still life, a pictorial representation of inanimate objects. The term derives from the 17th-century Dutch still-leven, meaning a motionless natural object or objects.

Evolution of Still Life

Until the Renaissance, elements of still life, often imbued with symbolic or ritual significance, appeared as subordinate subject matter in religious or allegorical paintings. Hellenistic frescoes and mosaics from Pergamon, Alexandria, Rome, and Pompeii included depictions of plants and food in which a trompe l'oeil illusionism was often stressed. In early Christian and Byzantine religious paintings still-life elements were handled in a schematized and symbolic fashion until the end of the Middle Ages. Franco-Flemish paintings of the late Gothic era revealed close observation of natural details, as seen in much of the period's manuscript illumination.

At the beginning of the Italian Renaissance such detail was handled far more formally and was utterly dominated by the religious theme of the work, as in the paintings of Giotto. By the 15th cent. still-life objects were used to enhance the illusion of scientific perspective, a subject of passionate study in the new humanism. At that time still life became a separate genre in Italy; it was used to great effect by masters of marquetry.

It was in the religious works of Northern European masters that the revival of the study of nature was most completely revealed. The van Eycks, van der Weyden, van der Goes, and Robert Campin, to name but a few, observed carefully and recorded exactly objects of everyday use and subjects from nature. They incorporated these into religious works, giving them more and more importance until the still-life elements appeared in the foreground and diminished the religious, or landscape subject, as in the works of Aertsen and Beuckelaer.

Specialists in the handling of specific textures or effects such as glass, fur, plants, and the translucence of grapes came into being. Where Italian artists had communication with Northern masters, their works reflected the Northern interest in still-life subjects. The direction of this influence was reversed by the time of Caravaggio. Specialty pictures were the first major separate still lifes. These included works on the vanitas vanitatum theme featuring skull, hourglass, candle, book, and flowers in their iconography, as well as the banquet pieces that had become popular with collectors of 1600.

Still Life in the Seventeenth to Nineteenth Centuries

Still life was developed as a separate genre primarily in the Netherlands in the works of Jan Bruegel (see under Bruegel, family), Rubens, Snyders, and Rembrandt. In France still life was used in the 17th cent. primarily for trompe l'oeil exercises and not significantly elevated until it received brilliant handling by Chardin in the 18th cent. French 19th-century masters, including Courbet and Cézanne, adopted still life wholeheartedly, giving it status equal to that of their other subjects. In the United States, Harnett and Peto used still life in order to display brilliant trompe l'oeil techniques.

Still Life in the Twentieth Century

In the 20th cent. both American and European artists' most characteristic subject matter was still life. The cubist artists, Picasso, Braque, and Gris, painted still-life subjects predominantly. The artists in many schools of abstract painting, beginning with Cézanne and continuing to the present day, forsook the objective representation of still life and developed myriad varieties of treatment of the subject, concentrating on color, form, and composition. Occasionally they painted other subjects, applying to these their still-life stylistic techniques. The painters of the pop art movement and their followers frequently criticized contemporary social values using, almost exclusively, still-life subject matter. They chose objects of popular culture relevant to their thesis such as soup cans and comic strips.

East Asian Still Life

In East Asia still-life subjects were depicted as early as the 11th cent. Chinese works were distinguished by brilliant brushwork and rapid execution. Objects were frequently endowed with symbolic import in both Chinese works and the Japanese compositions often derived from them. The importance of illusionistic representation of the object was minimized in East Asian Art, and in general its treatment of still life does not correspond with that of Western art.

life support system: see artificial life support; Life Support for Human Spaceflight under space science.

life preserver, a personal flotation device (PFD) intended to keep the wearer afloat, particularly in case of shipwreck. A Type I PFD will keep even unconscious people afloat in a face-up position; it is the most common type used at sea. Another common type, developed during World War II for fliers and called the Mae West (named for the actress because of its shape), is made of inflatable rubber; it is still carried on commercial aircraft. Other types of life preservers are meant to be used only as a stopgap by a conscious wearer; these take the form of rings, cushions, or vests, and are either inflatable or filled with buoyant material such as unicellular foam, fibrous glass, or kapok. The large balsa wood life rafts once carried by all ships have been replaced by canisters containing inflatable life rafts capable of holding from four to twenty-four people. Most countries require that ships, and airplanes crossing the water, must carry life preservers and that crew and passengers must be drilled in their use.

life insurance: see insurance.

life, although there is no universal agreement as to a definition of life, its biological manifestations are generally considered to be organization, metabolism, growth, irritability, adaptation, and reproduction. Protozoa perform, in a single cell, the same life functions as those carried on by the complex tissues and organs of humans and other highly developed organisms. The attributes of life are inherent in such minute structures as viruses, bacteria, and genes, just as they are in the whale and the giant sequoia. In seeking an understanding of life, scientists have broken down many barriers that once separated the physical sciences from the biological sciences; a result of the growth of biochemistry, biophysics, and other interrelated fields of study has been a better understanding of the composition and functioning of living tissues of all kinds.

