The Method of Local Restriction: in search of potential great ape culture-dependent forms

Humans possess a perhaps unique type of culture among primates called cumulative culture. In this type of culture, behavioural forms cumulate changes over time, which increases their complexity and/or efficiency, eventually making these forms culture-dependent. As changes cumulate, culture-dependent forms become causally opaque, preventing the overall behavioural form from being acquired by individuals on their own; in other words, culture-dependent forms must be copied between individuals and across generations. Despite the importance of cumulative culture for understanding the evolutionary history of our species, how and when cumulative culture evolved is still debated. One of the challenges faced when addressing these questions is how to identify culture-dependent forms that result from cumulative cultural evolution. Here we propose a novel method to identify the most likely cases of culture-dependent forms. The ‘Method of Local Restriction’ is based on the premise that as culture-dependent forms are repeatedly transmitted via copying, these forms will unavoidably cumulate population-specific changes (due to copying error) and therefore must be expected to become locally restricted over time. When we applied this method to our closest living relatives, the great apes, we found that most known ape behavioural forms are not locally restricted (across domains and species) and thus are unlikely to be acquired via copying. Nevertheless, we found 25 locally restricted forms across species and domains, three of which appear to be locally unique (having been observed in a single population of a single species). Locally unique forms represent the best current candidates for culture-dependent forms in non-human great apes. Besides these rare exceptions, our results show that overall, ape cultures do not rely heavily on copying, as most ape behaviours appear across sites and/or species, rendering them unlikely to be culture-dependent forms resulting from cumulative cultural evolution. Yet, the locally restricted forms (and especially the three locally unique forms) identified by our method should be tested further for their potential reliance on copying social learning mechanisms (and in turn, for their potential culture-dependence). Future studies could use the Method of Local Restriction to investigate the existence of culture-dependent forms in other animal species and in the hominin archaeological record to estimate how widespread copying is in the animal kingdom and to postulate a timeline for the emergence of copying in our lineage.     

Size and shape dimorphism in great ape mandibles and implications for fossil species recognition

Sexual dimorphism is an important source of morphological variation, and species differences in dimorphism may be reflected in magnitude, pattern, or both. While the extant great apes are commonly used as a reference sample for distinguishing between sexual dimorphism and intertaxic variation in the fossil record, few studies have evaluated mandibular dimorphism in these taxa. In this study, percentage, degree, and pattern of mandibular dimorphism are evaluated in Pongo, Gorilla, and Pan. Mandibular dimorphism patterns are explored to determine the extent to which such patterns accurately track great ape phylogeny. Pattern stability is assessed to determine whether there are stable patterns of mandibular size and shape dimorphism that may be usefully applied to hominoid or hominid fossil species recognition studies. Finally, the established patterns of dimorphism are used to address recent debates surrounding great ape taxonomy. Results demonstrate that mandibular dimorphism is universally expressed in size, but only Pongo and Gorilla exhibit shape dimorphism. Pattern similarity tends to be greater between subspecies of the same species than between higher-order taxa, suggesting that within the great apes, there is a relationship between dimorphism pattern and phylogeny. However, this relationship is not exact, given that dimorphism patterns are weakly correlated between some closely related taxa, while great ape subspecies may be highly correlated with taxa belonging to other species or genera. Furthermore, dimorphism patterns are not significantly correlated between great ape genera, even between Gorilla and Pan. Dimorphism patterns are more stable in Gorilla and Pongo as compared to Pan, but there is little pattern stability between species or genera. Importantly, few variables differ significantly between taxa that simultaneously show consistently relatively low levels of dimorphism and low levels of variation within taxa. Combined, these findings indicate that mandibular dimorphism patterns can and do vary considerably, even among closely related species, and suggest that it would be difficult to employ great ape mandibular dimorphism patterns for purposes of distinguishing between intra- and interspecies variation in fossil samples. Finally, the degree of pattern similarity in mandibular dimorphism is lower than previously observed by others for craniofacial dimorphism. Thus, the possibility cannot be ruled out that patterns of craniofacial dimorphism in great apes may be associated with a stronger phylogenetic signal than are patterns of mandibular dimorphism.     

