Sociobiology

From Wikipedia, the free encyclopedia

Sociobiology is a field of scientific study which is based on the hypothesis that social behavior has resulted from evolution and attempts to explain and examine social behavior within that context. A branch of biology that deals with social behavior, it also draws from ethology, anthropology, evolution, zoology, archaeology, population genetics, and other disciplines. Within the study of human societies, sociobiology is very closely allied to the fields of Darwinian anthropology, human behavioral ecology and evolutionary psychology.

Sociobiology investigates social behaviors, such as mating patterns, territorial fights, pack hunting, and the hive society of social insects. It argues that just as selection pressure led to animals evolving useful ways of interacting with the natural environment, it led to the genetic evolution of advantageous social behavior.

While the term "sociobiology" can be traced to the 1940s, the concept didn't gain major recognition until 1975 with the publication of Edward O. Wilson's book, Sociobiology: The New Synthesis. The new field quickly became the subject of heated controversy. Criticism, most notably from Richard Lewontin and Stephen Jay Gould, centered on sociobiology's contention that genes play an ultimate role in human behavior and that traits such as aggressiveness can be explained by biology rather than a person's social environment. Sociobiologists generally responded to the criticism by pointing to the complex relationship between nature and nurture. Anthropologist John Tooby and psychologist Leda Cosmides founded the field of evolutionary psychology.

Definition

E. O. Wilson defines sociobiology as: “The extension of population biology and evolutionary theory to social organization”^[1]

Sociobiology is based on the premise that some behaviors (both social and individual) are at least partly inherited and can be affected by natural selection. It begins with the idea that behaviors have evolved over time, similar to the way that physical traits are thought to have evolved. It predicts, therefore, that animals will act in ways that have proven to be evolutionarily successful over time. This can, among other things, result in the formation of complex social processes conducive to evolutionary fitness.

The discipline seeks to explain behavior as a product of natural selection. Behavior is therefore seen as an effort to preserve one's genes in the population. Inherent in sociobiological reasoning is the idea that certain genes or gene combinations that influence particular behavioral traits can be inherited from generation to generation.^{[citation needed]}

Introductory example

For example, newly dominant male lions often will kill cubs in the pride that were not sired by them. This behavior is adaptive in evolutionary terms because killing the cubs eliminates competition for their own offspring and causes the nursing females to come into heat faster, thus allowing more of his genes to enter into the population.
Sociobiologists would view this instinctual cub-killing behavior as being inherited through the genes of successfully reproducing male lions, whereas non-killing behavior may have "died out" as those lions were less successful in reproducing.

Support for premise

Genetic mouse mutants have now been harnessed to illustrate the power that genes exert on behaviour. For example, the transcription factor FEV (aka Pet1) has been shown, through its role in maintaining the serotonergic system in the brain, to be required for normal aggressive and anxiety-like behavior.^[2] Thus, when FEV is genetically deleted from the mouse genome, male mice will instantly attack other males, whereas their wild-type counterparts take significantly longer to initiate violent behaviour. In addition, FEV has been shown to be required for correct maternal behaviour in mice, such that their offspring do not survive unless cross-fostered to other wild-type female mice.^[3]

A genetic basis for instinctive behavioural traits among non-human species, such as in the above example, is commonly accepted among many biologists; however, attempting to use a genetic basis to explain complex behaviours in human societies has remained extremely controversial.^{[citation needed]}

History

E. O. Wilson, a central figure in the history of sociobiology.

According to the OED, E. O. Wilson coined the word "sociobiology" at a 1946 conference on genetics and social behaviour, and it became widely used after it was popularized by Edward O. Wilson in his 1975 book, Sociobiology: The New Synthesis. However, the influence of evolution on behavior has been of interest to biologists and philosophers since soon after the discovery of evolution itself. Peter Kropotkin's Mutual Aid: A Factor of Evolution, written in the early 1890s, is a popular example. Antecedents of modern sociobiological thinking can be traced to the 1960s and the work of such biologists as Richard D. Alexander, Robert Trivers and William D. Hamilton. The idea of the inheritance of behaviour arose from J B S Haldane's idea about how "altruistic behaviour" (see Altruism) could be passed from generation to generation ^[4] Nonetheless, it was Wilson's book that pioneered and popularized the attempt to explain the evolutionary mechanics behind social behaviors such as altruism, aggression, and nurturence, primarily in ants (Wilson's own research specialty) but also in other animals (bees, wasps and termites).^[5] The final chapter of the book is devoted to sociobiological explanations of human behavior, and Wilson later wrote a Pulitzer Prize winning book, On Human Nature, that addressed human behavior specifically.

