The evolution of cognition is the process by which life on Earth has gone from organisms with little to no cognitive function to a greatly varying display of cognitive function that we see in organisms today. Animal cognition is largely studied by observing behavior, which makes studying extinct species difficult. The definition of cognition varies by discipline; psychologists tend define cognition by human behaviors, while ethologists have widely varying definitions. Ethological definitions of cognition range from only considering cognition in animals to be behaviors exhibited in humans, while others consider anything action involving a nervous system to be cognitive.
Studying the evolution of cognition is accomplished through a comparative cognitive approach [1] [2] [3] where a cognitive ability and comparing it between closely related species and distantly related species. For example, a researcher may want to analyze the connection between spatial memory and food caching behavior. By examining two closely related animals (chickadees and jays) and/or two distantly related animals (jays and chipmunks), hypotheses could be generated about when and how this cognitive ability evolved. Another way cognition has been studied in animals, specifically insects, is through a cognitive test battery. This method measures "intelligence directly with a battery of cognitive tests rather than relying on proxies like relative brain size." [4]
Higher cognitive processes have evolved in many closely and distantly related animals. Some of these examples are considered convergent evolution, while others most likely shared a common ancestor that possessed higher cognitive function. For example, apes, humans, and cetaceans most likely had a common ancestor with high levels of cognition, and as these species diverged they all possessed this trait. Corvids (the crow family) and apes show similar cognitive abilities in some areas such as tool use. This ability is most likely an example of convergent evolution, due to their distant relatedness.
Social living is thought to have co-evolved with higher cognitive processes. It is hypothesized that higher cognitive function evolved to mitigate the negative effects of living in social groups. For example, the ability to recognize individual groups members could solve the problem of cheating behavior. If individuals within the group can keep track of the cheaters, then they can punish or exclude them from the group. There is also a positive correlation between relative brain size and aspects of sociality in some species [16] [17] There are many benefits to living in social groups such as division of labor and protection, but in order to reap these benefits the animals tend to possess high levels of cognition.
Many animals have complex mating rituals require higher levels of cognition to evaluate. [3] Birds are well known for their intense mating displays including swan dances that can last hours or even days. [18] There has also been studies on sexual selection and evolution of cognition in seed beetles. It shows that "cognitive ability did show sex-specificity: strong sexual selection improved cognitive ability for males but not females." [19]
Higher levels of cognition may have evolved to facilitate the formation of longer lasting relationships. Animals that form pair bonds and share parental responsibilities produce offspring that are more likely to survive and reproduce, which increases the fitness of these individuals. The cognitive requirements for this type of mating include the ability the differentiate individuals from their group and resolve social conflicts. [17]
Another hypothesis for the evolution of cognition is that cognition allowed individuals access to food and resources that were previously unavailable. For example, the genetic mutation for color vision allowed for a greatly increased efficiency in finding and foraging fruit. [1] Food caching behavior displayed in some birds and mammals is an example of a behavior that may have co-evolved with higher cognitive processes. This ability to store food for later consumption allows these animals to take advantage of temporary surpluses in food availability. [20] Corvids have displayed incredible abilities to create and remember the locations of up to hundreds of caches. [21] In addition, there is evidence that this is not just an instinctual behavior, but an example of future planning. Jays have been found to diversify the types of food they cache, possible indicating they understand the need to eat a variety of food. [22] Some supporters of this hypothesis suggest that higher cognitive processes require a large brain to body ratio. This higher brain to body size ratio in turn requires a large metabolic input to function. The idea is that the two processes (greater access to food and the brain's growing need for energy) may have snowballed the evolution of these two features.
The cognitive ability to use tools and pass information from one generation to the next is thought to have been a driving force of the evolution of cognition. Many animals use tools including: primates, elephants, cetaceans, birds, fish, and some invertebrates. [3] Tool use varies widely depending on the species. For example, sea otters have been observed using a rock to break open snail shells, while primates and New Caledonian crows have demonstrated an ability to fashion a new tool for a specific use. [23] The ability to use tools seems to provide animals with a fitness advantage, usually in the form of access to food previously unavailable, which allows a competitive advantage for these individuals.
