Taxon, Site and Temporal Differentiation Using Dental Microwear in the Southern African Papionins

The evolutionary history of the South African papionins is a useful analog for the emergence of hominids in South Africa. However, the taxonomic relationships of the papionins are unclear. This study uses low-magnification stereomicroscopy to examine dental microwear and uses the microwear signals to explore the existing classification of these papionins. The results from the species and site level analyses are equivocal. However, the genera and time period results show clear evidence for a dietary change between the extinct and extant forms of Papio and Parapapio. This adds an additional tool for distinguishing these two groups. The dietary changes witnessed in the papionins are likely found in the hominids from the Plio-Pleistocene. Using the papionin analog, hominid dietary evolution may be explored

Gambling and Decision-Making Among Primates: The Primate Gambling Task

Humans have a tendency to engage in economically irrational behaviors such as gambling, which typically leads to long-term financial losses. While there has been much research on human gambling behavior, relatively little work has been done to explore the evolutionary origins of this behavior. To examine the adaptive pressures that may have led to this seemingly irrational behavior in humans, nonhuman primates were tested to explore their reactions to gambling type scenarios. Several experiments based on traditional human economic experiments were adapted for use with a wider variety of primate species including chimpanzees and capuchin monkeys. This allowed for testing multiple species using similar methodologies in order to make more accurate comparisons of species abilities. This series of tasks helps to elucidate risky decision-making behavior in three primate species

Leveraging Embedded Undergraduate Research to Bolster Research Culture: A Multi-Pronged Approach Case Study

Introducing research into UG curriculum is critical toward the development of empirically informed future researchers and practitioners. Developing mechanisms to embed research into curriculum and culture can be challenging. To address these challenges, our UG psychology program has implemented initiatives to increase research participation. We will discuss several which include embedded class research, laboratory experiments, poster opportunities, and faculty research team participation. We also facilitate UG through research centers, partnering with public and private organizations, and novel approaches such as Roach Lab (roachlab.org). We will specifically highlight outcomes attributed to engaging students in research

Visual Processing Speed in Capuchin Monkeys (Cebus apella) and Rhesus Macaques (Macaca mulatta)

Visual acuity is a defining feature of the primates. Humans can process visual stimuli at extremely rapid presentation durations, as short as 14 ms. Evidence suggests that other primates, including chimpanzees and rhesus macaques, can process visual information at similarly rapid rates. What is lacking is information on the abilities of New World monkeys, which is necessary to determine whether rapid processing is present across the primates or is specific to Old World primates. We tested capuchin (Cebus apella) and rhesus (Macaca mulatta) monkeys on a computerized matching-to-sample paradigm to determine the shortest presentation duration at which stimuli could be correctly identified. In Study 1, using clip art images, both species achieved presentation durations as short as 25 ms while maintaining high accuracy rates. In Study 2, we used logographic Asian language characters to see if stimuli that were more similar in appearance would reveal species differences. Neither species was as accurate, or achieved as short of presentation durations, as with clip-art images. In particular, capuchins were initially less accurate than rhesus in Study 2, but with experience, achieved similar accuracy rates and presentation durations. These data indicate that rapid visual processing abilities are widespread in the primate lineage, and that the form of the stimuli presented can have an effect on processing across species

How Fairly do Chimpanzees Play the Ultimatum Game?

Humans can behave fairly, but can other species? Recently we tested chimpanzees on a classic human test for fairness, the Ultimatum Game, and found that they behaved similarly to humans. In humans, Ultimatum Game behavior is cited as evidence for a human sense of fairness. By that same logic, we concluded that chimpanzees behaved fairly in our recent study. However, we make a distinction between behavior and motivation. Both humans and chimpanzees behaved fairly, but determining why they did so is more challenging