Edward H. Hagen writes in The Handbook of Evolutionary Psychology that sociobiology is, despite the public controversy regarding the applications to humans, "one of the scientific triumphs of the twentieth century." "Sociobiology is now part of the core research and curriculum of virtually all biology departments, and it is a foundation of the work of almost all field biologists" Sociobiological research on nonhuman organisms has increased dramatically and continuously in the world's top scientific journals such as Nature and Science. The more general term behavioral ecology is commonly used as substitute for the term sociobiology in order to avoid the public controversy.^[6]

Sociobiological theory

Sociobiologists believe that human behavior, as well as nonhuman animal behavior, can be partly explained as the outcome of natural selection. They contend that in order to fully understand behavior, it must be analyzed in terms of evolutionary considerations.

Natural selection is fundamental to evolutionary theory. Variants of hereditary traits which increase an organism's ability to survive and reproduce will be more greatly represented in subsequent generations, i.e., they will be "selected for". Thus, inherited behavioral mechanisms that allowed an organism a greater chance of surviving and/or reproducing in the past are more likely to survive in present organisms. That inherited adaptive behaviors are present in nonhuman animal species has been multiply demonstrated by biologists, and it has become a foundation of evolutionary biology. However, there is continued resistance by some researchers over the application of evolutionary models to humans, particularly from within the social sciences, where culture has long been assumed to be the predominant driver of behavior.

Nikolaas Tinbergen, whose work influenced sociobiology.

Sociobiology is based upon two fundamental premises:

• Certain behavioral traits are inherited,
• Inherited behavioral traits have been honed by natural selection. Therefore, these traits were probably "adaptive" in the species` evolutionarily evolved environment.

Sociobiology uses Nikolaas Tinbergen's four categories of questions and explanations of animal behavior. Two categories are at the species level; two, at the individual level. The species-level categories (often called “ultimate explanations”) are

• the function (i.e., adaptation) that a behavior serves and
• the evolutionary process (i.e., phylogeny) that resulted in this functionality.

The individual-level categories (often called “proximate explanations”) are

• the development of the individual (i.e., ontogeny) and
• the proximate mechanism (e.g., brain anatomy and hormones).

Sociobiologists are interested in how behavior can be explained logically as a result of selective pressures in the history of a species. Thus, they are often interested in instinctive, or intuitive behavior, and in explaining the similarities, rather than the differences, between cultures. For example, mothers within many species of mammals – including humans – are very protective of their offspring. Sociobiologists reason that this protective behavior likely evolved over time because it helped those individuals which had the characteristic to survive and reproduce. Over time, individuals who exhibited such protective behaviours would have had more surviving offspring than those who did not display such behaviours, such that this parental protection would increase in frequency in the population. In this way, the social behavior is believed to have evolved in a fashion similar to other types of nonbehavioral adaptations, such as (for example) fur or the sense of smell.

Individual genetic advantage often fails to explain certain social behaviors as a result of gene-centred selection, and evolution may also act upon groups.^{[citation needed]} The mechanisms responsible for group selection employ paradigms and population statistics borrowed from evolutionary game theory. E.O. Wilson argued that altruistic individuals must reproduce their own altruistic genetic traits for altruism to survive. When altruists lavish their resources on non-altruists at the expense of their own kind, the altruists tend to die out and the others tend to grow. In other words, altruism is more likely to survive if altruists practice the ethic that "charity begins at home". Altruism is defined as "a concern for the welfare of others". An extreme example of altruism involves a soldier risking his life to help a fellow soldier. This example raises questions about how altruistic genes can be passed on if this soldier dies without having any children to exhibit the same altruistic traits.^[7]

Within sociobiology, a social behavior is first explained as a sociobiological hypothesis by finding an evolutionarily stable strategy that matches the observed behavior. Stability of a strategy can be difficult to prove, but usually, a well-formed strategy will predict gene frequencies. The hypothesis can be supported by establishing a correlation between the gene frequencies predicted by the strategy, and those expressed in a population.

Altruism between social insects and littermates has been explained in such a way. Altruistic behavior, behavior that increases the reproductive fitness of others at the apparent expense of the altruist,^[8] in some animals has been correlated to the degree of genome shared between altruistic individuals. A quantitative description of infanticide by male harem-mating animals when the alpha male is displaced as well as rodent female infanticide and fetal resorption are active areas of study. In general, females with more bearing opportunities may value offspring less, and may also arrange bearing opportunities to maximize the food and protection from mates.