Preliminary bonobo and chimpanzee nesting by habitat type in the northern Lac Tumba Landscape,Democratic Republic of Congo

Knowing how habitat determines the distribution of great apes is essential for understanding their ecology and conservation requirements. Habitats in the northern Lac Tumba Landscape where this study was conducted are mostly swamp and flooded forests, which types have been overlooked in many great ape surveys. This study describes and discusses patterns of bonobo and chimpanzee nesting sites across these habitat types in the general scope of habitat use by great apes. Considerable efforts were deployed to survey forests of the Ngiri Triangle (186 km), Bomongo‐Lubengo (126 km) and Bolombo‐Losombo (112 km). Great ape nesting site encounter rates (r) were calculated for Bonobos (r = 0.21 nesting sites km^?1; Bolombo‐Losombo), chimpanzees (r = 0.11 nesting sites km^?1; Ngiri Triangle) and (r = 0.02 nesting sites km^?1; Bomongo‐Lubengo). Swamps and flooded forests dominated the three zones. Nesting sites were at the highest encounter rates in flooded forests; both great ape species were significantly associated with swampy and flood forests. Human signs did not influence the occurrence of nesting sites in these forests. These results confirm findings from other sites where great apes were observed using swamps; they suggest that future surveys include these types of habitat to avoid under‐estimating population sizes.     

What we don't know about great ape variation

The patterning of intraspecific variation among the great apes is proving more complex than has been recognized previously. The great ape species, as currently defined, may include markedly different subspecies, alternatively, the majority of intraspeclflc variation may be observed at the populational level within a single subspecies. Recent studies have raised a number of questions about great ape evolutionary biology. How many species of living great apes exist? What was the original dietary adaptation of gorillas? How should we define male orang-utan adulthood?     

The ecology of Ebola virus

Since Ebola virus was first identified more than 30 years ago, tremendous progress has been made in understanding the molecular biology and pathogenesis of this virus. However, the means by which Ebola virus is maintained and transmitted in nature remains unclear despite dedicated efforts to answer these questions. Recent work has provided new evidence that fruit bats might have a role as a reservoir species, but it is not clear whether other species are also involved or how transmission to humans or apes takes place. Two opposing hypotheses for Ebola emergence have surfaced; one of long-term local persistence in a cryptic and infrequently contacted reservoir, versus another of a more recent introduction of the virus and directional spread through susceptible populations. Nevertheless, with the increasing frequency of human filovirus outbreaks and the tremendous impact of infection on the already threatened great ape populations, there is an urgent need to better understand the ecology of Ebola virus in nature.     

Pathogen Transmission from Humans to Great Apes is a Growing Threat to Primate Conservation

All six great ape species are listed as endangered or critically endangered by the IUCN and experiencing decreasing population trends. One of the threats to these non-human primates is the transmission of pathogens from humans. We conducted a literature review on occurrences of pathogen transmission from humans to great apes to highlight this often underappreciated issue. In total, we found 33 individual occurrences of probable or confirmed pathogen transmission from humans to great apes: 23 involved both pathogen and disease transmission, 7 pathogen transmission only, 2 positive antibody titers to zoonotic pathogens, and 1 pathogen transmission with probable disease. Great ape populations were categorized into captive, semi-free-living, and free-living conditions. The majority of occurrences involved chimpanzees (Pan troglodytes) (n = 23) or mountain gorillas (Gorilla beringei beringei) (n = 8). These findings have implications for conservation efforts and management of endangered great ape populations. Future efforts should focus on monitoring and addressing zoonotic pathogen and disease transmission between humans, great ape species, and other taxa to ensure the health of humans, wild and domestic animals, and the ecosystems we share.     

The capacity of animals to acquire language: do species differences have anything to say to us?

Following the Gardners' discovery that an ape named Washoe could learn to produce and combine a number of hand movements similar to those used by deaf human beings, a variety of 'ape-language projects' sprang up. Some projects used different symbol systems, others used different training techniques, and others used different species of apes. While debate still rages regarding the appropriate way to interpret the symbolic productions of apes, three species of great apes (gorilla, orangutan, and chimpanzee) have now been credited with this capacity while no lesser apes or monkeys have been reported, at present, to have acquired such communicative skills. Among all of the claims made for the various animal species, the philosophers have entered the fray attempting to define the essence of what it is about language that makes it 'human'. This paper will compare and contrast the above positions to arrive at behavioural definitions of symbolic usage that can be applied across species. It will then present new data on a fourth ape species Pan paniscus which is proving to be the first non-human species to acquire symbolic skills in a spontaneous manner.     

