Primate Diversity Research Articles

Evolutionary Insights from Dental Diversity in Afro-Asian Primates

Evolutionary Insights from Dental Diversity in Afro-Asian Primates

Taxonomy and systematics of the Neotropical primates: a review and update

The database of the IUCN SSC Primate Specialist Group currently (December 2023) registers 218 species and subspecies of Neotropical primates in 24 genera and five families. In the early 1960s, the diversity of Neotropical primates was estimated to be around 200 species and subspecies. From then, through the 1970s to the mid-1990s, however, the perception of the region’s primate diversity dropped, and reached an all-time low at 83 species and subspecies in 1980 (A World List of Mammalian Species, G. B. Corbet and J. E. Hill, British Museum (Natural History), Comstock Publishing, Cornell University Press, London and Ithaca). Interest in taxonomy and primate field research in the Neotropics was subdued up to the late 1970s. Change was sparked by the burgeoning capture of primates for biomedical research in the 1950s and 1960s, and the increasing destruction of the Amazon rainforests from the late 1970s. The numbers increased, at first slowly, but then, in 1995, they leapt back to the 200s in anticipation of a book by C. P. Groves (2001, Primate Taxonomy, Smithsonian Institution Press, Washington, DC). The species’ counts (not including subspecies) rose due to the adoption of the Phylogenetic Species Concept over the Biological Species Concept, the former favoring the category of species over subspecies. In this article, we discuss the changes in species and subspecies numbers in the classification of the Neotropical primates, and report on the taxonomic changes resulting from taxonomic research ongoing since 2012. We emphasize the importance of taxonomic research for an understanding of the diversity of primates, and for conservation planning, not least in identifying the populations that are threatened.

Multidimensional primate niche space sheds light on interspecific competition in primate evolution

Characterising how the totality of primate diversity is distributed across the order, and how it evolved, is challenging because diversity in individual traits often show opposing phylogenetic patterns. A species’ combination of traits can be conceptualised as its ‘niche’. Here, we describe and analyse seven-dimensional niche space, comprising 11 traits, for 191 primate species. Multifaceted diversity is distributed unequally among taxonomic groups. Cercopithecoidea and Hominidae occupy the largest areas of niche space, and are the most diverse families; platyrrhine families occupy small areas, and this space overlaps with strepsirrhines. The evolution of species’ locations in niche space is regulated by selection for adaptive optima in trait combinations. Given that niche similarity results in interspecific competition, we quantify two measures of species’ niche locations relative to others. We find that omnivores, frugivores, and species tolerating higher temperatures experience stronger interspecific competition. Hominidae occupation of niche space suggests competitive exclusion from niches by Cercopithecoidea over evolutionary time; but living great apes experience the lowest levels of interspecific competition. Callitrichids experience the highest levels of interspecific competition. Our results provide a standardised measure of primate niches that sheds light on the partitioning and evolution of primate diversity, and how this is driven by interspecific competition.

Fruit–frugivore dependencies are important in Ebolavirus outbreaks in Sub‐Saharan Africa

Ebolaviruses have the ability to infect a wide variety of species, with many African mammals potentially serving either as primary reservoirs or secondary amplifying hosts. Previous work has shown that frugivorous bats and primates are often associated with spillover and outbreaks. Yet the role that patterns of biodiversity, either of mammalian hosts or of common fruiting species such as Ficus (figs, fruit resources used by a wide variety of species), play in driving outbreak risk remains unclear. We investigated what factors most directly influence Ebolavirus outbreak risk in Sub‐Saharan Africa by using a phylogenetically informed path analysis to compare a wide array of potential models (path diagrams) of spatial dynamics. We considered mammalian frugivore richness, cercopithecid and hominid primate richness, richness of pteropodid (fruit) bats, the spatial distribution of species that have tested positive for Ebolavirus antibodies in the wild, Ficus habitat suitability, and environmental conditions (mean annual and variability in temperature and rainfall). The proximate factors that most influenced whether a given host species range contained a site of a previous outbreak event were 1) habitat suitability for Ficus and 2) the diversity of cercopithecid primates. Frugivore richness overall (including bats, primates, and a few other mammals) and the richness of bats in the family Pteropodidae had a strong effect on which species tested positive for Ebolavirus antibodies, but did not influence outbreak risk directly in pathways explored. We interpret this as evidence that foraging around Ficus and frugivorous mammals (such as cercopithecid primates which are commonly hunted for food) play a prominent role in driving outbreaks into human communities, relative to other factors we considered which influence outbreak risk more indirectly.