An important concept in sociobiology is that temperamental traits within a gene pool and between gene pools exist in an ecological balance. Just as an expansion of a sheep population might encourage the expansion of a wolf population, an expansion of altruistic traits within a gene pool may also encourage the expansion of individuals with dependent traits.

Sociobiology is sometimes associated with arguments over the "genetic" basis of intelligence. While sociobiology is predicated on the observation that genes do affect behavior, it is perfectly consistent to be a sociobiologist while arguing that measured IQ variations between individuals reflect mainly cultural or economic rather than genetic factors. However, many critics point out that the usefulness of sociobiology as an explanatory tool breaks down once a trait is so variable as to no longer be exposed to selective pressures. In order to explain aspects of human intelligence as the outcome of selective pressures, it must be demonstrated that those aspects are inherited, or genetic, but this does not necessarily imply differences among individuals: a common genetic inheritance could be shared by all humans, just as the genes responsible for number of limbs are shared by all individuals.

Studies of human behavior genetics have generally found behavioral traits such as creativity, extroversion, aggressiveness, and IQ have high heritability. The researchers who carry out those studies are careful to point out that heritability does not constrain the influence that environmental or cultural factors may have on those traits.^[9][10]

Criminality is actively under study, but extremely controversial. There are arguments that in some environments criminal behavior might be adaptive.^[11] The novelist Elias Canetti also has noted applications of sociobiological theory to cultural practices such as slavery and autocracy.^[12]

Differences from evolutionary psychology

Sociobiology differs in important ways from evolutionary psychology. Evolutionary psychology studies the animal nervous system from an evolutionary perspective, including aspects such as vision and navigation that are not necessarily related to social behavior. Sociobiology is restricted to the biology of social behavior but also studies organisms like plants. Evolutionary psychologists focus on the neural mechanisms that cause behavior whereas sociobiologists usually study only behavior. Evolutionary psychology emphasizes that, for humans, neural mechanisms evolved in an ancestral environment that differed from the current environment whereas animal sociobiologists look at animal adaptions to the current environment.^[6]

Reception

In the decades after World War II, the term "eugenics" had taken on a negative connotation and became increasingly unpopular within academic science. Many organizations and journals that had their origins in the eugenics movement began to distance themselves from the philosophy, as when Eugenics Quarterly became Social Biology in 1969.

Many critics^[who?] draw an intellectual link between sociobiology and biological determinism, the belief that most human differences can be traced to specific genes rather than differences in culture or social environments. Critics also see parallels between sociobiology and biological determinism as a philosophy underlying the social Darwinian and eugenics movements of the early 20th century, and controversies in the history of intelligence testing.

Pinker argues that critics have been overly swayed by politics and a fear of biological determinism, accusing among others Gould and Lewontin of being "radical scientists", whose stance on human nature is influenced by politics rather than science,^[13] while Lewontin, Rose and Kamin who drew a distinction between the politics and history of an idea and its scientific validity^[14] argue that sociobiology fails on scientific grounds, independent of their political critiques as has Gould.^[15]

Wilson and his supporters counter the intellectual link by denying that Wilson had a political agenda, still less a right-wing one. They pointed out that Wilson had personally adopted a number of liberal political stances and had attracted progressive sympathy for his outspoken environmentalism. They argued that as scientists they had a duty to uncover the truth whether that was politically correct or not. They argued that sociobiology does not necessarily lead to any particular political ideology, as many critics implied. Many subsequent sociobiologists, including Robert Wright, Anne Campbell, Frans de Waal and Sarah Blaffer Hrdy, have used sociobiology to argue quite separate points.

It is often and incorrectly argued that Noam Chomsky is a critic of sociobiology. During a 1976 meeting of the Sociobiology Study Group, as reported by Ullica Segerstråle, Chomsky argued for the importance of a sociobiologically informed notion of human nature: "Chomsky even stated that he thought it was important for political radicals to postulate a relatively fixed human nature in order to be able to struggle for a better society. We need a clear view of human needs in order to know the kind of society we want, Chomsky proclaimed. Not surprisingly ... no Chomsky critique of sociobiology emerged."^[16] The argument that human beings are biological organisms and ought to be studied as such is a deeply entrenched theme in Chomsky's work and he has been the foremost critic of the doctrine of the "blank slate" in the social sciences (which would inspire a great deal of Steven Pinker's and others' work in evolutionary psychology), sentiments that are well articulated in the following passage:

The development of personality, behavior patterns, and cognitive structures in higher organisms has often been approached in a very different way. It is generally assumed that in these domains, social environment is the dominant factor. The structures of mind that develop over time are taken to be arbitrary and accidental; there is no “human nature” apart from what develops as a specific historical product. According to this view, typical of empiricist speculation, certain general principles of learning that are common in their essentials to all (or some large class of) organisms suffice to account for the cognitive structures attained by humans, structures which incorporate the principles by which human behavior is planned, organized, and controlled.
But human cognitive systems, when seriously investigated, prove to be no less marvelous and intricate than the physical structures that develop in the life of the organism. Why, then, should we not study the acquisition of a cognitive structure such as language more or less as we study some complex bodily organ?^[17]

Chomsky has also hinted at the possible reconciliation of his anarchist political views and sociobiology in a discussion of Peter Kropotkin's Mutual Aid: A Factor of Evolution, which focused more on altruism than aggression, suggesting that anarchist societies were feasible because of an innate human tendency to cooperate.^[18]

Wilson's claims that he had never meant to imply what ought to be, only what is the case are supported by his writings, which are descriptive, not prescriptive. However, some critics have argued that the language of sociobiology sometimes slips from "is" to "ought",^[14] leading sociobiologists to make arguments against social reform on the basis that socially progressive societies are at odds with our innermost nature.^{[citation needed]} Views such as this, however, are often criticized as examples of the naturalistic fallacy, when reasoning jumps from descriptions about what is to prescriptions about what ought to be. (A common example is the justification of militarism if scientific evidence showed warfare was part of human nature.) It has also been argued that opposition to stances considered anti-social, such as ethnic nepotism, are based on moral assumptions, not bioscientific assumptions, meaning that it is not vulnerable to being disproved by bioscientific advances.^[19]:145 The history of this debate, and others related to it, are covered in detail by Cronin (1992), Segerstråle (2000), and Alcock (2001).^[20][21][22]

Ethology

From Wikipedia, the free encyclopedia

A range of animal behaviours.

Ethology is the scientific and objective study of animal behaviour, usually with a focus on behaviour under natural conditions.^[1] Behaviourism is a term that also describes the scientific and objective study of animal behaviour, but it usually refers to the study of trained behavioural responses in a laboratory context.

Many naturalists have studied aspects of animal behaviour throughout history. The modern discipline of ethology is generally considered to have begun during the 1930s with the work of Dutch biologist Nikolaas Tinbergen and by Austrian biologists Konrad Lorenz and Karl von Frisch, joint winners of the 1973 Nobel Prize in Physiology or Medicine.^[2] Ethology is a combination of laboratory and field science, with a strong relation to some other disciplines such as neuroanatomy, ecology, and evolution. Ethologists are typically interested in a behavioural process rather than in a particular animal group, and often study one type of behaviour, such as aggression, in a number of unrelated animals.

The desire to understand animals has made ethology a rapidly growing field. Since the turn of the 21st century, many aspects of animal communication, animal emotions, animal culture, learning, and even sexual conduct that experts long thought they understood, have been re-examined, and new conclusions reached. New fields have developed, such as neuroethology.

Understanding ethology or animal behaviour can be important in animal training. Considering the natural behaviours of different species or breeds enables the trainer to select the individuals best suited to perform the required task. It also enables the trainer to encourage the performance of naturally occurring behaviours and also the discontinuance of undesirable behaviours.^[3]

Etymology

The term ethology derives from the Greek language: ἦθος, ethos meaning "character" and -λογία, -logia meaning "the study of". The term was first popularized by American myrmecologist (the study of ants) William Morton Wheeler in 1902.^[4] An earlier, slightly different sense of the term was proposed by John Stuart Mill in his 1843 System of Logic.^[5] He recommended the development of a new science, "ethology," the purpose of which would be explanation of individual and national differences in character, on the basis of associationistic psychology. This use of the word was never adopted.

Other words that derive from ethos include ethics^[6] and ethical.

Relationship with comparative psychology

Comparative psychology also studies animal behaviour, but, as opposed to ethology, is construed as a sub-topic of psychology rather than as one of biology. Historically, where comparative psychology has included research on animal behaviour in the context of what is known about human psychology, ethology involves research on animal behaviour in the context of what is known about animal anatomy, physiology, neurobiology, and phylogenetic history. Furthermore, early comparative psychologists concentrated on the study of learning and tended to research behaviour in artificial situations, whereas early ethologists concentrated on behaviour in natural situations, tending to describe it as instinctive.

The two approaches are complementary rather than competitive, but they do result in different perspectives, and occasionally conflicts of opinion about matters of substance. In addition, for most of the twentieth century, comparative psychology developed most strongly in North America, while ethology was stronger in Europe. From a practical standpoint, early comparative psychologists concentrated on gaining extensive knowledge of the behaviour of very few species. Ethologists were more interested in understanding behaviour across a wide range of species to facilitate principled comparisons across taxonomic groups. Ethologists have made much more use of a truly comparative method^{[disambiguation needed]} than comparative psychologists have.

