Hunting behavior of wild chimpanzees in the Taï National Park

Hunting is often considered one of the major behaviors that shaped early hominids' evolution, along with the shift toward a drier and more open habitat. We suggest that a precise comparison of the hunting behavior of a species closely related to man might help us understand which aspects of hunting could be affected by environmental conditions. The hunting behavior of wild chimpanzees is discussed, and new observations on a population living in the tropical rain forest of the Taï National Park, Ivory Coast, are presented. Some of the forest chimpanzees' hunting performances are similar to those of savanna-woodlands populations; others are different. Forest chimpanzees have a more specialized prey image, intentionally search for more adult prey, and hunt in larger groups and with a more elaborate cooperative level than savanna-woodlands chimpanzees. In addition, forest chimpanzees tend to share meat more actively and more frequently. These findings are related to some theories on aspects of hunting behavior in early hominids and discussed in order to understand some factors influencing the hunting behavior of wild chimpanzees. Finally, the hunting behavior of primates is compared with that of social carnivores.     

Cutmarked bones from Pliocene archaeological sites at Gona, Afar, Ethiopia: implications for the function of the world's oldest stone tools

Newly recorded archaeological sites at Gona (Afar, Ethiopia) preserve both stone tools and faunal remains. These sites have also yielded the largest sample of cutmarked bones known from the time interval 2.58-2.1 million years ago (Ma). Most of the cutmarks on the Gona fauna possess obvious macroscopic (e.g., deep V-shaped cross-sections) and microscopic (e.g., internal microstriations, Herzian cones, shoulder effects) features that allow us to identify them confidently as instances of stone tool-imparted damage caused by hominid butchery. In addition, preliminary observations of the anatomical placement of cutmarks on several of the recovered bone specimens suggest that Gona hominids may have eviscerated carcasses and defleshed the fully muscled upper and intermediate limb bones of ungulates--activities that further suggest that Late Pliocene hominids may have gained early access to large mammal carcasses. These observations support the hypothesis that the earliest stone artifacts functioned primarily as butchery tools and also imply that hunting and/or aggressive scavenging of large ungulate carcasses may have been part of the behavioral repertoire of hominids by c. 2.5 Ma, although a larger sample of cutmarked bone specimens is necessary to support the latter inference.     

The impact of tourist hunting on large mammals in Tanzania: an initial assessment

In Tanzania, where tourist hunting is employed as a conservation tool for habitat protection, information on population sizes and hunting offtake was used to assess the impact of tourist hunting on mammal densities. In general, tourist hunting pressure was unrelated to local population sizes, but for most species, animals were removed at a level of less than 10% of the local population size, suggesting that over-exploitation was unlikely. Eland, however, and perhaps small antelope, bushbuck, kudu and reedbuck were hunted at levels which may be unsustainable in the long term. Analyses also identified areas of Tanzania with high levels of tourist hunting pressure, showed that, in certain areas, species with small population sizes such as eland could be declining as a result of tourist hunting, and suggested that current levels of lion and leopard offtake are too high. These findings, although preliminary, allow recommendations to be put forward for changing hunting quotas for certain species in particular areas of Tanzania.     

The relative importance of direct and indirect effects of hunting mortality on the population dynamics of brown bears

There is increasing evidence of indirect effects of hunting on populations. In species with sexually selected infanticide (SSI), hunting may decrease juvenile survival by increasing male turnover. We aimed to evaluate the relative importance of direct and indirect effects of hunting via SSI on the population dynamics of the Scandinavian brown bear (Ursus arctos). We performed prospective and retrospective demographic perturbation analyses for periods with low and high hunting pressures. All demographic rates, except yearling survival, were lower under high hunting pressure, which led to a decline in population growth under high hunting pressure (λ = 0.975; 95% CI = 0.914–1.011). Hunting had negative indirect effects on the population through an increase in SSI, which lowered cub survival and possibly also fecundity rates. Our study suggests that SSI could explain 13.6% of the variation in population growth. Hunting also affected the relative importance of survival and fecundity of adult females for population growth, with fecundity being more important under low hunting pressure and survival more important under high hunting pressure. Our study sheds light on the importance of direct and indirect effects of hunting on population dynamics, and supports the contention that hunting can have indirect negative effects on populations through SSI.     

