life

View more Religion & Spirituality videos

For more information on life, visit Britannica.com.

noun

1. A lively, emphatic, eager quality or manner: animation, bounce, brio, dash, élan, esprit, liveliness, pertness, sparkle, spirit, verve, vigor, vim, vivaciousness, vivacity, zip. Informal ginger, pep, peppiness. Slang oomph. See action/inaction.
2. A member of the human race: being, body, creature, homo, human, human being, individual, man, mortal, party, person, personage, soul. See beings.
3. The period during which someone or something exists: day (often used in plural), duration, existence, lifetime, span, term. See live/die, time.

Idioms beginning with life:
life is too short
life of the party

See also bet one's ass (life); big as life; breathe new life into; bring to life; change of life; charmed life; come alive (to life); dog's life; facts of life; for dear life; for the life of; get a life; good life; late in life; lay down (one's life); lead a double life; matter of life and death; new lease on life; not on your life; of one's life; once in a lifetime; prime of life; risk life and limb; run for it (one's life); staff of life; story of my life; take someone's life; to save one's life; to the life; true to (life); variety is the spice of life; walk of life; while there's life there's hope; you bet (your life).

Definition: animation
Antonyms: death, inanimacy, inanimate object, nonexistence

1. A cellular-automata game invented by John Horton Conway and first introduced publicly by Martin Gardner (Scientific American, October 1970); the game's popularity had to wait a few years for computers on which it could reasonably be played, as it's no fun to simulate the cells by hand. Many hackers pass through a stage of fascination with it, and hackers at various places contributed heavily to the mathematical analysis of this game (most notably Bill Gosper at MIT, who even implemented life in TECO!). When a hacker mentions ‘life’, he is much more likely to mean this game than the magazine, the breakfast cereal, or the human state of existence. Many web resources are available starting from the Open Directory page of Life. The Life Lexicon is a good indicator of what makes the game so fascinating.

In biblical thought the Commandments of God to man form a "tree of life" (Prov. 3:18) and through loving God and heeding His commandments the Jew "shall have life and shall long endure" (Deut. 30:20). God also presents the human being with the choice between life and good on the one hand and death and evil on the other, and enjoins him to "choose life that you and your seed shall live" (Deut. 30:15-19).

The words in Leviticus 18:5 "to live by them [i.e., the commandments]" are interpreted in rabbinic teaching to mean that God's commandments are to be a means of life, not destruction, for His children. Therefore, with the exception of three prohibitions (idolatry, bloodshed, and sexual license), all commandments of the law may be violated if life is endangered.

While one is alive, every effort must be made to enhance life, both in its physical and spiritual dimension. The destruction of a single life (Sanh. 4:5) is considered tantamount to the destruction of the whole world, just as the saving of a life is the saving of an entire world. Although the Bible defines the desecration of the Sabbath as a capital crime, Pikku'Aḥ Nefesh (the saving of a life) supersedes the Sabbath commandments. In the same spirit, insuring the health of the mother and infant during childbirth or feeding a sick person on the Day of Atonement is more important than the observance of any of the commandments. These acts are not merely desirable, they are required by Jewish law.

Thanksgiving for the beauty and sanctity of life is expressed in Benedictions to be recited on various occasions. Rav's comment on the last verse of Psalms, "Let everything that breathes praise the Lord," is that "we must thank God for every fragrant breath that we breathe."

See also Death; Resurrection; Soul, Immortality of.

The Bible's central concern and main issue is the paramount importance of life, and how to maintain and sanctify it.

The underlying concept for the biblical view of life is the creation of man in God's image (Gen 1:26). God breathed into the nostrils of the man the breath of life and man thereby became a living being (Gen 2:7). By this divine act man was set apart from all other creatures, to stand only a step lower than the angels (Ps 8:5). The divine likeness serves man, not to achieve immortality, but to attain sanctity; nevertheless, having been created in the divine image, one of man's prime tasks is the preservation of life. Since life is a divine gift, no one has the right to take either his own life or that of others (Ex 20:13; Deut 5:17).

Life in the biblical sense means to live according to God's way (imitatio Dei) which can be summarized in the command "You shall be holy: for I the Lord your God am holy" (Lev 19:2). In the Psalms and Proverbs, life is clearly connected with the observing of the commandments of God's laws: "keep my commands and live" (Prov 4:4; 7:2). To prolong one's life, it is required to fear the Lord (Prov 10:27). Prolongation of days is granted to all those who keep God's statutes and commandments (Deut 6:2). The Torah itself is seen as "a tree of life to those who take hold of her: and happy are all who retain her" (Prov 3:18).

Trust in God who sustains the world is likewise a basic theme in the NT: "Do not worry about your life, what you will eat or what you will drink; nor about your body, what you will put on. Is not life more than food and the body more than clothing ?" (Matt 6:25; cf Luke 12:22-23). In the NT, as in contemporary rabbinic literature, life is seen in the double dimension: in this world and in the world to come (Matt 16:25; Mark 8:35; John 6:26-58; 8:12).