Chimpanzees Play the Ultimatum Game

Is the sense of fairness uniquely human? Human reactions to reward division are often studied by means of the Ultimatum Game (UG), in which both partners need to agree on a distribution for both to receive rewards. Humans typically offer generous portions of the reward to their partner, a tendency our close primate relatives have thus far failed to show in experiments. Here, we tested chimpanzees (Pan troglodytes) and human children on a modified UG. One individual chose between two tokens that, with their partner\u27s cooperation, could be exchanged for rewards. One token offered equal rewards to both players, whereas the other token favored the chooser. Both apes and children responded like humans typically do. If their partner\u27s cooperation was required, they split the rewards equally. However, with passive partners -- a situation akin to the so-called Dictator Game -- they preferred the selfish option. Thus, humans and chimpanzees show similar preferences regarding reward division, suggesting a long evolutionary history to the human sense of fairness

Adult Cleaner Wrasse Outperform Capuchin Monkeys, Chimpanzees and Orang-utans in a Complex Foraging Task Derived from Cleaner – Client Reef Fish Cooperation

The insight that animals’ cognitive abilities are linked to their evolutionary history, and hence their ecology, provides the framework for the comparative approach. Despite primates renowned dietary complexity and social cognition, including cooperative abilities, we here demonstrate that cleaner wrasse outperform three primate species, capuchin monkeys, chimpanzees and orang-utans, in a foraging task involving a choice between two actions, both of which yield identical immediate rewards, but only one of which yields an additional delayed reward. The foraging task decisions involve partner choice in cleaners: they must service visiting client reef fish before resident clients to access both; otherwise the former switch to a different cleaner. Wild caught adult, but not juvenile, cleaners learned to solve the task quickly and relearned the task when it was reversed. The majority of primates failed to perform above chance after 100 trials, which is in sharp contrast to previous studies showing that primates easily learn to choose an action that yields immediate double rewards compared to an alternative action. In conclusion, the adult cleaners’ ability to choose a superior action with initially neutral consequences is likely due to repeated exposure in nature, which leads to specific learned optimal foraging decision rules

Prestige Affects Cultural Learning in Chimpanzees

Humans follow the example of prestigious, high-status individuals much more readily than that of others, such as when we copy the behavior of village elders, community leaders, or celebrities. This tendency has been declared uniquely human, yet remains untested in other species. Experimental studies of animal learning have typically focused on the learning mechanism rather than on social issues, such as who learns from whom. The latter, however, is essential to understanding how habits spread. Here we report that when given opportunities to watch alternative solutions to a foraging problem performed by two different models of their own species, chimpanzees preferentially copy the method shown by the older, higher-ranking individual with a prior track-record of success. Since both solutions were equally difficult, shown an equal number of times by each model and resulted in equal rewards, we interpret this outcome as evidence that the preferred model in each of the two groups tested enjoyed a significant degree of prestige in terms of whose example other chimpanzees chose to follow. Such prestige-based cultural transmission is a phenomenon shared with our own species. If similar biases operate in wild animal populations, the adoption of culturally transmitted innovations may be significantly shaped by the characteristics of performers

Margarita de Sossa, Sixteenth-Century Puebla de los Ángeles, New Spain (Mexico)

Margarita de Sossa’s freedom journey was defiant and entrepreneurial. In her early twenties, still enslaved in Portugal, she took possession of her body; after refusing to endure her owner’s sexual demands, he sold her, and she was transported to Mexico. There, she purchased her freedom with money earned as a healer and then conducted an enviable business as an innkeeper. Sossa’s biography provides striking insights into how she conceptualized freedom in terms that included – but was not limited to – legal manumission. Her transatlantic biography offers a rare insight into the life of a free black woman (and former slave) in late sixteenth-century Puebla, who sought to establish various degrees of freedom for herself. Whether she was refusing to acquiesce to an abusive owner, embracing entrepreneurship, marrying, purchasing her own slave property, or later using the courts to petition for divorce. Sossa continued to advocate on her own behalf. Her biography shows that obtaining legal manumission was not always equivalent to independence and autonomy, particularly if married to an abusive husband, or if financial successes inspired the envy of neighbors