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Infant injury death in Washington State, 1981 through 1990.

OBJECTIVE: To measure annual rates of infant injury death in Washington State and identify potential risk factors for infant injury death. METHODS: A population-based case-control study using a linked file of birth and death certificates for the years 1981 through 1990. RESULTS: The leading causes of infant injury death, per 100,000 live births, were intentional injury (9.1); suffocation, choking, or hanging (6.9); motor vehicle crashes (4.4); and drowning (3.2). Unintentional injury death rates fell steeply during the 1970s but remained steady during the 1980s. Infanticide rates rose during the 1980s. Young maternal age (odds ratio, 9.0; 95% confidence interval, 4.5 to 17.9, for age < 20 years vs age > 30 years) and higher parity (odds ratio, 5.0; 95% confidence interval, 3.1 to 8.3, for parity of two or more vs parity of zero) were associated with infant injury death. There was a twofold increase in the risk of infant injury death if the mother smoked, was black, or lived in a rural area. Male sex of the infant, late prenatal care, and low income were associated only with intentional deaths, while higher parity was more strongly associated with unintentional injury deaths. CONCLUSIONS: During 1981 through 1990, infant mortality caused by injuries increased in Washington State. Young maternal age and higher parity were strongly associated with infant injury death.

Accidents↗

Reproduction in free-ranging Propithecus verreauxi: estrus and the relationship between multiple partner matings and fertilization.

Female sifaka mate selectively with one or more resident and/or non-resident males during the breeding season. Various adaptive explanations have been advanced to explain why female primates mate with multiple males including that 1) females seek to confuse paternity and thereby forestall male infanticide and/or ensure male infant care or 2) females seek to ensure fertilization. Assessing the power of fertilization insurance to explain mating patterns in females requires information on the temporal relationship between mating and ovarian hormones. The hormonal correlates of reproduction and mating in free-ranging Propithecus verreauxi were investigated using excreted steroids as indices of reproductive state. Solid-phase extraction and radioimmunoassay techniques were used to measure unconjugated estradiol (E(2)) and progesterone (P(4)) in 485 desiccated fecal samples collected from five female sifaka before and during the breeding season at Beza Mahafaly, Madagascar. Results suggest that behavioral estrus was characterized by 10 to 15-day elevations in E(2); hormonal activity was observed to be similar to pseudo-estrus reported for other lemur species; apparent conception was associated with sustained P4 elevations beginning 1 to 3 days post-estrus with gestational phase elevations of E2 beginning 42 to 45 days post-conception; and mating with multiple partners appeared not to be a prerequisite to fertilization, as conception resulted from both monoandrous and polyandrous matings. These preliminary data suggest that fertilization insurance is not adequate to explain polyandrous mating in sifaka at Beza Mahafaly.

Animals↗

Primate natal coats: a preliminary analysis of distribution and function.

Pelage coloration of infants was compiled for 138 species of primates. Three functional hypotheses--alloparental, infant defense, and paternity cloak--for primate natal coats are tested. Neonatal pelage contrasted with adult pelage in over half of the species examined. Subtle or inconspicuous contrast was more common than flamboyant contrast. Natal coats began to change at 5.7 weeks and disappeared by 18.0 weeks postpartum on average. The first body part to lose natal coloration was the head and/or dorsum in the majority of species. Functional analyses provided no support for the only published hypothesis--alloparental--while providing partial support for two new hypotheses--infant defense and paternity cloak. A significant association between testes weight and natal coat contrast supports a link between mating system and infant contrast. This is discussed in terms of infanticide avoidance. Natal coats are proposed to be categorically differentiated into inconspicuous and flamboyant types, not differentiated by a continuous gradation, such as color. Subspecific differentiation and patterns of shared ancestry are assessed.

Animals↗

Female sooty mangabeys (Cercocebus torquatus atys) respond differently to males depending on the male's residence status-preliminary data.

I tested the hypothesis that free-ranging female mangabeys (Cercocebus torquatus atys) differentiate between males depending on their residence status. Adult males in this species employ two group-membership strategies: they are either full-time residents or part-time residents (i.e., present for several weeks at a time, then gone for several weeks, then present again, etc.). In a playback experiment I tested whether adult females with young infants responded differently to calls of adult males that were group members during the previous mating season as compared to males that belonged to neighboring groups during the mating season or were complete strangers. Males whose calls were played were present residents, part-time residents (absent for at least 3 months), neighbors, or complete strangers. Because infanticide is a potential risk in mangabeys, I predicted that females would respond differently to males that had resided in the group when their infant was conceived than they would to those that had not been present. The females showed a clear difference in their reaction to the playbacks of vocalizations from resident and part-time resident males as opposed to nonresidents.