For the Gospel According to John, more abundant life for the believer is the whole goal of the coming of Jesus (John 10:10). It is the greatest existential theme of the entire gospel (John 20:31). Resurrection, eternal life and faith in Christ are closely related (John 11:25-26). According to Paul, Gentiles can fill their lives with the hope of salvation, which consists of being raised together with Christ (I Cor 15:23-28; I Thes 5:15-17, 23). While Christians await God's son (I Thes 1:10), they have the Holy Spirit manifest in spiritual gifts (Gal 5:22-26). Paul urges the Christians to remain pure and blameless until the Day of the Lord (I Cor 6:11). The messianic aspect of waiting actively by living according to God's will is common to both Jewish and Christian traditions.

Life, American weekly illustrated magazine, launched by Henry Luce (1898-1967) on 23 November 1936, with a cover picture of the Fort Peck Dam in Montana by Margaret Bourke-White. Luce had already founded Time (1923) and Fortune (1930), and created Sports Illustrated in 1954. After heavy initial losses Life began to make a profit in 1939, when its circulation was c.2 million; by 1960 it was 6 million. In December 1972 publication was suspended, although Life appeared as an annual until 1978, then monthly 1978-2000, finally expiring in May 2000.

Life was the 20th century's most famous magazine, and a model for countless others. It developed the photo-essay to a fine art and published work by many of the world's finest photojournalists. Its ‘concept’ was a mixture of entertainment and improvement, informed by belief in a society based on optimism, patriotism, cooperation, and enterprise. Luce's confidence that this ‘middle-American’ model could be extended worldwide was expressed in his essay ‘The American Century’ in Life on 17 February 1941. Significantly, many Life photographers were represented in Steichen's Family of Man exhibition in 1955.

As Erika Doss has argued, it is probably too simple to blame Life's decline simply on the rise of television, although the diversion of advertising revenue to TV weakened its finances. There was also competition from a new generation of niche magazines, and friction within the organization: many photographers, including Robert Capa and W. Eugene Smith, resented the often high-handed editorial treatment of their work, and the management's support for Richard Nixon in 1972 enraged employees. Most fundamental, however, was perhaps the fact that Luce's original vision of an integrated liberal society did not, or had ceased to, correspond to reality.

— Amanda Hopkinson/Robin Lenman

Bibliography

• LIFE: The First 50 Years, 1936-86 (1986).
• Doss, E. (ed.), Looking at LIFE Magazine (2001)

Joe Cocker

From our Archives: Today's Highlights, May 20, 2009

n.

A spiritual pickle preserving the body from decay. We live in daily apprehension of its loss; yet when lost it is not missed. The question, "Is life worth living?" has been much discussed; particularly by those who think it is not, many of whom have written at great length in support of their view and by careful observance of the laws of health enjoyed for long terms of years the honors of successful controversy.

    "Life's not worth living, and that's the truth,"
    Carelessly caroled the golden youth.
    In manhood still he maintained that view
    And held it more strongly the older he grew.
    When kicked by a jackass at eighty-three,
    "Go fetch me a surgeon at once!" cried he.
                                                             Han Soper

• Genetics, Heredity, and Evolution - life: distinguishing characteristics of organisms, esp. growth capacity, metabolism, reproduction, and adaptation to environment
• Paraphernalia and Behavior - life: Slang. the life; syndrome of drug addiction and attendant patterns of behavior and activity

For other uses, see Life (disambiguation).

Life (Biota / Vitae / Eobionti)
Plants in the Rwenzori Mountains, Uganda
Scientific classification
Domains and kingdoms
Life on Earth: Non-cellular life (viruses) [note 1] Cellular life Bacteria Archaea Eukarya Protista Fungi Plantae Animalia

Life (cf. biota) is a characteristic that distinguishes objects that have signaling and self-sustaining processes (i.e., living organisms) from those that do not,^[1][2] either because such functions have ceased (death), or else because they lack such functions and are classified as inanimate.^[3][4] Biology is the science concerned with the study of life.

Living organisms undergo metabolism, maintain homeostasis, possess a capacity to grow, respond to stimuli, reproduce and, through natural selection, adapt to their environment in successive generations. More complex living organisms can communicate through various means.^[1][5] A diverse array of living organisms (life forms) can be found in the biosphere on Earth, and the properties common to these organisms—plants, animals, fungi, protists, archaea, and bacteria—are a carbon- and water-based cellular form with complex organization and heritable genetic information.

In philosophy and religion, the conception of life and its nature varies. Both offer interpretations as to how life relates to existence and consciousness, and both touch on many related issues, including life stance, purpose, conception of a god or gods, a soul or an afterlife.

