Ants appeared in the Jurassic and diversified into a multitude of new forms during the Cretaceous, around 100 million years ago. Today, ants are ecologically dominant in most terrestrial ecosystems. In tropical rain forest, ant biomass is four times greater than the biomass of all the vertebrates. The trait common to all ant species is sociality: they are all social insects that live in colonies. As in human societies, the size of ant societies varies enormously, from just a few individuals to tens of millions. Ants show extraordinary adaptations. They evolved the ability to build complex nest structures; they cultivate fungi for food and milk aphids, thus practicing agriculture and animal farming; they have nurseries and cemeteries, they cooperate. The key to their evolutionary success is efficient division labour in which the colony behaves as an organism. To achieve this remarkable social organization, ants rely on effective communication. Even though they use several different channels, such as the visual, acoustic and tactile, chemical communication is the most widespread way to exchange messages in an ant colony. Ants have developed multicomponent body odours, a myriad of exocrine glands and refined chemosensory abilities.

Many studies have documented the types of memory evident in nonhuman primates.These range in time scales of remembering for seconds to remembering for minutes or even years. An important distinction in human memory is between recognition and recall modes of remembering. Recognition occurs when an external cue aids in memory performance, where the cue evokes the memory. Recall, however, requires a more spontaneous and internally driven memory process. In humans, recall typically is seen when people report experiences verbally, without need of specific cues. This is more difficult to demonstrate in nonhuman animals but can be done if a test can be used that provides no specific, recognizable cues included in the assessment of what is remembered. Some of those tests, as given to different nonhuman primate species, are outlined in this chapter. The resulting data indicate that nonhuman primates do engage in memory recall without the need of external cues, and the implications of this reflect another commonality in the cognitive systems of humans and other animals.

The social intelligence hypothesis states that a complex social life is cognitively challenging and thus a driving force for mental evolution. Support for the hypothesis comes mainly from studies on primates, and more recently also from birds, specifically corvids. In this paper, I review what is known about the socio-cognitive skills of common ravens, a corvid species that has been intensively studied over the past twenty-five years. The findings show that temporary foraging groups are composed of individuals with different degrees of familiarity and structured by different types of social relationships. Familiar ravens show profound knowledge about their own and others’ relationships, and they appear to use this knowledge selectively and strategically in cooperative and competitive settings. The studies on ravens may thus inform our understanding of what constitutes social complexity and which cognitive skills are selected for.

The history of attempts to identify a correlational structure across a battery of cognitive tasks in nonhumans is reviewed, specifically with respect to mice. The literature on human cognition has long included the idea that subjects retain something of their rank-ordering across a battery of cognitive tasks, yielding what is characterized as a positive manifold of cross-task correlations. This manifold is often referred to as marking a general intelligence factor (g). The literature on individual differences in nonhumans has until recently evidenced a different conclusion, one that emphasized the evolution of niche-specific adaptive specializations rather than the evolution of general cognitive mechanisms. That conclusion in the nonhuman literature has now been successfully challenged. There is little doubt that nonhuman subjects also reveal a positive manifold that is of a similar magnitudecompared to the human data. Problems remain in deciding whether this nonhuman g is the same g as is found using human subjects. The available data are promising but not decisive in suggesting that the two constructs are marking similar processes.

Fishes offer fantastic systems in which to study the evolutionary drivers of cognition because they comprise more than 30,000 species occupying a diverse range of habitats. Many researchers have taken advantage of this diversity to examine the ecological correlates of brain morphology and learning, but memory abilities per se are still fairly understudied compared to terrestrial vertebrates. Here, we review studies that have examined memory retention in fish, sharks, and rays and summarize the mechanisms of regulation of memory in these groups. Mechanisms of memory regulation are similar to those of terrestrial vertebrates, and it is clear that they can retain information from several days, months, and even years. We also address the potential for episodic-like memory in fish, which appears to be on par with evidence from other nonhuman vertebrates, further suggesting the process of memory retention is conserved across all vertebrates. In the last section of this review, we discuss avenues of memory research in which fish have been given little attention and highlight areas of future investigation.

