(bī-ŏl'ə-jē) pronunciation
  1. The science of life and of living organisms, including their structure, function, growth, origin, evolution, and distribution. It includes botany and zoology and all their subdivisions.
  2. The life processes or characteristic phenomena of a group or category of living organisms: the biology of viruses.
  3. The plant and animal life of a specific area or region.

[German Biologie : Greek bio-, bio- + Greek -logiā, -logy.]

biologist bi·ol'o·gist n.

Study of living things and their vital processes. An extremely broad subject, biology is divided into branches. The current approach is based on the levels of biological organization involved (e.g., molecules, cells, individuals, populations) and on the specific topic under investigation (e.g., structure and function, growth and development). According to this scheme, biology's main subdivisions include morphology, physiology, taxonomy, embryology, genetics, and ecology, each of which can be further subdivided. Alternatively, biology can be divided into fields especially concerned with one type of living thingfor example, botany (plants), zoology (animals), ornithology (birds), entomology (insects), mycology (fungi), microbiology (microorganisms), and bacteriology (bacteria). biochemistry; molecular biology.

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A natural science concerned with the study of all living organisms. Although living organisms share some unifying themes, such as their origin from the same basic cellular structure and their molecular basis of inheritance, they are diverse in many other aspects. The diversity of life leads to many divisions in biological science involved with studying all aspects of living organisms. The primary divisions of study in biology consist of zoology (animals), botany (plants), and protistology (one-celled organisms), and are aimed at examining such topics as origins, structure, function, reproduction, growth and development, behavior, and evolution of the different organisms. In addition, biologists consider how living organisms interact with each other and the environment on an individual as well as group basis. Therefore, within these divisions are many subdivisions such as molecular and cellular biology, microbiology (the study of microbes such as bacteria and viruses), taxonomy (the classification of organisms into special groups), physiology (the study of function of the organism at any level), immunology (the investigation of the immune system), genetics (the study of inheritance), and ecology and evolution (the study of the interaction of an organism with its environment and how that interaction changes over time).

The study of living organisms is an ongoing process that allows observation of the natural world and the acquisition of new knowledge. Biologists accomplish their studies through a process of inquiry known as the scientific method, which approaches a problem or question in a well-defined orderly sequence of steps so as to reach conclusions. The first step involves making systematic observations, either directly through the sense of sight, smell, taste, sound, or touch, or indirectly through the use of special equipment such as the microscope. Next, questions are asked regarding the observations. Then a hypothesis—a tentative explanation or educated guess—is formulated, and predictions about what will occur are made. At the core of any scientific study is testing of the hypothesis. Tests or experiments are designed so as to help substantiate or refute the basic assumptions set forth in the hypothesis. Therefore, experiments are repeated many times. Once they have been completed, data are collected and organized in the form of graphs or tables and the results are analyzed. Also, statistical tests may be performed to help determine whether the data are significant enough to support or disprove the hypothesis. Finally, conclusions are drawn that provide explanations or insights about the original problem. By employing the scientific method, biologists aim to be objective rather than subjective when interpreting the results of their experiments. Biology is not absolute: it is a science that deals with theories or relative truths. Thus, biological conclusions are always subject to change when new evidence is presented. As living organisms continue to evolve and change, the science of biology also will evolve. See also Animal; Botany; Cell biology; Ecology; Genetics; Immunology; Microbiology; Plant; Zoology.

biology, the science that deals with living things. It is broadly divided into zoology, the study of animal life, and botany, the study of plant life. Subdivisions of each of these sciences include cytology (the study of cells), histology (the study of tissues), anatomy or morphology, physiology, and embryology (the study of the embryonic development of an individual animal or plant). Also included in biological studies are the sciences of genetics, evolution, paleontology, and taxonomy or systematics, the study of classification. The methods and attitudes of other sciences are brought to the study of biology in such fields as biochemistry (physiological chemistry), biophysics (the physics of life processes), bioclimatology and biogeography (ecology), bioengineering (the design of artificial organs), biometry or biostatistics, bioenergetics, and biomathematics. Evidences of early human observations of nature are seen in prehistoric cave art. Biological concepts began to develop among the early Greeks. The biological works of Aristotle include his observations and classification of his large collections of animals. The invention of the microscope in the 16th cent. gave a great stimulus to biology, broadening and deepening its scope and creating the sciences of microbiology, the study of microscopic forms of life, and microscopy, the microscopic study of living cells. Among the many who contributed to the science are Claude Bernard, Cuvier, Darwin, T. H. Huxley, Lamarck, Linnaeus, Mendel, and Pasteur. See marine biology.


