Cebus Apella Tolerate Intermittent Unreliability in Human Experimenters

Monkeys form expectations for outcomes based on interactions with human experimenters. Not only do they anticipate receiving rewards which the experimenter indicates, but capuchin monkeys, a cooperative new world monkey species, apparently anticipate rewards based on what the experimenter has given to their partner. However, this could be due to subjects responding to either outcomes or experimenters. Here we examine whether capuchin monkeys will continue to interact with human experimenters who are occasionally unreliable. We tested ten monkeys with a series of familiar human experimenters using an exchange task. The experimenters had never before participated in exchange studies with these monkeys, hence the monkeys learned about their behavior during the course of testing. Occasionally experimenters were unreliable, failing to give a reward after the monkey returned the token. We found that monkeys did recognize these interactions as different, responding much more quickly in trials following those which were non-rewarded than in other situations with the same experimenter. However, subjects did not change their preference for experimenters when given the opportunity to choose between the unreliable exchanger and another exchanger, nor did subjects learn to prefer reliable experimenters from watching other monkeys’ interactions. Instead, subjects returned the tokens to the same location from which they received it. These results indicate that capuchin monkeys may not be sensitive to isolated instances in which experimenters are unreliable, possibly because of a strong bias to returning the token to the location from which it was donated

Nematode control in suckler beef cattle over their first two grazing seasons using a targeted selective treatment approach

peer-reviewedBackground With concerns over the development of anthelmintic resistance in cattle nematode populations, we must re-examine our approach to nematode control in cattle. Targeted selective treatments (TST), whereby individual animals are treated instead of entire groups, are being investigated as an alternative. The study objective was to determine if anthelmintic usage could be reduced using a TST-based approach to nematode control in spring-born suckler beef cattle over their first and second grazing seasons (SGS) without affecting performance. In the first grazing season (FGS), 99 calves with an initial mean (s.d.) calf age and live weight on day 0 (June 28th 2012) of 107 (23.1) days and 160 (32.5) kg, respectively, were used. The study commenced on day 0 when calves were randomised and allocated to one of two treatments; 1), standard treatment (control) and 2), TST. Control calves were treated subcutaneously with ivermectin on days 0, 41 and 82 in the FGS. All calves were treated with ivermectin on day 124 and housed on day 133. In the SGS, only heifer calves from the FGS were used and control heifers were treated with ivermectin on day 393. Animals were weighed, blood and faecal sampled every three weeks. The TST animals were treated with ivermectin if thresholds based on a combination of plasma pepsinogen concentrations, faecal egg count and/or the presence of Dictyocaulus viviparus larvae in faeces (FGS only) were reached. Results No TST calves reached the treatment threshold criteria in the FGS. The FGS average daily live weight gain (ADG ± s.e.m.) for control and TST group calves was 0.89 ± 0.02 kg and 0.94 ± 0.02 kg day−1, respectively (P = 0.17). In the SGS, all heifers were treated with ivermectin on day 431 due to clinical signs of respiratory disease. The ADG for control and TST heifers from turnout on day 321 to day 431 was 0.90 ± 0.04 and 0.80 ± 0.04 kg day−1, respectively (P = 0.03). Conclusions Spring-born FGS suckler beef calves require minimal anthelmintic treatment to maintain performance. In contrast, clinical parasitic disease may develop in the SGS unless appropriate anthelmintic treatment is provided

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

Research Chimpanzees May Get a Break

A recent report by the Institute of Medicine leaves few urgent reasons standing for the continued use of chimpanzees in biomedical research. It is high time to think about their retirement, Frans de Waal argues, without neglecting prospects for non-invasive research on behavior, cognition, and genetics

A preliminary investigation of the dietary habits of Indian University students

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Toshisada Nishida (1941–2011): Chimpanzee Rapport

Frans de Waal pays tribute to pioneering primatologist Toshisada Nishida, who transformed our understanding of chimpanzee behavior and culture and galvanized efforts to ensure their conservation

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