human-factors engineering: see ergonomics.

human rights, universal rights held to belong to individuals by virtue of their being human, encompassing civil, political, economic, social, and cultural rights and freedoms, and based on the notion of personal human dignity and worth. Conceptually derived from the theory of natural law and originating in Greco-Roman doctrines, the idea of human rights appears in some early Christian writers' works and is reflected in the Magna Carta (1215). The concept winds as a philosophical thread through 17th- and 18th-century European and American thought, including the Declaration of Independence (1776) and the French Declaration of the Rights of Man and Citizen (1789). The United Nation's Commission on Human Rights, with Eleanor Roosevelt as chair, created the UN's Universal Declaration of Human Rights (1948), which reasserted the concept of human rights after the horrors of World War II. Human rights have since become a universally espoused yet widely disregarded concept.

Organizations such as Amnesty International and Human Rights Watch promote human rights and denounce human-rights abuses. In addition, such abuses around the world are monitored and documented by independent investigators ("special rapporteurs") appointed by the UN Human Rights Council, which, in turn, rebukes cited nations for their human-rights failures. (The council replaced the UN Human Rights Commission, which had been accused of protecting human-rights violators, in mid-2006; similar accusations have been leveled at the new council.) The charging in 1998 by a Spanish court of former Chilean president Augusto Pinochet with human-rights violations and the 1999 British ruling that he could be extradited to Spain, as well as the indictment and arrest (2000) in Senegal of former Chadian president Hissène Habré for human-rights violations during his presidency (although charges were later dropped, he was subsequently rearrested on a Belgian warrant), were regarded as small steps forward in the international protection of human rights.

See also civil rights; feminism; gay-rights movement; war crimes.

human papillomavirus (HPV), any of a family of more than 60 viruses that cause various growths, including plantar warts and genital warts, a sexually transmitted disease. Detectable warts can be or removed, usually by chemicals, freezing, or laser, but often recur. Intralesional alpha interferon has been effective in the treatment of genital warts. Genital warts, sometimes called condylomata acuminata, are soft and often occur in clusters. They can occur internally or externally, but even in the absence of warts the virus may be present and transmittable. Problems can result from untreated warts, which can grow quite large, or, in rare cases, from infection of an infant during delivery. In addition, certain strains of HPV are associated with cancer of the cervix, vulva, vagina, and penis. HPV 16 has been shown to be associated with some forms of Kaposi's sarcoma (see AIDS) and throat cancer. A vaccine approved by the Food and Drug Administration in 2006 can protect a woman against those strains that cause most cases of cervical cancer and genital warts; HPV vaccination is recommended for girls beginning at 11 to 12 years of age.

human growth hormone (HGH): see growth hormone.

human granulocytic ehrlichiosis: see ehrlichiosis.

human evolution, theory of the origins of the human species, Homo sapiens. Modern understanding of human origins is derived largely from the findings of paleontology, anthropology, and genetics, and involves the process of natural selection (see Darwinism). Although gaps in the fossil record due to differential preservation prevent the complete specification of the line of human descent, H. sapiens share clear anatomical, genetic, and historic relationships to other primates. Of all primates, humans bear particularly close affinity to other members of a group known as hominoids, or apes, which includes orangutans, gibbons, gorillas, chimpanzees, and humans. Humans and their immediate ancestors, known as hominids, are notable among hominoids for their bipedal locomotion, slow rate of maturation, large brain size, and, at least among the more recent hominids, the development of a relatively sophisticated capacity for language, tool use, and social activity.

The Evolutionary Tree

Humans are mammals of the Primate order. The earliest primates evolved about 65 million years ago in the geological period known as the Paleocene epoch. They were small-brained, arboreal fruit eaters, similar to modern tree shrews. Primates of the Eocene epoch (55 to 38 million years ago) were similar and ancestral to contemporary tarsiers, lemurs, and tree shrews, and are classified as lower primates or prosimians. During the late Eocene, the higher primates, or anthropoids, developed from prosimian ancestors and, aided by continental drift, diverged into New World (or platyrrhine) and Old World (or catarrhine) monkeys. The branching of Old World monkeys and hominoids apparently occurred in the late Oligocene (38 to 25 million years ago) or early Miocene (25 to 8 million years ago), a time period poorly represented in the fossil record. The lesser apes (gibbons and siamangs) and other hominoid lines diverged about 20 million years ago, while the Asian great apes (the orangutan being the only surviving form) diverged from the African hominoids about 15 to 10 million years ago. Genetic evidence suggests that the ancestral lines of gorillas diverged about 8 million years ago and that chimpanzees and hominids diverged about 5 million years ago.

