingestion of placenta enhances δ- and κ-opioid-receptor-mediated hypoalgesia and attenuates μ-opioid-receptor-mediated hypoalgesia (DiPirro and Kristal, 2004), which is consisten...

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...ntophagia; POEF; Antinociception; Opioid; Parturition; DPDPE; DAMGO; Spiradoline; Rat; Opioid receptor 1. Introduction Ingestion of placenta or amniotic fluid enhances opioid-mediated antinociception =-=[39]-=-. The active substance(s) in placenta and amniotic fluid has been termed Placental Opioid-Enhancing Factor (POEF) [43]. The antinociception-enhancing effect of POEF has been well documented in rats of...