Zoonotic pathogens in wild Asian primates: a systematic review highlighting research gaps.

Ongoing global changes, including natural land conversion for agriculture and urbanization, modify the dynamics of human-primate contacts, resulting in increased zoonotic risks. Although Asia shelters high primate diversity and experiences rapid expansion of human-primate contact zones, there remains little documentation regarding zoonotic surveillance in the primates of this region. Using the PRISMA guidelines, we conducted a systematic review to compile an inventory of zoonotic pathogens detected in wild Asian primates, while highlighting the coverage of primate species, countries, and pathogen groups surveyed, as well as the diagnostic methods used across the studies. Moreover, we compared the species richness of pathogens harbored by primates across diverse types of habitats classified according to their degree of anthropization (i.e., urban vs. rural vs. forest habitats). Searches of Scopus, PubMed, and the Global Mammal Parasite Database yielded 152 articles on 39 primate species. We inventoried 183 pathogens, including 63 helminthic gastrointestinal parasites, two blood-borne parasites, 42 protozoa, 45 viruses, 30 bacteria, and one fungus. Considering each study as a sample, species accumulation curves revealed no significant differences in specific richness between habitat types for any of the pathogen groups analyzed. This is likely due to the insufficient sampling effort (i.e., a limited number of studies), which prevents drawing conclusive findings. This systematic review identified several publication biases, particularly the uneven representation of host species and pathogen groups studied, as well as a lack of use of generic diagnostic methods. Addressing these gaps necessitates a multidisciplinary strategy framed in a One Health approach, which may facilitate a broader inventory of pathogens and ultimately limit the risk of cross-species transmission at the human-primate interface. Strengthening the zoonotic surveillance in primates of this region could be realized notably through the application of more comprehensive diagnostic techniques such as broad-spectrum analyses without a priori selection.

Human activity and climate change accelerate the extinction risk to non-human primates in China.

Human activity and climate change affect biodiversity and cause species range shifts, contractions, and expansions. Globally, human activities and climate change have emerged as persistent threats to biodiversity, leading to approximately 68% of the ~522 primate species being threatened with extinction. Here, we used habitat suitability models and integrated data on human population density, gross domestic product (GDP), road construction, the normalized difference vegetation index (NDVI), the location of protected areas (PAs), and climate change to predict potential changes in the distributional range and richness of 26 China's primate species. Our results indicate that both PAs and NDVI have a positive impact on primate distributions. With increasing anthropogenic pressure, species' ranges were restricted to areas of high vegetation cover and in PAs surrounded by buffer zones of 2.7-4.5 km and a core area of PAs at least 0.1-0.5 km from the closest edge of the PA. Areas with a GDP below the Chinese national average of 100,000 yuan were found to be ecologically vulnerable, and this had a negative impact on primate distributions. Changes in temperature and precipitation were also significant contributors to a reduction in the range of primate species. Under the expected influence of climate change over the next 30-50 years, we found that highly suitable habitat for primates will continue to decrease and species will be restricted to smaller and more peripheral parts of their current range. Areas of high primate diversity are expected to lose from 3 to 7 species. We recommend that immediate action be taken, including expanding China's National Park Program, the Ecological Conservation Redline Program, and the Natural Forest Protection Program, along with a stronger national policy promoting alternative/sustainable livelihoods for people in the local communities adjacent to primate ranges, to offset the detrimental effects of anthropogenic activities and climate change on primate survivorship.

Preliminary Assessment on Primate Diversity and Potential of PrimaTourism Among Local People and Orang Asli Jakun (Aborigines: Proto-Malay) in Tasik Chini Biosphere Reserve, Pahang, Malaysia

