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Integrative Psychological & Behavioral... Mar 2022A perennial challenge of evolutionary psychology is explaining prosocial traits such as a preference for fairness rather than inequality, compassion towards suffering,...
A perennial challenge of evolutionary psychology is explaining prosocial traits such as a preference for fairness rather than inequality, compassion towards suffering, and an instinctive ability to coordinate within small teams. Considering recent fossil evidence and a novel logical test, we deem present explanations insufficiently explanatory of the divergence of hominins. In answering this question, we focus on the divergence of hominins from the last common ancestor (LCA) shared with Pan. We consider recent fossil discoveries that indicate the LCA was bipedal, which reduces the cogency of this explanation for hominin development. We also review evolutionary theory that claims to explain how hominins developed into modern humans, however it is found that no mechanism differentiates hominins from other primates. Either the mechanism was available to the last common ancestor (LCA) (with P. troglodytes as its proxy), or because early hominins had insufficient cognition to utilise the mechanism. A novel mechanism, sub-group level selection (sGLS) is hypothesised by triangulating two pieces of data rarely considered by evolutionary biologists. These are behavioural dimorphism of Pan (chimpanzees and bonobos) that remain identifiable in modern humans, and the social behaviour of primate troops in a savannah ecology. We then contend that sGLS supplied an exponential effect which was available to LCA who left the forest, but was not sufficiently available to any other primates. In conclusion, while only indirectly supported by various evidence, sGLS is found to be singularly and persuasively explanatory of human's unique evolutionary story.
Topics: Animals; Biological Evolution; Fossils; Hominidae; Humans; Pan troglodytes; Social Behavior
PubMed: 33893612
DOI: 10.1007/s12124-021-09606-y -
Journal of Human Evolution Oct 2022Previous research has suggested that magnitudes of integration may be distinct in the postcranium of hominoids when compared to other primate species. To test this...
Previous research has suggested that magnitudes of integration may be distinct in the postcranium of hominoids when compared to other primate species. To test this hypothesis, we estimated and compared magnitudes of integration of eight postcranial bones from three-dimensional surface scans for 57 Hylobates lar, 58 Gorilla gorilla, 60 Pan troglodytes, 60 Homo sapiens, 60 Chlorocebus pygerythrus, and 60 Macaca fascicularis. We tested the hypotheses that 1) magnitudes of integration would be distinct in the postcranium of hominoids compared to cercopithecoids, with the explicit prediction that magnitudes of integration would be lower in hominoids than in cercopithecoids, and 2) girdle elements (scapula, os coxa) would have lower magnitudes of integration across all taxa. Integration was quantified using the integration coefficient of variation from interlandmark distances reflecting anatomical and developmental modules defined according to a priori criteria. A resampling protocol was employed to generate distributions of integration values that were then compared statistically using Mann-Whitney U tests with Bonferroni adjustment. Support for hypothesis 1 was mixed: with the exception of Gorilla, hominoid taxa were less integrated than the cercopithecoids for all anatomical modules. However, Homo, Gorilla, and, to a lesser extent, Pan showed higher integration than Hylobates and the cercopithecoids for homologous limb elements, with magnitudes of integration for both modules being lowest for Hylobates. These results generally support the hypothesis of distinct patterns of magnitudes of integration in the hominoid postcranium. The high integration of Gorilla may be explained by the effects of overall body size. The results supported the predictions of the second hypothesis. Regardless of taxon, the os coxa and scapula were generally the least integrated skeletal elements, while the femur and radius were the most integrated. The lower integration of the girdle elements suggests that the geometric complexities of particular elements may significantly influence study outcomes.
Topics: Animals; Chlorocebus aethiops; Gorilla gorilla; Hominidae; Hylobates; Pan troglodytes; Primates; Scapula
PubMed: 36095909
DOI: 10.1016/j.jhevol.2022.103239 -
Primates; Journal of Primatology May 2021
Topics: Animals; Pan troglodytes
PubMed: 33835330
DOI: 10.1007/s10329-021-00903-z -
Philosophical Transactions of the Royal... Aug 2023Reproductive inequality, or reproductive skew, drives natural selection, but has been difficult to assess, particularly for males in species with promiscuous mating and... (Review)
Review
Reproductive inequality, or reproductive skew, drives natural selection, but has been difficult to assess, particularly for males in species with promiscuous mating and slow life histories, such as bonobos () and chimpanzees (). Although bonobos are often portrayed as more egalitarian than chimpanzees, genetic studies have found high male reproductive skew in bonobos. Here, we discuss mechanisms likely to affect male reproductive skew in , then re-examine skew patterns using paternity data from published work and new data from the Kokolopori Bonobo Reserve, Democratic Republic of Congo and Gombe National Park, Tanzania. Using the multinomial index (), we found considerable overlap in skew between the species, but the highest skew occurred among bonobos. Additionally, for two of three bonobo communities, but no chimpanzee communities, the highest ranking male had greater siring success than predicted by priority-of-access. Thus, an expanded dataset covering a broader demographic range confirms that bonobos have high male reproductive skew. Detailed comparison of data from highlights that reproductive skew models should consider male-male dynamics including the effect of between-group competition on incentives for reproductive concessions, but also female grouping patterns and factors related to male-female dynamics including the expression of female choice. This article is part of the theme issue 'Evolutionary ecology of inequality'.
