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Infants of many primate species have extensive interactions with group members other than their mothers, which can affect an infant's fitness. Patterns of nonmaternal infant handling vary according to the mother's response as well as the number, sex, age, and dominance ranks of social partners. The primary goal of this study was to identify the basic pattern and explore the function of nonmaternal infant handling behavior in wild white-headed langurs ( Trachypithecus leucocephalus) at the Nongguan Hills in Guangxi, Southwest China. We report nonmaternal interactions in the first 3 mo after birth for 15 infants born during six birth seasons in a 67-mo field study. The nonmaternal infant handling we observed was generally in the form of caregiving, and mothers permitted most handling attempts. Infants were handled by nonmothers from the first day after birth. Infants spent 20-30% of the daytime associated with nonmothers during the first month of life, and time in contact with nonmothers decreased with infant age. Rates of nonmaternal infant handling varied significantly with the sex and age of handlers. Juvenile and subadult females handled infants significantly more than expected from their proportional representations in the group, whereas adult females did so less frequently than expected. Older male infants and juvenile males rarely handled infants, and adult males never did so. Infant handling behavior showed no correlation with the dominance rank of handlers relative to the mothers. Our data, although limited in some analyses, are in line with the predictions of the learning-to-mother hypothesis, but do not support the female competition or alliance formation hypotheses. [ABSTRACT FROM AUTHOR]

Direct intervention in infant delivery by non-parturient individuals is a rare phenomenon in nonhuman primates. In contrast, birth assistance by other individuals, or the practice of midwifery, is universal among human societies and generally believed to be a behavior unique to our species. It has been proposed that the enlarged head of the human fetus and the relatively narrow birth canal constrained by bipedalism has made human parturition more difficult than in nonhuman primates, and these anatomic challenges have led to the rotation of the fetus in the birth canal and an occiput anterior (i.e., backward-facing) orientation of emergence. These characteristics have hindered the mother's ability to self-assist the delivery of the infant, therefore necessitating assistance by other individuals or midwives for successful birth. Here we report the first high-definition video recordings of birth intervention behavior in a wild nonhuman primate, the white-headed langur ( Trachypithecus leucocephalus). We observed that while a primiparous female gave birth to an infant in an occiput posterior (i.e., forward-facing) orientation, a multiparous female intervened in the delivery by manually pulling the infant out of the birth canal and cared for it in the following hours. Our finding shows extensive social interactions throughout parturition, and presents an unequivocal case of non-maternal intervention with infant birth in a nonhuman primate. [ABSTRACT FROM AUTHOR]

There are few detailed descriptions of parturition behavior in wild primates. Here we report for the first time birth-related behaviors in a highly endangered colobine monkey endemic to southwest China, the white-headed langur ( Trachypithecus leucocephalus). We video recorded three complete birth events in three parturient females living in one reproductive group. The births occurred during the night at one of the group's sleeping sites. One parturient was primiparous, while the other two were multiparous. All three delivered close to other group members. Common behaviors among the parturients included adopting a raised-rump posture during contractions, manual inspection of the anogenital area followed by hand-licking, manual self-assistance as the infant emerged, holding and licking the infant immediately after the birth, and ingesting the placenta. However, we found considerable individual variation in birth-related behaviors. The primiparous female had the longest prepartum phase and more contractions than the two multiparous females. All three mothers ingested the placenta, but the primipare took much longer than the two multiparous mothers to deliver the placenta, start to ingest it, and consume it. Other group members had little interaction with the parturients during the prepartum phase, but showed intense interest in the neonates. The newly born infants were held by nonmaternal adult females of the group within 5-9 h of their birth. Our case studies stress the importance of the social context at parturition in group-living primates, and suggest that parity of parturients may influence birth-related behavior. [ABSTRACT FROM AUTHOR]

Infanticide by males is common in mammalian species such as primates in which lactation lasts much longer than gestation. It frequently occurs in one-male groups following male takeovers and is likely a male reproductive strategy. Reported female countertactics include abrupt weaning of infants, dispersal, or paternity confusion. Here, we estimated costs of female countertactics in terms of weaning ages and interbirth intervals. We observed a population of white-headed leaf monkeys ( Trachypithecus leucocephalus) in Nongguan Nature Reserve, China (1995-2006) mainly composed of one-male groups. Takeovers ( N = 11) coincided with the peak conception period. Detailed data are presented for five takeovers (34 females, 29 infants, and 47 group-years) leading to six infant disappearances (42.9% of infant mortality). All presumed infanticides were in accordance with the sexual selection hypothesis. Following a takeover, females without infants or with old infants stayed with the new males, incurring no or low costs (via abrupt weaning). Females with young infants dispersing with the old males also experienced low costs. High costs (due to infant loss) were incurred by pregnant females and those with young infants who stayed with the new males indicating that paternity was not confused. Costs in terms of long interbirth intervals were also high for females leaving with the old males to later join the new males, despite infant survival. Female countertactics reflected female philopatry mediated by infant age. Presumably due to the seasonal timing of takeovers, most countertactics seemed successful given that 32.3% of females apparently incurred no costs and 41.2% incurred only low costs. [ABSTRACT FROM AUTHOR]

