This is thought to have led to the evolution of several female counter-strategies against infanticide ranging from physical defense of infants from infanticidal individuals to promiscuous mating to confuse paternity. Both males and females can be the perpetrators of infanticide in animals and both parents (filial infanticide) and non-parent individuals have been observed to display the behavior.Filial infanticide, which can be accompanied by cannibalism (filial cannibalism), i… Borries, Carola, et al.  The victim of infanticide for parental manipulation does not necessarily have to be defective but can simply be born at a bad time, consequently being a supplementary cost to the parents. 1614, 2007, pp. The benefits of infanticide for male non-human primates, and its costs to females, probably vary across mammalian social and mating systems  and between different primate species as well. This was the first ever photograph of a male leopard committing infanticide. avoid adopting and providing providing care to unrelated offpsring (the adoption avoidance hypothesis). The form of exploitation in non-human primates most attributable to adult females is when non-lactating females take an infant from its mother (allomothering) and forcibly retain it until starvation. Thanks for signing up! As a result of infanticide the infants of young 4-7 year old females die most of all. 13–40., doi:10.1016/0162-3095(79)90004-9, https://www.newscientist.com/article/dn18454-hippy-apes-caught-cannibalising-their-young/, Harano, Tomohiro, and Nobuyuki Kutsukake. It has long been viewed … “Infanticide as Sexual Conflict: Coevolution of Male Strategies and Female Counterstrategies.” Cold Spring Harbor Perspectives in Biology, vol. Culot, Laurence, et al.  Males may also physically defend their own offspring.  In these species, new dominant males could kill the infants of the previous dominant male so that more of the new dominant male’s genes are transferred to the next generation. Infanticide is the killing of a child up to one year old, by a parent who has not fully recovered from pregnancy and who typically suffers from some degree of mental disturbance often associated with postpartum mental illness (Bourget & Labelle, 1992).  This provides an advantage to the male because the female will more quickly copulate with him and raise his young rather than the young from the previous mate; his fitness increases through use of infanticide. Hamai, Miya, et al. But there is some evidence to suggest that female synchrony serves to increase competition pressures and thus aggression in females.  Promiscuous mating as a result of some reproductive adaptations/changes creates paternity confusion among the primate group thereby decreasing the likelihood of infanticide since perpetrators would not be sure if they were killing their children. The probability of infanticide during the introduction of older males is lower. “The Behavioral Ecology of Infanticide by Males.” Infanticide by Males and Its Implications, Feb. 2000, pp. In an act that seems savage, cold, and downright heartless, helpless young are occasionally killed and even eaten by the very animals that either brought them into the world or helped to nurture them from a very young age. Females in some primate species such as langur and gelada have also been known to terminate pregnancies to end investment in that offspring early after exposure to new replacement males through a process known as the Bruce effect. , Females may also avoid the costs of continued reproductive investment when infanticide is likely. 25, no. Infanticide in non-human primates occurs when an individual kills its own or another individual's dependent young.  For example, female white-headed leaf monkeys were observed to wean their infants significantly more quickly during male takeovers as compared to socially stable periods. In the eyes of mankind, infanticide is undoubtedly heartbreaking. gain increased access to physical resources like food, nesting sites, or space (the resource competition hypothesis). 32, no. . 6211, 2014, pp.  If it is unlikely that the infant will survive, infanticide may occur. In the animal kingdom, infanticide involves the killing of young offspring by a mature animal of its own species, and is studied in zoology, specifically in the field of ethology. 83, no. “New Records of within-Group Infanticide and Cannibalism in Wild Chimpanzees.” Primates, vol.  It is proposed that maternal infanticide occurs when the mother assesses the probability for infant survival based on previous infant deaths. The Lion guardians are challenged by younger males looking for lionesses of their own. WENNER-GREN FOUNDATION INTERNATIONAL SYMPOSIUM #88* August 16 - 22, 1982 Cornell University, Ithaca, New York. The adaptive significance of infanticide, if the behavior is considered adaptive for a population, most likely differs from population to population meaning the advantage of the strategy is multifarious, not unitary.  