Hominid Evolution

The earliest known hominids are members of the genus Australopithecus, the earliest of which date to more than 4 million years ago. Unlike other primates, but like all hominids, australopithecines were bipedal. Their crania, however, were small and apelike, with an average cranial capacity of about 450 cc in the gracile species and 600 cc in the robust forms. Australopithecines that have been considered ancestral in the lineage leading to the human genus Homo include A. afarensis (an important skeleton of which is popularly known as Lucy) and A. africanus. The exact position of these and other early species on the hominid family tree continues to be disputed.

The first member of the genus Homo, a small gracile species known as H. habilis, was present in east Africa at least 2 million years ago. H. habilis was the first hominid to exhibit the marked expansion of the brain (with an average cranial capacity of about 750 cc) that would become a hallmark of subsequent hominid evolutionary history. By about 1.6 million years ago, H. habilis had evolved into a larger, more robust, and larger-brained species known as Homo erectus. Cranial capacities ranged from about 900 cc in early specimens to 1050 cc in later ones. H. erectus persisted for well over a million years and migrated off the African continent into Asia, Indonesia, and Europe.

Between 500,000 and 250,000 years ago, H. erectus evolved into H. sapiens. Transitional forms between H. erectus and H. sapiens are referred to as archaic H. sapiens. With the exception of H. sapiens neandertalensis (see Neanderthal man), no additional subspecies are recognized. Indeed, some scientists consider Neanderthal a separate species. Archaic H. sapiens changed gradually, becoming somewhat larger, more gracile and larger-brained through time. Cranial capacity, for example, increased from about 1150 cc in early transitional forms to the current world average of just over 1350 cc. By 150,000 years ago in Africa and Asia and 28,000 years ago in Europe (see Cro-Magnon man), the transition to H. sapiens was complete, and fully modern humans became the single surviving hominid species.

The Evolution of Culture

Among hominids, a parallel evolutionary process involving increased intelligence and cultural complexity is apparent in the material record. Evidence of greater behavioral flexibility and adaptability presumably reflects the decreased influence of genetically encoded behaviors and the increased importance of learning and social interaction in transmitting and maintaining behavioral adaptations (see culture). Because the organization of neural circuitry is more significant than overall cranial capacity in establishing mental capabilities, direct inferences from the fossil record are likely to be misleading. Contemporary humans, for example, exhibit considerable variability in cranial capacity (1150 cc to 1600 cc), none of which is related to intelligence.

Tool use was once thought to be the hallmark of members of the genus Homo, beginning with H. habilis, but is now known to be common among chimpanzees. The earliest stone tools of the lower Paleolithic, known as Oldowan tools and dating to about 2 to 2.5 million years ago, were once thought to have been manufactured by H. habilis. Recent finds suggest that Oldowan tools may also have been made by robust australopithecines. The simultaneous emergence of H. erectus and the more complex Achuelian tool tradition may indicate shifting adaptations as much as increased intelligence.

While it is clear that H. erectus was much more versatile than any of its predecessors, adapting its technologies and behaviors to diverse environmental conditions, the extent and limitations of its intellectual endowment remain a subject of heated debate. This is also the case for both archaic H. sapiens and Neanderthals, the latter associated with the more sophisticated technologies of the middle Paleolithic. However impressive the achievements of H. erectus and early H. sapiens, most material remains predating 40,000 years ago reflect utilitarian concerns. Nonetheless, there is now scattered African archaeological evidence from before that time (in one case as early as 90,000 years ago) of the production by H. sapiens of beads and other decorative work, perhaps indicating a gradual development of the aesthetic concerns and other symbolic thinking characteristic of later human societies. Whether the emergence of modern H. sapiens corresponds to the explosion of technological innovations and artistic activities associated with Cro-Magnon culture or was a more prolonged process of development is a subject of archaeological debate.

human engineering: see ergonomics.

human chorionic gonadotropin (HCG): see gonadotropic hormone.

human: see anthropology; human evolution; race.