History

Scala naturae and Lamarck's theories

Jean-Baptiste Lamarck (1744–1829)

Until the 19th century, the most common theory among scientists was still the concept of scala naturae, proposed by Aristotle. According to this theory, living beings were classified on an ideal pyramid that represented the simplest animals on the lower levels, with complexity increasing progressively toward the top, occupied by human beings. In the Western world of the time, people believed animal species were eternal and immutable, created with a specific purpose, as this seemed the only possible explanation for the incredible variety of living beings and their surprising adaptation to their habitats.^[4]

Jean-Baptiste Lamarck (1744 - 1829) was the first biologist to describe a complex theory of evolution. His theory substantially comprised two statements: first, that animal organs and behaviour can change according to the way they are used; and second, that those characteristics can transmit from one generation to the next (the example of the giraffe whose neck becomes longer while trying to reach the upper leaves of a tree is well-known). The second statement is that every living organism, humans included, tends to reach a greater level of perfection. When Charles Darwin went to the Galapagos Islands, he was well aware of Lamarck's theories and was influenced by them.

Theory of evolution by natural selection and the beginnings of ethology

Charles Darwin (1809–1882)

Because ethology is considered a topic of biology, ethologists have been concerned particularly with the evolution of behaviour and the understanding of behaviour in terms of the theory of natural selection. In one sense, the first modern ethologist was Charles Darwin, whose book The Expression of the Emotions in Man and Animals influenced many ethologists. He pursued his interest in behaviour by encouraging his protégé George Romanes, who investigated animal learning and intelligence using an anthropomorphic method, anecdotal cognitivism, that did not gain scientific support.

Other early ethologists, such as Oskar Heinroth and Julian Huxley, instead concentrated on behaviours that can be called instinctive, or natural, in that they occur in all members of a species under specified circumstances. Their beginning for studying the behaviour of a new species was to construct an ethogram (a description of the main types of behaviour with their frequencies of occurrence).^[4] This provided an objective, cumulative data-base of behaviour, which subsequent researchers could check and supplement.

Social ethology and recent developments

In 1970, the English ethologist John H. Crook published an important paper in which he distinguished comparative ethology from social ethology, and argued that much of the ethology that had existed so far was really comparative ethology—examining animals as individuals—whereas, in the future, ethologists would need to concentrate on the behaviour of social groups of animals and the social structure within them.

Also in 1970, Robert Ardrey's book The Social Contract: A Personal Inquiry into the Evolutionary Sources of Order and Disorder was published.^[7] The book and study investigated animal behaviour and then compared human behaviour to it as a similar phenomenon.

E. O. Wilson's book Sociobiology: The New Synthesis appeared in 1975, and since that time, the study of behaviour has been much more concerned with social aspects. It has also been driven by the stronger, but more sophisticated, Darwinism associated with Wilson, Robert Trivers, and William Hamilton. The related development of behavioural ecology has also helped transform ethology. Furthermore, a substantial reapprochement with comparative psychology has occurred, so the modern scientific study of behaviour offers a more or less seamless spectrum of approaches: from animal cognition to more traditional comparative psychology, ethology, sociobiology, and behavioural ecology. Sociobiology has more recently^[when?] developed into evolutionary psychology.

Growth of the field

Due to the work of Lorenz and Tinbergen, ethology developed strongly in continental Europe during the years prior to World War II.^[4] After the war, Tinbergen moved to the University of Oxford, and ethology became stronger in the UK, with the additional influence of William Thorpe, Robert Hinde, and Patrick Bateson at the Sub-department of Animal Behaviour of the University of Cambridge, located in the village of Madingley.^[8] In this period, too, ethology began to develop strongly in North America.

