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The snail looking into a microscope appeared at the end of the introductory essay announcing the launch of new journal—The American Naturalist—in March 1867. It was drawn by E. S. Morse, one of the journal's founders. Morse also illustrated his article, "The Land Snails of New England," in that issue, though those snails are less studious.

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Seasonal plasticity in the adult brain

Trends in Neurosciences Volume 23, Issue 6 June 01, 2000

Anthony D. Tramontin, Eliot A. Brenowitz

Seasonal plasticity of structure and function is a fundamental feature of nervous systems in a wide variety of animals that occupy seasonal environments. Excellent examples of seasonal brain changes are found in the avian song control system, which has become a leading model of morphological and functional plasticity in the adult CNS. The volumes of entire brain regions that control song increase dramatically in anticipation of the breeding season. These volumetric changes are induced primarily by vernal increases in circulating sex steroids and are accompanied by increases in neuronal size, number and spacing. In several species, these structural changes in the song control circuitry are associated with seasonal changes in song production and learning. Songbirds provide important insights into the mechanisms and behavioral consequences of plasticity in the adult brain.

doi: 10.1016/s0166-2236(00)01558-7

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Social diffusion of novel foraging methods in brown capuchin monkeys (Cebus apella)

Proceedings of the Royal Society of London. Series B, Biological sciences 31 Oct 2007

Marietta Dindo, Bernard Thierry, Andrew Whiten

It has been reported that wild capuchin monkeys exhibit several group-specific behavioural traditions. By contrast, experiments have found little evidence for the social learning assumed necessary to support such traditions. The present study used a diffusion chain paradigm to investigate whether a novel foraging task could be observationally learned by capuchins (Cebus apella) and then transmitted along a chain of individuals. [The authors] used a two-action paradigm to control for independent learning. Either of two methods (lift or slide) could be used to open the door of a foraging apparatus to retrieve food. Two chains were tested (N1=4; N2=5), each beginning with an experimenter-trained model who demonstrated to a partner its group-specific method for opening the foraging apparatus. After the demonstration, if the observer was able to open the apparatus 20 times by either method, then it became the demonstrator for a new subject, thus simulating the spread of a foraging tradition among ‘generations’ of group members. Each method was transmitted along these respective chains with high fidelity, echoing similar results presently available only for chimpanzees and children. These results provide the first clear evidence for faithful diffusion of alternative foraging methods in monkeys, consistent with claims for capuchin traditions in the wild.

doi: 10.1098/rspb.2007.1318

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Conformism in the food processing techniques of white-faced capuchin monkeys (Cebus capucinus)

Animal Cognition, 20 May 2009

Susan Perry

Researchers of “culture” have long been interested in the role of social learning in establishing patterns of behavioral variation in wild animals, but very few studies examine this issue using a developmental approach. This 7-year study examines the acquisition of techniques used to process Luehea candida fruits in a wild population of white-faced capuchin monkeys, Cebus capucinus, residing in and near Lomas Barbudal Biological Reserve, Costa Rica. The two techniques for extracting seeds (pounding or scrubbing) were approximately equal in efficiency, and subjects experimented with both techniques before settling on one technique—typically the one they most frequently observed. In a sample of 106 subjects that had already settled on a preferred technique, the females adopted the maternal technique significantly more often than expected by chance, but the males did not. Using a longitudinal approach, [the author] examined the acquisition of Luehea processing techniques during the first 5 years of life. Regression analysis revealed that the technique most frequently observed (measured as proportion of Luehea processing bouts observed that used pounding as opposed to scrubbing) significantly predicted the technique adopted by female observers, particularly in the second year of life; the amount of impact of the observed technique on the practiced technique was somewhat less significant for male observers. These results held true for (a) observations of maternal technique only, (b) observations of technique used by all individuals other than the mother, and (c) observations of maternal and non-maternal techniques combined.

doi: 10.1007/s10071-009-0230-3

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Extreme binocular vision and a straight bill facilitate tool use in New Caledonian crows