The hypothesis states that infanticide results from certain conditions created by human-induced disturbances or changes in nature.  The fitness advantage the behavior has, the associated costs and the different ways it is thought to have affected the structure of primate populations make the evolution and genetics of the behavior very interesting to study.  Similar to promiscuous mating, female primates are proceptive during the first and second trimester of pregnancy in order to increase paternity confusion of their offspring. Infanticide is common among India's lions, but females have developed a clever strategy to keep their cubs safe. include over 9S per cent of all the known animals. “Hippy Apes Caught Cannibalising Their Young.” New Scientist, 1 Feb. 2010, https://www.upi.com/Science_News/2014/11/13/Big-testes-are-sign-that-a-species-has-history-of-infanticide/8601415916184/, https://www.newser.com/story/198646/why-25-of-mammals-commit-infanticide.html, https://science.sciencemag.org/content/346/6211/841. 6, 1993, pp. Rogers, Jeffrey. But after you study it for a long time, you distance yourself from it.” It was a controversial idea when she first proposed it four decades ago, but not any more. , Infanticide by females other than the mother have been observed in wild groups of common marmosets (Callithrix jacchus). There are several ways this is accomplished including concealed ovulation. ... For example, the ancient Romans believed that the child was more like a plant than an animal until the seventh day after birth. 165, 2018, pp. . 1422, July 1999, pp. Got it! Infanticide (in animals) generally refers to the killing of an infant or a young offspring by an adult or mature individual of the same species and is observed in a variety of species ranging from humans to microscopic rotifers and especially in primates. Infanticide, the killing of the newborn.It has often been interpreted as a primitive method of birth control and a means of ridding a group of its weak and deformed children; but most societies actively desire children and put them to death (or allow them to die) only under exceptional circumstances. "Before the 1970s, any type of infanticide in animals was considered pathological," says Craig Stanford, a primatologist at the University of Southern California in Los Angeles.  Further, the implications of infanticide and cannibalism for populations that engage in group cannibalism such as chimpanzees could be far-reaching. The adaptive significance, occurrence, and variability of male infanticide remains unclear in many species because there is still lack enough data to compare directly the lifetime reproductive success of the “infanticidal” versus alternative “noninfanticidal” strategies. 322–360., doi:10.1017/cbo9780511542312.016. Primate infanticide motivated by resource competition can also involve cannibalizing the infant as a source of nutrition.  Social disturbances such as overcrowding have been documented to have resulted in infanticide in rats , and similar factors may be at play in primate communities in which infanticide has been observed.  It is also important to consider that infanticide risk is low in solitary species, the ancestral mammalian social organization, and is unlikely to motivate evolutionary transitions from a solitary lifestyle to other social organizations. “Male Infanticide Leads to Social Monogamy in Primates.” Proceedings of the National Academy of Sciences, vol. This also allows sneak copulations in which non-dominant males sire offspring. The practice has been observed in many species throughout the animal kingdom, especially primates (primate infanticide). 335–339., doi:10.1016/j.beproc.2007.12.009. , Maternal infanticide, although very rarely observed in non-human primates, has been considered as a way of paternal manipulation to end investment in certain offspring. , In some social systems, lower-ranking primate females may delay reproduction to avoid infanticide by dominant females, as seen in common marmosets. “Genetic Mediation of Infanticide and Parental Behavior in Male and Female Domestic and Wild Stock House Mice.” Behavior Genetics, vol. . ] “Infanticide Common among Adult Males in Many Mammal Species.” Reuters, Thomson Reuters, 13 Nov. 2014.  Other female reproductive counter-strategies include but are not limited to concealed ovulation (paternity is obscured by the absence of reliable signals of ovulation and/or by variability in the timing of ovulation) and copulation with specific males (like those most likely to commit infanticide or more likely to protect the offspring).  Furthermore, infanticide is more likely to occur in mammalian species where there are more males per females in social groups and dominant males obtain a higher share of reproduction in a given season but maintain their dominant position for short periods of time.  