Some animals have demonstrated the ability to pass information from one generation to the next (culture) including: primates, cetaceans, and birds. [3] Primates and birds can pass information of specific tool use strategies on to their offspring who can, in turn, pass it on to their offspring. In this way, the information can remain in a group on individuals even after the original users are gone. One famous example of this is in a group of macaque monkeys in Japan. Researchers studying this species observed these monkeys feeding behavior in a population in Japan. The researchers witnessed one female, named Imo, realize that by washing potatoes in the nearby river you could remove much more sand and dirt then by simply wiping it off. Over the next few generations the researcher saw this behavior begin to appear in other individuals throughout the group. [24]
Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, magpies, jackdaws, jays, treepies, choughs, and nutcrackers. In colloquial English, they are known as the crow family or corvids. Currently, 135 species are included in this family. The genus Corvus containing 47 species makes up over a third of the entire family. Corvids (ravens) are the largest passerines.
In primatology, Machiavellian intelligence is the capacity of an organism to be in a successful political engagement with social groups. The first introduction of this concept came from Frans de Waal's book Chimpanzee Politics (1982). In the book de Waal notes that chimpanzees performed certain social maneuvering behaviors that reminded him of the works of Machiavelli.
Cetacean intelligence is the overall intelligence and derived cognitive ability of aquatic mammals belonging in the infraorder Cetacea (cetaceans), including baleen whales, porpoises, and dolphins. In 2014, a study found for first time that the long-finned pilot whale has more neocortical neurons than any mammal studied to date, including humans.
Animal cognition encompasses the mental capacities of non-human animals including insect cognition. The study of animal conditioning and learning used in this field was developed from comparative psychology. It has also been strongly influenced by research in ethology, behavioral ecology, and evolutionary psychology; the alternative name cognitive ethology is sometimes used. Many behaviors associated with the term animal intelligence are also subsumed within animal cognition.
Dog intelligence or dog cognition is the process in dogs of acquiring information and conceptual skills, and storing them in memory, retrieving, combining and comparing them, and using them in new situations.
Brain–body mass ratio, also known as the brain–body weight ratio, is the ratio of brain mass to body mass, which is hypothesized to be a rough estimate of the intelligence of an animal, although fairly inaccurate in many cases. A more complex measurement, encephalization quotient, takes into account allometric effects of widely divergent body sizes across several taxa. The raw brain-to-body mass ratio is however simpler to come by, and is still a useful tool for comparing encephalization within species or between fairly closely related species.
Encephalization quotient (EQ), encephalization level (EL), or just encephalization is a relative brain size measure that is defined as the ratio between observed and predicted brain mass for an animal of a given size, based on nonlinear regression on a range of reference species. It has been used as a proxy for intelligence and thus as a possible way of comparing the intelligence levels of different species. For this purpose, it is a more refined measurement than the raw brain-to-body mass ratio, as it takes into account allometric effects. Expressed as a formula, the relationship has been developed for mammals and may not yield relevant results when applied outside this group.
The California scrub jay is a species of scrub jay native to western North America. It ranges from southern British Columbia throughout California and western Nevada near Reno to west of the Sierra Nevada. The California scrub jay was once lumped with Woodhouse's scrub jay and collectively called the western scrub jay. The group was also lumped with the island scrub jay and the Florida scrub jay; the taxon was then called simply scrub jay. The California scrub jay is nonmigratory and can be found in urban areas, where it can become tame and will come to bird feeders. While many refer to scrub jays as "blue jays", the blue jay is a different species of bird entirely.
Hoarding or caching in animal behavior is the storage of food in locations hidden from the sight of both conspecifics and members of other species. Most commonly, the function of hoarding or caching is to store food in times of surplus for times when food is less plentiful. However, there is evidence that a certain amount of caching or hoarding is actually undertaken with the aim of ripening the food so stored, and this practice is thus referred to as ‘ripening caching’. The term hoarding is most typically used for rodents, whereas caching is more commonly used in reference to birds, but the behaviors in both animal groups are quite similar.
