Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians. Primates arose 85–55 million years ago first from small terrestrial mammals, which adapted to living in the trees of tropical forests: many primate characteristics represent adaptations to life in this challenging environment, including large brains, visual acuity, color vision, a shoulder girdle allowing a large degree of movement in the shoulder joint, and dexterous hands. Primates range in size from Madame Berthe's mouse lemur, which weighs 30 g (1 oz), to the eastern gorilla, weighing over 200 kg (440 lb). There are 376–524 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the 2000s, 36 in the 2010s, and three in the 2020s.
The bonobo, also historically called the pygmy chimpanzee, is an endangered great ape and one of the two species making up the genus Pan. While bonobos are, today, recognized as a distinct species in their own right, they were initially thought to be a subspecies of Pan troglodytes, due to the physical similarities between the two species. Taxonomically, the members of the chimpanzee/bonobo subtribe Panina—composed entirely by the genus Pan—are collectively termed panins.
Apes are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia, which together with its sister group Cercopithecidae form the catarrhine clade, cladistically making them monkeys. Apes do not have tails due to a mutation of the TBXT gene. In traditional and non-scientific use, the term ape can include tailless primates taxonomically considered Cercopithecidae, and is thus not equivalent to the scientific taxon Hominoidea. There are two extant branches of the superfamily Hominoidea: the gibbons, or lesser apes; and the hominids, or great apes.
Franciscus Bernardus Maria "Frans" de Waal is a Dutch primatologist and ethologist. He is the Charles Howard Candler Professor of Primate Behavior in the Department of Psychology at Emory University in Atlanta, Georgia, director of the Living Links Center at the Yerkes National Primate Research Center at Emory, and author of numerous books including Chimpanzee Politics (1982) and Our Inner Ape (2005). His research centers on primate social behavior, including conflict resolution, cooperation, inequity aversion, and food-sharing. He is a member of the United States National Academy of Sciences and the Royal Netherlands Academy of Arts and Sciences.
Research into great ape language has involved teaching chimpanzees, bonobos, gorillas and orangutans to communicate with humans and each other using sign language, physical tokens, lexigrams, and imitative human speech. Some primatologists argue that the use of these communication methods indicate primate "language" ability, though this depends on one's definition of language.
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.
Michael Tomasello is an American developmental and comparative psychologist, as well as a linguist. He is professor of psychology at Duke University.
Emily Sue Savage-Rumbaugh is a psychologist and primatologist most known for her work with two bonobos, Kanzi and Panbanisha, investigating their linguistic and cognitive abilities using lexigrams and computer-based keyboards. Originally based at Georgia State University's Language Research Center in Atlanta, Georgia, she worked at the Iowa Primate Learning Sanctuary in Des Moines, Iowa from 2006 until her departure in November 2013. She currently sits on the Board of Directors of Bonobo Hope.
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.
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.
The cooperative eye hypothesis is a proposed explanation for the appearance of the human eye. It suggests that the eye's distinctive visible characteristics evolved to make it easier for humans to follow another's gaze while communicating or while working together on tasks.
Josep Call is a Spanish comparative psychologist specializing in primate cognition.
Culture and social cognition is the relationship between human culture and human cognitive capabilities. Cultural cognitive evolution proposes that humans’ unique cognitive capacities are not solely due to biological inheritance, but are in fact due in large part to cultural transmission and evolution. Modern humans and great apes are separated evolutionarily by about six million years. Proponents of cultural evolution argue that this would not have been enough time for humans to develop the advanced cognitive capabilities required to create tools, language, and build societies through biological evolution. Biological evolution could not have individually produced each of these cognitive capabilities within that period of time. Instead, humans must have evolved the capacity to learn through cultural transmission. This provides a more plausible explanation that would fit within the given time frame. Instead of having to biologically account for each cognitive mechanism that distinguishes modern humans from previous relatives, one would only have to account for one significant biological adaptation for cultural learning. According to this view, the ability to learn through cultural transmission is what distinguishes humans from other primates. Cultural learning allows humans to build on existing knowledge and make collective advancements, also known as the “ratchet effect”. The ratchet effect simply refers to the way in which humans continuously add on to existing knowledge through modifications and improvements. This unique ability distinguishes humans from related primates, who do not seem to build collaborative knowledge over time. Instead, primates seem to build individual knowledge, in which the expertise of one animal is not built on by others, and does not progress across time.
Deep social mind is a concept in evolutionary psychology; it refers to the distinctively human capacity to 'read' the mental states of others while reciprocally enabling those others to read one's own mental states at the same time. The term 'deep social mind' was first coined in 1999 by Andrew Whiten, professor of Evolutionary and Developmental Psychology at St. Andrews University, Scotland. Together with closely related terms such as 'reflexivity' and 'intersubjectivity', it is now well-established among scholars investigating the evolutionary emergence of human sociality, cognition and communication.
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.
Pointing is a gesture specifying a direction from a person's body, usually indicating a location, person, event, thing or idea. It typically is formed by extending the arm, hand, and index finger, although it may be functionally similar to other hand gestures. Types of pointing may be subdivided according to the intention of the person, as well as by the linguistic function it serves.
Inequity aversion in animals is the willingness to sacrifice material pay-offs for the sake of greater equality, something humans tend to do from early age. It manifests itself through negative responses when rewards are not distributed equally between animals. In controlled experiments it has been observed, to varying degrees, in capuchin monkeys, chimpanzees, macaques, marmosets, dogs, wolves, rats, crows and ravens. No evidence of the effect was found in tests with orangutans, owl monkeys, squirrel monkeys, tamarins, kea, and cleaner fish. Based on mixed results in experimental studies it may be concluded that some bonobos, baboons, gibbons, and gorillas are inequity averse. Disadvantageous inequity aversion, which occurs when the animal protests as it gets a lesser reward than another animal, is most common. But advantageous inequity aversion has been observed as well, in chimpanzees, baboons and capuchins: the animal protests when it gets a better reward. Scientists believe that sensitivity to inequity co-evolved with the ability to cooperate, as it helps to sustain benefitting from cooperation. There is little evidence for inequity aversion in non-cooperative species.
Clive D. L. Wynne is a British-Australian ethologist specializing in the behavior of dogs and their wild relatives. He has worked in the United States, Australia, and Europe, and is currently based at Arizona State University in Tempe, AZ. He was born and raised on the Isle of Wight, off the south coast of England, studied at University College London, and got his Ph.D. at Edinburgh University. He has studied the behavior of many species - ranging from pigeons to dunnarts, but starting around 2006 melded his childhood love of dogs with his professional training and now studies and teaches about the behavior of dogs and their wild relatives.
Survival of the Friendliest: Understanding Our Origins and Rediscovering Our Common Humanity is a book by anthropologist Brian Hare and writer Vanessa Woods, first published in 2020, based on Hare's research hypothesis of human self-domestication. The main thesis of the book is that late in human evolution Homo sapiens underwent a process of extreme selection for friendliness that led to the self-domestication syndrome, as seen in other animals. The self-domestication syndrome led to a series of cognitive changes that allowed modern humans to out compete other species of humans in the Pleistocene, including Neanderthals, and become the most successful mammal on the planet. Hare and Woods argue that self-domestication is an ongoing process that continues today.