Females in some primate species may form associations or coalitions with other females and with males to defend their offspring and reduce the risk of infanticide. 1–8., doi:10.1007/s10682-017-9925-0.  Some of the counter strategies listed above such as multi-male mating or physical defense are generally associated with the increased expenditure of energy, increased exposure to predation and, obviously, increased risk of injury for both the perpetrator and defender. Moore, Jim. Infanticide in animals is the killing of young by members of the same species. Hrdy, Eds.) , To protect their young from infanticide, many species of primate mothers will form social monogamous pairs to prevent paternal infanticide. In monogamous species, since pairs of reproducing adults live together with their offspring their whole lives, male infanticide of unrelated infants would not be as adaptive for individuals. These effects result from acceleration of the termination of lactational amenorrhea. 3, 2008, pp. Edited by MEHERET OURGESSA, student of Joan Slonczewski for BIOL 116 Information in Living Systems, 2019, Kenyon College.  One such hypothesis, social pathology, argues that infanticide is genetically inconsequential and maladaptive in normal conditions. 33, no.  Adult Japanese macaque males were eight times more likely to attack infants when females had not mated with the male himself. Through eliminating infants of another species in the same environment, the probability that the aggressor and their own infants will obtain more resources increases. 274, no.  Among primates, 62% of species with female susceptibility to infanticide show promiscuity, compared to the 11% of non-vulnerable species showing promiscuity.  Another important situation in which paternity confusion can arise is when females mate with multiple males; this includes mating patterns such as polyandry and promiscuity in multi-male multi-female groups.  Filial infanticide, which can be accompanied by cannibalism (filial cannibalism), is widespread in fishes and is also seen in terrestrial animals. For example, in baboons at Amboseli, rates of fetal loss increase following the immigration of aggressive males.  However, complex interactions can arise when females have different social rankings and when resource availability is threatened.  In chimpanzees, cannibalism has been suggested to be the primary function of infanticide. In one case of maternal infanticide in wild black-fronted titi monkeys (Callicebus nigrifrons), the observed deceased infant was clinically healthy with no signs of health abnormalities. Dixson, A. F. “Male Infanticide and Primate Monogamy.” Proceedings of the National Academy of Sciences, vol. 1, 1984, pp.  In support of this hypothesis, phylogenetic reconstructions indicate that relative testis size (which is an indicator of sperm competition) is larger in lineages in which more time has elapsed since the evolution of infanticide. Shannon Dawn Rayner of Charlottetown pleaded guilty to three counts of infanticide related to incidents in 2014, 2015 and 2016, as well as a charge of concealing a dead body. 841–844., doi:10.1126/science.1257226. Ovicide is the analogous destruction of eggs. , On the other hand, the evolution of (nonparental) male infanticide has often been explained by the sexual selection hypothesis, which posits that infanticide improves male reproductive success by shortening the interbirth intervals of the mothers of the killed offspring.  Male infanticide occurs most frequently in social species, less frequently in solitary species and least frequently in monogamous species. Seasonal breeders cannot resume (reproductive) cycling before the next breeding season.  In addition to these counter-strategies, males are also thought to display behavior that prevents infanticide when their own offspring is involved.  Whatever the adaptive significance of infanticide maybe, the behavior and counterstrategies against it are clearly costly. 151–162., doi:10.1007/bf02382746. Ramsden, Edmund. One such occurrence is known as the Bruce Effect, in which female primates may abort the pregnancy when presented with a new male. Five hypotheses have been proposed to explain infanticide in non-human primates: exploitation, resource competition, parental manipulation, sexual selection, and social pathology.. The invertebrates constitute a vast and varied assemblage of animal forms and! Infanticide (in animals) generally refers to the killing of an infant or a young offspring by an adult or mature individual of the same species and is observed in a variety of species ranging from humans to microscopic rotifers and especially in primates. Palombit, Ryne A. 1, 1999, pp. Rudolf, Volker H.w, and Janis Antonovics. Infanticide in general usage is defined as "the homicide of a person older than one week but less than one year of age." “Counter-Strategies to Infanticide in Mammals: Costs and Consequences.” Oikos, vol. In primates, resource competition is a prime motivator for infanticide. In an extensive study of wild Japanese macaques which tracked instances of infanticide, DNA analysis revealed that males would not attack their own offspring or offspring of a female with whom they mated.  