Scavenging or Hunting in Early Hominids: Theoretical Framework and Tests

Evidence from Bed I, Olduvai, supports the hypothesis that scavenging, not hunting, was the major meat-procurement strategy of hominids between 2 and 1.7 million years ago. Data used to evaluate the hunting and scavenging hypotheses are derived from studying cut marks on Bed I bovids, comparing adaptations necessary for scavenging with those of early hominids, and a pa-leoecological reconstruction of Bed I carcass biotnass, carnivore guild, and hominidforaging area.     

The adaptive response of human skin to the savanna

In the early stage of human evolution, as the hominids began to inhabit the savanna mosaic in Africa some three or four million years ago, a functional complex of skin features contributed to their effective exploitation of resources and survival in the new environment. Thermal radiation from the sun combined with internally generated heat from muscular effort posed problems of thermoregulation. As a mechanism for dissipating body heat and maintaining brain temperature, eccrine sweat glands throughout the body surface combined with reduction in body hair enhanced the evaporative cooling effects of sweating. As body hair diminished, deeply pigmented skin was selected for as a protection against harmful ultraviolet radiation. When human populations left the equatorial regions of Africa, the adaptive significance of deeply pigmented skin may have shifted in response to other factors, such as latitude, diet and cultural pratices. We view the structure and function of human skin within a comparative and evolutionary framework that focuses on the environment in which the hominids evolved.     

桦甸仙人洞遗址出土的动物化石与孢粉

桦甸仙人洞旧石器遗址的上、下文化层出土了大量动物化石, 本文通过动物化石的分布状况、出土状态分析, 复原了上、下文化层沉积时期古人类的狩猎和处置猎物的行为, 总体来看, 远古人类生计方式以狩猎为主, 晚期古人类比早期对猎物资源开发得更彻底。另外, 从洞穴内大量碎骨片和石制品来看, 该洞穴可能为临时的营地或者屠宰场。通过对动物群组成、年代和孢粉分析的综合研究, 认为该遗址所处环境经历了剧烈的变化, 总体处于寒冷干燥的气候环境中, 植被以草原为主, 伴有少量森林。这一研究为探讨中国东北地区晚更新世人类的生存行为和演化特征提供了重要的研究材料和数据。     

Knuckle-walking and the evolution of hominoid hands

Knuckle-walking is a pattern of digitigrade locomotion unique to African apes among Primates. Only chimpanzees and gorillas are specially adapted for supporting weight on the dorsal aspects of middle phalanges of flexed hand digits II–V. When forced to the ground, most orangutans assume one of a variety of flexed hand postures, but they cannot knuckle-walk. Some orangutans place their hands in palmigrade postures which are impossible to African apes. The knuckle-walking hands and plantigrade feet of African apes are both morphologically and adaptively distinct from those of Pongo, their nearest relative among extant apes. These features are associated with a common adaptive shift to terrestrial locomotion and support placing chimpanzees and gorillas in the same genus Pan. It is further suggested than Pan comprises the subgenera (a) Pan, including P. troglodytes and pygmy chimpanzees, and (b) Gorilla, including mountain and lowland populations of P. gorilla. African apes probably diverged from ancestral pongids that were specially adapted for distributing their weight in terminal branches of the forest canopy. Early adjustments to terrestrial locomotion may have involved fist-walking which later evolved into knuckle-walking. Orangutans continued to adapt to feeding and locomotion in the forest canopy and their hands and feet became highly specialized for four-digit prehension. Although chimpanzees retained arboreal feeding and nesting habits, they moved from tree to tree by terrestrial routes and became less restricted in habitat. While adapting to a diet of ground plants gorillas increased in size to the point that arboreal nesting is less frequent among them than among chimpanzees and orangutans. Early hominids probably diverged from pongids that had not developed prospective adaptations to knuckle-walking, and therefore did not evolve through a knuckle-walking stage. Initial adjustments to terrestrial quadrupedal locomotion and resting stance probably included palmigrade hand posturing. Their thumbs may have been already well developed as an adaptation for grasping during arboreal climbing. A combination of selection pressures for efficient terrestrial locomotor support and for object manipulation further advanced early hominid hands toward modern human configuration.     