Ape behavior in two alternating environments: comparing exhibit and short‐term holding areas

In many facilities, primates are voluntarily transferred between different enclosures on a daily basis to facilitate animal husbandry and exhibit maintenance. This procedure is particularly relevant in the management of great apes living in zoos, where the requirements of functional management must be balanced with the desire to maintain enriching and naturalistic exhibit enclosures that benefit ape residents and attract the visiting public. In these settings, examinations of ape behavior and welfare typically focus exclusively on activity in the primary exhibit area. However, physical, social and sensory experiences unique to each area may shape different patterns of behavior. In the current study, zoo‐living chimpanzees and gorillas were moved each day from exhibit areas to off‐exhibit holding areas for a short duration as a part of regular management procedures. Behavioral data indicated species‐specific reactions to the holding area, including increased aggression and self‐directed behavior by chimpanzees and increased activity and prosocial behavior among gorilla subjects. Both species showed more feeding‐foraging behavior while in the exhibit enclosure. Results suggest that holding areas may not meet all behavior needs of captive great apes and demonstrate the importance of including all components of the captive enclosure in comprehensive analyses of great ape behavior and welfare. Am. J. Primatol. 72:951–959, 2010. © 2010 Wiley‐Liss, Inc.     

Young children spontaneously invent wild great apes’ tool-use behaviours

The variety and complexity of human-made tools are unique in the animal kingdom. Research investigating why human tool use is special has focused on the role of social learning: while non-human great apes acquire tool-use behaviours mostly by individual (re-)inventions, modern humans use imitation and teaching to accumulate innovations over time. However, little is known about tool-use behaviours that humans can invent individually, i.e. without cultural knowledge. We presented 2- to 3.5-year-old children with 12 problem-solving tasks based on tool-use behaviours shown by great apes. Spontaneous tool use was observed in 11 tasks. Additionally, tasks which occurred more frequently in wild great apes were also solved more frequently by human children. Our results demonstrate great similarity in the spontaneous tool-use abilities of human children and great apes, indicating that the physical cognition underlying tool use shows large overlaps across the great ape species. This suggests that humans are neither born with special physical cognition skills, nor that these skills have degraded due to our species’ long reliance of social learning in the tool-use domain.     

Rotator cuff muscle function and its relation to scapular morphology in apes

It is widely held that many differences among primate species in scapular morphology can be functionally related to differing demands on the shoulder associated with particular locomotor habits. This perspective is largely based on broad scale studies, while more narrow comparisons of scapular form often fail to follow predictions based on inferred differences in shoulder function. For example, the ratio of supraspinous fossa/infraspinous fossa size in apes is commonly viewed as an indicator of the importance of overhead use of the forelimb, yet paradoxically, the African apes, the most terrestrial of the great apes, have higher scapular fossa ratios than the more suspensory orangutan. The recent discovery of several nearly complete early hominin scapular specimens, and their apparent morphological affinities to scapulae of orangutans and gorillas rather than chimpanzees, has led to renewed interest in the comparative analysis of human and extant ape scapular form. To facilitate the functional interpretation of differences in ape scapulae, particularly in regard to relative scapular fossa size, we used electromyography (EMG) to document the activity patterns in all four rotator cuff muscles in orangutans and gibbons, comparing the results with previously published data for chimpanzees.     

The behavioral ecology of sympatric African apes: implications for understanding fossil hominoid ecology

The behavioral ecology of the great apes is key evidence used in the reconstruction of the behavior of extinct ape and hominid taxa. Chimpanzees and gorillas have been studied in detail in the wild, and some studies of their behavioral ecology in sympatry have also been been carried out. Although the two ape species have divergent behavior and ecology in important respects, recent studies have shown that the interspecific differences are not as stark as previously thought and subsequently urge new consideration of how they share forest resources when sympatric. These new data require re-examination of assumptions about key aspects of chimpanzee-gorilla ecological divergence, such as diet, ranging and nesting patterns, and the mating system. Diet is a key component of the species adaptive complexes that facilitates avoidance of direct competition from the other. While the nutritional basis for chimpanzee food choice remains unclear and no doubt varies from site to site, this species is a ripe fruit specialist and ranges farther during periods of ripe fruit scarcity. Gorillas in the same habitat also feed on ripe fruit when widely available, but fall back onto fibrous plant foods during lean periods. The inclusion of animal protein in the diet of the chimpanzees and its absence in that of the gorillas also distinguish the species ecologically. It may also offer clues to aspects of ecological divergence among early members of the hominid phylogeny. The paper concludes by suggesting likely characteristics of sympatric associations of Pliocene hominids, based on field data from extant sympatric apes.     