Acoustic Stimulation↗

Sex differences in scent marking in Propithecus edwardsi of Ranomafana National Park, Madagascar.

In this study we compared the scent-marking rates of females with those of males. Specifically, we examined the ability of season, dominance status, and natal status to explain the frequency of scent marking in female sifakas living wild in Ranomafana National Park, Madagascar, and compared the results with those published for males [Pochron et al., American Journal of Primatology, in press]. We also sought to determine whether vulnerability to infanticide affects marking frequency in adults of either sex, and whether female reproductive status affects female marking behavior. We found that males marked at twice the rate of females, and like males, females in single-female groups marked at the highest rates. Dominant females and non-natal females marked at higher rates than did subordinate females and natal females, a pattern also seen in males. This suggests that scent marks may convey important information about status. Neither females nor males varied their marking frequency with the presence of vulnerable infants. Females did not alter marking frequency with reproductive state, and like males, they marked at higher rates in the period prior to the mating season than they did in the mating season itself. This implies that females may use scent marks more for intrasexual aggression or territoriality than for mate attraction.

Age Factors↗

Violent coalitionary attack by female mandrills against an injured alpha male.

Female contact aggression against males is relatively rare in species in which the adult males are larger than the females, but it has the potential to influence group structure, male group membership, tenure, and dominance rank. We report an incident in which female mandrills living in a semi-free-ranging group in Franceville, Gabon, attacked a male that was apparently incapacitated after a fight with another male and was unable to escape. The attack involved the alpha male and did not occur in a sexual or infanticidal context. Other adult and adolescent males observed the attack, but when one adult male attempted to participate he was chased away by the females. This observation adds to reports of female coalitions excluding unwanted males from primate groups, or even killing them. The fact that this can also occur in mandrills suggests that females have a degree of control over male group membership, despite the large degree of sexual dimorphism in this species, and highlights the importance of coalitions in primate social organization.

Aggression↗

A congenital meningocoele in prehistoric Australia.

This report concerns a congenital meningocoele in a young adult Aboriginal female from north-western New South Wales, Australia. The fact that this individual reached adulthood throws new light on the attitude of these nomadic people towards such conditions. Evidence of this kind may prompt also a re-evaluation by prehistorians and anthropologists of the popularly held belief that all such malformations were automatically eliminated by infanticide. The discovery of this form of pathology helps provide new information not only on past cultural attitudes towards disease, but its frequency and geographical incidence, and adds to our knowledge concerning the range of pathological conditions suffered by prehistoric societies worldwide.

Australia↗

Male investment under changing conditions among chacma baboons at Suikerbosrand.

Male investment in infant baboons was measured by frequency of carrying from 1978 through 1985. A series of hypotheses was generated and tested with the carrying data, based on the assumptions that: male baboons have some capacity to estimate likelihood of paternity; where paternity probability is greater, males will invest more, where potential benefits to males or infants are higher, males will invest more. Carrying was affected by probability of paternity, availability of estrous females, season of conception and season of carrying, infant age, subtrooping, and predation risk. Infants were carried by probable fathers, siblings, mothers' siblings, and unrelated "suitors." Male investment increased female reproductive fitness: carried infants were more likely to survive, and mothers of carried infants had shorter interbirth intervals. Males appeared to estimate paternity both by observed copulations by other males and by the likelihood that copulations could have occurred without being observed. Male care of infant baboons may also be affected by female choice among males, the distribution of probable infants in time, male tenure at alpha rank, the number of males per troop, the probability of infanticide, and energy demands. Subtrooping seems to be historically crucial, by initially creating a situation in which some males have high paternity certainty.

Animals↗

Rat pups reduce ultrasonic vocalization after exposure to an adult male rat.