Evolution of Plasmodium and the recent origin of the world populations of Plasmodium falciparum

We have investigated the evolution of Plasmodium parasites by analyzing DNA sequences of several genes. We reach the following conclusions: (1) The four human parasites, P. falciparum, P. malariae, P. ovale, and P. vivax are very remotely related to each other, so that their evolutionary divergence predates the origin of the hominids; several of these parasites became associated with the human lineage by lateral transfer from other hosts. (2) P. falciparum diverged from P. reichenowi about 8 million years ago, consistently with the time of divergence of the human lineage from the apes; a parsimonious inference is that falciparum has been associated with humans since the origin of the hominids. (3) P. malariae is genetically indistinguishable from P. brasilianum, a parasite of New World monkeys; and, similarly. (4) P. vivax is genetically indistinguishable from the New World monkey parasite P. simium. We infer in each of these two cases a very recent lateral transfer between the human and monkey hosts, and explore alternative hypotheses about the direction of the transfer. We have also investigated the population structure of P. falciparum by analyzing 10 genes and conclude that the extant world populations of this parasite have evolved from a single strain within the last several thousand years. The extensive polymorphisms observed in the highly repetitive central region of the Csp gene, as well as the apparently very divergent two classes of alleles at the Msa-1 gene, are consistent with this conclusion.     

Africa's wild C4 plant foods and possible early hominid diets

A small minority of Africa's wild plant foods are C4. These are primarily the seeds of some of the C4 grasses, the rootstocks and stem/leaf bases of some of the C4 sedges (especially papyrus), and the leaves of some of the C4 herbaceous dicots (forbs). These wild food plants are commonly found in disturbed ground and wetlands (particularly the grasses and sedges). Multiple lines of evidence indicate that C4 grasses were present in Africa by at least the late Miocene. It is a reasonable hypothesis that the prehistory of the C4 sedges parallels that of the C4 grasses, but the C4 forbs may not have become common until the late Pleistocene. CAM plants may have a more ancient history, but offer few opportunities for an additional C4-like dietary signal. The environmental reconstructions available for the early South African hominid sites do not indicate the presence of large wetlands, and therefore probably the absence of a strong potential for a C4 plant food diet. However, carbon isotope analyses of tooth enamel from three species of early South African hominids have shown that there was a significant but not dominant contribution of C4 biomass in their diets. Since it appears unlikely that this C4 component could have come predominantly from C4 plant foods, a broad range of potential animal contributors is briefly considered, namely invertebrates, reptiles, birds, and small mammals. It is concluded that the similar average C4 dietary intake seen in the three South African hominid species could have been acquired by differing contributions from the various sources, without the need to assume scavenging or hunting of medium to large grazing ungulates. Effectively similar dominantly dryland paleo-environments may also be part of the explanation. Theoretically, elsewhere in southern and eastern Africa, large wetlands would have offered early hominids greater opportunities for a C4 plant diet.     