Human Genome Project, international scientific effort to map all of the genes on the 23 pairs of human chromosomes and, to sequence the 3.1 billion DNA base pairs that make up the chromosomes (see nucleic acid). Begun in 1990 with the goal of enabling scientists to understand the basis of genetic diseases and to gain insight into human evolution, the project was largely completed in 2000 when 85% of the human genome was decoded, and ended in 2003 with 99% decoded; detailed analyses of all the pairs were published by 2006. In the process, scientists identified genes for cystic fibrosis, neurofibromatosis, Huntington's disease, and an inherited form of breast cancer. In addition, the project decoded the genome of the bacterium E. coli, a fruit fly, and a nematode worm (see phylum Nematoda), in order to study genetic similarities among species, and a mouse genome was also decoded.

The Human Genome Project involved laboratories in the United States, France, Great Britain, Germany, and Japan. It was financed in the United States by the National Institutes of Health and by the Department of Energy and in Great Britain by the Wellcome Trust of London. A comparable project using new DNA (genetic material) sequencing machines was begun as a private industry venture in the United States in 1998, with a stated goal of completing the mapping of the genome in three years.

Early in 2001 scientists from both teams jointly announced the "completion" of the mapping of the human genome, indicating that they had identified an estimated 30,000 genes (instead of the expected 100,000), constituting just 1% of the total human DNA. Subsequent comparison of the two teams' data has indicated that, because of differences in the genes identified by the teams, there may in fact be as many as 40,000 human genes. A subsequent, more refined estimate (2004) based on additional work on the genome was that there are between 20,000 and 25,000 genes. Work continues on further refining the sequencing of the genes on the chromosomes, eliminating the remaining gaps in the genome map, and identifying the extent of variation in the human genome. In 2007 the first sequences of human individuals (James D. Watson and J. Craig Venter, who led the public and private human genome sequencing efforts, respectively) were released. The NIH's National Center for Biotechnology Information maintains GenBank, a database of publicly available genetic sequences from the genomes of plants and animals, including some extinct species.

Health and Human Services, United States Department of, federal executive department charged with administering government health programs. Successor to the Department of Health, Education, and Welfare, which had been created in 1953, it was redesignated in 1979 with the creation of the Department of Education. The secretary advises the President on health and welfare matters. The department has several components. The Administration for Children and Families is responsible for Operation Head Start, the enforcement of child support laws, and programs concerning adoption, job training, and runaway youths. The Public Health Service is divided into 42 subdivisions; it carries out research on disease and health concerns through the National Institutes of Health, protects consumers from adulterated or untested foods and drugs through the Food and Drug Administration, and implements public health measures and monitors the spread of infectious diseases through the Centers for Disease Control and Prevention. The Substance Abuse and Mental Health Services Administration develops and analyzes information relating to the prevention and treatment of addictive and mental disorders. The Centers for Medicare and Medicaid Services administers Medicare and Medicaid. The Social Security Administration, formerly part of the department, became an independent agency in 1995 (see social security). The Administration on Aging develops policy and programs to promote the welfare of older Americans and administers grants to states to establish community programs for them.

European Court of Human Rights: see Council of Europe.

Organ system by which humans reproduce. In females, the ovaries sit near the openings of the fallopian tubes, which carry eggs from the ovaries to the uterus. The cervix extends from the lower end of the uterus into the vagina, whose opening, as well as that of the urethra (see urinary system), is covered by four folds of skin (the labia); the clitoris, a small erectile organ, is located where the labia join in front. The activity of the ovaries and uterus goes through a monthly cycle of changes (see menstruation) throughout the reproductive years except during pregnancy and nursing. In males, the testes lie in a sac of skin (the scrotum). A long duct (the vas deferens) leads from each testis and carries sperm to the ejaculatory ducts in the prostate gland; these join the urethra, which continues through the penis. In the urethra, sperm mixes with secretions from the seminal vesicles, prostate gland, and Cowper gland to form semen. In early embryos, the reproductive systems are undetermined. By birth the organs appropriate to each sex have typically developed but are not functioning. They continue to grow, and at puberty their activity increases and maturation occurs, enabling sexual reproduction.