See T. Lenoir, The Strategy of Life (1989); C. A. Villee et al., Biology (3d ed. 1989); N. A. Campbell, Biology (3d ed. 1993).

The science of biology as such did not exist in the early modern period; the term biology itself came into use only around 1800. Nonetheless, research in subjects now encompassed by biology was avidly pursued, principally by physicians but also by natural philosophers. The philosopher of science Francis Bacon (1561–1626) called for intensified descriptive study of physical forms ("natural history") and the analytical study of their functions, classified as part of "physic." Institutional sites for inquiry included the universities, with those in southern Europe dominant earlier and those in northern Europe later in the period. Private individuals often worked with the support of aristocratic, princely, and ecclesiastical patrons. In the seventeenth century omnibus scientific societies were founded in Rome and Florence. The Royal Society of London (founded 1660) and the Academy of Sciences in Paris (founded 1666) were highly influential. Specialized learned societies came into existence only at the end of the period. Instruments were less important than in physical science, but the microscope proved crucial to advances in knowledge. Much inquiry was tied to the pursuit of fine and technical arts (painting and sculpture, optics, printing and illustrating) and to collecting practices ("cabinets of curiosities"). Public gardens and zoological collections were essential to naturalists from the seventeenth century forward.

Natural Philosophy

At the beginning of the period the natural philosophy taught in the universities was dominated by Aristotelianism as recast by the late Scholastics to harmonize with Roman Catholic orthodoxy. Aristotelian philosophy established the linguistic and conceptual framework for inquiry and conveyed specific doctrines such as the "great chain of being," a posited hierarchy of natural forms ranging from the simplest to the most complex. Aside from Aristotelian influence, medicine was dependent on the legacy of the Greek physician Hippocrates (460–c. 370 B.C.E.), especially the doctrine of the humors, and of the Hellenistic surgeon and Roman court physician Galen (129/130–199/200 C.E.), whose general teleology and specific teachings in anatomy and physiology undergirded universitybased medical training. Competing intellectual traditions derived from Plato (427–348/347 B.C.E.) as well as the occult sciences of the cabala, natural magic, hermeticism, astrology, and alchemy.

The greatest master of the occult sciences in medicine was Philippus Aureolus Theophrastus Bombast von Hohenheim, called Paracelsus (1493–1541). Paracelsus rejected the study of anatomy, basing pathology and therapeutics instead on the doctrine of correspondences between the macrocosm and the microcosm. His "ontological" theory of disease, which held that the "seeds" of all maladies are present in every organism, undermined humor theory and encouraged the search for specific remedies, especially new ones derived from metals. Paracelsianism spread most rapidly in Protestant lands and Protestant enclaves in Catholic Europe. Its diffusion contributed to the decline of Aristotelianism, which was, however, principally undermined by the emergent "mechanical philosophy." Mechanism, which viewed living bodies as sophisticated machines, was dominant from the later seventeenth century until challenged around 1750 by vitalists who posited a distinctive "principle of life" or individuated vital "forces." By the eighteenth century many investigators rejected all "systems" and embraced a scientific ethos based on observation and experimentation.

