Abstract: Behavioural lateralization has been observed in many species of fishes during stimulus-specific tasks. However, one area that has been overlooked is the study of naïve side bias in motor behaviour of fishes in the absence of direct visual stimulus. To this end, we examined naïve side biases in motor behaviour in five species of minnows (Osteichthyes: Cyprinidae). Fifteen individuals of each species were subjected to a T-shaped test arena, with 40 randomized replicates per individual. We took advantage of rheotaxis by running a slow current of water through each arm of the test apparatus. Of the 75 individuals tested, 55 showed a rightward turning preference. The overall right-biased behaviour observed in these fishes in the absence of systematic stimulus strongly suggests that a stimulus-free control condition be included in the experimental design whenever plausible for studies of laterality in fishes and presumably in other organisms.

Abstract: One important element of complex and flexible tool use, particularly where tool manufacture is involved, is the ability to select or manufacture appropriate tools anticipating the needs of any given task-an ability that has been rarely tested in non-primates. We examine aspects of this ability in New Caledonian crows-a species known to be extraordinary tool users and manufacturers. In a 2002 study, Chappell and Kacelnik showed that these crows were able to select a tool of the appropriate length for a task among a set of different lengths, and in 2002, Weir, Chappell and Kacelnik showed that New Caledonian crows were able to shape unfamiliar materials to create a usable tool for a specific task. Here we examine their handling of tool diameter. In experiment 1, we show that when facing three loose sticks that were usable as tools, they preferred the thinnest one. When the three sticks were presented so that one was loose and the other two in a bundle, they only disassembled the bundle when their preferred tool was tied. In experiment 2, we show that they manufacture, and modify during use, a tool of a suitable diameter from a tree branch, according to the diameter of the hole through which the tool will have to be inserted. These results add to the developing picture of New Caledonian crows as sophisticated tool users and manufacturers, having an advanced level of folk physics.

Abstract: Chimpanzees (Pan troglodytes) are the most proficient and versatile users of tools in the wild. How such skills become integrated into the behavioural repertoire of wild chimpanzee communities is investigated here by drawing together evidence from three complementary approaches in a group of oil-palm nut- ( Elaeis guineensis) cracking chimpanzees at Bossou, Guinea. First, extensive surveys of communities adjacent to Bossou have shown that population-specific details of tool use, such as the selection of species of nuts as targets for cracking, cannot be explained purely on the basis of ecological differences. Second, a 16-year longitudinal record tracing the development of nut-cracking in individual chimpanzees has highlighted the importance of a critical period for learning (3-5 years of age), while the similar learning contexts experienced by siblings have been found to result in near-perfect (13 out of 14 dyads) inter-sibling correspondence in laterality. Third, novel data from field experiments involving the introduction of unfamiliar species of nuts to the Bossou group illuminates key aspects of both cultural innovation and transmission. We show that responses of individuals toward the novel items differ markedly with age, with juveniles being the most likely to explore. Furthermore, subjects are highly specific in their selection of conspecifics as models for observation, attending to the nut-cracking activities of individuals in the same age group or older, but not younger than themselves. Together with the phenomenon of inter-community migration, these results demonstrate a mechanism for the emergence of culture in wild chimpanzees.

Abstract: Abstract: Brain lateralization has been the matter of extensive research over the last centuries, but it remains an unsolved issue. While hand preferences have been extensively studied, very few studies have investigated laterality of eye use in non-human primates. We examined eye preference in 14 Campbell"s monkeys (Cercopithecus c. campbelli). We assessed eye preference to look at a seed placed inside a tube using monocular vision. Eye use was recorded for 100 independent and non-rewarded trials per individual. All of the 14 monkeys showed very strong preferences in the choice of the eye used to look inside the tube (mean preference: 97.6%). Eight subjects preferred the right eye and six subjects preferred the left eye. The results are discussed in light of previous data on eye preference in primates, and compared to data on hand preference from these subjects. Our findings would support the hypothesis for an early emergence of lateralization for perceptual processes compared to manual motor functions.

Abstract: Laterality in horses has been studied in recent decades. Although most horses are kept for riding purposes, there has been almost no research on how laterality may be affected by carrying a rider. In this study, 23 horses were tested for lateral preferences, both with and without a rider, in three different experiments. The rider gave minimal aids and rode on a long rein to allow the horse free choice. Firstly, motor laterality was assessed by observing forelimb preference when stepping over a pole. Secondly, sensory laterality was assessed by observing perceptual side preferences when the horse was confronted with (a) an unfamiliar person or (b) a novel object. After applying a generalised linear model, this preliminary study found that a rider increased the strength of motor laterality (p = 0.01) but did not affect sensory laterality (p = 0.8). This suggests that carrying a rider who is as passive as possible does not have an adverse effect on a horse�s stress levels and mental state.