Therefore, it is thought that group cannibalism including such cannibalism that follows infanticide (which has been documented in chimpanzees), may play an important role in the transmission and maintenance of blood-borne infections like simian immunodeficiency virus or different types of hepatitis in these populations. Since it was first …  In addition to addressing these points, future research into infanticide could reveal the genetic basis for the behavior for non-human primates and answer questions surrounding the curious existence of such a behavior in animals. The higher frequency in common marmosets may be due to a variety of social, reproductive, and ecological characteristics - including higher likelihood for overlapping pregnancies and births (due to short intervals between births), habitat saturation, and lower costs of infant care compared to other callitrichids - that increase the chance of two breeding females inhabiting the same group, leading to more intense competition. Infanticide is the act of deliberately causing the death of a very young child (under 1 year old). Male infanticide has been proposed to alter social evolution in mammals (and primates) by favoring female gregariousness or permanent male-female associations or by promoting a higher number of resident males that may help mothers to protect their infants from male intruders.  It has also been proposed that male infanticide likely led to social monogamy in primates and, potentially, humans. Stable polymorphism in such behaviour could be maintained by negative frequency-dependent selection (benefit … 1, 1979, pp. Early in her career, Hrdy published ground-breaking work on infanticide in langurs, a subfamily of monkey species scattered across Asia. Recently, a male Leopard was photographed killing and eating a cub in the Okavango delta, Botswana. 78, no.  This type of behavior has also been seen in the great apes such as bonobos and chimpanzees. Many people regard it as reprehensible to even think about it . " Infanticide in one-male breeding units has also been observed in red-tailed monkeys and blue monkeys.  Females with infants too young to be weaned left with the old males and returned after their offspring had fully weaned, again after a significantly shorter weaning period than during stable times. 469–494., doi:10.1017/cbo9780511542312.021.  A female gorilla benefits more from protection by the silverback male, despite the fact that mating with only one male increased paternity certainty and thus increases the number of males in the population that would benefit reproductively from infanticide. In these instances of direct aggression, the aggressor was the previous target of intra-species aggression directed towards them.  Several primate species have been observed to engage in the killing and subsequent cannibalism of infants. , According to the resource competition hypothesis animals engage in infanticide to exploit the infants in different ways. In one instance, the dominant marmoset female killed the offspring of a subordinate female. Killing conspecific infants (infanticide) is among the most puzzling phenomena in nature. “Reproductive Failure, Possible Maternal Infanticide, and Cannibalism in Wild Moustached Tamarins, Saguinus Mystax.” Primates, vol. 23–36., doi:10.1002/ajpa.23384. Male Lions that take over a pride will often kill all the young cubs in the pride but will seldom eat them. Females utilize paternity confusion to reduce the likelihood that a male she has mated with will kill her offspring. “The Urban Aminal: Population Density and Social Pathology in Rodent and Humans.” Bulletin of the World Health Organization, vol. Though it is not clear which genes are involved in primate infanticide, there is likely a genetic basis for the behavior that is yet to be discovered. This page was last edited on 7 December 2019, at 01:40.  The same study also found that the infants that were killed were cannibalized by their mothers. In most observed cases in common marmosets, the socially dominant breeding females killed the infants of a subordinate female, allowing them to maintain their dominance. , Whatever the benefit of male infanticide to the perpetrators, there is little doubt that it usually imposes a substantive cost on females’ fitness and reproductive success (as well as infants), particularly in the slowly reproducing species in which infanticide due to sexual selection is expected to operate.  