The evolution of human intelligence is closely tied to the evolution of the human brain and to the origin of language. The timeline of human evolution spans approximately seven million years, from the separation of the genus Pan until the emergence of behavioral modernity by 50,000 years ago. The first three million years of this timeline concern Sahelanthropus, the following two million concern Australopithecus and the final two million span the history of the genus Homo in the Paleolithic era.
The difficulty of defining or measuring intelligence in non-human animals makes the subject difficult to study scientifically in birds. In general, birds have relatively large brains compared to their head size. Furthermore, bird brains have two-to-four times the neuron packing density of mammal brains, for higher overall efficiency. The visual and auditory senses are well developed in most species, though the tactile and olfactory senses are well realized only in a few groups. Birds communicate using visual signals as well as through the use of calls and song. The testing of intelligence in birds is therefore usually based on studying responses to sensory stimuli.
Cognitive specialization suggests that certain behaviors, often in the domain of social communication, are passed on to offspring and refined to be maximally beneficial by the process of natural selection. Specializations serve an adaptive purpose for an organism by allowing the organism to be better suited for its habitat. Over time, specializations often become essential to the species' continued survival. Cognitive specialization in humans has been thought to underlie the acquisition, development, and evolution of language, theory of mind, and specific social skills such as trust and reciprocity. These specializations are considered to be critical to the survival of the species, even though there are successful individuals who lack certain specializations, including those diagnosed with autism spectrum disorder or who lack language abilities. Cognitive specialization is also believed to underlie adaptive behaviors such as self-awareness, navigation, and problem solving skills in several animal species such as chimpanzees and bottlenose dolphins.
Animal culture can be defined as the ability of non-human animals to learn and transmit behaviors through processes of social or cultural learning. Culture is increasingly seen as a process, involving the social transmittance of behavior among peers and between generations. It can involve the transmission of novel behaviors or regional variations that are independent of genetic or ecological factors.
Mate choice is one of the primary mechanisms under which evolution can occur. It is characterized by a "selective response by animals to particular stimuli" which can be observed as behavior. In other words, before an animal engages with a potential mate, they first evaluate various aspects of that mate which are indicative of quality—such as the resources or phenotypes they have—and evaluate whether or not those particular trait(s) are somehow beneficial to them. The evaluation will then incur a response of some sort.
Comparative cognition is the comparative study of the mechanisms and origins of cognition in various species, and is sometimes seen as more general than, or similar to, comparative psychology. From a biological point of view, work is being done on the brains of fruit flies that should yield techniques precise enough to allow an understanding of the workings of the human brain on a scale appreciative of individual groups of neurons rather than the more regional scale previously used. Similarly, gene activity in the human brain is better understood through examination of the brains of mice by the Seattle-based Allen Institute for Brain Science, yielding the freely available Allen Brain Atlas. This type of study is related to comparative cognition, but better classified as one of comparative genomics. Increasing emphasis in psychology and ethology on the biological aspects of perception and behavior is bridging the gap between genomics and behavioral analysis.
Animal consciousness, or animal awareness, is the quality or state of self-awareness within an animal, or of being aware of an external object or something within itself. In humans, consciousness has been defined as: sentience, awareness, subjectivity, qualia, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind. Despite the difficulty in definition, many philosophers believe there is a broadly shared underlying intuition about what consciousness is.
Primate cognition is the study of the intellectual and behavioral skills of non-human primates, particularly in the fields of psychology, behavioral biology, primatology, and anthropology.
Theory of mind in animals is an extension to non-human animals of the philosophical and psychological concept of theory of mind (ToM), sometimes known as mentalisation or mind-reading. It involves an inquiry into whether non-human animals have the ability to attribute mental states to themselves and others, including recognition that others have mental states that are different from their own. To investigate this issue experimentally, researchers place non-human animals in situations where their resulting behavior can be interpreted as supporting ToM or not.
The cooperative pulling paradigm is an experimental design in which two or more animals pull rewards toward themselves via an apparatus that they cannot successfully operate alone. Researchers use cooperative pulling experiments to try to understand how cooperation works and how and when it may have evolved.
Researchers study the reactions of animals observing humans performing magic tricks in order to better understand animal cognition. Using these studies, evolutionary psychologists aim to gain insights into the evolution of perception and attention by comparing responses of different species, including humans.