Characteristics of Life

Organization is found in the basic living unit, the cell, and in the organized groupings of cells into organs and organisms. Metabolism includes the conversion of nonliving material into cellular components (synthesis) and the decomposition of organic matter (catalysis), producing energy. Growth in living matter is an increase in size of all parts, as distinguished from simple addition of material; it results from a higher rate of synthesis than catalysis. Irritability, or response to stimuli, takes many forms, from the contraction of a unicellular organism when touched to complex reactions involving all the senses of higher animals; in plants response is usually much different than in animals but is nonetheless present. Adaptation, the accommodation of a living organism to its present or to a new environment, is fundamental to the process of evolution and is determined by the individual's heredity. The division of one cell to form two new cells is reproduction; usually the term is applied to the production of a new individual (either asexually, from a single parent organism, or sexually, from two differing parent organisms), although strictly speaking it also describes the production of new cells in the process of growth.

The Basis of Life

Much of the history of biology and of philosophy as related to biology has been marked by a division of thought between vitalistic (or animistic) and mechanistic (or materialistic) concepts. In the most antithetic interpretations of these concepts, the vitalistic school maintains that there is a vital force that distinguishes the living from the nonliving and the mechanistic school holds that there is no essential difference between the animate and inanimate and that all life can be explained by physical and chemical laws. Such diametrically opposed views have actually seldom been held by investigators of either school; elements of both are usually involved. The animistic school, largely predicated on the inexplicability of the basic phenomena of life, has been greatly overshadowed by the accumulating weight of scientific data. As more and more is learned of the minute details of the structure and composition of the substances that make up the cell (to the extent that some have been synthesized chemically), it has become increasingly apparent that living matter is made up of the same (and only those) elements found in inorganic material, except that they are differently organized.

The Origin of Life

Fundamental religious concepts center around special creation and belief in the infusion of life into inanimate substance by God or another superhuman entity. On the other hand, many scientists have hypothesized that during an early geological period there gradually formed in the atmosphere increasingly complex organic substances composed of available inorganic compounds and water, utilizing ultraviolet rays and electrical discharges as energy sources. At a certain stage they formed a diffuse solution of "nutrient broth." Then in some way they were drawn together and developed the capacity for self-renewal and self-reproduction. In 1953, S. L. Miller synthesized several of the most basic amino acids in a glass flask by introducing an electrical discharge into an atmosphere of water vapor and some simple compounds thought to have been present naturally at the time when life first developed on earth. A more recent theory now widely held is that life originated in a volcanic setting more than 3.5 billion years ago, perhaps in hot deep-sea vents, utilizing a biochemistry based largely on sulfur and iron. The theory that life on earth came in a simple form from another planet has had small currency, although the discovery by Melvin Calvin of molecules resembling genetic material in meteors has given it some force.

half-life, measure of the average lifetime of a radioactive substance (see radioactivity) or an unstable subatomic particle. One half-life is the time required for one half of any given quantity of the substance to decay. For example, the half-life of a particular radioactive isotope of thorium is 8 minutes. If 100 grams of the isotope are originally present, then only 50 grams will remain after 8 minutes, 25 grams after 16 minutes (2 half-lives), 12.5 grams after 24 minutes (3 half-lives), and so on. Of course the 87.5 grams that are no longer present as the original substance after 24 minutes have not disappeared but remain in the form of one or more other substances in the isotope's radioactive decay series. Individual decays are random and cannot be predicted, but this statistical measure of the great number of atoms in the sample is very accurate. The half-life of a radioactive isotope is a characteristic of that isotope and is not affected by any change in physical or chemical conditions.

artificial life support, systems that use medical technology to aid, support, or replace a vital function of the body that has been seriously damaged. Such techniques include artificial pacemakers, internal defibrillators, dialysis machines (see kidney, artificial), and respirators. The use of life-support systems to prolong the life of a patient who has suffered apparently irreversible damage to a vital organ system may raise such ethical issues as the quality of life, euthanasia, and the right to die, and has been the subject of much legal and moral debate. Some people specify their wishes concerning prolonged artificial life support, especially should they be in a persistent vegetative state (see coma), in a living will. A health-care proxy is another legal means of insuring that a person's wishes regarding artificial life support are respected, even if the person is unable to communicate those wishes.

Life of Adam and Eve: see Adam and Eve, Life of.

Census of Marine Life, an international program to assess and explain the diversity, distribution, and abundance of living organisms in the oceans. A 10-year project involving scientists in more than 70 nations, the census began in 2001 and is directed by an international scientific steering committee, subcommittees, and national and regional committees. In addition to coordinating field surveys, which have identifed previously unknown species, the census is producing the Ocean Biogeographic Information System to manage the database that results. Historical research is also being undertaken so as to provide an understanding of the past diversity and distribution of marine species. The secretariat for the project is at the Consortium for Oceanographic Research and Education, Washington, D.C.

Brothers of the Common Life: see Groote, Gerard.