Pathology and diseases of great apes at the National Zoological Park

Knowledge of the diseases of great apes in captivity is essential for captive management of self-sustaining populations. This survey of medical and pathology records of orangutans, gorillas, and one chimpanzee at the National Zoological Park was conducted to provide a data base for improving health care of captive apes. Strongyloidiasis, balantidiasis, and entamoebiasis were recurrent problems in adult and juvenile apes of all species. Cardiac fibrosis also was prevalent in middle-aged apes and was a major cause of mortality. Bacterial infections were prevalent in perinatal orangutans and resulted in the death of two. For gorillas, rheumatoid arthritis associated with mycoplasma infections, and infertility were major problems. Because the pathogenesis of many of these lesions is unknown, survival of great ape populations in captivity may depend on future research on these problems.     

Ebola in great apes – current knowledge,possibilities for vaccination,and implications for conservation and human health

相似文献   

Welfare of apes in captive environments: comments on, and by, a specific group of apes

Accurately determining the proper captive environment for apes requires adequately assessing the psychological similarities between apes and humans. Scientists currently believe apes lack mental complexity (Millikan, 2006), raising questions concerning the evolution of human culture from ape-like societies (Tomasello, 1999). A long-term cultural study with bonobos suggests less intellectual divergence from humans than currently postulated (Savage-Rumbaugh, 2005). Because humans view apes as mentally limited, some current captive environments may appear idyllic while offering only an illusion of appropriate care, derived from a simplistic view of what apes are, rather than what they might be. This perception of apes determines their handling, which determines their mental development, which perpetuates the prevailing perception. Only breaking this cycle will allow the current perception of apes to change. Their usual captive environment limits any demonstration of culture. However, the bonobo study reveals what ape culture can become, which should affect future welfare considerations for at least those species genetically close to humans (bonobos and chimpanzees). Development of a languaged bonobo culture allows these nonhuman animals to provide their own responses regarding adequate ape welfare.     

A New Approach for Monitoring Ebolavirus in Wild Great Apes

Background

Central Africa is a “hotspot” for emerging infectious diseases (EIDs) of global and local importance, and a current outbreak of ebolavirus is affecting multiple countries simultaneously. Ebolavirus is suspected to have caused recent declines in resident great apes. While ebolavirus vaccines have been proposed as an intervention to protect apes, their effectiveness would be improved if we could diagnostically confirm Ebola virus disease (EVD) as the cause of die-offs, establish ebolavirus geographical distribution, identify immunologically naïve populations, and determine whether apes survive virus exposure.

Methodology/Principal findings

Here we report the first successful noninvasive detection of antibodies against Ebola virus (EBOV) from wild ape feces. Using this method, we have been able to identify gorillas with antibodies to EBOV with an overall prevalence rate reaching 10% on average, demonstrating that EBOV exposure or infection is not uniformly lethal in this species. Furthermore, evidence of antibodies was identified in gorillas thought previously to be unexposed to EBOV (protected from exposure by rivers as topological barriers of transmission).

Conclusions/Significance

Our new approach will contribute to a strategy to protect apes from future EBOV infections by early detection of increased incidence of exposure, by identifying immunologically naïve at-risk populations as potential targets for vaccination, and by providing a means to track vaccine efficacy if such intervention is deemed appropriate. Finally, since human EVD is linked to contact with infected wildlife carcasses, efforts aimed at identifying great ape outbreaks could have a profound impact on public health in local communities, where EBOV causes case-fatality rates of up to 88%.     

Lingual incisor traits in modern hominoids and an assessment of their utility for fossil hominoid taxonomy

The morphology of the anterior dentition has received scant attention for purposes of taxonomic discrimination. Recently, however, lingual incisor morphology was used in differentiating several Miocene ape species and genera. This paper assesses the utility of this morphology for taxonomic discrimination by examining the nature and patterns of variation in lingual incisor morphology in extensive samples of modern chimpanzees, gorillas, orangutans, and gibbons. This paper documents discrete morphological traits on the lingual side of incisors. Trait frequencies are used in univariate and multivariate analyses to examine the apportionment of variation in species, subspecies, and populations. A correlation between lingual incisor traits, tooth dimensions, and sex attempts to determine if such factors affect the manifestation of traits. Finally, the findings are applied to understanding patterns of variation in the Miocene hominids. The study demonstrates that: 1) lingual incisor morphology differs substantially between the hylobatids and great apes; 2) variation in incisor traits is high within species, and most of it is found within local populations; and 3) incisor traits do not correlate significantly with incisor dimensions or sex. Species and to some extent subspecies of extant hominoids can be differentiated statistically using lingual incisor traits, but the frequency of traits such as continuous or discontinuous cingulum, or the presence or absence of pillars, differentiates them. Given this pattern of variation, I argue that it is necessary to assume and document similar patterns of variation in Miocene apes before incisor morphology is used for differentiating taxa.     

