Cost-effective solutions for high-throughput enzymatic DNA methylation sequencing.

Characterizing DNA methylation patterns is important for addressing key questions in evolutionary biology, geroscience, and medical genomics. While costs are decreasing, whole-genome DNA methylation profiling remains prohibitively expensive for most population-scale studies, creating a need for cost-effective, reduced representation approaches (i.e.

Conserved and differing functions of the endocrine system across different social systems - oxytocin as a case study.

A key goal of the field of endocrinology has been to understand the hormonal mechanisms that drive social behavior and influence reactions to others, such as oxytocin. However, it has sometimes been challenging to understand which aspects and influences of hormonal action are conserved and common among mammalian species, and which effects differ based on features of these species, such as social system. This challenge has been exacerbated by a focus on a relatively small number of traditional model species.

Frans de Waal (1948-2024).

Primatologist who brought animals and humans "a little closer".

No evidence of attentional bias toward threatening conspecific and allospecific faces in capuchin monkeys (Sapajus [Cebus] apella) using a dot-probe task.

The ability to quickly perceive and interpret threatening facial expressions from others is critical for successfully maintaining group cohesion in social nonhuman primate species. Rapid detection of threatening or negative stimuli in the environment compared to neutral stimuli, referred to as an attentional bias toward threat, is adaptive in that faster threat detection can lead to greater survival outcomes. However, the evolutionary roots of attentional bias formation toward social threat are not well understood.

Capuchin monkeys' (Sapajus [Cebus] apella) categorization of photos of unknown male conspecifics suggests attention to fWHR and a dominance bias.

The ability to quickly perceive others' rank minimizes costs by helping individuals behave appropriately when interacting with strangers. Indeed, humans and at least some other species can quickly determine strangers' rank or dominance based only on physical features without observing others' interactions or behavior. Nonhuman primates can determine strangers' ranks by observing their interactions, and some evidence suggests that at least some cues to dominance, such as facial width-to-height ratio (fWHR), are also present in other primates.

The Joint Simon task is not joint for capuchin monkeys.

Human cooperation can be facilitated by the ability to create a mental representation of one's own actions, as well as the actions of a partner, known as action co-representation. Even though other species also cooperate extensively, it is still unclear whether they have similar capacities. The Joint Simon task is a two-player task developed to investigate this action co-representation.

In search of animal normativity: a framework for studying social norms in non-human animals.

Social norms - rules governing which behaviours are deemed appropriate or inappropriate within a given community - are typically taken to be uniquely human. Recently, this position has been challenged by a number of philosophers, cognitive scientists, and ethologists, who have suggested that social norms may also be found in certain non-human animal communities. Such claims have elicited considerable scepticism from norm cognition researchers, who doubt that any non-human animals possess the psychological capacities necessary for normative cognition.

Evaluation of decision-making behavior under uncertainty in capuchin monkeys (Sapajus apella) and humans (Homo sapiens) using a modified Balloon Analogue Risk Task.

Many animals, including humans, must make decisions when outcomes involve risk and/or ambiguity. To explore the evolutionary roots of decision making when outcomes are unknown, we modified the Balloon Analogue Risk Task (BART) for use with tufted capuchin monkeys (), creating the Primate Analogue Risk Task (PART). Using both the BART and the PART, we first compared human performance across the two tasks using analogous parameters.

Humans' (Homo sapiens), capuchin monkeys' (Sapajus [Cebus] apella), and rhesus macaques' (Macaca mulatta) size judgments shift when stimuli change in frequency.

When making decisions, humans often strive to uphold objective, absolute standards, such as about what is small versus large, blue versus purple, or unfair versus fair, suggesting that our judgments should not be swayed by extraneous factors such as the sequence or frequency of events to be judged. Yet in previous research, when some items (e.g.

State-dependent risky choices in primates: Variation in energy budget does not affect tufted capuchin monkeys' (Sapajus spp.) risky choices.

Economic models predict that rational decision makers' choices between a constant, "safe" option and a variable, "risky" option leading, on average, to the same payoff, should be random. However, a wealth of research has revealed that, when faced with risky decisions, both human and nonhuman animals deviate from economic rationality. According to the risk-sensitivity theory, individuals should prefer a safe option when they are in a positive energy state and a risky option when they are in a negative energy state.

Sex differences in white matter tracts of capuchin monkey brains.

