Even under majority influence, great apes fail to copy novel actions

It remains unclear when and why the ability to copy actions evolved and also its uniqueness to humans. Thus far, a lack of valid evidence for spontaneous action copying by other apes supports the view that only humans spontaneously copy actions. However, wild apes have access to multiple demonstrators and have been demonstrated to be affected by majority influences, thus raising the possibility that ape action copying might require a majority ratio of demonstrators to observers. We tested for spontaneous ape action copying across all four non-human great ape species using a demonstrator majority. Nineteen captive mother-reared apes (across 4 species) were tested (Raage=9-52; Mage=18.63; ♀=14; ♂=5). All failed to copy the demonstrated actions, despite observing it in a majority influence condition. We conclude that culture in non-human great apes is more likely supported by variants of social learning which regulate frequencies, rather than forms, of observed behaviours.

Comparable Number of Genes Having Experienced Positive Selection among Great Ape Species

Alleles that cause advantageous phenotypes with positive selection contribute to adaptive evolution. Investigations of positive selection in protein-coding genes rely on the accuracy of orthology, models, the quality of assemblies, and alignment. Here, based on the latest genome assemblies and gene annotations, we present a comparative analysis on positive selection in four great ape species and identify 211 high-confidence positively selected genes (PSGs). Even the differences in population size among these closely related great apes have resulted in differences in their ability to remove deleterious alleles and to adapt to changing environments, we found that they experienced comparable numbers of positive selection. We also uncovered that more than half of multigene families exhibited signals of positive selection, suggesting that imbalanced positive selection resulted in the functional divergence of duplicates. Moreover, at the expression level, although positive selection led to a more non-uniform pattern across tissues, the correlation between positive selection and expression patterns is diverse. Overall, this updated list of PSGs is of great significance for the further study of the phenotypic evolution in great apes.

Exploring the potential effect of COVID-19 on an endangered great ape

The current COVID-19 pandemic has created unmeasurable damages to society at a global level, from the irreplaceable loss of life, to the massive economic losses. In addition, the disease threatens further biodiversity loss. Due to their shared physiology with humans, primates, and particularly great apes, are susceptible to the disease. However, it is still uncertain how their populations would respond in case of infection. Here, we combine stochastic population and epidemiological models to simulate the range of potential effects of COVID-19 on the probability of extinction of mountain gorillas. We find that extinction is sharply driven by increases in the basic reproductive number and that the probability of extinction is greatly exacerbated if the immunity lasts less than 6 months. These results stress the need to limit exposure of the mountain gorilla population, the park personnel and visitors, as well as the potential of vaccination campaigns to extend the immunity duration.

Captivity and the co-diversification of great ape microbiomes

Wild great apes harbor clades of gut bacteria that are restricted to each host species. Previous research shows the evolutionary relationships among several host-restricted clades mirror those of great-ape species. However, processes such as geographic separation, host-shift speciation, and host-filtering based on diet or gut physiology can generate host-restricted bacterial clades and mimic patterns of co-diversification across host species. To gain insight into the distribution of host-restricted taxa, we examine captive great apes living under conditions where sharing of bacterial strains is readily possible. Here, we show that increased sampling of wild and captive apes identifies additional host-restricted lineages whose relationships are not concordant with the host phylogeny. Moreover, the gut microbiomes of captive apes converge through the displacement of strains that are restricted to their wild conspecifics by human-restricted strains. We demonstrate that host-restricted and co-diversifying bacterial strains in wild apes lack persistence and fidelity in captive environments.

Chimpanzee facial gestures and the implications for the evolution of language

Great ape manual gestures are described as communicative, flexible, intentional, and goal-oriented. These gestures are thought to be an evolutionary pre-cursor to human language. Conversely, facial expressions are thought to be inflexible, automatic, and derived from emotion. However, great apes can make a wide range of movements with their faces, and they may possess the control needed to gesture with their faces as well as their hands. We examined whether chimpanzee facial expressions possess the four important gesture properties and how they compare to manual gestures. To do this, we quantified variables that have been previously described through largely qualitative means. Chimpanzee facial expressions met all four gesture criteria and performed remarkably similar to manual gestures. Facial gestures have implications for the evolution of language. If other mammals also show facial gestures, then the gestural origins of language may be much older than the human/great ape lineage.

Great ape communication as contextual social inference: a computational modeling perspective

Human communication has been described as a contextual social inference process. Research into great ape communication has been inspired by this view to look for the evolutionary roots of the social, cognitive, and interactional processes involved in human communication. This approach has been highly productive, yet it is often compromised by a too-narrow focus on how great apes use and understand individual signals. In this paper, we introduce a computational model that formalizes great ape communication as a multi-faceted social inference process that relies on information contained in the signal, the relationship between communicative partners, and the social context. This model makes accurate qualitative and quantitative predictions about real-world communicative interactions between semi-wild-living chimpanzees. When enriched with a pragmatic reasoning process, the model explains repeatedly reported differences between humans and great apes in the interpretation of ambiguous signals (e.g. pointing gestures). This approach has direct implications for observational and experimental studies of great ape communication and provides a new tool for theorizing about the evolution of uniquely human communication.

Mitigating Impacts of the COVID-19 Pandemic on Gorilla Conservation: Lessons From Bwindi Impenetrable Forest, Uganda

The COVID-19 pandemic, affecting all countries, with millions of cases and deaths, and economic disruptions due to lockdowns, also threatens the health and conservation of endangered mountain gorillas. For example, increased poaching due to absence of tourism income, led to the killing on 1st June 2020 of a gorillaby a hungry community member hunting duiker and bush pigs. Conservation Through Public Health (CTPH), a grassroots NGO and non-profit founded in 2003 promotes biodiversity conservation by enabling people to co-exist with wildlife through integrated programs that improve animal health, community health, and livelihoods in and around Africa's protected areas and wildlife rich habitats. Through these programs, we have helped to mitigate these impacts. CTPH worked with Uganda Wildlife Authority and other NGOs to improve great ape viewing guidelines and prevent transmission of COVID-19 between people and gorillas. Park staff, Gorilla Guardians herding gorillas from community land to the park and Village Health and Conservation Teams were trained to put on protective face masks, enforce hand hygiene and a 10-meter great ape viewing distance. To reduce the communities' need to poach, CTPH found a UK-based distributor, for its Gorilla Conservation Coffee social enterprise enabling coffee farmers to earn revenue in the absence of tourism and provided fast growing seedlings to reduce hunger in vulnerable community members. Lessons learned show the need to support non-tourism dependent community livelihoods, and more responsible tourism to the great apes, which CTPH is advocating to governments, donors and tour companies through an Africa CSO Biodiversity Alliance policy brief.

Current Progress in Evolutionary Comparative Genomics of Great Apes

The availability of high-quality genome sequences of great ape species provides unprecedented opportunities for genomic analyses. Herein, we reviewed the recent progress in evolutionary comparative genomic studies of the existing great ape species, including human, chimpanzee, bonobo, gorilla, and orangutan. We elaborate discovery on evolutionary history, natural selection, structural variations, and new genes of these species, which is informative for understanding the origin of human-specific phenotypes.