Animal communication in the context of Display behaviour

A natural language or ordinary language is any spoken language or signed language used organically in a human community, first emerging without conscious premeditation and subject to: replication across generations of people in the community, regional expansion or contraction, and gradual internal and structural changes. The vast majority of languages in the world are natural languages. As a category, natural language includes both standard dialects (ones with high social prestige) as well as nonstandard or vernacular dialects. Even an official language with a regulating academy such as Standard French, overseen by the Académie Française, is still classified as a natural language (e.g. in the field of natural language processing), as its prescriptive aspects do not make it regulated enough to be considered a constructed or controlled natural language. Linguists broadly consider writing to be a static visual representation of a particular natural language, though, in many cases in highly literate modern societies, writing itself can also be considered natural language.

Excluded from the definition of natural language are: artificial and constructed languages, such as those developed for works of fiction; languages of formal logic, such as those in computer programming; and non-human communication systems in nature, such as whale vocalizations or honey bees' waggle dance. The academic consensus is that particular key features prevent animal communication systems from being classified as languages at all. Certain human communication or linguistic systems with no native speakers, as sometimes used in cross-cultural contexts, are also not natural languages.

Primates is an order of mammals, which is further divided into the strepsirrhines, which include lemurs, galagos, and lorisids; and the haplorhines, which include tarsiers and simians (monkeys and apes). Primates arose 74–63 million years ago first from small terrestrial mammals, which adapted for life in tropical forests: many primate characteristics represent adaptations to the challenging environment among tree tops, including large brain sizes, binocular vision, color vision, vocalizations, shoulder girdles allowing a large degree of movement in the upper limbs, and opposable thumbs (in most but not all) that enable better grasping and dexterity. 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 six in the 2020s.

Primates have large brains (relative to body size) compared to other mammals, as well as an increased reliance on visual acuity at the expense of the sense of smell, which is the dominant sensory system in most mammals. These features are more developed in monkeys and apes, and noticeably less so in lorises and lemurs. Some primates, including gorillas, humans and baboons, are primarily ground-dwelling rather than arboreal, but all species have adaptations for climbing trees. Arboreal locomotion techniques used include leaping from tree to tree and swinging between branches of trees (brachiation); terrestrial locomotion techniques include walking on two hindlimbs (bipedalism) and modified walking on four limbs (quadrupedalism) via knuckle-walking.

Whales use a variety of sounds for communication and sensation. The mechanisms used to produce sound vary from one family of cetaceans to another. Marine mammals, including whales, dolphins, and porpoises, are much more dependent on sound than land mammals due to the limited effectiveness of other senses in water. Sight is less effective for marine mammals because of the way particulates in the ocean scatter light. Smell is also limited, as molecules diffuse more slowly in water than in air, which makes smelling less effective. However, the speed of sound is roughly three times greater in water than in the atmosphere at sea level. As sea mammals are so dependent on hearing to communicate and feed, environmentalists and cetologists are concerned that they are being harmed by the increased ambient noise in the world's oceans caused by ships, sonar and marine seismic surveys.

The word "song" is used to describe the pattern of regular and predictable sounds made by some species of whales, notably the humpback whale. This is included with or in comparison with music, and male humpback whales have been described as "inveterate composers" of songs that are "'strikingly similar' to human musical traditions". This position has been complicated by more recent research, however. It has been suggested that humpback songs communicate male fitness to female whales, although this explanation has been challenged on various grounds.

Animal languages are forms of communication between non-human animals that show similarities to human language. Animals communicate through a variety of signs, such as sounds and movements. Signing among animals may be considered a form of language if the inventory of signs is large enough, the signs are relatively arbitrary, and the animals seem to produce them with a degree of volition (as opposed to relatively automatic conditioned behaviors or unconditioned instincts, usually including facial expressions).

The current academic consensus is that animal communication systems lack key aspects that might define them as languages (or equivalent to human languages), one such aspect being humans' creation of new patterns of signs under varied circumstances. Humans routinely produce entirely new combinations of words. Some researchers, including the linguist Charles Hockett, argue that human language and animal communication differ so much that the underlying principles are unrelated. Accordingly, linguist Thomas A. Sebeok has proposed to not use the term "language" for animal sign systems. However, other linguists and biologists, including Marc Hauser, Noam Chomsky, and W. Tecumseh Fitch, assert that an evolutionary continuum exists between the communication methods of animal and human language.