Parrots are sometimes referred to as "feathered apes,"` as they rival our closest relatives in many cognitive abilities. Similar to apes, they show a high propensity for innovative behaviour. Factors that were suggested to influence innovativeness are manifold. We discuss the various reasons why parrots might be particularly well-equipped to innovate. Many psittaciformes have ecological backgrounds that have been suggested to correlate with innovativeness, and recent neurological findings suggest a link between their brain anatomy and advanced cognitive abilities. The parrots’ beak has been described as a "multi-purpose tool" that allows them to employ a wide range of motoric interactions with different substrates, foods, or objects. Moreover, parrots generally approach novel situations with curiosity and caution, and explore in a haptic and playful manner, which presumably provides them with more opportunities to innovate. Studies on model species in innovative problem-solving, such as the kea and the Goffin’s cockatoos, highlight their sensitivity to changes in their environment and their ability to flexibly adjust to them. Multiple parrot species show tool innovations in captivity. However, controlled comparisons between captive and wild populations are still scarce. In summary, studying innovation in large-brained, non-primate models, such as parrots, will ultimately contribute to our understanding of the evolution of inventive minds.

The ability to engage in some form of communication is essential for any social species. Communication generally relies on species-specific adaptations that provide animals with a cognitive tool to pass on messages from one conspecific to the other. This means that communication between members of different species is relatively rare and potentially requires qualitatively different cognitive abilities. This form of communication is not only challenging due to the fact that different species may rely on distinct sets of codes to convey messages but also because the primary modality used for this purpose may be different. Dogs represent a special case in the animal kingdom as they have been uniquely adapted to be receptive to the communicative signals of a species relatively distant in terms of their genome: humans. In this chapter, we will first focus on those characteristics of canids’ intraspecific communication that are shared between the dog and their phylogenetically closest relative, the wolf. Similarities in these forms of communication are likely the result of the common ancestry of the two species. Next, we turn to describing those attributes of canine communication that selectively pertain to how dogs communicate with their conspecifics. Finally, we discuss the ubiquitous nature of heterospecific communication between dogs and humans.

Episodic memory refers to the ability to recollect personal past events, allowing mental time travel.In contrast, semantic memory has been defined as the storage of general facts about the world. The field of comparative psychology has adopted this distinction in order to study what nonhuman animals recall about their past. The aim in this chapter is to reflect on the concept of episodic memory as well as on the experimental approaches used in comparative psychology to study this ability. A critical analysis of both the conceptualization of episodic memory and the experimental paradigms is provided.

This chapter reviews available evidence on cognitive contributions to orangutan innovation and problem-solving. Evidence derives from orangutans in three living conditions (wild, captive, rehabilitation), and as such includes spontaneous as well as experimentally elicited innovations. Reviewed are the range and quality of orangutans’ innovations and problem-solving, including instigating factors, cognitive complexity, and facilitating–inhibiting factors.

People remember specific earlier events that happened to them by using episodic memory. Accordingly, researchers have sought to evaluate the hypothesis that nonhumans retrieve episodic memories. The central hypothesis of an animal model of episodic memory proposes that, at the moment of memory assessment, the animal retrieves a memory of the specific earlier event. Testing this hypothesis requires the elimination of the hypothesis that animals solve such problems by using non-episodic memory. Most of the research on event memory in nonhumans focuses on memory of a single event. Here, I describe approaches that we have used with rats to move from episodic memory of one event to two events, to many events, and to sequentially ordered events. These studies focus on source memory, binding of episodic memories, remembering items-in-context, and the replay of episodic memories. Connections between episodic memory and hippocampal replay are explored. These approaches may be used to explore the evolution of cognition.

Humans often appear to defy principles of economic "rationality" when making decisions, by falling prey to a suite of choice biases including over-weighting immediate gratification, avoiding risk, treating identical options differently depending on whether they are perceived as a relative loss or gain, or attaching more value to objects in their possession. Here we examine what animals can tell us about these choice patterns. First, we provide an overview of different theoretical frameworks for rational decision making from psychology, economics, and biology. Next, we review empirical work examining how different species make decisions and discuss how many potentially puzzling patterns of decision making may be biologically adaptive when considering the environment in which they are made. Finally, we propose that integrating various theoretical perspectives with comparative data can elucidate the ultimate origins of variations in decision-making strategies across species and provide a new framework to illuminate the adaptive value of these strategies.