PrimaTourismis a well-known aspect of nature tourism that provides valuable benefits for the primate species conservation. Malaysia, with its rich diversity of more than 25 primate species inhabited in the country, holds significant potential for enhancing primate-based tourism. However, the information on primate species in potential tourism spots like Tasik Chini remains limited, with only a few data on their behaviour and ecology. Additionally, the lack of comprehensive information on the primate species poses challenges in identifying potential PrimaTourismproduct. Thus, this study aimed to assess primate diversity and explore the perception of PrimaTourism among local people in Tasik Chini. A survey and interview session were conducted over five days in two villages around Tasik Chini (Kampung Gumum and Felda Chini), involving a total of 32 respondents. Most respondents reported the presence of two common primate species in their area: the long-tailed macaque (Macaca fascicularis) and the pig-tailed macaque (Macaca nemestrina). The result suggested a significant majority (81%) of respondents expressed support for the dusky leaf monkey (Trachypithecus obscurus) as an ideal primate species for PrimaTourism in Tasik Chini, citing its attractive coloration and favoring the development of primate-based tourism. Overall, these findings can serve as essential baseline data for implementing primate tourism in the area, engaging the local community to attract tourists to Tasik Chini effectively and eventually serve as a conservation tool for the primate species.

Alu RNA fold links splicing with signal recognition particle proteins.

Transcriptomic diversity in primates was considerably expanded by exonizations of intronic Alu elements. To better understand their cellular mechanisms we have used structure-based mutagenesis coupled with functional and proteomic assays to study the impact of successive primate mutations and their combinations on inclusion of a sense-oriented AluJ exon in the human F8 gene. We show that the splicing outcome was better predicted by consecutive RNA conformation changes than by computationally derived splicing regulatory motifs. We also demonstrate an involvement of SRP9/14 (signal recognition particle) heterodimer in splicing regulation of Alu-derived exons. Nucleotide substitutions that accumulated during primate evolution relaxed the conserved left-arm AluJ structure including helix H1 and reduced the capacity of SRP9/14 to stabilize the closed Alu conformation. RNA secondary structure-constrained mutations that promoted open Y-shaped conformations of the Alu made the Alu exon inclusion reliant on DHX9. Finally, we identified additional SRP9/14 sensitive Alu exons and predicted their functional roles in the cell. Together, these results provide unique insights into architectural elements required for sense Alu exonization, identify conserved pre-mRNA structures involved in exon selection and point to a possible chaperone activity of SRP9/14 outside the mammalian signal recognition particle.

Phylogenomic analyses provide insights into primate evolution.

Comparative analysis of primate genomes within a phylogenetic context is essential for understanding the evolution of human genetic architecture and primate diversity. We present such a study of 50 primate species spanning 38 genera and 14 families, including 27 genomes first reported here, with many from previously less well represented groups, the New World monkeys and the Strepsirrhini. Our analyses reveal heterogeneous rates of genomic rearrangement and gene evolution across primate lineages. Thousands of genes under positive selection in different lineages play roles in the nervous, skeletal, and digestive systems and may have contributed to primate innovations and adaptations. Our study reveals that many key genomic innovations occurred in the Simiiformes ancestral node and may have had an impact on the adaptive radiation of the Simiiformes and human evolution.

A reassessment of the distinctiveness of dryopithecine genera from the Iberian Miocene based on enamel-dentine junction geometric morphometric analyses.

A vast diversity of catarrhines primates has been uncovered in the Middle to Late Miocene (12.5-9.6Ma) of the Vallès-Penedès Basin (northeastern Spain), including several hominid species (Pierolapithecus catalaunicus, Anoiapithecus brevirostris, Dryopithecus fontani, Hispanopithecus laietanus, and Hispanopithecus crusafonti) plus some remains attributed to 'Sivapithecus' occidentalis (of uncertain taxonomic validity). However, Pierolapithecus and Anoiapithecus have also been considered junior synonyms of Dryopithecus by some authors, which entail a lower generic diversity and an inflated intrageneric variation of the latter genus. Since the distinction of these taxa partly relies on dental features, the detailed and quantitative analysis of tooth shape might help disentangling the taxonomic diversity of these Miocene hominids. Using diffeomorphic surface matching and three-dimensional geometric morphometrics, we investigate the enamel-dentine junction shape (which is a reliable taxonomic proxy) of these Miocene hominids, with the aim of investigating their degree of intra- and intergeneric variation compared with that of extant great ape genera. We conducted statistical analyses, including between-group principal component analyses, canonical variate analyses, and permutation tests, to investigate whether the individual and combined (i.e., Dryopithecus s.l.) variation of the extinct genera exceeds that of the extant great apes. Our results indicate that Pierolapithecus, Anoiapithecus, Dryopithecus, and Hispanopithecus show morphological differences of enamel-dentine junction shape relative to the extant great apes that are consistent with their attribution to different genera. Specifically, the variation displayed by the Middle Miocene taxa combined exceeds that of extant great ape genera, thus undermining the single-genus hypothesis. 'Sivapithecus' occidentalis specimens fall close to Dryopithecus but in the absence of well-preserved comparable teeth for Pierolapithecus and Anoiapithecus, their taxonomic attribution remains uncertain. Among the Hispanopithecus sample, IPS1802 from Can Llobateres stands out and might either be an outlier in terms of morphology, or represent another dryopithecine taxon.