Historical Context

European contact with the New World resulted in a challenge to existing conceptions of creation, the lineage of humankind, and the number and types of living creatures. Other influences included the continuing recovery of the heritage of Greco-Roman antiquity; the emergence of centralizing "new monarchies" and elaborated forms of princely and municipal government; and long-term economic revival from the ravages of the pandemic of plague that first struck Europe in 1348. In connection with these changes, new and fuller editions of the works of ancient philosophers and physicians appeared; the arts and sciences enjoyed expanded prestige and public patronage; and new commodities, both natural and manufactured, came into use. The Protestant Reformation destroyed the religious unity of Europe and encouraged challenges to tradition. The absolutist state emergent in the seventeenth century established new guardians of orthodoxy but also provided new resources for learned inquiry. More powerful government, coupled with economic growth and differentiation, encouraged the spread of literacy and the extension of modes of communication and transportation. These combined forces unsettled social hierarchies based on bloodlines, corporate status, and gender. The self-styled "Enlightenment" of the eighteenth century was marked by a commitment to the methods and values of "science," variously defined, and by a heightened critical spirit. Broader historical developments were linked both as cause and effect to changes in the world of learning that, by the period's end, encouraged the emergence of modern life science.

Anatomy and Physiology

Because in Aristotelian-Galenic medicine the heart was considered central, many Renaissance-era inquirers were drawn to the study of this organ. Aristotle viewed the heart as the center of the body, the seat of the "vital heat" that empowered its functions. Galen delineated the structure and functions of the heart and other organs dominant in three body "centers" of head, chest, and abdomen. In his system, blood flowed only as part of an ebb and flow to and from the dominant organ to peripheral structures; arterial blood produced in the right ventricle of the heart seeped into the left ventricle via "pores" in the septum. In his anatomical atlas De humani corporis fabrica (1543), the anatomist and professor at Padua Andreas Vesalius (1514–1564) questioned the existence of the septal pores without challenging the overall outlines of Galenic physiology. After Vesalius, other investigators at Padua contributed to the study of the heart. Realdo Colombo (1510–1559) described the "lesser circulation" (the transit of blood from the right to the left side of the heart via the lungs), and Girolamo Fabrici (1533–1619) described the valves in the veins. The Padua tradition was crowned by the achievement of William Harvey (1578–1657), who studied with Fabrici. After taking his medical degree in 1602, Harvey returned to England, where he became a staff physician at St. Bartholomew's Hospital, Fellow of the College of Physicians, and court physician to the Stuart kings.

A committed Aristotelian, Harvey upheld Aristotle's conception of the heart as the vivifying center of the body and the principle of the perfection of the circle. Yet Harvey was also a powerful innovator methodologically and conceptually. He designed and performed experiments using a wide range of cold- and warm-blooded animals. He drew compelling analogies between the work of the heart and vessels and mechanical actions. Most tellingly, he quantified the amount of blood that passed through the body with each beat of the heart. Judging it too great to be produced by nutritional activity, he was convinced that the blood must move in one great circulatory motion throughout the body. This discovery was incorporated in his Anatomical Treatise on the Movement of the Heart and Blood (1628). Although the impact of Harvey's work was delayed because of an entrenched Galenism, in time his findings revolutionized thinking about the heart and blood as well as general physiology. Harvey's work also lent great prestige to the emergent "mechanical philosophy," although Harvey himself was not a mechanist.

The chief intellectual force behind the body-machine analogy was the French philosopher René Descartes (1596–1650). Descartes's cosmology sought to explain all known physical phenomena, including, in his posthumously published treatise Man (1664), mechanisms of digestion, respiration, reproduction, and other vital activities. Fruitful applications of mechanist thinking were found in works such as Giovanni Alfonso Borelli's On the Motions of Animals (1680–1681), which explored the mechanics of the human muscular and skeletal systems. Mechanist thinking also had a profound impact on inquiry into the cluster of problems called "generation."

The Problem of Generation

Learned interest in processes of reproduction, including heredity, developed in response both to internal scientific dynamics and to sociocultural pressures for clarity in respect to family lineages, gender roles, and rules for inheritance. Aristotelian teaching posited a union in reproduction of male "form," embodied in semen gathered from throughout the body, with female "matter" (menstrual blood), presenting the male as the "perfect" result while the female was a continuously appearing "monster" of nature. A competing, Galenic account of generation posited two "semens," one male and one female. Inspired by Aristotle, Fabrici and other inquirers at Padua pursued a comparative study of the embryos of horses, sheep, and other animals. Harvey conducted extensive experiments designed to elucidate developmental processes. The most famous was his dissection during and after mating season of does in whom he found no trace of male semen. His Anatomical Treatise on the Generation of Animals (1651) declared that "all living beings arise from eggs." This was the beginning of "ovism," which held that the female alone contributed materially to the embryo.