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Permanent change of residence by an individual or group, excluding such movements as nomadism and migrant labour. Migrations may be classed as internal or international and as voluntary or forced. Voluntary migration is usually undertaken in search of a better life; forced migrations include expulsions during war and the transportation of slaves or prisoners. The earliest humans migrated from Africa to all the continents except Antarctica within about 50,000 years. Other mass migrations include the forced migration of 20 million people as slaves from Africa to North America in the 16th–19th centuries and the Great Atlantic Migration of 37 million people from Europe to North America between 1820 and 1980. War-related forced migrations and refugee flows continue to be very large, as are voluntary migrations from developing nations to industrialized ones. Internal migrations have tended to be from rural areas to urban centers.

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or human engineering or human factors engineering

Profession of designing machines, tools, and work environments to best accommodate human performance and behaviour. It aims to improve the practicality, efficiency, and safety of a person working with a single machine or device (e.g., using a telephone, driving a car, or operating a computer terminal). Taking the user into consideration has probably always been a part of tool design; for example, the scythe, one of the oldest and most efficient human implements, shows a remarkable degree of ergonomic engineering. Examples of common devices that are poorly designed ergonomically include the snow shovel and the computer or typewriter keyboard.

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Malignant tumour of the skin, including some of the most common human cancers. Though recognizable at an early stage, it has a significant death rate. Light-skinned people have the highest risk but can reduce it by limiting exposure to sunlight and to ionizing radiation. The most common types arise in the epidermis (outer skin layer) and have become more frequent with the thinning of the atmosphere's ozone layer. The most serious form is melanoma, which is frequently fatal if not treated early with surgery. Cancers arising from the dermis are rare; the best-known is Kaposi sarcoma.

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Surface covering of the body that protects it and receives external sensory stimuli, consisting of an epidermis over a thicker dermis. The epidermis contains cells involved in immune defenses, sensory receptors, pigment cells, and keratin-producing cells. The last harden and migrate to the surface to form a dead, relatively dry outer layer of horny tissue that constantly sloughs away. The dermis contains sensory nerves and blood vessels within connective tissue. Collagen and elastin fibres give skin its tough, elastic quality. Cells scattered through it produce its components and take part in immune and other skin responses. A fat layer under the dermis provides nutritional storage, cushioning, and insulation. Skin disorders range from dermatitis and acne to skin cancer. Changes in skin colour (e.g., jaundice) or texture may be clues to systemic disorders. Seealso dermatology; hair; integument; nail; perspiration; sebaceous gland; sweat gland.

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Offering of the life of a human being to a god. In some ancient cultures, the killing of a human being, or the substitution of an animal for a person, was an attempt to commune with the god and to participate in the divine life. It also sometimes served as an attempt to placate the god and expiate the sins of the people. It was especially common among agricultural people (e.g., in the ancient Near East), who sought to guarantee the fertility of the soil. The Aztecs sacrificed thousands of victims (often slaves or prisoners of war) annually to the sun, and the Incas made human sacrifices on the accession of a ruler. In ancient Egypt and elsewhere in Africa, human sacrifice was connected with ancestor worship, and slaves and servants were killed or buried alive along with dead kings in order to provide service in the afterlife. A similar tradition existed in China. The Celts and Germanic peoples are among the European peoples who practiced human sacrifice.

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Rights that belong to an individual as a consequence of being human. The term came into wide use after World War II, replacing the earlier phrase “natural rights,” which had been associated with the Greco-Roman concept of natural law since the end of the Middle Ages. As understood today, human rights refer to a wide variety of values and capabilities reflecting the diversity of human circumstances and history. They are conceived of as universal, applying to all human beings everywhere, and as fundamental, referring to essential or basic human needs. Human rights have been classified historically in terms of the notion of three “generations” of human rights. The first generation of civil and political rights, associated with the Enlightenment and the English, American, and French revolutions, includes the rights to life and liberty and the rights to freedom of speech and worship. The second generation of economic, social, and cultural rights, associated with revolts against the predations of unregulated capitalism from the mid-19th century, includes the right to work and the right to an education. Finally, the third generation of solidarity rights, associated with the political and economic aspirations of developing and newly decolonized countries after World War II, includes the collective rights to political self-determination and economic development. Since the adoption of the Universal Declaration of Human Rights in 1948, many treaties and agreements for the protection of human rights have been concluded through the auspices of the United Nations, and several regional systems of human rights law have been established. In the late 20th century ad hoc international criminal tribunals were convened to prosecute serious human rights violations and other crimes in the former Yugoslavia and Rwanda. The International Criminal Court, which came into existence in 2002, is empowered to prosecute crimes against humanity, crimes of genocide, and war crimes.

