Norm reinforcement, not conformity or environmental factors, is predicted to sustain cultural variation.

The maintenance of cross-cultural variation and arbitrary traditions in human populations is a key question in cultural evolution. Conformist transmission, the tendency to follow the majority, was previously considered central to this phenomenon. However, recent theory indicates that cognitive biases can greatly reduce its ability to maintain traditions.

Culture in humans and other animals.

Migration provides evidence for cumulative cultural evolution in chimpanzees.

Human culture is uniquely open-ended rather than uniquely cumulative.

Theories of how humans came to be so ecologically dominant increasingly centre on the adaptive abilities of human culture and its capacity for cumulative change and high-fidelity transmission. Here we revisit this hypothesis by comparing human culture with animal cultures and cases of epigenetic inheritance and parental effects. We first conclude that cumulative change and high transmission fidelity are not unique to human culture as previously thought, and so they are unlikely to explain its adaptive qualities.

Environmental complexity and regularity shape the evolution of cognition.

The environmental complexity hypothesis suggests that cognition evolves to allow animals to negotiate a complex and changing environment. By contrast, signal detection theory suggests cognition exploits environmental regularities by containing biases (e.g.

When does metacognition evolve in the opt-out paradigm?

Metacognition (awareness of one's own knowledge) is taken for granted in humans, but its evolution in non-human animals is not well understood. While there is experimental evidence of seemingly metacognitive judgements across species, studies rarely focus on why metacognition may have evolved. To address this, I present an evolutionary model of the opt-out paradigm, a common experiment used to assess animal's metacognition.

Idiosyncratic gesture use in a mother-infant dyad in chimpanzees (Pan troglodytes schweinfurthii) in the wild.

One promising method to tackle the question, "In which modality did language evolve?" is by studying the ontogenetic trajectory of signals in human's closest living relatives, including chimpanzees (Pan troglodytes). Concerning gestures, current debates centre on four different hypotheses: "phylogenetic ritualization", "social transmission through imitation", "ontogenetic ritualization", and "social negotiation". These differ in their predictions regarding idiosyncratic gestures, making such occurrences a crucial area of investigation.

A 4.3-million-year-old Australopithecus anamensis mandible from Ileret, East Turkana, Kenya, and its paleoenvironmental context.

A hominin mandible, KNM-ER 63000, and associated vertebrate remains were recovered in 2011 from Area 40 in East Turkana, Kenya. Tephrostratigraphic and magnetostratigraphic analyses indicate that these fossils date to ∼4.3 Ma.

Third-party arbitration and forgiving strategies increase cooperation when perception errors are common.

Humans cooperate in groups in which mutual monitoring is common, and this provides the possibility of third-party arbitration. Third-party arbitration stabilizes reciprocity in at least two ways: first, when it is accurate, it reduces the frequency of misunderstandings resulting from perception errors, and second, even when it is inaccurate, it provides a public signal that allows pairs to align their expectations about how to behave after errors occur. Here, we describe experiments that test for these two effects.

Long-term biotic homogenization in the East African Rift System over the last 6 million years of hominin evolution.

Eastern Africa preserves the most complete record of human evolution anywhere in the world but we have little knowledge of how long-term biogeographic dynamics in the region influenced hominin diversity and distributions. Here, we use spatial beta diversity analyses of mammal fossil records from the East African Rift System to reveal long-term biotic homogenization (increasing compositional similarity of faunas) over the last 6 Myr. Late Miocene and Pliocene faunas (~6-3 million years ago (Ma)) were largely composed of endemic species, with the shift towards biotic homogenization after ~3 Ma being driven by the loss of endemic species across functional groups and a growing number of shared grazing species.

3.3 million years of stone tool complexity suggests that cumulative culture began during the Middle Pleistocene.

Cumulative culture, the accumulation of modifications, innovations, and improvements over generations through social learning, is a key determinant of the behavioral diversity across populations and their ability to adapt to varied ecological habitats. Generations of improvements, modifications, and lucky errors allow humans to use technologies and know-how well beyond what a single naive individual could invent independently within their lifetime. The human dependence on cumulative culture may have shaped the evolution of biological and behavioral traits in the hominin lineage, including brain size, body size, life history, sociality, subsistence, and ecological niche expansion.

On the scientific credibility of paleoanthropology.

Smith and Smith and Wood proposed that the human fossil record offers special challenges for causal hypotheses because "unique" adaptations resist the comparative method. We challenge their notions of "uniqueness" and offer a refutation of the idea that there is something epistemologically special about human prehistoric data. Although paleontological data may be sparse, there is nothing inherent about this information that prevents its use in the inductive or deductive process, nor in the generation and testing of scientific hypotheses.

Animal behavior: A tale of two apes.

A new paper shows that rates of aggression are higher, and rates of coalition formation are lower, among male bonobos than among male chimpanzees. These findings are noteworthy because they challenge the view that female bonobos' preferences for less aggressive males favored a reduction in male aggression and an increase in social tolerance.

