Laboratory rats have been widely used to study the development and neural underpinnings of play behavior. However, it is not known whether domestic rats play in the same way and at the same frequency as their wild counterparts. In this study, the play of juvenile rats from a colony of wild rats maintained in captivity was compared to that of a strain of domesticated rats (e.g., Long Evans hooded). Three predictions were tested. First, it was predicted that wild rats would incorporate more agonistic behavior in their play. This was not found, as in all cases, both the wild and the laboratory rats attacked and defended the nape during play, a nonagonistic body target. Second, because play is typically more frequent in domesticated animals than their wild progenitors, it was predicted that the wild rats should play less than the laboratory rats. This was found to be the case. Third, because wild animals tend to be less tolerant of proximity by conspecifics and tend to be more agile in their movements, it was predicted that there would be less contact between wild pair mates. This was found to be the case; data show that the play of laboratory rats involves the same target (i.e., the nape of the neck) and tactics of defense as those used by wild rats. However, the laboratory rats initiated playful attacks more frequently, and were more likely to use tactics that promoted bodily contact. These similarities and differences need to be considered when using laboratory animals as models for play in general.

Laboratory strains of rats are a commonly used subject to study play behavior. Recent research has shown that play in one laboratory strain of rat (e.g., Long-Evans hooded) differs in a number of ways from its wild counterparts. These findings suggest that domestication affects some aspects of play behavior. However, there are multiple strains of laboratory rats, which have been domesticated through different lineages all derived from wild rats and it cannot be assumed that all domestic strains are identical in their play. Therefore, the aim of this study was to compare the play behavior of three other strains of laboratory rats (e.g., Wistar, Sprague-Dawley, and Brown Norway). All strains were similar to each other as they all engaged in high frequencies of play, tolerated similar interanimal distances before initiating playful defense and displayed similar acrobatic capacities, suggesting domestication produces some common changes in play and other factors that influence play. However, strains differed significantly from one another in the use of tactics that promote bodily contact during play. Indeed, in this regard, some strains were more similar to wild rats than others, suggesting that some domestication-induced changes are either unique or more prominent in some laboratory strains than others. Such a mosaic pattern of transformation not only offers the possibility of using strain differences to characterize the genetic factors contributing to different facets of play, but also cautions researchers from making rat-general conclusions from studies on any one strain.

Limiting meat consumption has recently become one of the key issues linked to public health and environmental sustainability. This is reflected in the strong emphasis on increasing promotion of plant-based nutritional styles, such as vegan and vegetarian diets. Vegan/vegetarian diets appeal to certain demographic groups more than to others. The most striking difference, however, is found between the sexes. Men and women differ in their preferences for plant products and in their attitudes to meat consumption. There are also differences between their motivations to start and/or follow a vegan/vegetarian diet. Major differences have also been observed in men’s and women’s attitudes towards people following plant-based diets. Vegetarian diets are generally considered to be less masculine than meat-based diets, and omnivores exhibit more prejudice against vegetarian men than women. This study follows the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) systematic literature review model. The Web of Science and PubMed databases were searched (up to January 2020) to identify studies, which analysed variables directly or indirectly related to inter-sex differences with regard to the vegan/vegetarian diet. After the screening process based on the relevance and quality criteria, 29 articles were included in the study. The purpose of this review is to raise awareness of these gender differences, not only as regards social perceptions, but also in terms of individual attitudes to vegetarian/vegan diets. Ignoring those differences hinders the promotion of plant-based diets and may explain the relatively meager success of previous efforts to promote sustainable nutritional styles.

Although empirical studies comparing neophobia in wild and laboratory rats have been conducted in the past, a few decades have passed since most of them were completed. This is a substantial period of time in the case of fast-breeding animals such as rats. Equally important are the inconsistencies in research findings with respect to comparisons between wild and laboratory rats, and within domesticated strains. As well as having the aim of updating knowledge of neophobia among different types of rats, the present experiment was also an attempt to isolate a specific fear of a new food from a general fear of a novel object. The procedure was that rats accustomed to one type of food served in a specific location and in a familiar container were given a different type of food. Test trials were preceded by food deprivation. The following variables were measured: feeding latency, the pace of eating, the number of approaches to the container, and the number of times food was sampled in each trial. The amount of food consumed in each trial was weighed and also taken into account. Grooming time served as the measure of stress among the rats in the experiment. The results of the experiment did not confirm the assertion of some authors that wild rats avoid eating unfamiliar foods. All groups demonstrated only a temporary decrease in the amount of food consumed, the magnitude of which was similar in all strains. No evidence of particularly low neophobia in albino rats was found. However, the behavioral symptoms indicated higher levels of stress in wild rats compared to the other groups.