Feticide is a related but distinct phenomenon by which physical or psychological trauma mediated by male behavior results in fetal loss. The most immediate and obvious form of protection against infanticide is physical defense wherein mothers either directly prevent aggressive acts toward their offspring or recruit other individuals for assistance. “DNA Analyses Support the Hypothesis That Infanticide Is Adaptive in Langur Monkeys.” Proceedings of the Royal Society of London. A quantitative model", "Loss of oestrus, concealed ovulation and paternity confusion in free-ranging Hanuman langurs", "Infanticide and reproductive restraint in a polygynous social mammal", "Conditional fetal and infant killing by male baboons", https://en.wikipedia.org/w/index.php?title=Infanticide_in_primates&oldid=986477421, Creative Commons Attribution-ShareAlike License, This page was last edited on 1 November 2020, at 03:04. As Vancouver police probe the suspected murder of a baby in the city, CTV News investigates the difference between homicide and infanticide -- a charge that is inapplicable to fathers. .  Although previously considered pathological and maladaptive and attributed to environmental conditions such as overcrowding and captivity , there are currently several explanations for why infanticide has evolved in non-human primate communities. Similarly, studies of birds, fish, amphibians, and invertebrates demonstrate egg and larval mortality in these species, a phenomenon directly analogous to infanticide in mammals.  Finally, in multi-male multi-female groups, female synchrony, in which females are all fertile at the same time, can prohibit the dominant male from monopolizing all of the females.  The study also concludes that there is a sex difference in the genetic substrate that regulates the inheritance of infanticidal behavior.  In social primates such as baboons and macaques, the main role of male-male aggression may be to provide exclusive reproductive access to females and defend them and their young from stranger males. What is infanticide? Further, females in the study were found to be motivated to form social bonds with males in order to protect them from infanticide. 3, 1998, p. 507., doi:10.2307/3546678. Infanticide is the killing of young offspring’s by a mature animal of its own species (Wikipedia). The sexual selection hypothesis is supported by findings that indicate that infanticide mostly occurs in social species, less in solitary species, and least in monogamous species since according to the sexual selection hypothesis, infanticide would be most adaptive in stable bisexual groups where a few males monopolize reproduction over short periods of time .In social species where a few males monopolize reproduction over short periods, killing the offspring of males who had previously been monopolizing reproduction would be adaptive for the individuals committing infanticide. , In mammals, interaction between the sexes is usually limited to the female estrous or copulation. “The Evolution of Male Infanticide in Relation to Sexual Selection in Mammalian Carnivores.” Evolutionary Ecology, vol. Infanticide in non-human primates occurs when an individual kills its own or another individual's dependent young. Opie, C., et al. , In many primate species, mothers have been documented to increase visual monitoring of potentially infanticidal male and/or offspring, and restrain and/or maintain proximity to infants more under conditions of heightened infanticide risk. Forming this socially monogamous pair causes the males to form parental relationships and social bonds with the female's offspring.  Resource competition and sexual selection are ruled out because it is the mother that is performing the infanticide, not another female. Cornell University ethologist Glenn Hausfater states that " infanticide has not received much study because it's a repulsive subject [ . Female catarrhine primates such as Hanuman langurs have evolved an extended estrous state with variable ovulation in order to conceal the paternity of the fertilization.  It is important to consider various factors that could be affecting the frequency and distribution of infanticide (such as overcrowding in a population) or those that could be affected by it (such as testes size). 1–22., doi:10.1007/bf02557698.  This suggests that there is some correlation between infanticide and promiscuity in primates. Maternal infanticide has been reported once in brown mantled tamarins, Saguinus fuscicollis, once in black fronted titis, Callicebus nigrifrons, and four times in mustached tamarins, Saguinus mystax. Alas, infanticide has gone beyond mere advocacy in the modern world. “Population Density, Social Pathology, and Behavioral Ecology.” Primates, vol. It has been estimated that infanticide occurs in 25% of all mammals and, in some of these populations, infanticide is a major contributor to infant mortality.. Infanticide in Animals and Man.  Primates from outside of familial groups might infiltrate areas and kill infants from other groups to eliminate competition for resources. , In order to reduce the amount of time that infants are particularly vulnerable to infanticide, females have been shown to wean infants earlier when risk of infanticide is high. Infanticide is a recurring motif in the mythology of ancient Greece. “At first, it’s deeply upsetting. 