Analysis of a bone assemblage made by chimpanzees at Gombe National Park, Tanzania

Chimpanzee hunting provides information on prey characteristics and constraints acting on a large-bodied primate lacking a hunting technology, and has important implications for modeling hunting by fossil hominids. Analysis of the remains of five red colobus monkeys captured and consumed by Gombe chimpanzees in a single hunting bout provides one of the first opportunities to investigate the characteristics of prey bones surviving chimpanzee consumption. Four of the five individuals (an older infant, two juveniles and one subadult) were preserved in the bone assemblage; a neonate was entirely consumed. Cranial and mandibular fragments had the highest survivorships, followed by the scapulae and long bones. Post-cranial axial elements had the lowest survivorships. A high percentage (80%) of the long bones and ribs surviving consumption were damaged, most commonly through crenulation and step fracturing of bone ends. One of two partially reconstructed crania preserves a canine puncture through its left parietal. Proposed characteristics of faunal assemblages formed through chimpanzee-like hunting include small modal prey size, limited taxonomic diversity, a high proportion of immature individuals and a high frequency of skull bones. These characteristics would not uniquely identify hunting by fossil primates in the geological record, necessitating a contextual approach to diagnose hunting by hominids not forming an archeological record.Hominid utilization of vertebrate tissue is first unambiguously documented at 2.5 m.y.a. Rather than representing a strict "scavenging phase" in the evolution of hominid-prey interactions, Oldowan hominid carnivory may represent the overlay of large mammal scavenging on a tradition of small mammal hunting having a low archeological visibility.     

An analysis of intrinsic and extrinsic factors affecting the activity of a nocturnal species: The wild boar

Over the last century, the wild boar (Sus scrofa) has become an important wildlife species in both economic and ecological terms. Considered a pest by some and a resource by others, its rapid increase in population and distribution has raised management concerns. Studies on activity rhythms may provide useful insights into its overall ecology and help develop effective management strategies. By examining highly detailed activity data collected by means of accelerometers fitted on GPS-collars, we studied wild boar daily activity rhythms and the effect of environmental conditions on their diurnal and nocturnal activity. We thus provided evidence of the predominantly nocturnal and monophasic activity of wild boars. All year round, we reported low activity levels during the day, which opportunistically increased under the most favourable environmental conditions. Activity was found to be significantly affected by such weather conditions as temperature, precipitation and air relative humidity. Moreover, we found that nocturnal activity slightly increased as moonlight increased. Part of our analysis was focused on the hunting period in order to investigate whether wild boars modify their activity levels in response to hunting disturbance. Our results suggested that wild boar nocturnal habits are not directly influenced by the current hunting disturbance, though we hypothesised that they may have evolved over several decades of hunting harassment. Alternatively, but not exclusively, nocturnal habits may have evolved as a low-cost strategy to achieve an optimum thermal balance (i.e., behavioural thermoregulation).     

Host genotype and genetic diversity shape the evolution of a novel bacterial infection

Pathogens continue to emerge from increased contact with novel host species. Whilst these hosts can represent distinct environments for pathogens, the impacts of host genetic background on how a pathogen evolves post-emergence are unclear. In a novel interaction, we experimentally evolved a pathogen (Staphylococcus aureus) in populations of wild nematodes (Caenorhabditis elegans) to test whether host genotype and genetic diversity affect pathogen evolution. After ten rounds of selection, we found that pathogen virulence evolved to vary across host genotypes, with differences in host metal ion acquisition detected as a possible driver of increased host exploitation. Diverse host populations selected for the highest levels of pathogen virulence, but infectivity was constrained, unlike in host monocultures. We hypothesise that population heterogeneity might pool together individuals that contribute disproportionately to the spread of infection or to enhanced virulence. The genomes of evolved populations were sequenced, and it was revealed that pathogens selected in distantly-related host genotypes diverged more than those in closely-related host genotypes. S. aureus nevertheless maintained a broad host range. Our study provides unique empirical insight into the evolutionary dynamics that could occur in other novel infections of wildlife and humans.Subject terms: Molecular evolution, Bacterial evolution, Bacterial genetics     

