Female squirrel monkeys' (Saimiri boliviensis) responses to inequity in a group context; testing a link between cooperation and inequity responses.

Primates of several species respond negatively to receiving less preferred rewards than a partner for completing the same task (inequity responses), either rejecting rewards or refusing to participate in the task when disadvantaged. This has been linked to cooperation, with species that cooperate frequently refusing to participate in inequity tasks (the 'cooperation hypothesis'). However, inequity is a social response, and previous research has involved dyads, precluding studying the effects of additional social partners. While dyads allow for tighter control in experimental settings, dyadic interactions in nature do not take place in a social vacuum, so understanding the role of the social context is needed to verify that the pattern of results supports the cooperation hypothesis. Here we focus on Bolivian squirrel monkeys, Saimiri boliviensis, a highly social species that does not generally cooperate and has not responded to inequity in previous dyadic research, although they do respond to receiving a lower reward than they expected. In the current study, we provide a more nuanced test by studying female Bolivian squirrel monkeys, the demographic most likely to cooperate in both field and laboratory contexts, in a more socially relevant group setting. For some reward values, females responded in both the inequity condition, rejecting less preferred rewards when they were disadvantaged relative to their social group, and a contrast condition, wherein all animals received a lower reward than they expected, making it difficult to disentangle contrast from inequity. As in capuchin monkeys, refusals increased when monkeys were to receive low-value rewards compared to medium-value rewards. These results suggest that the relationship between cooperation and inequity responses may be more nuanced than previously suggested, with demographic, social context and reward value potentially influencing outcomes even within species.

The importance of thinking about the future in culture and cumulative cultural evolution.

Thinking about possibilities plays a critical role in the choices humans make throughout their lives. Despite this, the influence of individuals' ability to consider what is possible on culture has been largely overlooked. We propose that the ability to reason about future possibilities or prospective cognition, has consequences for cultural change, possibly facilitating the process of cumulative cultural evolution. In particular, by considering potential future costs and benefits of specific behaviours, prospective cognition may lead to a more flexible use of cultural behaviours. In species with limited planning abilities, this may lead to the development of cultures that promote behaviours with future benefits, circumventing this limitation. Here, we examine these ideas from a comparative perspective, considering the relationship between human and nonhuman assessments of future possibilities and their cultural capacity to invent new solutions and improve them over time. Given the methodological difficulties of assessing prospective cognition across species, we focus on planning, for which we have the most data in other species. Elucidating the role of prospective cognition in culture will help us understand the variability in when and how we see culture expressed, informing ongoing debates, such as that surrounding which social learning mechanisms underlie culture. This article is part of the theme issue 'Thinking about possibilities: mechanisms, ontogeny, functions and phylogeny'.

Dentistry, bite marks and the investigation of crime.

Bite-mark evidence has become accepted as a powerful tool in the investigation of crime. Human bite marks are found most frequently in cases of murder, rape, child abuse or altercation. When they contain sufficient detail, bite marks may be used to establish the identity of the biter. This article presents cases in which bite marks have provided major evidence in homicide investigations. In addition, all dentists should be familiar with the appearance of bite marks because they may be a primary sign of child abuse.

Forensic dentistry in the Cerritos air disaster.

On Aug 31, 1986, 82 people were killed in the worst air disaster in the history of Los Angeles International Airport. The Los Angeles County Forensic Dentistry Team worked with the Medical Examiner-Coroner's Office, the Federal Bureau of Investigation, and other agencies during the identification process. The investigation demonstrated the importance of involving forensic anthropologists and forensic dentists along with investigative agencies in the at-scene search for evidence at disaster sites.

Anatomical distribution of human bite marks in a series of 67 cases.

A study was made of the anatomical distribution of human bite marks, as well as their distribution by age of victim and type of crime involved. Bite marks in this study occurred primarily in sex-related crimes, child abuse cases, and cases involving other types of physical altercations. Bite marks were found on virtually all areas of the body, with more than one bite mark on 40% of the victims. Female victims were most commonly bitten on the breasts, arms, and legs, while male victims were most commonly bitten on the arms and shoulders.

Unusual three-dimensional bite mark evidence in a homicide case.

A comparison has been made between bite marks observed on the nose of a female homicide victim and the configuration of the dental structures of a male suspect. The victim's bite marks showed a number of demonstrable characteristics which could be reproduced by models of the dentition of the suspect. Special peculiarities within and between individual teeth, together with the upper and lower jaw relationship, were demonstrably consistent with the bite mark patterns on the victim's nose. Detailed examination of the scientific evidence led the dental investigators to the conclusion that there was a positive match between the suspect's dentition and the bite mark on the decedent's nose. The dental investigation and subsequent dental testimony were prime factors leading to the defendant's conviction of manslaughter in the first case in California involving the major use of bite mark evidence.