We examined how the experience of a threatening stimulus alters subsequent behavior in a situation where the immediate threat is absent. A small huddle of 12-day-old rats was exposed to a potentially infanticidal adult male rat for 5 min. During male exposure, pups were significantly more immobile than control pups. Thirty, 60, and 180 min after male exposure, the pups were isolated for 5 min from litter and dam in an unfamiliar environment. When isolated, pups that had been previously exposed to the male emitted significantly fewer ultrasonic vocalizations than controls, but did not differ in immobility. Low levels of vocalization were apparent 30 and 60 min after male exposure and were not evident at 180 min. The pups seemed to have adjusted their behavior to a potential male threat in a different context for a limited period of time.

Age Factors↗

Developmental changes in responsivity to threat are stimulus-specific in rats.

During early ontogeny, stimuli that pose a threat to an animal change. Unrelated adult male rats may kill young rats, but infanticide ends around weaning. Predation, on the other hand, may increase during early ontogeny when rats begin to extend their activity range. We investigated the developmental course of two defensive responses, immobility and analgesia, in young rats exposed to an adult male rat or to predator cues. Preweaning 14-day-old rats became immobile and analgesic when exposed to the male and showed immobility but not analgesia when exposed to cat odor. On Day 26, around weaning, the presence of the male rat no longer induced immobility and analgesia whereas cat odor produced higher levels of immobility and analgesia compared to control and male-exposed animals. This developmental change in responsivity may reflect the differences in the risk of being harmed by a male or a cat during different periods of ontogeny.

Animals↗

Variability in "spontaneous" maternal behavior is associated with anxiety-like behavior and affiliation in naïve juvenile and adult female prairie voles (Microtus ochrogaster).

Juvenile female prairie voles (Microtus ochrogaster) are spontaneously maternal, while virgin adult females show significant variability in their response to first pup exposure, ranging from infanticidal to full maternal behavior. In the present study, we investigated whether differences in anxiety-like behavior and affiliation are associated with juvenile-adult and adult individual differences in the response to pups. Forty juvenile (19-20 days) and 42 adult (60-90 days) female prairie voles were exposed to pups for the first time and tested for maternal behavior, anxiety-like behavior (elevated plus maze, open field), and affiliation toward age-matched, same sex conspecifics. Juveniles displayed less anxiety-like behavior, were more affiliative to unfamiliar conspecifics, and interacted with pups more positively than adults. Adults that displayed maternal behavior spent less time immobile, made more crosses through the center of the open field arena, and were more affiliative than adults that attacked the pups. This suggests that lower locomotion or exploration in a novel environment and poor affiliative behavior are negatively associated with maternal responsiveness in female prairie voles.

Age Factors↗

Developmental changes in pre-adult behavior in confined colonies of golden hamsters.

Eight litters of hamsters living in a large enclosure were observed from birth to 120 days. For the first 65 days each litter was confined to a separate compartment. Basic motor coordination was reached by the 3rd week. Marking was seen during the 6th week when males began to mount their mothers sexually, but lordosis was not seen in female pups before the 7th week. Fighting appeared at this time with the females being the more aggressive. At 65 days the litters were combined into 2 groups of 4.A gradual shift followed in the relative aggressiveness of the sexes. Females, which had previously initiated over 90% of attacks, became less aggressive, whereas attacks by males increased to the former female level. This unusual behavior for hamsters, where females are normally dominant, may have been due to crowding. Also, severe disruption of maternal behavior occurred with marked infanticidal tendencies.

Aggression↗

Discrimination between conspecific and allospecific infants by male gerbils and mice before and after experience of their own young.

Prior to the birth of their 1st litter, male gerbils generally respond paternally toward both gerbil and mouse pups. Once they have experience of their own pups, however, they continue to respond paternally toward unrelated gerbil pups but kill mouse pups. Male CSI mice, on the other hand, respond paternally to unrelated mouse pups both before and after the birth of their own litter but tend to ignore gerbil pups at these times. These data are discussed with respect to infanticide, onset of paternal care and the narrowing of effective stimuli for eliciting paternal care.

Aggression↗

Social control of reproduction in banded mongooses.