The hunters and the hunted revisited

The dietary niches of extinct animals, including hominids and predators, may be constrained using stable carbon isotope ratios in fossil tooth enamel.(13)C/(12)C ratios of many of the primates abundant in the faunal assemblages of Members 1 and 2 at Swartkrans, including cercopithecoids and Australopithecus (Paranthropus) robustus, and a range of other possible prey species, have been reported previously. Resulting suggestions of a mixed, or omnivorous, diet for A. robustus raise questions about niche overlap with coeval, larger brained Homo. Here we present(13)C/(12)C data from Homo and several large predators including Panthera pardus, Dinofelis sp., Megantereon cultridens and Chasmoporthetes nitidula in Member 1, and P. pardus and P. leo in Member 2, in order to compare the two hominid species and to determine likely predators of the various primates and other macrovertebrates. Results for three Homo cf. ergaster individuals are indistinguishable from those of A. robustus, showing that proportions of C(3)- and C(4)-based foods in their diets did not differ. P. pardus, Megantereon and Crocuta are shown to be likely predators of the hominids and Papio baboons in Member 1, while the Dinofelis individual concentrated on prey which consumed C(4)grasses. The hunting hyaenid C. nitidula preyed on either mixed feeders or on a range of animals across the spectrum of C(3)and C(4)variation. The data from Members 1 and 2 confirm a shift in leopard diets towards animals that consumed C(4)grasses.     

Increased breathing control: Another factor in the evolution of human language

Investigation into the evolution of human language has involved evidence of many different kinds and approaches from many different disciplines. For full modern language, humans must have evolved a range of physical abilities for the production of our complex speech sounds, as well as sophisticated cognitive abilities. Human speech involves free‐flowing, intricately varied, rapid sound sequences suitable for the fast transfer of complex, highly flexible communication. Some aspects of human speech, such as our ability to manipulate the vocal tract to produce a wide range of different types of sounds that form vowels and consonants, have attracted considerable attention from those interested in the evolution of language. 1 , 2 However, one very important contributory skill, the human ability to attain very fine control of breathing during speech, has been neglected. Here we present evidence of the importance of breathing control to human speech, as well as evidence that our capabilities greatly exceed those of nonhuman primates. Human speech breathing demands fine neurological control of the respiratory muscles, integrated with cognitive processes and other factors. Evidence from comparison of the vertebral canals of fossil hominids and those of extant primates suggests that a major increase in thoracic innervation evolved in later hominid evolution, providing enhanced breathing control. If that is so, then earlier hominids would have had quite restricted speech patterns, whereas more recent hominids, with human‐like breath control abilities, would have been capable of faster, more varied speech sequences.     

Red deer hunting—commercializing versus availability

Many deer populations in Europe and North America have increased in abundance over the last decades. The increasing populations potentially entail both ecological and economic challenges and opportunities, but in practice we still know little about the extent to which these opportunities are being exploited in different management systems. The Norwegian red deer population has increased in density and expanded rapidly since the 1950s. Traditionally, red deer hunting has been undertaken by the local landowner and his relatives and friends. The present large population raises the question whether attracting other hunters could provide a higher economic return for the landowners and, if so, if they are interested in providing such hunting opportunities. We designed a survey to learn more about the landowners, both with respect to the present level of hunting income as well as economic costs of, for example, forest and agricultural damage; we also sought to understand their interest in increasing their income from red deer hunting and potential obstacles to realizing such an increased economic benefit. The results indicate that landowners on average think that red deer populations on their land result in higher costs than income but are nevertheless satisfied with the way things are. This highlights that increased numbers of deer need not automatically lead to more income for landowners and that the potential for income may be hindered by cultural factors such as reluctance to allow access to non-local hunters.     

An unusual case of cooperative hunting in a solitary carnivore

Cooperative hunting has been documented for several group-living carnivores and had been invoked as either the cause or the consequence of sociality. We report the first detailed observation of cooperative hunting for a solitary species, the Malagasy fossa (Cryptoprocta ferox). We observed a 45 min hunt of a 3 kg arboreal primate by three male fossas. The hunters changed roles during the hunt and subsequently shared the prey. We hypothesize that social hunting in fossas could have either evolved to take down recently extinct larger lemur prey, or that it could be a by-product of male sociality that is beneficial for other reasons.     