Lorenz, Tinbergen, and von Frisch were jointly awarded the Nobel Prize in Physiology or Medicine in 1973 for their work of developing ethology.^[9]

Ethology is now a well-recognised scientific discipline, and has a number of journals covering developments in the subject, such as Animal Behaviour, Animal Welfare, Applied Animal Behaviour Science, Behaviour, Behavioral Ecology and Journal of Ethology. In 1972, the International Society for Human Ethology was founded to promote exchange of knowledge and opinions concerning human behaviour gained by applying ethological principles and methods and published their journal, The Human Ethology Bulletin. In 2008, in a paper published in the journal Behaviour, ethologist Peter Verbeek introduced the term "Peace Ethology" as a sub-discipline of Human Ethology that is concerned with issues of human conflict, conflict resolution, reconciliation, war, peacemaking, and peacekeeping behaviour.^[10]

Today, along with ethologists, many biologists, zoologists, primatologists, anthropologists, veterinarians, and physicians study ethology and other related fields such as animal psychology, the study of animal social groups, animal cognition and animal welfare science

Fixed action patterns, animal communication and modal action patterns

An important development, associated with the name of Konrad Lorenz though probably due more to his teacher, Oskar Heinroth, was the identification of fixed action patterns (FAPs). Lorenz popularized FAPs as instinctive responses that would occur reliably in the presence of identifiable stimuli (called sign stimuli or releasing stimuli).
These FAPs can be compared across species, and the similarities and differences between behaviour compared with the similarities and differences in morphology. A much quoted study^{[citation needed]} of the Anatidae (ducks and geese) by Heinroth used this technique. Ethologists noted that sign stimuli were commonly features of the behaviour of conspecifics and they were able to prove how animal communication could be mediated by FAPs. One investigation of this kind was the study of the waggle dance ("dance language") in bee communication by Karl von Frisch.^[11] Lorenz subsequently developed a theory of the evolution of animal communication based on his observations of fixed action patterns and the circumstances in which they are expressed.

Instinct

Kelp Gull chicks peck at red spot on mother's beak to stimulate regurgitating reflex.

The Merriam-Webster dictionary defines instinct as a largely inheritable and unalterable tendency of an organism to make a complex and specific response to environmental stimuli without involving reason.^[12] For ethologists, instinct means a series of predictable behaviours for fixed action patterns. Such schemes are only acted when a precise stimulating signal is present. When such signals act as communication among members of the same species, they are known as releasers. A notable example of a releaser is the beak movements in many bird species performed by the newly hatched chicks, which stimulates the mother's regurgitating process to feed her offspring.^[13] Another well-known case is the classic experiments by Tinbergen on the Graylag Goose. Like similar waterfowl, the goose rolls a displaced egg near its nest back to the others with its beak. The sight of the displaced egg triggers this mechanism. If the egg is taken away, the animal continues with the behaviour, pulling its head back as if an imaginary egg is still being manoeuvred by the underside of its beak.^[14] However, it also attempts to move other egg-shaped objects, such as a giant plaster egg, door knob, or even a volleyball back into the nest. Such objects, when they exaggerate the releasers found in natural objects, can elicit a stronger version of the behavior than the natural object, so that the goose ignores its own displaced egg in favour of the giant dummy egg. These exaggerated releasers for instincts were named supernormal stimuli by Tinbergen.^[15] Tinbergen found he could produce supernormal stimuli for most instincts in animals—such as cardboard butterflies that male butterflies preferred to mate with if they had darker stripes than a real female, or dummy fish that a territorial male stickleback fish fought more violently than a real invading male if the dummy had a brighter-coloured underside. Harvard psychologist Deirdre Barrett wrote a book about how easily humans respond to supernormal stimuli for sexual, nurturing, feeding, and social instincts.^[16] However, a behaviour only made of fixed action patterns would be particularly rigid and inefficient, reducing the probability of survival and reproduction, so the learning process has great importance, as does the ability to change the individual's responses based on its experience. It can be said^{[by whom?]} that the more the brain is complex and the life of the individual long, the more its behaviour is "intelligent" (in the sense of being guided by experience rather than stereotyped FAPs).

Learning

Habituation

Habituation is a simple form of learning and occurs in many animal taxa. It is the process whereby an animal ceases responding to a stimulus. Often, the response is an innate behaviour. Essentially, the animal learns not to respond to irrelevant stimuli. For example, prairie dogs (Cynomys ludovicianus) give alarm calls when predators approach, causing all individuals in the group to quickly scramble down burrows. When prairie dog towns are located near trails used by humans, giving alarm calls every time a person walks by is expensive in terms of time and energy. Habituation to humans is therefore an important adaptation in this context.^[17][18][19]

Associative learning

Associative learning, in animal behaviour, is any learning process in which a new response becomes associated with a particular stimulus.^[20] The first studies of associative learning were made by Russian physiologist Ivan Pavlov.^[21] Examples of associative learning include when a goldfish swims to the water surface when a human is going to feed it, or the excitement of a dog whenever it sees a collar as a prelude for a walk.