Investigating the effects of social information on spite in an online game.

While humans are highly cooperative, they can also behave spitefully. Yet spite remains understudied. Spite can be normatively driven and while previous experiments have found some evidence that cooperation and punishment may spread via social learning, no experiments have considered the social transmission of spiteful behaviour.

Adaptive foraging behaviours in the Horn of Africa during Toba supereruption.

Although modern humans left Africa multiple times over 100,000 years ago, those broadly ancestral to non-Africans dispersed less than 100,000 years ago. Most models hold that these events occurred through green corridors created during humid periods because arid intervals constrained population movements. Here we report an archaeological site-Shinfa-Metema 1, in the lowlands of northwest Ethiopia, with Youngest Toba Tuff cryptotephra dated to around 74,000 years ago-that provides early and rare evidence of intensive riverine-based foraging aided by the likely adoption of the bow and arrow.

The development and diversity of religious cognition and behavior: Protocol for Wave 1 data collection with children and parents by the Developing Belief Network.

The Developing Belief Network is a consortium of researchers studying human development in diverse social-cultural settings, with a focus on the interplay between general cognitive development and culturally specific processes of socialization and cultural transmission in early and middle childhood. The current manuscript describes the study protocol for the network's first wave of data collection, which aims to explore the development and diversity of religious cognition and behavior. This work is guided by three key research questions: (1) How do children represent and reason about religious and supernatural agents? (2) How do children represent and reason about religion as an aspect of social identity? (3) How are religious and supernatural beliefs transmitted within and between generations? The protocol is designed to address these questions via a set of nine tasks for children between the ages of 4 and 10 years, a comprehensive survey completed by their parents/caregivers, and a task designed to elicit conversations between children and caregivers.

Poor Oral Health Is Associated With Inflammation, Aortic Valve Calcification, and Brain Volume Among Forager-Farmers.

Poor oral health is associated with cardiovascular disease and dementia. Potential pathways include sepsis from oral bacteria, systemic inflammation, and nutritional deficiencies. However, in post-industrialized populations, links between oral health and chronic disease may be confounded because the lower socioeconomic exposome (poor diet, pollution, and low physical activity) often entails insufficient dental care.

Female chimpanzees avoid inbreeding even in the presence of substantial bisexual philopatry.

Inbreeding (reproduction between relatives) often decreases the fitness of offspring and is thus expected to lead to the evolution of inbreeding avoidance strategies. Chimpanzees () are expected to avoid inbreeding as they are long-lived, invest heavily in offspring and may encounter adult, opposite sex kin frequently, especially in populations where both males and females commonly remain in the group in which they were born (bisexual philopatry). However, it is unclear whether substantial bisexual philopatry has been a feature of chimpanzees' evolutionary history or whether it is a result of recent anthropogenic interference, as the only groups for which it has been documented are significantly impacted by human encroachment and experience notable rates of potentially unsustainable inbreeding.

Group-structured cultural selection can explain both war and peace.

Glowacki recognizes the importance of norms in enabling war and peace, but does not focus on the cultural evolutionary mechanisms by which these norms are maintained. We highlight how group-structured cultural selection shapes the scale and nature of peaceful intergroup interactions. The mechanistic perspective reveals that there are many more cases of peaceful intergroup relations than the current account implies.

Testosterone is positively associated with coronary artery calcium in a low cardiovascular disease risk population.

Background: In industrialized populations, low male testosterone is associated with higher rates of cardiovascular mortality. However, coronary risk factors like obesity impact both testosterone and cardiovascular outcomes. Here, we assess the role of endogenous testosterone on coronary artery calcium in an active subsistence population with relatively low testosterone levels, low cardiovascular risk and low coronary artery calcium scores.

Evolutionary Insight into the Association between New Jersey Polyomavirus and Humans.

Advances in viral discovery techniques have led to the identification of numerous novel viruses in human samples. However, the low prevalence of certain viruses in humans raises doubts about their association with our species. To ascertain the authenticity of a virus as a genuine human-infecting agent, it can be useful to investigate the diversification of its lineage within hominines, the group encompassing humans and African great apes.

Between-group cooperation in bonobos.

Bonobos provide insight into the origins of partner-specific cooperation in human groups.

Agentic processes in cultural evolution: relevance to Anthropocene sustainability.

Humans have evolved culturally and perhaps genetically to be unsustainable. We exhibit a deep and consistent pattern of short-term resource exploitation behaviours and institutions. We distinguish agentic and naturally selective forces in cultural evolution.

Demographic and hormonal evidence for menopause in wild chimpanzees.

Among mammals, post-reproductive life spans are currently documented only in humans and a few species of toothed whales. Here we show that a post-reproductive life span exists among wild chimpanzees in the Ngogo community of Kibale National Park, Uganda. Post-reproductive representation was 0.