Nature Communications 3:1110, 2012

Jolyon Troscianko, Auguste M.P. von Bayern, Jackie Chappell, Christian Rutz, Graham R. Martin

Humans are expert tool users, who manipulate objects with dextrous hands and precise visual control. Surprisingly, morphological predispositions, or adaptations, for tool use have rarely been examined in non-human animals. New Caledonian crows Corvus moneduloides use their bills to craft complex tools from sticks, leaves and other materials, before inserting them into deadwood or vegetation to extract prey. Here we show that tool use in these birds is facilitated by an unusual visual-field topography and bill shape. Their visual field has substantially greater binocular overlap than that of any other bird species investigated to date, including six non-tool-using corvids. Furthermore, their unusually straight bill enables a stable grip on tools, and raises the tool tip into their visual field's binocular sector. These features enable a degree of tool control that would be impossible in other corvids, despite their comparable cognitive abilities. To our knowledge, this is the first evidence for tool-use-related morphological features outside the hominin lineage.

doi: 10.1038/ncomms2111

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Sponge Carrying by Dolphins (Delphinidae, Tursiops sp.): A Foraging Specialization Involving Tool Use?

Ethology 103, 1997

Rachel Smolker, Andrew Richards, Richard Connor, Janet Mann, Per Berggren

During long-term research on bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia, several individuals were observed carrying sponges, Echinodictyum mesenterinum, on their rostra. Over multiple years, five regularly sighted individuals were usually carrying sponges when encountered (67–100% of encounters). Four additional regularly sighted individuals were observed with sponges just one time each. All five individuals that routinely carried sponges were female. Two of the anomalous, one-time carriers were female, one was likely female, and one was male. Most observations of sponge carrying occurred within a restricted area, a relatively deep water channel (8–10 m deep). Surface observations of sponge carrying, including focal animal observations, revealed a stereotyped surfacing and diving pattern, and occasional indications of prey consumption. Three hypotheses are considered regarding the function of sponge carrying: 1. dolphins were playing with the sponges; 2. the sponges contain some compound of use to the dolphins (e.g. for medicinal purposes); and 3. the sponges were used as a tool to aid in foraging. The foraging tool hypothesis is best supported, but the exact manner in which sponges are used remains to be discovered. Sponge carrying is a behavioural specialization, probably involving foraging, and regularly engaged in by only a small proportion of female dolphins in Shark Bay.

doi: 10.1111/j.1439-0310.1997.tb00160.x

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Manufacture and use of allogrooming tools by wild killer whales

Current Biology Volume 35, Issue 12, 23 June 2025

Michael N. Weiss, Rachel E. John, Alondra M. Caro-Ruiz, David K. Ellifrit, Charli A. Grimes, Taylor A. Redmond, Arlene A. Vargas, Darren P. Croft

The manufacture and use of tools, while widespread in terrestrial animals, has been less frequently reported in marine taxa. In cetaceans, clear examples of tool use are largely restricted to foraging contexts, with no reports of cetaceans fashioning tools by modifying objects. Here, we report evidence of the widespread manufacture and use of allogrooming tools in a population of resident killer whales (Orcinus orca ater).

doi: 10.1016/j.cub.2025.04.021

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A group-specific arbitrary tradition in chimpanzees (Pan troglodytes)

Animal Cognition Volume 17, 11 June 2014

Edwin J. C. van Leeuwen, Katherine A. Cronin, Daniel B. M. Haun

Social learning in chimpanzees has been studied extensively and it is now widely accepted that chimpanzees have the capacity to learn from conspecifics through a multitude of mechanisms. Very few studies, however, have documented the existence of spontaneously emerged traditions in chimpanzee communities. While the rigour of experimental studies is helpful to investigate social learning mechanisms, documentation of naturally occurring traditions is necessary to understand the relevance of social learning in the real lives of animals. In this study, we report on chimpanzees spontaneously copying a seemingly non-adaptive behaviour (“grass-in-ear behaviour”). The behaviour entailed chimpanzees selecting a stiff, straw-like blade of grass, inserting the grass into one of their own ears, adjusting the position, and then leaving it in their ear during subsequent activities. Using a daily focal follow procedure, over the course of 1 year, we observed 8 (out of 12) group members engaging in this peculiar behaviour. Importantly, in the three neighbouring groups of chimpanzees (n = 82), this behaviour was only observed once, indicating that ecological factors were not determiners of the prevalence of this behaviour. These observations show that chimpanzees have a tendency to copy each other’s behaviour, even when the adaptive value of the behaviour is presumably absent.