Exploring the Relationship between Spontaneous Sister Chromatid Exchange and Genome Instability in Two Cryptic Species of Non-Human Primates.

There are extensive studies on chromosome morphology and karyotype diversity in primates, yet we still lack insight into genomic instability as a key factor underlying the enormous interspecies chromosomal variability and its potential contribution to evolutionary dynamics. In this sense, the assessment of spontaneous sister chromatid exchange (SCE) frequencies represents a powerful tool for evaluating genome stability. Here, we employed G-banding, fluorescence plus Giemsa (FPG), and chromosome orientation fluorescence in situ hybridization (CO-FISH) methodologies to characterize both chromosome-specific frequencies of spontaneously occurring SCE throughout the genome (G-SCE) and telomere-specific SCE (T-SCE). We analyzed primary fibroblast cultures from two male species of Ateles living in captivity: Ateles paniscus (APA) and Ateles chamek (ACH). High frequencies of G-SCEs were observed in both species. Interestingly, G-SCEs clustered on evolutionary relevant chromosome pairs: ACH chromosomes 1, 2, 3, 4, and 7, and APA chromosomes 1, 2, 3, 4/12, 7, and 10. Furthermore, a statistically significant difference between the observed and expected G-SCE frequencies, not correlated with chromosome size, was also detected. CO-FISH analyses revealed the presence of telomere-specific recombination events in both species, which included T-SCE, as well as interstitial telomere signals and telomere duplications, with APA chromosomes displaying higher frequencies, compared to ACH. Our analyses support the hypothesis that regions of Ateles chromosomes susceptible to recombination events are fragile sites and evolutionary hot spots. Thus, we propose SCE analyses as a valuable indicator of genome instability in non-human primates.

The Australopithecus assemblage from Sterkfontein Member 4 (South Africa) and the concept of variation in palaeontology.

Interpreting morphological variation within the early hominin fossil record is particularly challenging. Apart from the fact that there is no absolute threshold for defining species boundaries in palaeontology, the degree of variation related to sexual dimorphism, temporal depth, geographic variation or ontogeny is difficult to appreciate in a fossil taxon mainly represented by fragmentary specimens, and such variation could easily be conflated with taxonomic diversity. One of the most emblematic examples in paleoanthropology is the Australopithecus assemblage from the Sterkfontein Caves in South Africa. Whereas some studies support the presence of multiple Australopithecus species at Sterkfontein, others explore alternative hypotheses to explain the morphological variation within the hominin assemblage. In this review, I briefly summarize the ongoing debates surrounding the interpretation of morphological variation at Sterkfontein Member 4 before exploring two promising avenues that would deserve specific attention in the future, that is, temporal depth and nonhuman primate diversity.

Taxonomic review of Saguinus mystax (Spix, 1823) (Primates, Callitrichidae), and description of a new species.

Although the Amazon has the greatest diversity of primates, there are still taxonomic uncertainties for many taxa, such as the species of the Saguinus mystax group. The most geographically broadly distributed and phenotypically diverse species in this group is S. mystax, and its phenotypic diversity has been recognized as three subspecies-S. mystax mystax, S. mystax pileatus and S. mystax pluto-with non-overlapping geographic distributions. In this sense, we carried out an extensive field survey in their distribution areas and used a framework of taxonomic hypothesis testing of genomic data combined with an integrative taxonomic decision-making framework to carry out a taxonomic revision of S. mystax. Our tests supported the existence of three lineages/species. The first species corresponds to Saguinus mystax mystax from the left bank of the Juruá River, which was raised to the species level, and we also discovered and described animals from the Juruá-Tefé interfluve previously attributed to S. mystax mystax as a new species. The subspecies S. m. pileatus and S. m. pluto are recognized as a single species, under a new nomenclatural combination. However, given their phenotypic distinction and allopatric distribution, they potentially are a manifestation of an early stage of speciation, and therefore we maintain their subspecific designations.