Imprinting

Example of imprinting in a moose

Being able to discriminate the members of one's own species is also of fundamental importance for reproductive success. Such discrimination can be based on a number of factors. However, this important type of learning only takes place in a very limited period of time. This kind of learning is called imprinting,^[22] and was a second important finding of Lorenz. Lorenz observed that the young of birds such as geese and chickens followed their mothers spontaneously from almost the first day after they were hatched, and he discovered that this response could be imitated by an arbitrary stimulus if the eggs were incubated artificially and the stimulus were presented during a critical period that continued for a few days after hatching.

Observational learning

Imitation

Imitation is an advanced behaviour whereby an animal observes and exactly replicates the behaviour of another. The National Institutes of Health reported that capuchin monkeys preferred the company of researchers who imitated them to that of researchers who did not. The monkeys not only spent more time with their imitators but also preferred to engage in a simple task with them even when provided with the option of performing the same task with a non-imitator.^[23] Imitation has been observed in recent research on chimpanzees; not only did these chimps copy the actions of another individual, when given a choice, the chimps preferred to imitate the actions of the higher-ranking elder chimpanzee as opposed to the lower-ranking young chimpanzee.^[24]

Stimulus enhancement

There are various ways animals can learn using observational learning but without the process of imitation. One of these is stimulus enhancement in which individuals become interested in an object as the result of observing others interacting with the object.^[25] Increased interest in an object can result in object manipulation which allows for new object-related behaviours by trial-and-error learning. Haggerty (1909) devised an experiment in which a monkey climbed up the side of a cage, placed its arm into a wooden chute, and pulled a rope in the chute to release food. Another monkey was provided an opportunity to obtain the food after watching a monkey go through this process on four separate occasions. The monkey performed a different method and finally succeeded after trial-and-error.^[26] Another example familiar to some cat and dog owners is the ability of their animals to open doors. The action of humans operating the handle to open the door results in the animals becoming interested in the handle and then by trial-and-error, they learn to operate the handle and open the door.

Social transmission

A well-documented example of social transmission of a behaviour occurred in a group of macaques on Hachijojima Island, Japan. The macaques lived in the inland forest until the 1960s, when a group of researchers started giving them potatoes on the beach: soon, they started venturing onto the beach, picking the potatoes from the sand, and cleaning and eating them.^[27] About one year later, an individual was observed bringing a potato to the sea, putting it into the water with one hand, and cleaning it with the other. This behaviour was soon expressed by the individuals living in contact with her; when they gave birth, this behaviour was also expressed by their young - a form of social transmission.^[28]

Teaching

Teaching is a highly specialised aspect of learning in which the "teacher" (demonstrator) adjusts its behaviour to increase the probability of the "pupil" (observer) achieving the desired end-result of the behaviour. Killer whales are known to intentionally beach themselves to catch and eat pinnipeds.^[29] Mother killer whales teach their young to catch pinnipeds by pushing them onto the shore and encouraging them to attack and eat the prey. Because the mother killer whale is altering her behaviour to help her offspring learn to catch prey, this is evidence of teaching.^[29] Teaching is not limited to mammals. Many insects, for example, have been observed demonstrating various forms of teaching to obtain food. Ants, for example, will guide each other to food sources through a process called "tandem running," in which an ant will guide a companion ant to a source of food.^[30] It has been suggested that the pupil ant is able to learn this route to obtain food in the future or teach the route to other ants.

Mating and the fight for supremacy

Individual reproduction is the most important phase in the proliferation of individuals or genes within a species: for this reason, there exist complex mating rituals, which can be very complex even if they are often regarded as fixed action patterns (FAPs). The Stickleback's complex mating ritual was studied by Niko Tinbergen and is regarded as a notable example of a FAP.

Often in social life, animals fight for the right to reproduce, as well as social supremacy. A common example of fighting for social and sexual supremacy is the so-called pecking order among poultry. Every time a group of poultry cohabitate for a certain time length, they establish a pecking order. In these groups, one chicken dominates the others and can peck without being pecked. A second chicken can peck all the others except the first, and so on.
Higher level chickens are easily distinguished by their well-cured aspect, as opposed to lower level chickens. While the pecking order is establishing, frequent and violent fights can happen, but once established, it is broken only when other individuals enter the group, in which case the pecking order re-establishes from scratch.

Living in groups

Several animal species, including humans, tend to live in groups. Group size is a major aspect of their social environment. Social life is probably a complex and effective survival strategy. It may be regarded as a sort of symbiosis among individuals of the same species: a society is composed of a group of individuals belonging to the same species living within well-defined rules on food management, role assignments and reciprocal dependence.