This view was contradicted by Antoni van Leeuwenhoek (1632–1723), who, using a microscope, identified the spermatozoon ("animalcule") in 1677. Ensuing controversy pitted "ovists" against "animalculists," who held that the male contributed all parts of the embryo. In most cases both ovists and animalculists rejected Aristotle's view that the embryo developed in a process of epigenesis, the progressive elaboration of new structures. Both generally favored the "preformationist" view that each individual exists as a preformed miniature in the matter present at conception and develops through mechanical enlargement. The epigenesistpreformationist debate culminated in an exchange between the Swiss physiologist Albrecht von Haller (1708–1777) and the German naturalist Caspar Friedrich Wolff (1733–1794). Initially a preformationist, Haller converted to epigenesis after studying the discovery by Abraham Trembley (1710–1784) of the regenerative capacities of the freshwater polyp. He later settled on ovist preformationism, fearing the irreligious implications of epigenesist theories like that of Georges Louis Leclerc Buffon (1707–1788), who postulated an "interior mold" that shaped development and disregarded the role of the creator. Challenging Haller, Wolff argued for a vis essentialis, or essential force, responsible for patterns of differentiation evident in development. Wolff made extensive use of plants to study development and thus effected a juncture with this branch of natural history.

Natural History and Classification

Early description and ordering of plants and animals was undertaken as an adjunct to both the search for remedies and the humanist effort to identify references in works of the ancients. Herbals based principally on classical, Arabic, and Medieval Latin sources were among the first printed books. Sixteenth-century naturalists such as Conrad Gessner (1516–1565) began organizing local collecting expeditions. Accurate description and representation of distinctive external characteristics of leaf, flower, and fruit were emphasized. The number of species described steadily increased until, in the 1680s, the English naturalist John Ray (1627–1705) described some eighteen thousand species.

Interest in the comparative structure of the parts of plants distinguished the work of Andrea Cesalpino (1519–1603), medical professor first at Pisa and then Rome. Cesalpino sought unifying principles of classification and, after an interval, was followed in that effort by Joachim Junge (1587–1657), also a medical professor. The quest for a "natural" system of classification culminated in the work of Carl Linneaus (1707–1778), the Swedish naturalist whose work formed the basis for modern taxonomy.

Animals were similarly the focus of joint artistic and learned pursuits. Leonardo da Vinci (1452–1519) did his own dissections and compared the structure of body parts in humans, horses, bears, cats, monkeys, and other animals. The humanist lexicographer William Turner (1508–1568) compiled existing accounts of birds and added observations of his own. French naturalists including Pierre Belon (1517–1564) and Guillaume Rondelet (1507–1566) undertook comparative studies of fish. Much seventeenth-century work on the comparative morphology of animals was tied to the investigations into generation discussed above.

The natural history of plants and animals was of keen interest to both trained investigators and the educated public by the late seventeenth century. Religious feeling was central to the popularity of "natural theology." While the mechanical philosophy dispensed with direct intervention in nature by the deity, natural histories such as Spectacle of Nature (1732–1750), by Noël-Antoine, the Abbé Pluche, drew attention to the marvels of God's creation. The most influential naturalists of the eighteenth century, Linnaeus and Buffon, focused not on religious but scientific themes, especially the problem of how best to approach classification itself. Buffon's Natural History, a general history of the earth and living creatures, was published in many volumes beginning in 1749. Determinedly non-religious, it largely ignored biblical chronology and posited the passage of eons in which natural forms had altered.


Conventional history of science divided the early modern era into the Renaissance (1400–1550), the scientific revolution (1550–1700), and the Enlightenment (1700–1800), and generally treated life science as peripheral to the revolutionary changes under way in physical science. An alternate scheme divides the era into two phases, roughly 1450–1670 and 1670–1800, more appropriate to biology, with the break marked by a decisive rejection of both Aristotelian thinking and competing occult traditions in favor of inquiry based first on deductive reasoning and, finally, modern inductive science.