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Organ system involved in respiration. In humans, the diaphragm and, to a lesser extent, the muscles between the ribs generate a pumping action, moving air in and out of the lungs through a system of pipes (conducting airways), divided into upper and lower airway systems. The upper airway system comprises the nasal cavity (see nose), sinuses, and pharynx; the lower airway system consists of the larynx, trachea, bronchi, bronchioles, and alveolar ducts (see pulmonary alveolus). The blood and cardiovascular system can be considered elements of a working respiratory system. Seealso thoracic cavity.

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Any of a group of viruses that cause warts and other harmless tumours in humans. More than 100 distinct types are known. Different types are responsible for warts of the hands, plantar warts (of the feet), and throat warts. Genital warts are caused by other types, which are spread by sexual intercourse. Some types of papillomaviruses that cause genital infections have been linked with various cancerous tumours, especially cervical cancers; their presence can be detected through a Pap smear.

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In government and military operations, evaluated information concerning the strength, activities, and probable courses of action of international actors that are usually, though not always, enemies or opponents. The term also refers to the collection, analysis, and distribution of such information and to the secret intervention in the political or economic affairs of other countries, an activity commonly known as “covert action.” Intelligence is an important component of national power and a fundamental element in decision making regarding national security, defense, and foreign policies. It is conducted on three levels: strategic, tactical, and counterintelligence. Despite the public image of intelligence operatives as cloak-and-dagger secret agents, much intelligence work involves an undramatic search of “open” sources, such as radio broadcasts and various publications. Among covert sources of intelligence are imagery intelligence, which includes aerial and space reconnaissance, signals intelligence, which includes electronic eavesdropping and code breaking, and human intelligence, which involves the secret agent working at the classic spy trade. Leading national intelligence organizations are the Central Intelligence Agency (CIA) in the U.S.; the Federal Security Service in Russia; MI5 and MI6 in Britain; and the Mossad in Israel.

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Ability of a machine to perform tasks thought to require human intelligence. Typical applications include game playing, language translation, expert systems, and robotics. Although pseudo-intelligent machinery dates back to antiquity, the first glimmerings of true intelligence awaited the development of digital computers in the 1940s. AI, or at least the semblance of intelligence, has developed in parallel with computer processing power, which appears to be the main limiting factor. Early AI projects, such as playing chess and solving mathematical problems, are now seen as trivial compared to visual pattern recognition, complex decision making, and the use of natural language. Seealso Turing test.

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Principal intelligence and counterintelligence agency of the U.S., established in 1947 as a successor to the World War II-era Office of Strategic Services. The law limits its activities to foreign countries; it is prohibited from gathering intelligence on U.S. soil, which is a responsibility of the Federal Bureau of Investigation. Officially a part of the U.S. Defense Department, it is responsible for preparing analyses for the National Security Council. Its budget is kept secret. Though intelligence gathering is its chief occupation, the CIA has also been involved in many covert operations, including the expulsion of Mohammad Mosaddeq from Iran (1953), the attempted Bay of Pigs invasion of Cuba (1961), and support of the Nicaraguan contras in the 1980s.

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or somatotropin

Peptide hormone secreted by the anterior lobe of the pituitary gland. It promotes growth of bone and other body tissues by stimulating protein synthesis and fat breakdown (for energy). Excessive production causes gigantism, acromegaly, or other malformations; deficient production results in dwarfism, dramatically relieved if GH is given before puberty. Genetic engineering techniques now permit large-scale production of adequate amounts of GH for that purpose.