1, 2017, pp.  As a result, infanticide in seasonal breeders doesn't accelerate the mother's return to sexual activity, relatively decreasing its adaptive advantage. Female burying beetles kill off their rivals’ larvae before their own hatch to ensure their survival. “Male Infanticide and Paternity Analyses in a Socially Natural Herd of Przewalskis Horses: Sexual Selection?” Behavioral Processes, vol. However, in non-human primates, these male-female bonds persist past the estrous. , In the instances of maternal infanticide in tamarins, there were multiple breeding females.  A large set of potential female counterstrategies involves deterrence through cooperation with conspecifics (individuals of the same species). 52, no. 13328–13332., doi:10.1073/pnas.1307903110. Although commonly used in the context of food or shelter, the resource competition model can be applied to other limited resources, such as breeding opportunities or access to helpers. However, it is likely that antipredation is also a closely linked motivation to the formation of gorilla social units. Five hypotheses have been proposed to explain infanticide in non-human primates: exploitation, resource competition, parental manipulation, sexual selection, and social pathology. Agrell, Jep, et al. 2, 1992, pp. Trapanese, Cinzia, et al. Alternate nonadaptive explanations such as social-pathology and side effect hypotheses have also been proposed. 2, 2011, pp. Van, and Carel P. Van Schaik. Perrigo, Glenn, et al.  Phylogenetic reconstructions have also shown that male infanticide is significantly more likely to evolve after transitions toward group living than in their solitary ancestors. Hrdy calls this “sexually selected infanticide.” “You hear me talk so cavalierly and casually about infanticide,” she says. Crime Nov 25, 2019 This is known as the "aunting to death" phenomena; these non-lactating female primates gain mothering-like experience, yet lack the resources to feed the infant.  Year-round association serves to lower the probability of infanticide by other males. 7, no. Infanticide by males is widespread in mammals and may be the main cause of infant mortality in some populations (1). , While the majority of the explanations for why infanticide exists as a behavior posit that infanticide is an adaptive heritable behavior in primates, some have explained infanticide as a pathological behavior that is non-adaptive and does not need an evolutionary explanation. 6, 2015, doi:10.1101/cshperspect.a017640, Hrdy, Sarah Blaffer. Therefore, the direct aggression and infanticide carried out by these aggressors could be attributed to re-directed aggression.  Recent advances in technology have shown that genetics heavily influences behavior or behavioral phenotype in primates and have led to the beginning of the identification of genes mediating different behaviors .  Both of these counter-strategies result in costs such as expenditure of extra energy and increased risk of injuries. Infanticide in non-human primates occurs as a result of exploitation when the individuals enacting the infanticide directly benefit from consumption or use of their victim.  As mentioned above, male infanticide could have led to the evolution of multi-male mating or promiscuity of females in some primates species. 2019, doi:10.1007/s10329-019-00747-8. This behavior has been an observed consequence of multiple primate inter-species conflicts. These bonds motivate males to defend their offspring against infanticide from unrelated individuals and to never commit infanticide against their own offspring. The death of infants commonly occurs during the introduction of young males into the group.  Notably in primates, male infanticide can increase the reproductive success of male individuals by accelerating the return of females to fertilizable condition and ensuring that a greater percentages of the individuals’ offspring become the next generation when the male kills the offspring of other rival males . Most callitrichids have restrictive breeding patterns, which would be compatible with the model, but this infanticide behavior has only been documented in wild groups of common marmosets and not in wild groups of other callitrichid species. Many primates such as the gorilla, chimpanzee, baboon, and langur have been known to practice infanticide while others, such as the orangutan, bonobo and mouse lemur have not been observed to do so. “Prolonged Care and Cannibalism of Infant Corpse by Relatives in Semi-Free-Ranging Capuchin Monkeys.” Primates, Mar. The prevailing adaptive explanation for the behavior, however, has been the sexual-selection hypothesis according to which males increase reproductive opportunity by killing unrelated, unweaned offspring, thus hastening the mother's next ovulation, at which time the infanticidal male can mate with her .