doi: 10.1007/s10071-014-0766-8

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Wolves Are Better Imitators of Conspecifics than Dogs

PLOS One, 29 January 2014

Friederike Range, Zsófia Virányi

Domestication is thought to have influenced the cognitive abilities of dogs underlying their communication with humans, but little is known about its effect on their interactions with conspecifics. Since domestication hypotheses offer limited predictions in regard to wolf-wolf compared to dog-dog interactions, we extend the cooperative breeding hypothesis suggesting that the dependency of wolves on close cooperation with conspecifics, including breeding but also territory defense and hunting, has created selection pressures on motivational and cognitive processes enhancing their propensity to pay close attention to conspecifics’ actions. During domestication, dogs’ dependency on conspecifics has been relaxed, leading to reduced motivational and cognitive abilities to interact with conspecifics. Here we show that 6-month-old wolves outperform same aged dogs in a two-action-imitation task following a conspecific demonstration. While the wolves readily opened the apparatus after a demonstration, the dogs failed to solve the problem. This difference could not be explained by differential motivation, better physical insight of wolves, differential developmental pathways of wolves and dogs or a higher dependency of dogs from humans. Our results are best explained by the hypothesis that higher cooperativeness may come together with a higher propensity to pay close attention to detailed actions of others and offer an alternative perspective to domestication by emphasizing the cooperativeness of wolves as a potential source of dog-human cooperation.

doi: 10.1371/journal.pone.0086559

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Defensive tool use in a coconut-carrying octopus

Current Biology Volume 19, Issue 23, 15 December 2009

Julian K. Finn, Tom Tregenza, Mark D. Norman

The use of tools has become a benchmark for cognitive sophistication. Originally regarded as a defining feature of our species, tool-use behaviours have subsequently been revealed in other primates and a growing spectrum of mammals and birds [1]. Among invertebrates, however, the acquisition of items that are deployed later has not previously been reported. We repeatedly observed soft-sediment dwelling octopuses carrying around coconut shell halves, assembling them as a shelter only when needed. Whilst being carried, the shells offer no protection and place a requirement on the carrier to use a novel and cumbersome form of locomotion — ‘stilt-walking’.

doi: 10.1016/j.cub.2009.10.052

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A Simple Reason for a Big Difference: Wolves Do Not Look Back at Humans, but Dogs Do

Current Biology Volume 13, Issue 9, 29 April 2003

Ádám Miklósi, Enikö Kubinyi, József Topál, Márta Gácsi, Zsófia Virányi, Vilmos Csányi

The present investigations were undertaken to compare interspecific communicative abilities of dogs and wolves, which were socialized to humans at comparable levels. The first study demonstrated that socialized wolves were able to locate the place of hidden food indicated by the touching and, to some extent, pointing cues provided by the familiar human experimenter, but their performance remained inferior to that of dogs. In the second study, we have found that, after undergoing training to solve a simple manipulation task, dogs that are faced with an insoluble version of the same problem look/gaze at the human, while socialized wolves do not. Based on these observations, we suggest that the key difference between dog and wolf behavior is the dogs' ability to look at the human's face. Since looking behavior has an important function in initializing and maintaining communicative interaction in human communication systems, we suppose that by positive feedback processes (both evolutionary and ontogenetically) the readiness of dogs to look at the human face has lead to complex forms of dog-human communication that cannot be achieved in wolves even after extended socialization.

doi: 10.1016/S0960-9822(03)00263-X