Topics: Female; Male; Animals; Pan paniscus; Pan troglodytes; Biological Evolution; Cell Communication; Congo
PubMed: 37381849
DOI: 10.1098/rstb.2022.0301 -
American Journal of Primatology Jan 2023Infectious disease is a major concern for both wild and captive primate populations. Primate sanctuaries in Africa provide critical protection to thousands of wild-born,...
Infectious disease is a major concern for both wild and captive primate populations. Primate sanctuaries in Africa provide critical protection to thousands of wild-born, orphan primates confiscated from the bushmeat and pet trades. However, uncertainty about the infectious agents these individuals potentially harbor has important implications for their individual care and long-term conservation strategies. We used metagenomic next-generation sequencing to identify viruses in blood samples from chimpanzees (Pan troglodytes) in three sanctuaries in West, Central, and East Africa. Our goal was to evaluate whether viruses of human origin or other "atypical" or unknown viruses might infect these chimpanzees. We identified viruses from eight families: Anelloviridae, Flaviviridae, Genomoviridae, Hepadnaviridae, Parvoviridae, Picobirnaviridae, Picornaviridae, and Rhabdoviridae. The majority (15/26) of viruses identified were members of the family Anelloviridae and represent the genera Alphatorquevirus (torque teno viruses) and Betatorquevirus (torque teno mini viruses), which are common in chimpanzees and apathogenic. Of the remaining 11 viruses, 9 were typical constituents of the chimpanzee virome that have been identified in previous studies and are also thought to be apathogenic. One virus, a novel tibrovirus (Rhabdoviridae: Tibrovirus) is related to Bas-Congo virus, which was originally thought to be a human pathogen but is currently thought to be apathogenic, incidental, and vector-borne. The only virus associated with disease was rhinovirus C (Picornaviridae: Enterovirus) infecting one chimpanzee subsequent to an outbreak of respiratory illness at that sanctuary. Our results suggest that the blood-borne virome of African sanctuary chimpanzees does not differ appreciably from that of their wild counterparts, and that persistent infection with exogenous viruses may be less common than often assumed.
Topics: Animals; Africa; Pan troglodytes; Virus Diseases; Animals, Zoo
PubMed: 36329642
DOI: 10.1002/ajp.23452 -
Wiley Interdisciplinary Reviews.... Sep 2020Collaboration or social interactions in which two or more individuals coordinate their behavior to produce outcomes from which both individuals benefit are common in... (Review)
Review
Collaboration or social interactions in which two or more individuals coordinate their behavior to produce outcomes from which both individuals benefit are common in nature. Individuals from many species hunt together, defend their territory, and form coalitions in intragroup competition. However, we still know very little about the proximate mechanisms underlying these behaviors. Recent theories of human cognitive evolution have emphasized the role collaboration may have played in the selection of socio-cognitive skills. It has been argued that the capacity to form shared goals and joint intentions with others, is what allows humans to collaborate so flexibly and efficiently. Although there is no evidence that nonhuman animals are capable of shared intentionality, there is conceivably a wide range of proximate mechanisms that support forms of, potentially flexible, collaboration in other species. We review the experimental literature with the aim of evaluating what we know about how other species achieve collaboration; with a particular focus on chimpanzees. We structure the review with a new categorization of collaborative behavior that focuses on whether individuals intentionally coordinate actions with others. We conclude that for a wider comparative perspective we need more data from other species but the findings so far suggest that chimpanzees, and possibly other great apes, are capable of understanding the causal role of a partner in collaboration. This article is categorized under: Cognitive Biology > Evolutionary Roots of Cognition Psychology > Comparative Psychology.