First Molecular Identification of Trypanosomes and Absence of Babesia sp. DNA in Faeces of Non-Human Primates in the Ecuadorian Amazon.

Trypanosomes are a group of pathogens distributed in the continents of Africa, America, Asia and Europe, and they affect all vertebrates including the neotropical primate group. Information about the trypanosome's diversity, phylogeny, ecology and pathology in non-human primates (NHPs) from the neotropical region is scarce. The objective of the study was to identify Trypanosoma and Babesia molecularly in NHPs under the phylogenetic species concept. We extracted DNA from a total of 76 faecal samples collected between 2019 and 2021, from a total of 11 non-human primate species of which 46 are from captive NHPs and 30 are free-living NHPs in the Western Amazon region of Ecuador. We did not detect DNA of Babesia sp. by polymerase chain reaction test in any of the faecal samples. However, the nested-PCR-based method revealed Trypanosoma parasites by ITS gene amplification in two faecal samples; one for the species Leontocebus lagonotus (from the captive population) and a second one for Cebus albifrons (from the free-ranging population). Maximum parsimony and likelihood methods with the Kimura2+G+I model inferred the evolutionary history of the two records, which showed an evolutionary relationship with the genus Trypanosoma. Two sequences are monophyletic with Trypanosoma. However, the number of sequences available in GenBank for their species identification is limited. The two samples present different molecular identifications and evolutionary origins in the tree topology. We are most likely referring to two different species, and two different localities of infection. We suggest that health management protocols should be implemented to prevent the transmission of blood-borne pathogens such as Trypanosoma sp. among captive populations. In addition, these protocols also protect the personnel of wildlife rehabilitation centers working in close proximity to NHPs and vice versa.

Human Retrotransposons and Effective Computational Detection Methods for Next-Generation Sequencing Data.

Transposable elements (TEs) are classified into two classes according to their mobilization mechanism. Compared to DNA transposons that move by the “cut and paste” mechanism, retrotransposons mobilize via the “copy and paste” method. They have been an essential research topic because some of the active elements, such as Long interspersed element 1 (LINE-1), Alu, and SVA elements, have contributed to the genetic diversity of primates beyond humans. In addition, they can cause genetic disorders by altering gene expression and generating structural variations (SVs). The development and rapid technological advances in next-generation sequencing (NGS) have led to new perspectives on detecting retrotransposon-mediated SVs, especially insertions. Moreover, various computational methods have been developed based on NGS data to precisely detect the insertions and deletions in the human genome. Therefore, this review discusses details about the recently studied and utilized NGS technologies and the effective computational approaches for discovering retrotransposons through it. The final part covers a diverse range of computational methods for detecting retrotransposon insertions with human NGS data. This review will give researchers insights into understanding the TEs and how to investigate them and find connections with research interests.

Variation in population density of the Andean night monkey (Aotus lemurinus) in areas with different landscape characteristics

In the Colombian Andes, most of the populations of Andean night monkeys (Aotus lemurinus) are found in fragmented landscapes due to the predominant changes in land use in the region. Thus, forest fragments differ in shape, size, degree of isolation, and availability of resources. These factors have had a differential effect on the ecology and permanence of their populations. In order to determine the effect of fragmentation on A. lemurinus, we estimated its population density in a protected area of 489 ha of sub-Andean forest - at Otún Quimbaya Wildlife Sanctuary- which is structurally connected with other protected areas; then, we compared it with another study carried out in the unprotected Sub-andean forest fragments (900 ha) of Dapa, at the Valle del Cauca department. To estimate its density, the distance sampling method was used with 31 linear transects, and the data were analyzed with the software Distance. Landscape metrics was estimate with patch analyses tools with a Corine Land Cover information 1:100,000 scale. The plant structure and diversity were measurement with transects to 50 x 4 m and taking account the trees with diameter at breast height over 10 cm. We use average comparison to evaluate the similarities between patrons of the population density and explanatory variables. A population density of 39 ind/km2 was found in our study, which is lower than the 113 ind/km2 found in the Dapa. This relation was similar to relations of mean shape index, mean patch size and mean diameter at breast height, and inverse with the relations of proportion of the forest in the area, weighted cover index, plant diversity and density of trees. It is likely that the protected area, by being connected and having a greater diversity of primates and trees, allows this population not to suffer from a crowding phenomenon, and that the population does not increase it carrying capacity due to the low presence of competing species, conversely to what could be occurring in the unprotected fragments. Conversely, high density in Dapa could be reflect a system depletion in diversity and ecological processes.