A talking animal or speaking animal is any non-human animal that can produce sounds or gestures resembling those of a human language. Several species or groups of animals have developed forms of communication which superficially resemble verbal language, however, these usually are not considered a language because they lack one or more of the defining characteristics, e.g. grammar, syntax, recursion, and displacement. Researchers have been successful in teaching some animals to make gestures similar to sign language, although whether this should be considered a language has been disputed.

In linguistics, displacement is the capability of language to communicate about things that are not immediately present (spatially or temporally); i.e., things that are either not here or are not here now.

In 1960, Charles F. Hockett proposed displacement as one of 13 design features of language that distinguish human language from animal communication systems (ACSs):

Tool use by non-humans is a phenomenon in which a non-human animal uses any kind of tool in order to achieve a goal such as acquiring food and water, grooming, combat, defence, communication, recreation or construction. Originally thought to be a skill possessed only by humans, some tool use requires a sophisticated level of cognition. There is considerable discussion about the definition of what constitutes a tool and therefore which behaviours can be considered true examples of tool use. A wide range of animals, including mammals, birds, fish, cephalopods, and insects, are considered to use tools.

Primates are well known for using tools for hunting or gathering food and water, cover for rain, and self-defence. Chimpanzees have often been the object of study in regard to their usage of tools, most famously by Jane Goodall, since these animals are frequently kept in captivity and are closely related to humans. Wild tool use in other primates, especially among apes and monkeys, is considered relatively common, though its full extent remains poorly documented, as many primates in the wild are mainly only observed distantly or briefly when in their natural environments and living without human influence. Some novel tool-use by primates may arise in a localised or isolated manner within certain unique primate cultures, being transmitted and practised among socially connected primates through cultural learning. Many famous researchers, such as Charles Darwin in his 1871 book The Descent of Man, have mentioned tool use in monkeys (such as baboons).

Certain words in the English language represent animal sounds: the noises and vocalizations of particular animals, especially noises used by animals for communication. The words can be used as verbs or interjections in addition to nouns, and many of them are also specifically onomatopoeic.

A roar /rɔːr/ is a type of animal vocalization that is loud, deep and resonating. Many mammals have evolved to produce roars and other roar-like vocals for purposes such as long-distance communication and intimidation. These include various species of big cats, bears, pinnipeds, deer, bovids, elephants, and simians.

The anatomical basis for the ability to roar often involves modifications to the larynx and hyoid bone and enlarged internal air spaces for low-frequency vocal resonation. While roaring, animals may stretch out their necks and elevate their heads to increase the space for resonance.

The origin of language, its relationship with human evolution, and its consequences have been subjects of study for centuries. Scholars wishing to study the origins of language draw inferences from evidence such as the fossil record, archaeological evidence, and contemporary language diversity. They may also study language acquisition as well as comparisons between human language and systems of animal communication (particularly other primates). Many argue for the close relation between the origins of language and the origins of modern human behavior, but there is little agreement about the facts and implications of this connection.

The shortage of direct, empirical evidence has caused many scholars to regard the entire topic as unsuitable for serious study; in 1866, the Linguistic Society of Paris banned any existing or future debates on the subject, a prohibition which remained influential across much of the Western world until the late twentieth century. Various hypotheses have been developed on the emergence of language. While Charles Darwin's theory of evolution by natural selection had provoked a surge of speculation on the origin of language over a century and a half ago, the speculations had not resulted in a scientific consensus by 1996. Despite this, academic interest had returned to the topic by the early 1990s. Linguists, archaeologists, psychologists, and anthropologists have renewed the investigation into the origin of language with modern methods.

A spectrogram is a visual representation of the spectrum of frequencies of a signal as it varies with time. When applied to an audio signal, spectrograms are sometimes called sonographs, voiceprints, or voicegrams. When the data are represented in a 3D plot they may be called waterfall displays.