When biologists interested in evolution theory first started examining social behaviour, some apparently unanswerable questions arose, such as how the birth of sterile castes, like in bees, could be explained through an evolving mechanism that emphasizes the reproductive success of as many individuals as possible, or why, amongst animals living in small groups like squirrels, an individual would risk its own life to save the rest of the group. These behaviours may be examples of altruism.^[31] Of course, not all behaviours are altruistic, as indicated by the table below. For example, revengeful behaviour was at one point claimed to have been observed exclusively in Homo sapiens. However, other species have been reported to be vengeful, including reports of vengeful camels^[32] and chimpanzees.^[33]

Classification of social behaviours

Type of behaviour	Effect on the donor	Effect on the receiver
Egoistic	Increases fitness	Decreases fitness
Cooperative	Increases fitness	Increases fitness
Altruistic	Decreases fitness	Increases fitness
Revengeful	Decreases fitness	Decreases fitness

Altruistic behaviour has been explained by the gene-centered view of evolution.

Benefits and costs of group living

One advantage of group living can be decreased predation. If the number of predator attacks stays the same despite increasing prey group size, each prey may have a reduced risk of predator attacks through the dilution effect.^[34] Additionally, a predator that is confused by a mass of individuals can find it more difficult to single out one target. For this reason, the zebra’s stripes offer not only camouflage in a habitat of tall grasses, but also the advantage of blending into a herd of other zebras.^[35] In groups, prey can also actively reduce their predation risk through more effective defense tactics, or through earlier detection of predators through increased vigilance.^[34]

Another advantage of group living can be an increased ability to forage for food. Group members may exchange information about food sources between one another, facilitating the process of resource location.^[34] Honeybees are a notable example of this, using the waggle dance to communicate the location of flowers to the rest of their hive.^[36] Predators also receive benefits from hunting in groups, through using better strategies and being able to take down larger prey.^[34]

Some disadvantages accompany living in groups. Living in close proximity to other animals can facilitate the transmission of parasites and disease, and groups that are too large may also experience greater competition for resources and mates.^[37]

Group size

Theoretically, social animals should have optimal group sizes that maximize the benefits and minimize the costs of group living. However, in nature, most groups are stable at slightly larger than optimal sizes.^[34] Because it generally benefits an individual to join an optimally-sized group, despite slightly decreasing the advantage for all members, groups may continue to increase in size until it is more advantageous to remain alone than to join an overly full group.^[38]

Tinbergen's four questions for ethologists

Lorenz's collaborator, Niko Tinbergen, argued that ethology always needed to include four kinds of explanation in any instance of behaviour:

• Function – How does the behaviour affect the animal's chances of survival and reproduction? Why does the animal respond that way instead of some other way?
• Causation – What are the stimuli that elicit the response, and how has it been modified by recent learning?
• Development – How does the behaviour change with age, and what early experiences are necessary for the animal to display the behaviour?
• Evolutionary history – How does the behaviour compare with similar behaviour in related species, and how might it have begun through the process of phylogeny?

These explanations are complementary rather than mutually exclusive—all instances of behaviour require an explanation at each of these four levels. For example, the function of eating is to acquire nutrients (which ultimately aids survival and reproduction), but the immediate cause of eating is hunger (causation). Hunger and eating are evolutionarily ancient and are found in many species (evolutionary history), and develop early within an organism's lifespan (development). It is easy to confuse such questions—for example, to argue that people eat because they're hungry and not to acquire nutrients—without realizing that the reason people experience hunger is because it causes them to acquire nutrients.^[39]

List of ethologists

People who have made notable contributions to ethology (many listed here are actually comparative psychologists):

Robert Ardrey Patrick Bateson Marc Bekoff Ingeborg Beling John Bowlby Donald Broom Marian Stamp Dawkins Richard Dawkins Viktor Dolnik Irenäus Eibl-Eibesfeldt John Endler Jean-Henri Fabre Dian Fossey Karl von Frisch Douglas P. Fry Birutė Galdikas Jane Goodall

James L. Gould Temple Grandin Judith Hand Clarence Ellis Harbison Heini Hediger Oskar Heinroth Robert Hinde Bernard Hollander Sarah Hrdy Julian Huxley Julian Jaynes Erich Klinghammer John Krebs Konrad Lorenz Aubrey Manning Eugene Marais Peter Robert Marler

Ivan Pavlov Patricia McConnell Desmond Morris Martin Moynihan Irene Pepperberg Kevin Richardson George Romanes Thomas Sebeok Barbara Smuts William Homan Thorpe Niko Tinbergen Jakob von Uexküll Frans de Waal William Morton Wheeler E. O. Wilson Amotz Zahavi

Gallery of videos

• Play media

  Food manipulation behaviour by fox squirrels.