One of the most hotly debated and frontal issues in paleoanthropology focuses on the origins of modern humans. Recently, an incomplete hominin mandible with a distinctly weaker mental protuberance than modern human and a great variety of coexisting fossil mammals were unearthed from the Homo sapiens Cave of Mulan Mountain, Chongzuo, Guangxi. The mammalian fauna from the Homo sapiens Cave characterized by the combination of Elephas kiangnanensis, first occurring Elephas maixmus, and Megatapirus augustus, and strikingly different from the Early Pleistocene Gigantopithecus fauna and the Middle Pleistocene Ailuropoda-Stogodon fauna of South China could be regarded as an early representive of the typical Asian elephant fauna. Faunal analysis, biostratigraphic correlation, and, most importantly, U-series dating all consistently support an estimate of ca. 110 ka for the age of the fossil Homo sapiens and coexisting mammalian fauna, that is, the early Late Pleistocene. The fauna is mainly made up of tropical-subtropical elements, but grassland elements have a much greater variety than forest elements, which probably indicates a drier climate at that time. This discovery of early Homo sapiens at the Mulan Mountain will play a significant role in the study of the origin and its environmental background of modern humans. [ABSTRACT FROM AUTHOR]

Fossil records indicate orangutan-like hominoids have been widely distributed in south China during Pleistocene, although currently only surviving in the tropical forests of Kalimantan and Sumatra in Indonesia. This paper describes the recently discovered hominoid fossil teeth from human site of Mulanshan cave in Chongzuo of Guangxi, whose geological age is the Late Pleistocene, about 11000 yeas age based on associated mammal fauna and U-series dating. Compared with those of modern and subfossil orangutans from Indonesia, other fossil great apes from China, the hominoid teeth from Mulanshan cave are orangutan-like, but show somehow different from Indonesia's orangutans, the average sizes of cheek teeth larger and occlusal enamel wrinkles less and simpler. They are classified temporarily as the subspecies of Pongo pygmaeus weidenreichi. Concerning the variations of morphological features and dental sizes of orangutan-like teeth from southern China and neighboring northern Vietnam, different subspecies or species or genus possibly, but the key evidence is necessary to be identified. [ABSTRACT FROM AUTHOR]

Among the most important faunas in the Late Cenozoic, the Gigantopithecus faunas have received a good deal of attention. The Gigantopithecus fauna recently discovered in Sanhe Cave consists of more than 80 mammal species, including Cf. Hominidae, Pongo sp., Hylobates sp., Sinomastodon yangziensis, Stegodon preorientalis, Cervavitus fenqii, Dicoryphochoerus ultimus and Sus xiaozhu. It is the southernmost Gigantopithecus fauna found so far in China. Its geological age is estimated to be Early Pleistocene based on the fauna and stratigraphic correlation. The significant increase in the estimated body sizes of Ailuropoda, Gigantopithecus and Tapirus shows that the Sanhe fauna is middle Early Pleistocene, later than those from Wushan and Liucheng (early Early Pleistocene). Paleomagnetic dating of the fossil-bearing strata in Sanhe Cave gives an age of approximately 1.2 Ma. The fauna is characterized by tropical-subtropical forest types, including Pongo sp., Tupala sp., Ia sp., Typhiomys intermedius, etc., and it lacks Palaearctic types. It is a typical tropical forest fauna, suggesting an environment with a lush forest and a warm and humid climate. The discovery of the Sanhe Gigantopithecus fauna is significant for establishing the chronological stages of the Gigantopithecus faunas in China, and for discussing their origin, evolution and dynamics. [ABSTRACT FROM AUTHOR]

A population census of white-headed langurs ( Trachypithecus leucocephalus) was conducted using sleeping-site counts and the line-transect method from July to August 2002 at the Longrui Karst Hills, Guangxi, China. This area had been the largest habitat of the langurs across their range before the 1990s. While our survey revealed 146 old sleeping-sites, no white-headed langurs or fresh sleeping-sites were found in this area. Our study indicated that there had previously been a large population of langurs at Longrui Karst Hills, but now the langurs are possibly locally extinct in this area. If langurs still exist within the area, the population density must be very low. Interviews with local people confirmed that the number of white-headed langurs has been decreasing since the 1980s. Poaching was very common in the past and continues to be a problem at present, and it is likely that this has caused the decrease in the white-headed langur population at Longrui Karst Hills. [ABSTRACT FROM AUTHOR]