Hunting and Gathering in Tropical Rain Forest: Is It Possible?

Hunters and gatherers living in tropical forests represent an important part of the total range of variation among contemporary hunting and gathering societies. Studies of tropical forest hunting and gathering peoples have contributed to our perceptions of the foraging way of life. Yet no peoples have ever been directly observed living independently of agriculture in tropical rain forest. This article tests the hypothesis that humans do not exist nor have ever existed independently of agriculture in tropical rain forest. We find no convincing ethnographic evidence and, with the possible exception of Malaysia, no archeological evidence for pure foragers in undisturbed tropical rain forests. Negative evidence cannot be conclusive, but it suggests that we need to carefully reexamine common assumptions concerning the recent history of tropical forest dwellers, the adaptability of preagricultural humans, the geographic and environmental range of hominids, and the form and consequences of selection pressures acting on humans in warm, humid environments. The overriding purpose of this article is to stimulate further ecological and archeological research in the neglected tropical forest areas of the world.     

Causes of perceived faunal change in the later Neogene of East Africa

African terrestrial vertebrate faunas change over the time range from 14 my to 4 my, the period during which hominids are presumed to have diverged from other hominoids. The most complete local sequence showing this is provided by the Tugen Hills, west of Lake Baringo in Kenya. A large component of the pattern of faunal changes seen there, and at other relevant sites, could be explained by local environmental alterations, or by sampling properties of fossil assemblages and collections. It is hard to justify global climatic change as the sole explanation of observed faunal shifts, although such external factors cannot be ruled out and on general grounds are likely to be involved. As yet there is no convincing demonstration of synchronicity in faunal turnover. Evidence of a simple shift from forest conditions to grasslands, an event that has been correlated with the origins of hominid bipedalism, is hard to detect. Existing data suggest a more patchy distribution of forest and grassland in both space and time.     

Auditory-Motor Mapping Training: Comparing the Effects of a Novel Speech Treatment to a Control Treatment for Minimally Verbal Children with Autism

This study compared Auditory-Motor Mapping Training (AMMT), an intonation-based treatment for facilitating spoken language in minimally verbal children with autism spectrum disorder (ASD), to a matched control treatment, Speech Repetition Therapy (SRT). 23 minimally verbal children with ASD (20 male, mean age 6;5) received at least 25 sessions of AMMT. Seven (all male) were matched on age and verbal ability to seven participants (five male) who received SRT. Outcome measures were Percent Syllables Approximated, Percent Consonants Correct (of 86), and Percent Vowels Correct (of 61) produced on two sets of 15 bisyllabic stimuli. All subjects were assessed on these measures several times at baseline and after 10, 15, 20, and 25 sessions. The post-25 session assessment timepoint, common to all participants, was compared to Best Baseline performance. Overall, after 25 sessions, AMMT participants increased by 19.4% Syllables Approximated, 13.8% Consonants Correct, and19.1% Vowels Correct, compared to Best Baseline. In the matched AMMT-SRT group, after 25 sessions, AMMT participants produced 29.0% more Syllables Approximated (SRT 3.6%);17.9% more Consonants Correct (SRT 0.5); and 17.6% more Vowels Correct (SRT 0.8%). Chi-square tests showed that significantly more AMMT than SRT participants in both the overall and matched groups improved significantly in number of Syllables Approximated per stimulus and number of Consonants Correct per stimulus. Pre-treatment ability to imitate phonemes, but not chronological age or baseline performance on outcome measures, was significantly correlated with amount of improvement after 25 sessions. Intonation-based therapy may offer a promising new interventional approach for teaching spoken language to minimally verbal children with ASD.