Tools give humans superpowers, so why don’t all animals use them? Though technology is ubiquitous in our own species, we remain unable to predict when, why, and among whom tool use will arise elsewhere in the animal kingdom. Recent decades’ research by biologists, ethologists, and archaeologists has displaced a longstanding scientific rendering of humans as the exclusive tool-using taxon. Tool users inhabit diverse bodies and environments; from ants to archerfish, crabs to cockatoos. Many of these animals engage in tool use with bodies, minds, and sensory apparatuses, in habitats, and at scales very unlike our own. Given this recent sea-change in our understanding of who can be a tool user, we are presented with an opportunity to return to first principles. What exactly is tool use? Who are tool users, and what unites them? Is it possible—or even useful—to identify common traits, qualities, circumstances, or conditions among phylogenetically disparate tool-users? What does tool use tell us that we need to know? Here we take a pragmatic approach and define tools as enabling objects, and tool use as attentional use of such objects, agnostic to neural and physical anatomy. In reviewing animal technologies we identify active, timely feedback loops as critical for tool use adoption. Cybernetics emerges as an appropriate analytical framework; tool-using animals are temporary natural cyborgs. Ideas from game theory and behavioral economics then inform how technological innovations stabilize or vanish. We conclude that while nearly all animals can use tools, many face prohibitive physical, sensory, and social constraints, coupled to chance events. Viewing this behavior not as a fixed trait but as contingent, dynamic and continually reliant on environmental support offers insight into captive animal tool use and the partial uptake of tools in cohabiting groups. Our approach situates the hyper-reliance of humans on tools within our evolutionary milieu, and eliminates the need for special pleading when tool use arises in nonhuman contexts.
For humans, the face is a socially important visual stimulus, and the evolution of face perception has received considerable attention in research on non-human primates. However, little is known about face perception in gibbons, a key phylogenetic group among apes and humans. To address this gap, we used an eye-tracking device to examine how gibbons view face photographs, with the participation of three male adult gibbons. A total of 48 stimuli, consisting of gibbon and human faces showing neutral expressions were presented, and the gibbons were allowed to view them freely. Areas of interest (AOI) were defined for the eyes, nose, mouth, face periphery, and background in each image. We tested the effects of the AOIs and presented face species on viewing time. In analyses pooling data across individuals, gibbons spent significantly more time viewing the eyes than any other area and viewed gibbon eyes longer than human eyes. In separate analyses for each individual, two gibbons viewed the eyes significantly longer than the nose or mouth. Longer viewing times for gibbon eyes than human eyes were observed in all individuals. These results indicate that eyes are a highly salient facial feature for gibbons, albeit variably among individuals, and that gibbons’ viewing patterns differ when looking at a conspecific or an allospecific face. These findings are consistent with face-scanning studies in macaques and great apes. Further studies are needed to confirm the generality of these results and to uncover other characteristics of gibbon face perception.
Knowledge of Odontocete developmental patterns is important for general comparative understanding and the implementation of informed husbandry policies. Although beluga whale (Delphinapterus leucas) calf behavioral development has previously been assessed in the literature, no previous studies have attempted to observe the behavioral development of Pacific white-sided dolphins (Aethalodelphis obliquidens). Seven beluga whale calves and four Pacific white-sided dolphin calves were observed for the first 30 days of life to determine the first occurrence and developmental trajectory of several typically monitored behaviors. Generalized linear mixed models (GLMMs) were used to evaluate the first 30 days for each behavior in successful calves. Beluga calves nursed for significantly longer duration (s/bout), but not frequencies (bouts/hr) compared to Pacific white-sided dolphins. Nursing duration was highest for belugas in the first 10 days of life, but otherwise nursing duration and frequency did not change significantly over time for belugas or Pacific white-sided dolphins. Overall respiration rates across the 30 days did not significantly differ between species, but beluga rates significantly increased over time while Pacific white-sided dolphin rates decreased. Pacific white-sided dolphins spent significantly more time associating with their dams and swimming in the slipstream position than belugas, and only Pacific white-sided dolphins saw significant decreases in these behaviors over time. The results of this study provide additional information regarding Odontocete developmental norms. Future research should continue to focus on calf behavioral development with the goal of increasing calf survival rates and promoting positive welfare in managed care.
Howler monkeys (Alouatta) are characterized as energy minimizers, featuring a reduced daily foraging range, an above-branch quadrupedal positional repertoire and a reduced forelimb motion. The present study quantifies how these behavioral features influence the reach and grasp of the mantled howler monkey (Alouatta palliata) for harvesting a diet of leaves, fruit, flowers and vines. Wild howler monkeys, habituated to human observers, were filmed in Sector Santa Rosa (SSR), Área de Conservación Guanacaste in northwestern Costa Rica. Video recordings of the monkeys harvesting 20 food species were subject to frame-by-frame analysis. The monkeys suspended themselves by their tail for 58% of 2208 reaches. On 99% of reaches they hooked a branch with a power grasp and pulled it toward their mouth. Reaching for a branch featured a pronated hand and upper arm abduction/adduction with minimal hand or arm rotation. Fruit and flowers were plucked from the branch using the incisors and leaves were plucked using the molars. Plucking a food item from a branch was aided by lower arm extension that relaxed the hand’s pull on a branch, allowing the recoil of the branch to jerk the food from the branch. Independent grasps by hand (249 observations) were only used to adjust food in the mouth or take food from the mouth to reorient it for selective biting. Howler monkey tail prehension and branch withdraw feeding thus represents an almost exclusive use of a reach strategy with little/no use of an independent grasp by the hands or mouth. In requiring little hand or finger skill, branch pulling may contribute to the howler monkey’s energy minimizing lifestyle. This reduced motoric commitment to eating may enable a concordant reduction in brain size as a further source of energy minimization. The findings support the idea that variation in the use of the reach and the grasp contribute to the feeding diversity of primates.
Managed care facilities are confronted with many challenges when caring for animals. One of them is balancing the possibility for a species to express its natural behavioral repertoire, and being able to reproduce, with the constraint of available space for the social group. Recent reproductive bans for cetaceans in managed care have been implemented without considering the effects of a calf birth to a social group. Our goal was to investigate whether the presence of pre-weaned calves in a social group influenced activity level and engagement among group members, including but not limited to the mother(s). When pre-weaned calves were present, larger dolphin groups were observed with spacing among members dependent upon calf age; groups with younger calves exhibited tighter clusters whereas groups with older calves were loosely spaced. Also, more diverse behaviors, inter-individual contacts, intensity of exchange(s), and number of individuals involved were documented for groups with pre-weaned calves. These results support the notion that presence of one or more pre-weaned calves enhances the overall well-being and welfare of a dolphin social group as not only mothers but also other individuals in the group join calves to engage in behavioral exchanges that increases group size and diversity and intensity in activity level(s).