Twentieth- and twenty-first-century scholarship has been much affected by the work of the French philosopher Michel Foucault (1926–1984), who overturned traditional labels and periodization. Historians following his lead have questioned presumed continuities with modern science, recovered texts and formulations previously regarded as merely "curious," and investigated the interconnections between learned "discourses" and structures of power. Historical revisionism is also evident in the work of social "constructivists" who emphasize the social creation of knowledge rather than its emergence from autonomous intellectual dynamics.


Ackerknecht, Erwin H. A Short History of Medicine. Rev. ed. Baltimore, 1982. A brief account of medical history, with some attention to larger issues in life science.

Butterfield, Herbert. The Origins of Modern Science: 1300–1800. Rev. ed. London and New York, 1957.

Clark, William, Jan Golinski, and Simon Schaffer, eds. The Sciences in Enlightened Europe. Chicago, 1999. Chapters on biopolitics, monsters, and natural history in the Enlightenment, with emphasis on the social foundations of knowledge.

Crombie, A. C. Medieval and Early Modern Science. Vol. 2, Science in the Later Middle Ages and Early Modern Times: 13th–17th Centuries. Garden City, New York, 1959. A standard survey of early modern science.

Daston, Lorraine, and Katharine Park. Wonders and the Order of Nature, 1150–1750. New York and Cambridge, Mass., 1998. A Foucauldian study focused on the place of marvels in conceptions of natural order.

Foucault, Michel. The Order of Things: An Archaeology of the Human Sciences. New York, 1971. An early work of the French philosopher who has revolutionized intellectual and cultural history.

Hall, Thomas S. History of General Physiology, 600 B . C .to A . D . 1900. 2 vols. Chicago, 1975. Essential account of the history of physiology.

Impey, Oliver, and Arthur Mac Gregor, eds. The Origins of Museums: The Cabinet of Curiosities in Sixteenth and Seventeenth-Century Europe. Oxford and New York, 1985. A valuable work of institutional history.

Lovejoy, Arthur O. The Great Chain of Being: A Study of the History of an Idea. Cambridge, Mass., 1936. Classic study by the master of the "history of ideas."

Magner, Lois N. A History of the Life Sciences. 2nd ed. New York, 1994. Places early modern developments within the larger history of biology from the ancients to the era of genetics and molecular biology.

Roger, Jacques. The Life Sciences in Eighteenth-Century French Thought. Edited by Keith R. Benson. Translated by Robert Ellrich. Stanford, 1997. Translation of Les sciences de la vie dans la pensée française au XVIIIe siècle: La génération des animaux de Descartes à l'Encyclopédie. Magisterial work on the problem of generation, chiefly but not exclusively on French inquirers.


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IN BRIEF: The study of living things.

pronunciation He decided to study marine biology so he could work with dolphins. is a free vocabulary and spelling program where you only pay for results!

The study of life and living systems.

The study of plants and animals. See Chemistry, Biochemistry, Organic Chemistry, Genetic Engineering.

  1. the scientific study of living organisms, including their structure, functioning, development, distribution, interrelationships, and evolution.
  2. the animal and plant life of a particular region considered as a unit.
  3. the structure, functioning, etc. of a particular organism or group of organisms.
biologist n.

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The science of life or living matter in all its forms and phenomena.

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For a list of words related to biologist, see:


Dansk (Danish)
n. - biologi

Nederlands (Dutch)

Français (French)
n. - biologie

Deutsch (German)
n. - Biologie

Ελληνική (Greek)
n. - βιολογία

Italiano (Italian)

Português (Portuguese)
n. - biologia (f)

Русский (Russian)

Español (Spanish)
n. - biología

Svenska (Swedish)
n. - biologi

中文(简体)(Chinese (Simplified))
生物学, 生物

中文(繁體)(Chinese (Traditional))
n. - 生物學, 生物

한국어 (Korean)
n. - 생물학, 생태학, 생활사

日本語 (Japanese)
n. - 生物学

العربيه (Arabic)
‏(الاسم) بيولوجيا, علم الأحياء‏

עברית (Hebrew)
n. - ‮ביולוגיה‬

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