The Risk of Disease to Great Apes: Simulating Disease Spread in Orang-Utan (Pongo pygmaeus wurmbii) and Chimpanzee (Pan troglodytes schweinfurthii) Association Networks

All great ape species are endangered, and infectious diseases are thought to pose a particular threat to their survival. As great ape species vary substantially in social organisation and gregariousness, there are likely to be differences in susceptibility to disease types and spread. Understanding the relation between social variables and disease is therefore crucial for implementing effective conservation measures. Here, we simulate the transmission of a range of diseases in a population of orang-utans in Sabangau Forest (Central Kalimantan) and a community of chimpanzees in Budongo Forest (Uganda), by systematically varying transmission likelihood and probability of subsequent recovery. Both species have fission-fusion social systems, but differ considerably in their level of gregariousness. We used long-term behavioural data to create networks of association patterns on which the spread of different diseases was simulated. We found that chimpanzees were generally far more susceptible to the spread of diseases than orang-utans. When simulating different diseases that varied widely in their probability of transmission and recovery, it was found that the chimpanzee community was widely and strongly affected, while in orang-utans even highly infectious diseases had limited spread. Furthermore, when comparing the observed association network with a mean-field network (equal contact probability between group members), we found no major difference in simulated disease spread, suggesting that patterns of social bonding in orang-utans are not an important determinant of susceptibility to disease. In chimpanzees, the predicted size of the epidemic was smaller on the actual association network than on the mean-field network, indicating that patterns of social bonding have important effects on susceptibility to disease. We conclude that social networks are a potentially powerful tool to model the risk of disease transmission in great apes, and that chimpanzees are particularly threatened by infectious disease outbreaks as a result of their social structure.     

Social learning in animals: comparative analysis of different forms and levels

Social learning as one of the key concepts of cognitive ecology includes different forms of behavioural displays from relatively simple, such as "social release" and "stimulus enhancement" up to "teaching" and "cultural transmission" in animal communities. Rapid development of this fields resulted in some contradictions in methods and terminology. In this review different forms and levels of social learning are analyzed. Ecological aspects of social learning are connected with diet shaping, fear of predators and mate choice. The first aspect is the most studied but still discussible. Social learning being an intricate component of feeding behaviour matches with innate behaviour, imprinting as well as early associative learning. Investigation of cognitive aspects of social learning going back to Thorndike's crucial question "Do apes ape?" are now developing into series of questions including even: "Do ants ape?". Elaboration of universal methods of comparative studying of social learning such as "artificial fruit" and "two ways/one outcome" has essentially enlightened these questions and made comparative analysis possible. Large continuum of displays of cognitive skills in social learning has been revealed in non-primate species. One of the discussible issues in the role of social learning is distribution of innovations. Many authors have investigated this intriguing aspect of animal behaviour in different ways, such as long field observations as well as laboratory experiments based on "artificial innovators" that is specimens specially taught by experimentalists. Many impressive results were obtained; in particular it turned out in contradiction with some mathematical models that individuals in groups are rather different in their psychophysiological predisposition to innovative behaviour. Role of teaching in such different forms of behaviour as shaping of species-specific behavioural patterns and spread of innovations is considered. Although the majority of animals in wild populations are not good teachers and pupils, some cultural aspects of behaviour were recently revealed, mostly in primates. At the same time some classical results concerning cultural transmission of new patterns (for example, bottle-opening in tits) were experimentally revised. Many problems still remain unsolved, in particular, how spread of innovations may favour prosperity of populations; to what degree behavioural peculiarities of local groups may be determined by processes of social learning; which internal and external factors and under what circumstances invest into social learning in natural environment.     

Clastogenic activity of sodium fluoride in great ape cells

Conflicting evidence has been reported concerning the mutagenicity of sodium fluoride (NaF), especially clastogenicity at concentrations of more than 1 mM. NaF is known to induce chromosome aberrations at these concentrations in human cells, but not in most rodent cells. We considered that such species-specific difference in chromosomal sensitivity would be derived from the phylogenetic distance between rodents and man. To clarify the role of interspecies differences, we investigated the chromosomal sensitivity to NaF in cell lines from various primates, which diverged into many species, including rodent-like prosimians and human-like great apes. The results showed that the clastogenicity of NaF was limited to human and great ape cells.