Brotherhood of the New Life: see Harris, Thomas Lake.

Adam and Eve, Life of, early Jewish work included in the collection known as the Old Testament Pseudepigrapha. It was probably written in Hebrew between 100 B.C. and A.D. 100. Based on the Old Testament story, it supplements the original. It has been interpreted to teach that Eve was the source of Adam's sin and that she was responsible for the Fall.

Alcoholic beverage obtained by distillation from wine or other fermented fruit juice or from various cereal grains that have first been brewed. The essential ingredient is usually a natural sugar or a starchy substance that may be easily converted into a sugar. The distillation process is based on the different boiling points of water (212 °F [100 °C]) and alcohol (173 °F [78.5 °C]). The alcohol vapours that arise while the fermented liquid boils are trapped and recondensed to create a liquid of much greater alcoholic strength. The resultant distillate is matured, often for several years, before it is packaged and sold. Seealso aquavit; brandy; gin; liqueur; rum; vodka; and whiskey.

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(Latin: “tree of life”) Any of six species (genus Thuja) of resinous, evergreen ornamental and timber conifers of the cypress family, native to North America and eastern Asia. Arborvitae trees or shrubs have thin, scaling outer bark and fibrous inner bark; horizontal or ascending branches; and flattened, spraylike branchlets with scalelike leaves. The Oriental, or Chinese, arborvitae (T. orientalis), a popular ornamental native to Asia, is a gracefully symmetrical shrub. Arborvitae wood is soft and lightweight but very durable, fragrant, and easily worked. The giant arborvitae (T. plicata) is the most important timber-producing species, but the wood of the American arborvitae (T. occidentalis) is also frequently used. False arborvitae (Thujopsis dolabrata) is closely related.

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Depiction of inanimate objects for the sake of their qualities of form, colour, texture, composition, and sometimes allegorical or symbolical significance. Still lifes were painted in ancient Greece and Rome. In the Middle Ages they occur in the borders of illuminated manuscripts. The modern still life emerged as an independent genre in the Renaissance. Netherlandish still lifes often depicted skulls, candles, and hourglasses as allegories of mortality, or flowers and fruits to symbolize nature's cycle. Several factors contributed to the rise of still life in the 16th–17th century: an interest in realistic representation, the rise of a wealthy middle class that wanted artworks to decorate its homes, and increased demand for paintings of secular subjects other than portraits in the wake of the Reformation. Dutch and Flemish painters were the masters of still life in the 17th century. From the 18th century until the rise of nonobjective painting after World War II, France was the centre of still-life painting.

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In radioactivity, the average lifetime of all the nuclei of a particular unstable atomic species. This time interval is the sum of the lifetimes of all the individual unstable nuclei in a sample, divided by the total number of unstable nuclei present. It is the reciprocal of the decay constant. For a given isotope, the mean life is always 1.443 times its half-life. For example, lead-209 decays to bismuth-209 with a half-life of 3.25 hours and a mean life of 4.69 hours.

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Time between birth and death. It ranges from a mayfly's day to certain trees' thousands of years. Its limit appears to depend on heredity, but such factors as (in humans) disease, natural disasters, war, diet, and habits such as smoking reduce it. Maximum life span is theoretical; more meaningful is average life span, which life-insurance companies and actuaries analyze and tabulate. Long-lived progenitors tend to beget long-lived descendants. A very-low-calorie diet appears to prolong life. Reduced infant mortality and improved sanitation and nutrition account for much of the increase since circa 1800—from about 35 to over 70 years in most industrialized countries. The oldest well-documented age reached by a human is 122 years.

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Method by which large groups of individuals equalize the burden of financial loss from death by distributing funds to the beneficiaries of those who die. Life insurance is most developed in wealthy countries, where it has become a major channel of saving and investing. There are three basic types of life-insurance contract. Term insurance is issued for a specified number of years; protection expires at the end of the period and there is no cash value remaining. Whole-life contracts run for the whole of the insured's life and also accumulate a cash value, which is paid when the contract matures or is surrendered; the cash value is less than the policy's face value. Endowment contracts run for a specified time period and pay their full face value at the end of the period.

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State characterized by the ability to metabolize nutrients (process materials for energy and tissue building), grow, reproduce, and respond and adapt to environmental stimuli. Fossil evidence suggests that earth's first living organisms, bacteria and cyanobacteria, arose about 3.5 billion years ago. All known life-forms possess either DNA or RNA. Viruses, which possess DNA and RNA, cannot reproduce without a host cell and do not metabolize nutrients, and it is uncertain whether they should be classified as living or nonliving. Scientists disagree on the likelihood of extraterrestrial life. Seealso Drake equation.

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Interval of time required for one-half of the atomic nuclei of a radioactive sample to decay (change spontaneously into other nuclear species by emitting particles and energy), or the time required for the number of disintegrations per second of a radioactive material to decrease by one-half. Half-lives are characteristic properties of the various unstable atomic nuclei and the particular way in which they decay. Alpha decay and beta decay are generally slower processes than gamma decay.

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