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all the genetic content contained within an organism. An organism's genome is made up of molecules of deoxyribonucleic acid (DNA) that form long strands that are tightly wound into chromosomes, which are found in the nucleus of eukaryotic organisms and in the cytoplasm of prokaryotic organisms. Chromosomes that are unique to certain organelles within a cell, such as mitochondria or chloroplasts, are also considered a part of an organism's genome. A genome includes all the coding regions (regions that are translated into molecules of protein) of DNA that form discrete genes, as well as all the noncoding stretches of DNA that are often found on the areas of chromosomes between genes. The sequence, structure, and chemical modifications of DNA not only provide the instructions needed to express the information held within the genome but also provide the genome with the capability to replicate, repair, package, and otherwise maintain itself. The human genome contains approximately 25,000 genes within its 3,000,000,000 base pairs of DNA, which form the 46 chromosomes found in a human cell. In contrast, Nanoarchaeum equitans, a parasitic prokaryote in the domain Archaea, has one of the smallest known genomes, consisting of 552 genes and 490,885 base pairs of DNA. The study of the structure, function, and inheritance of genomes is called genomics. Genomics is useful for identifying genes, determining gene function, and understanding the evolution of organisms.

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U.S. research effort initiated in 1990 by the U.S. Department of Energy and the National Institutes of Health to analyze the DNA of human beings. The project, intended to be completed in 15 years, proposed to identify the chromosomal location of every human gene, to determine each gene's precise chemical structure in order to show its function in health and disease, and to determine the precise sequence of nucleotides of the entire set of genes (the genome). Another project was to address the ethical, legal, and social implications of the information obtained. The information gathered will be the basic reference for research in human biology and will provide fundamental insights into the genetic basis of human disease. The new technologies developed in the course of the project will be applicable in numerous biomedical fields. In 2000 the government and the private corporation Celera Genomics jointly announced that the project had been virtually completed, five years ahead of schedule.

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Evolution of modern human beings from extinct nonhuman and humanlike forms. Genetic evidence points to an evolutionary divergence between the lineages of humans and the great apes on the African continent 8–5 million years ago (mya). The earliest fossils considered to be remains of hominins (members of the human lineage) date to at least 4 mya in Africa; they are classified as genus Australopithecus. The next major evolutionary stage, Homo habilis, inhabited sub-Saharan Africa about 2–1.5 mya. Homo habilis appears to have been supplanted by a taller and more humanlike species, Homo erectus, which lived from circa 1,700,000 to 200,000 years ago, gradually migrating into Asia and parts of Europe. Between circa 600,000 and 200,000 years ago, Homo heidelbergensis, sometimes called archaic Homo sapiens, lived in Africa, Europe, and perhaps parts of Asia. Having features resembling those of both H. erectus and modern humans, H. heidelbergensis may have been an ancestor of modern humans and also of the Neanderthals (H. neanderthalensis), who inhabited Europe and western Asia from circa 200,000 to 28,000 years ago. Fully modern humans (H. sapiens) seem to have emerged in Africa only circa 150,000 years ago, perhaps having descended directly from H. erectus or from an intermediate species such as H. heidelbergensis.

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Group of ductless glands that secrete hormones necessary for normal growth and development, reproduction, and homeostasis. The major endocrine glands are the hypothalamus, pituitary, pineal, thyroid, parathyroids, adrenals, islets of Langerhans in the pancreas, ovaries, and testes. Secretion is regulated either by regulators in a gland that detect high or low levels of a chemical and inhibit or stimulate secretion or by a complex mechanism involving the hypothalamus and the pituitary. Tumours that produce hormones can throw off this balance. Diseases of the endocrine system result from over- or underproduction of a hormone or an abnormal response to a hormone.

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Branch of psychology concerned with changes in cognitive, motivational, psychophysiological, and social functioning that occur throughout the human life span. In the late 19th and early 20th centuries, developmental psychologists were concerned primarily with child psychology. In the 1950s they became interested in the relationship between child rearing and adult personality, as well as in examining adolescence in its own right. By the late 20th century they had become interested in all aspects of psychological development and change over the entire life span.

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In zoology, the eating of any animal by another member of the same species. Certain ants regularly consume injured immatures and, when food is scarce, eat healthy immatures; this practice allows the adults to survive the food shortage and live to breed again. Male lions taking over a pride may kill and eat the existing young. After losing her cubs the mother will become impregnated by the new dominant male, thereby ensuring his genetic contribution. Aquarium guppies sometimes regulate their population size by eating most of their young.

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