Nonhuman primates exhibit sexual dimorphism in behavior, suggesting that there could be underlying differences in brain organization and function. Understanding this neuroanatomical variation is critical for enhancing our understanding of the evolution of sex differences in the human brain. Tufted capuchin monkeys (Sapajus [Cebus] apella) represent a phylogenetically diverse taxa of neotropical primates that converge on several behavioral characteristics with humans relevant to social organization, making them an important point of comparison for studying the evolution of sex differences in primates.

Under pressure: the interaction between high-stakes contexts and individual differences in decision-making in humans and non-human species.

Observed behavior can be the result of complex cognitive processes that are influenced by environmental factors, physiological process, and situational features. Pressure, a feature of a situation in which an individual's outcome is impacted by his or her own ability to perform, has been traditionally treated as a human-specific phenomenon and only recently have pressure-related deficits been considered in relation to other species. However, there are strong similarities in biological and cognitive systems among mammals (and beyond), and high-pressure situations are at least theoretically common in the wild.

Oxytocin increases during fur-rubbing regardless of level of social contact in tufted capuchin monkeys.

Social interactions induce oxytocin release in many social species, suggesting that oxytocin is a critical part of social bonding among individuals. However, oxytocin also increases as a result of physical contact and stimulation, making it unclear which features of affiliative behaviors (for instance, social interaction or physical contact with a conspecific) drive the oxytocin increase observed after engaging in these behaviors. We attempted to tease this apart by studying the differential effect of social interaction, visual coordination with a conspecific, and physical stimulation during the fur-rubbing behavior of tufted capuchin monkeys (Sapajus [Cebus] apella), which often involves social contact with groupmates but is in some cases performed alone.

Comparative economics: how studying other primates helps us better understand the evolution of our own economic decision making.

The origins of evolutionary games are rooted in both economics and animal behaviour, but economics has, until recently, focused primarily on humans. Although historically, specific games were used in targeted circumstances with non-human species (i.e.

Dogs take into account the actions of a human partner in a cooperative task.

Humans stand out for their capacity to flexibly cooperate, possibly because they understand their partners' role. Researchers have explored if such understanding is unique to humans by assessing whether non-human species wait to manipulate a cooperative apparatus until a delayed partner arrives. If animals do wait, then it is assumed that they recognize the need for a partner.

Oxytocin and social gaze during a dominance categorization task in tufted capuchin monkeys.

Visual attention to facial features is an important way that group-living primate species gain knowledge about others. However, where this attention is focused on the face is influenced by contextual and social features, and emerging evidence in species suggests that oxytocin, a hormone involved in forming and maintaining affiliative bonds among members of the same group, influences social attention as measured by eye gaze. Specifically, bonobos tend to focus on conspecifics' eyes when viewing two-dimensional images, whereas chimpanzees focus more on the edges of the face.

Signatures of adaptive evolution in platyrrhine primate genomes.

The platyrrhine family Cebidae (capuchin and squirrel monkeys) exhibit among the largest primate encephalization quotients. Each cebid lineage is also characterized by notable lineage-specific traits, with capuchins showing striking similarities to Hominidae such as high sensorimotor intelligence with tool use, advanced cognitive abilities, and behavioral flexibility. Here, we take a comparative genomics approach, performing genome-wide tests for positive selection across five cebid branches, to gain insight into major periods of cebid adaptive evolution.

Validating Urinary Neopterin as a Biomarker of Immune Response in Captive and Wild Capuchin Monkeys.

Non-invasive health monitoring is advantageous for wild and captive primate populations because it reduces the need for traditional invasive techniques (i.e., anesthetization) that can be stressful and potentially harmful for individuals.

Nudges for Judges: An Experiment on the Effect of Making Sentencing Costs Explicit.

Judges are typically tasked to consider sentencing benefits but not costs. Previous research finds that both laypeople and prosecutors discount the costs of incarceration when forming sentencing attitudes, raising important questions about whether professional judges show the same bias during sentencing. To test this, we used a vignette-based experiment in which Minnesota state judges ( = 87) reviewed a case summary about an aggravated robbery and imposed a hypothetical sentence.

Endogenous cortisol correlates with performance under pressure on a working memory task in capuchin monkeys.

Humans often experience striking performance deficits when their outcomes are determined by their own performance, colloquially referred to as "choking under pressure." Physiological stress responses that have been linked to both choking and thriving are well-conserved in primates, but it is unknown whether other primates experience similar effects of pressure. Understanding whether this occurs and, if so, its physiological correlates, will help clarify the evolution and proximate causes of choking in humans.