Distribution and diversity of primates and threats to their survival in the Awi Zone, northwestern Ethiopia.

Habitat loss and fragmentation affect the diversity and distribution of primates in a human-modified landscape. Ethiopia has a high diversity of primates, but increasing human pressure has negatively impacted their distribution and abundance across the country, primarily due to deforestation. To date, the diversity and distribution of primate species are poorly known in northwestern Ethiopia. From October 2020 until September 2021, we assessed the diversity and distribution of primate species in 26 forest patches in the Awi Zone, Northwestern Ethiopiausing line transect surveys, and weexamined the potential conservation threats to thesurvival of these taxa. Across transects, we encountered 459 groups of four primate taxa: olive baboons (Papio anubis), grivet monkeys (Chlorocebus aethiops), Boutourlini's blue monkeys (Cercopithecus mitis boutourlinii), and black-and-white colobus monkeys (Colobus guereza spp. guereza). The latter two are endemic to Ethiopia. We observed black-and-white colobus monkeys in all surveyed forest patches, while we observed Boutourlini's blue monkeys in 18 patches. Black-and-white colobus monkeys were the most frequently observed (n = 325 sighting; relative encounter frequency = 70.8%), while grivet monkeys (Chlorocebus aethiops) were the least (n = 34 sighting; relative encounter frequency = 7.4%) in the region. Similarly, the relative encounter frequency of olive baboons was 9.2% (n = 42 sighting).The overall mean group size for each species was: Boutourlini's blue monkeys (26.1 individuals), black-and-white colobus monkeys (8.8 individuals), grivet monkeys (34.1 individuals), and olive baboons (41.4 individuals). We identified agricultural expansions, exotic tree plantations, deforestations, firewood collections, livestock grazing, and killings over their crop-feeding behaviors as the main threats to primates and their habitats in the region. This study provides crucial information on an area likely to support primate speciesthat we know very little about. Assigning protected connecting forest patches should be an urgent priority for the conservation of the primates in this region.

Convergent and Divergent Age Patterning of Gut Microbiota Diversity in Humans and Nonhuman Primates.

ABSTRACTThe gut microbiome has significant effects on healthy aging and aging-related diseases, whether in humans or nonhuman primates. However, little is known about the divergence and convergence of gut microbial diversity between humans and nonhuman primates during aging, which limits their applicability for studying the gut microbiome’s role in human health and aging. Here, we performed 16S rRNA gene sequencing analysis for captive rhesus macaques (Macaca mulatta) and compared this data set with other freely available gut microbial data sets containing four human populations (Chinese, Japanese, Italian, and British) and two nonhuman primates (wild lemurs [Lemur catta] and wild chimpanzees [Pan troglodytes]). Based on the consistent V4 region of the 16S rRNA gene, beta diversity analysis suggested significantly separated gut microbial communities associated with host backgrounds of seven host groups, but within each group, significant gut microbial divergences were observed, and indicator bacterial genera were identified as associated with aging. We further discovered six common anti-inflammatory gut bacteria (Prevotellamassilia, Prevotella, Gemmiger, Coprococcus, Faecalibacterium, and Roseburia) that had butyrate-producing potentials suggested by pangenomic analysis and that showed similar dynamic changes in at least two selected host groups during aging, independent of distinct host backgrounds. Finally, we found striking age-related changes in 66 plasma metabolites in macaques. Two highly changed metabolites, hydroxyproline and leucine, enriched in adult macaques were significantly and positively correlated with Prevotella and Prevotellamassilia. Furthermore, genus-level pangenome analysis suggested that those six common indicator bacteria can synthesize leucine and arginine as hydroxyproline and proline precursors in both humans and macaques.IMPORTANCE This study provides the first comprehensive investigation of age patterning of gut microbiota of four human populations and three nonhuman primates and found that Prevotellamassilia, Prevotella, Gemmiger, Coprococcus, Faecalibacterium, and Roseburia may be common antiaging microbial markers in both humans and nonhuman primates due to their potential metabolic capabilities for host health benefits. Our results also provide key support for using macaques as animal models in studies of the gut microbiome’s role during human aging.