Recent theoretical work suggests that the distribution of reproduction, or degree of reproductive skew, in animal societies depends crucially on (1) whether dominant individuals can fully control subordinate reproduction, and (2) how subordinate reproduction affects the fitness of dominants. I investigated these two factors in cooperatively breeding banded mongooses, Mungos mungo. Female packmates entered oestrus together and were closely guarded by dominant males. These males were aggressive to subordinate males who attempted to mate, but females still managed to mate with males other than their mate guard. Older females were guarded and mated a few days before their younger packmates, yet all females usually gave birth on the same day, suggesting that older females may have a longer gestation period. Moreover, older females carried more fetuses. Overall, ca. 83% of adult females conceived in each breeding attempt and 71% carried to term. These results indicate that, among males, dominant individuals did not have full control over the mating attempts of subordinates (since they could not fully control the mating behaviour of the females they guarded), while among females there was little or no attempt to prevent subordinates from breeding (at least, prior to parturition). Two within-group infanticides by males suggested that some control over reproduction may be exercised postpartum. Per capita survivorship of young in the den increased with the number of females who gave birth. Thus, dominant females may benefit from subordinate reproduction, providing a possible explanation for the lack of reproductive suppression among females in this species. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗

Parental Optimism and Progeny Choice: When is Screening for Offspring Quality Affordable.

Three general classes of fitness incentives have been proposed for parental overproduction of offspring: (1) tracking environmental variation; (2) developmental facilitation; and (3) replacements for failed or defective members of the core brood. In one version of this last category, called the progeny choice hypothesis, parents are seen as creating an enlarged array of offspring from which a genetically superior subset is chosen for full investment. In the selection process, parents may eliminate the victims either through personal effort (filial infanticide) or by proxy (by allowing or even encouraging fatal sibling rivalry). Because the culling process is non-random, it can elevate average offspring quality. Progeny choice, however, is only cost-effective if the expenses of early overproduction (including elevated levels of sibling competition) do not outweigh the eventual upgrade in offspring quality. A fair competition within the offspring "arena" offers the greatest potential for discriminating on the basis of intrinsic quality, but may be overwhelmed by high costs of sibling rivalry. Conversely, while parentally managed competition (conferring handicaps to some and advantages to others) can discount those rivalry costs, it simultaneously diminishes the system's capacity for distinguishing good offspring from bad. Ceteris paribus, one would expect to find progeny choice mechanisms in species with cheap sibling rivalry, large cohorts of evenly matched offspring, and exaggerated variation in offspring genetic quality. Conversely, this class of incentives of parental overproduction seems least suited to taxa in which parents dole out marked advantages or handicaps to various concurrent offspring (e.g. asynchronously hatching birds).Copyright 1998 Academic Press Limited

Journal Article↗

Gene-culture coevolution and sex ratios: II. Sex-chromosomal distorters and cultural preferences for offspring sex.

Cultural preferences for the sex of offspring may produce behavior, such as female infanticide, sex-selective abortion and sex-selective parental investment, which alter the sex ratio in a population. Empirical evidence suggests that some genetic sex-ratio distorters are located on the sex chromosomes. Interactions between cultural preferences and sex-linked sex-ratio distorters are examined. Criteria for the spread of cultural preferences and sex-chromosomal distorter alleles are derived analytically, and the coevolution of preferences and distorters is examined through numerical iteration. Evolutionary equilibria and trajectories of gene-culture interactions involving sex-chromosomal distorter alleles may produce severely male- or female-biased primary sex ratios and adult sex ratios in populations. Adult sex ratios, primary sex ratios, allele frequencies and the prevalence of cultural preferences in the population are sensitive to initial conditions and cultural transmission parameters. During the coevolutionary process phenoallelic association is observed in many cases and is associated with unusual dynamics.

Adult↗

A new method in criminology: use of ELISA to detect AFP on different materials with monoclonal anti-alpha-fetoprotein.

A new method has been introduced to distinguish normal adult serum stains from fetal or newborn serum and amniotic fluid stains with ELISA in cases of criminal abortion and infanticide. The method is based on the sensitive detection of alpha-fetoprotein (AFP) by a two-site enzyme immunoassay (EIA) following its elution with high efficiency from different materials (e.g., cotton, paper, synthetic fabric, or glass) by phosphate-buffered 0.5 M NaCl solution.

Adult↗

Sexuality in traditional China: its relationship to child abuse.

The sexual and marital history of China for 3000 year is reviewed, indicating a general open humanistic attitude about sex, with little perversion, sado-masochism, or denigration of sexuality. Foot fetishism (particularly foot binding) has been extensive in the past, but less so since World War I. Respect for women and their sexual rights and importance has been related to the low rate of child abuse. Currently, restrictions on sexual freedom and psychological injury to children is increasing in the urban areas (20% of the population) with resultant increase in infanticide particularly of little girls.

Adolescent↗