Spectrograms are used extensively in the fields of music, linguistics, sonar, radar, speech processing, seismology, ornithology, and others. Spectrograms of audio can be used to identify spoken words phonetically, and to analyse the various calls of animals.

The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory system is to extract oxygen from the atmosphere and transfer it into the bloodstream, and to release carbon dioxide from the bloodstream into the atmosphere, in a process of gas exchange. Respiration is driven by different muscular systems in different species. Mammals, reptiles and birds use their musculoskeletal systems to support and foster breathing. In early tetrapods, air was driven into the lungs by the pharyngeal muscles via buccal pumping, a mechanism still seen in amphibians. In humans, the primary muscle that drives breathing is the diaphragm. The lungs also provide airflow that makes vocalisation including speech possible.

Humans have two lungs, a right lung and a left lung. They are situated within the thoracic cavity of the chest. The right lung is bigger than the left, and the left lung shares space in the chest with the heart. The lungs together weigh approximately 1.3 kilograms (2.9 lb), and the right is heavier. The lungs are part of the lower respiratory tract that begins at the trachea and branches into the bronchi and bronchioles, which receive air breathed in via the conducting zone. These divide until air reaches microscopic alveoli, where gas exchange takes place. Together, the lungs contain approximately 2,400 kilometers (1,500 mi) of airways and 300 to 500 million alveoli. Each lung is enclosed within a pleural sac of two pleurae which allows the inner and outer walls to slide over each other whilst breathing takes place, without much friction. The inner visceral pleura divides each lung as fissures into sections called lobes. The right lung has three lobes and the left has two. The lobes are further divided into bronchopulmonary segments and lobules. The lungs have a unique blood supply, receiving deoxygenated blood sent from the heart to receive oxygen (the pulmonary circulation) and a separate supply of oxygenated blood (the bronchial circulation).

The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste buds housed in numerous lingual papillae. It is sensitive and kept moist by saliva and is richly supplied with nerves and blood vessels. The tongue also serves as a natural means of cleaning the teeth. A major function of the tongue is to enable speech in humans and vocalization in other animals.

The human tongue is divided into two parts, an oral part at the front and a pharyngeal part at the back. The left and right sides are also separated along most of its length by a vertical section of fibrous tissue (the lingual septum) that results in a groove, the median sulcus, on the tongue's surface.

Within evolutionary biology, signalling theory is a body of theoretical work examining communication between individuals, both within species and across species. The central question is how organisms with conflicting interests, such as in sexual selection, are expected to provide honest signals rather than deceive or cheat, given that the passing on of pleiotropic traits is subject to natural selection, which aims to minimize associated costs without assuming any conscious intent. Mathematical models describe how signalling can contribute to an evolutionarily stable strategy.

Signals are given in contexts such as mate selection by females, which subjects the advertising males' signals to selective pressure. Signals thus evolve because they modify the behaviour of the receiver to benefit the signaller. Signals may be honest, conveying information which usefully increases the fitness of the receiver, or dishonest. An individual can cheat by giving a dishonest signal, which might briefly benefit that signaller, at the risk of undermining the signalling system for the whole population.

Howling is a vocal form of animal communication seen in most canines, particularly wolves, coyotes, foxes, and dogs, as well as cats and some species of monkeys. Howls are lengthy sustained sounds, loud and audible over long distances, often with some variation in pitch over the length of the sound. Howling is generally used by animals that engage in this behavior to signal their positions to one another, to call the pack to assemble, or to note their territory. The behavior is occasionally copied by humans, and has been noted to have varying degrees of significance in human culture.

Hockett's Design Features are a set of features that characterize human language and set it apart from animal communication. They were defined by the linguist Charles F. Hockett in the 1960s. He called these characteristics the design features of language. Hockett originally believed there to be 13 design features. While primate communication utilizes the first 9 features, Hockett believed that the final 4 features (displacement, productivity, cultural transmission, and duality) were reserved for humans. Hockett later added prevarication, reflexiveness, and learnability to the list as uniquely human characteristics. He asserted that even the most basic human languages possess these 16 features.