Understanding dietary ecology in great apes from dental macrowear analysis

ObjectivesDietary diversity in primates is reflected in their dental morphology, with differences in size and shape of teeth. The objective of this study is to investigate the relationship between molar morphology and macrowear patterns in Pongo, Gorilla, and Pan to obtain dietary information.MethodsWe have examined 68 second lower molars using the Occlusal Fingerprint Analysis method including 18 chimpanzees, 28 gorillas, and 22 orangutans. We selected only molars from wildshot specimens characterized by a moderate degree of wear. High‐resolution digital models of teeth were created using a white scanning light system with a resolution of 45 μm.ResultsThe macrowear patterns of Pan were significantly different from those of Gorilla and of Pongo, differences that are mostly due to shearing wear. Gorilla and Pongo macrowear patterns are dominated by phase II areas, followed by lingual phase I facets, while in Pan we observe a significant increase in buccal phase I facets. The latter group also displays the highest macrowear variation across the sample examined in this study.ConclusionsThe molar macrowear patterns of the great apes analyzed in this study did not confirm our initial hypothesis of finding larger crushing and grinding areas in Pongo and more shearing wear in Gorilla. Pan shows the most variable macrowear, which is probably associated with their more flexible diet. The similarity between Pongo and Gorilla macrowear patterns may be due to a larger intake of mechanically challenging foods that could obfuscate dietary wear signals generated by softer foods.

What can monkey fossils tell us about early human evolution? New insights from the analysis of molar cusp proportions in fossil cercopithecoids from Laetoli, Tanzania

IntroductionLaetoli, Tanzania preserves the earliest fossils attributed to Australopithecus afarensis (3.7 mya). A diversity of non‐human primates including cercopithecoid monkeys have also been recovered. Cercopithecoids provide valuable insights into the paleoenvironments they shared with early humans and, by extension, early hominin paleobiology. Although cercopithecoid fossils at Laetoli represent both more omnivorous cercopihecines and more folivorous and arboreal colobines, the former is more abundant. The diversity and proportion of cercopithecoids figures prominently in debate over the prevalence of closed woodland/forested environments vs more open scrub/bushland. This study uses dental morphometrics to establish the morphological affinity of molar crowns from additional cercopithecoid craniodental fossils recovered from Laetoli localities 1, 2, 6 and 7 to clarify the paleoenvironmental context of our early human ancestors.MethodsStandard linear metric data (mesiodistal length, buccolingual breadth) were collected using dental calipers and total occlusal and individual cusp areas (mm2) were obtained for all molar crowns in an extant cercopithecoid sample (n=90; 18 genera) using high‐resolution 2D images and ImageJ. These data are a comparative baseline for a fossil cercopithecoid sample including a complete (LP) mandible (M1‐M3), maxillary fragment (M1‐M3) and four isolated maxillary molars (n=3 M1’s, n=1 M2). Discriminant function analysis (DFA) using subfamily (n=2 groups) and tribe (n=5 groups) was used to predict group membership and morphological affinity of the fossil sample.ResultsDFA results indicate that predictive accuracy is highest when subfamily is used as the grouping variable and ranges from 62.8% (M3) to 87.2% (M2). Mandibular molars more reliably segregate subfamilies (77.1% ‐ 87.2%) than do maxillary molars (64.4% ‐ 70.2%). The associated mandibular molars group are most closely associated with African colobines. All maxillary specimens cluster with cercopithecines and, more specifically, the papioni. Colobines have expanded hypoconids and metacones but reduced metaconids, entoconids and paracones relative to cercopithecoids.ConclusionMolar cusp proportions discriminate colobines from cercopithecines. This study provides additional evidence for the continued presence of both groups in the upper beds at Laetoli and confirms that the complete LP mandible is most closely aligned with the Colobinae.The presence of a large colobine is consistent with palaeoecological reconstructions supporting the significant presence of closed woodland/forested habitats.SignificanceDespite obligate bipedalism, early hominins retain numerous upper limb and torso adaptations consistent with the use of arboreal substrates. The continued presence of colobines at Laetoli confirms the presence of closed woodland/forested environments and suggests that Au. afarensis at Laetoli may have potentially exploited a variety of habitats including arboreal substrates.