Over the past quarter of a century, scientists have attempted to answer the question of whether humans are unique in their self-reflective abilities, or whether versions of this might exist in nonhuman animals as well. This chapter explores the research on whether nonhuman primates (hereafter, primates) have the ability to monitor and control their own knowledge states, or metacognition. The chapter describes the two main paradigms that have traditionally been used to investigate this question, as well as their associated variations and limitations. This is followed by a summary of what has been found to date, with respect to metacognitive abilities across the primate order. The chapter concludes with a brief discussion of the questions that remain and areas for future investigation.

Many animals cooperate even with unrelated individuals in various contexts, like providing food or allogrooming others. One possibility to explain the evolution of such apparently altruistic behaviour is reciprocity. In reciprocal cooperative interactions, individuals help those partners that have been previously cooperative and therefore exchange favours. This conditional help follows rules like “I help you because you helped me.” These rules are often assumed to be so cognitively demanding that they may be limited to humans. In this chapter, I will shed light on the cognitive underpinnings of reciprocal cooperation by reviewing work on one of the yet best-studied animal in this research area, the Norway rat (Rattus norvegicus). Various studies have demonstrated that Norway rats reciprocally exchange different goods and services. They most likely form attitudes toward social partners that are based on the cooperation level of the last encounter, which they remember over long time spans. Cooperation decisions based on attitudes appear cognitively less complex than calculations of received and given favors. Thus, reciprocal cooperation based on this cognitive mechanism might be in fact more widespread among nonhuman animals than commonly believed.

By responding to information gained through observing or interacting with other individuals, fish can learn about important aspects of their environment, including where to forage, how to recognize and avoid predators, and who to mate with. Social learning processes are often closely intertwined with the social environment; whether individuals engage in social learning, who they learn from, and what they learn frequently depend on complex, nonrandom patterns of social interaction. Social network analysis provides a sophisticated toolset for quantifying such elements of social structure. In this chapter, we discuss how integrating social network approaches with investigations into social learning have provided novel and important insights regarding the ways in which fish acquire and use social information in realistic social contexts.

Innovation – the process that generates novel learned behaviours – is a defining feature of intelligence, and has long attracted the interest of scientists for its implications in brain evolution, emergence of culture, and adaptation to environmental changes. Although most animals have the capacity to innovate, only a few excel in their innovative capacities. A salient feature of these animals is a highly encephalized brain, which provides the cognitive basis for complex behaviors. Highly innovative animals also tend to be ecological generalists, long-lived and sociable, features that are thought to enhance the payoff of innovation. The evolutionary origin of innovative abilities is unclear, however, because innovating implies coping with problems the animal has not experienced before. A possibility is to consider innovation as an emergent property that results from the combination of cognitive and noncognitive traits that have coevolved as part of a life-history syndrome to cope with environmental changes. The coevolution of innovation and social learning capacities is particularly relevant because it has facilitated the accumulation of the knowledge needed for more complex behaviours. The ability to socially transmit knowledge may thus be behind the exceptional variety and sophistication of human innovations.

Behavioral innovation, the ability to invent new behaviors and/or use preexisting behaviors in a new context to respond to a novel situation, can be critical to an individual’s survival (i.e., natural selection). Less studied is how innovation can be critical for mating success (i.e., sexual selection). Bowerbirds are an excellent system to study the latter, given the likely importance of sexual selection to their diversification. Bowerbirds are a family of birds that show remarkable diversity in their unique construction of courtship arenas out of sticks and use of various colored objects as decorations. In this chapter, I give background on what bowerbirds are and present inadvertent evidence from experimental manipulations of their off-body sexual displays that bowerbirds are extremely flexible in their behavior. The bulk of the chapter reviews experiments in which novel problem-solving tasks were presented to bowerbirds and then their performance was compared to their mating success. I conclude by suggesting that an important future research goal should be to study how innovativeness affects the speciation process via sexual selection.

Although fish represent approximately half of vertebrates, the quantitative abilities of fish have been investigated only recently. Two methodological approaches commonly used with mammals and birds have been used: the observation of spontaneous behaviour and training procedures. In the former, fish are observed in their preference for reaching the larger or smaller quantities of biologically relevant stimuli (in most cases, whether they join a larger shoal when placed in an unfamiliar environment). In the latter, fish are trained to select the larger or the smaller of two sets of abstract objects (e.g., two-dimensional figures that differ in numerosity). These studies showed that different fish species process numerical information in a similar way to that of mammals and birds. In this chapter, we review the relevant literature, giving particular regard to the strength and potential weaknesses of the two methodological approaches.