Topics: Animals; Behavior, Animal; Cooperative Behavior; Pan troglodytes
PubMed: 32342659
DOI: 10.1002/wcs.1529 -
Evolutionary Anthropology Nov 2021Chimpanzees (Pan troglodytes) are the only great apes that inhabit hot, dry, and open savannas. We review the environmental pressures of savannas on chimpanzees, such as... (Review)
Review
Chimpanzees (Pan troglodytes) are the only great apes that inhabit hot, dry, and open savannas. We review the environmental pressures of savannas on chimpanzees, such as food and water scarcity, and the evidence for chimpanzees' behavioral responses to these landscapes. In our analysis, savannas were generally associated with low chimpanzee population densities and large home ranges. In addition, thermoregulatory behaviors that likely reduce hyperthermia risk, such as cave use, were frequently observed in the hottest and driest savanna landscapes. We hypothesize that such responses are evidence of a "savanna landscape effect" in chimpanzees and offer pathways for future research to understand its evolutionary processes and mechanisms. We conclude by discussing the significance of research on savanna chimpanzees to modeling the evolution of early hominin traits and informing conservation programs for these endangered apes.
Topics: Animals; Grassland; Pan troglodytes
PubMed: 34542218
DOI: 10.1002/evan.21924 -
Science (New York, N.Y.) Nov 2023Cooperation beyond familial and group boundaries is core to the functioning of human societies, yet its evolution remains unclear. To address this, we examined grooming,...
Cooperation beyond familial and group boundaries is core to the functioning of human societies, yet its evolution remains unclear. To address this, we examined grooming, coalition, and food-sharing patterns in bonobos (), one of our closest living relatives whose rare out-group tolerance facilitates interaction opportunities between groups. We show that, as in humans, positive assortment supports bonobo cooperation across borders. Bonobo cooperative attitudes toward in-group members informed their cooperative relationships with out-groups, in particular, forming connections with out-group individuals who also exhibited high cooperation tendencies. Our findings show that cooperation between unrelated individuals across groups without immediate payoff is not exclusive to humans and suggest that such cooperation can emerge in the absence of social norms or strong cultural dispositions.
Topics: Animals; Humans; Grooming; Pan paniscus; Pan troglodytes; Group Processes; Cooperative Behavior; Social Norms
PubMed: 37972165
DOI: 10.1126/science.adg0844 -
Anatomical Record (Hoboken, N.J. : 2007) Aug 2022The facial differences between recent Pan troglodytes and Homo sapiens can be used as a proxy for the reduction of facial prognathism that happened during evolutionary...
The facial differences between recent Pan troglodytes and Homo sapiens can be used as a proxy for the reduction of facial prognathism that happened during evolutionary transition between Australopithecines and early Homo. The projecting nasal morphology of Homo has been considered both a passive consequence of anatomical reorganization related to brain and integrated craniofacial evolution as well as an adaptation related to air-conditioning during physiological and behavioral shifts in human evolution. Yet, previous research suggested impaired air-conditioning in Homo challenging respiratory adaptations based on computational fluid dynamics (CFD) and airflow simulations. Here we improved CFD model at the inflow region and also carried out three-dimensional (3D) geometric morphometrics to address the hypothesis of impaired air-conditioning in humans and species differences in airway shape. With the new CFD model we simulated pressure, velocity, and temperature changes in airflow of six adult humans and six chimpanzees and analyzed 164 semi-landmarks of 10 humans and 10 chimpanzees for 3D size and shape comparisons. Our finding shows significantly different internal 3D nasal airways. Also, species means of pressure, velocity, and temperature differed statistically significantly. However, form-related differences in temperature exchanges seem subtle and may question adaptive disadvantages. We rather support a hypothesis of craniofacial changes in the Australopithecus-Homo transition that are related to brain evolution and craniofacial integration with facial and nasal modifications that contribute to maintain respiratory adaptations related to air conditioning.
Topics: Adult; Animals; Computer Simulation; Humans; Hydrodynamics; Nasal Cavity; Nasopharynx; Nose; Pan troglodytes
PubMed: 34636487
DOI: 10.1002/ar.24790 -
Biology Letters May 2021Culture is a hallmark of the human species, both in terms of the transmission of material inventions (e.g. tool manufacturing) and the adherence to social conventions...
Culture is a hallmark of the human species, both in terms of the transmission of material inventions (e.g. tool manufacturing) and the adherence to social conventions (e.g. greeting mannerisms). While material culture has been reported across the animal kingdom, indications of social culture in animals are limited. Moreover, there is a paucity of evidencing cultural stability in animals. Here, based on a large dataset spanning 12 years, I show that chimpanzees adhere to arbitrary group-specific handclasp preferences that cannot be explained by genetics or the ecological environment. Despite substantial changes in group compositions across the study period, and all chimpanzees having several behavioural variants in their repertoires, chimpanzees showed and maintained the within-group homogeneity and between-group heterogeneity that are so characteristic of the cultural phenomenon in the human species. These findings indicate that human culture, including its arbitrary social conventions and long-term stability, is rooted in our evolutionary history.
Topics: Animals; Culture; Humans; Pan troglodytes; Social Behavior
PubMed: 34034527
DOI: 10.1098/rsbl.2021.0031