Contents 1 Early theories about life 1.1 Materialism 1.2 Hylomorphism 1.3 Vitalism 2 Definitions 2.1 Biology 2.1.1 Proposed 2.1.2 Viruses 2.2 Biophysics 2.3 Living systems theories 2.3.1 Gaia hypothesis 2.3.2 Nonfractionability 2.3.3 Life as a property of ecosystems 3 Origin 4 Conditions for life 4.1 Range of tolerance 4.2 Extremophiles 4.3 Chemical element requirements 5 Classification of life 6 Extraterrestrial life 7 Death 7.1 Extinction 7.2 Fossils 8 See also 9 Notes 10 References 11 Further reading 12 External links

Early theories about life

Materialism

Plant life

Herds of zebra and impala gathering on the Maasai Mara plain

An aerial photo of microbial mats around the Grand Prismatic Spring of Yellowstone National Park

Some of the earliest theories of life were materialist, holding that all that exists is matter, and that all life is merely a complex form or arrangement of matter. Empedocles (430 BC) argued that every thing in the universe is made up of a combination of four eternal "elements" or "roots of all": earth, water, air, and fire. All change is explained by the arrangement and rearrangement of these four elements. The various forms of life are caused by an appropriate mixture of elements. For example, growth in plants is explained by the natural downward movement of earth and the natural upward movement of fire.^[6]

Democritus (460 BC), the disciple of Leucippus, thought that the essential characteristic of life is having a soul (psyche). In common with other ancient writers, he used the term to mean the principle of living things that causes them to function as a living thing. He thought the soul was composed of fire atoms, because of the apparent connection between life and heat, and because fire moves.^[7] He also suggested that humans originally lived like animals, gradually developing communities to help one another, originating language, and developing crafts and agriculture.^[8]

In the scientific revolution of the 17th century, mechanistic ideas were revived by philosophers like Descartes.

Hylomorphism

Hylomorphism is the theory (originating with Aristotle (322 BC)) that all things are a combination of matter and form. Aristotle was one of the first ancient writers to approach the subject of life in a scientific way. Biology was one of his main interests, and there is extensive biological material in his extant writings. According to him, all things in the material universe have both matter and form. The form of a living thing is its soul (Greek psyche, Latin anima). There are three kinds of souls: the "vegetative soul" of plants, which causes them to grow and decay and nourish themselves, but does not cause motion and sensation; the "animal soul" which causes animals to move and feel; and the rational soul which is the source of consciousness and reasoning which (Aristotle believed) is found only in man.^[9] Each higher soul has all the attributes of the lower one. Aristotle believed that while matter can exist without form, form cannot exist without matter, and therefore the soul cannot exist without the body.^[10]

Consistent with this account is a teleological explanation of life. A teleological explanation accounts for phenomena in terms of their purpose or goal-directedness. Thus, the whiteness of the polar bear's coat is explained by its purpose of camouflage. The direction of causality is the other way round from materialistic science, which explains the consequence in terms of a prior cause. Modern biologists now reject this functional view in terms of a material and causal one: biological features are to be explained not by looking forward to future optimal results, but by looking backwards to the past evolutionary history of a species, which led to the natural selection of the features in question.

Vitalism

Vitalism is the belief that the life-principle is essentially immaterial. This originated with Stahl (17th century), and held sway until the middle of the 19th century. It appealed to philosophers such as Henri Bergson, Nietzsche, Wilhelm Dilthey, anatomists like Bichat, and chemists like Liebig.

Vitalism underpinned the idea of a fundamental separation of organic and inorganic material, and the belief that organic material can only be derived from living things. This was disproved in 1828 when Friedrich Wöhler prepared urea from inorganic materials.^[11] This so-called Wöhler synthesis is considered the starting point of modern organic chemistry. It is of historical significance because for the first time an organic compound was produced from inorganic reactants.

Later, Helmholtz, anticipated by Mayer, demonstrated that no energy is lost in muscle movement, suggesting that there were no vital forces necessary to move a muscle. These empirical results led to the abandonment of scientific interest in vitalistic theories, although the belief lingered on in non-scientific theories such as homeopathy, which interprets diseases and sickness as caused by disturbances in a hypothetical vital force or life force.

Definitions

It is still a challenge for scientists and philosophers to define life in unequivocal terms.^[12][13][14] Defining life is difficult—in part—because life is a process, not a pure substance.^[15] Any definition must be sufficiently broad to encompass all life with which we are familiar, and it should be sufficiently general that, with it, scientists would not miss life that may be fundamentally different from life on Earth.^[16]

Biology

Since there is no unequivocal definition of life, the current understanding is descriptive, where life is a characteristic of organisms that exhibit all or most of the following phenomena:^[15][17]

1. Homeostasis: Regulation of the internal environment to maintain a constant state; for example, electrolyte concentration or sweating to reduce temperature.
2. Organization: Being structurally composed of one or more cells, which are the basic units of life.
3. Metabolism: Transformation of energy by converting chemicals and energy into cellular components (anabolism) and decomposing organic matter (catabolism). Living things require energy to maintain internal organization (homeostasis) and to produce the other phenomena associated with life.
4. Growth: Maintenance of a higher rate of anabolism than catabolism. A growing organism increases in size in all of its parts, rather than simply accumulating matter.
5. Adaptation: The ability to change over a period of time in response to the environment. This ability is fundamental to the process of evolution and is determined by the organism's heredity as well as the composition of metabolized substances, and external factors present.
6. Response to stimuli: A response can take many forms, from the contraction of a unicellular organism to external chemicals, to complex reactions involving all the senses of multicellular organisms. A response is often expressed by motion, for example, the leaves of a plant turning toward the sun (phototropism) and by chemotaxis.
7. Reproduction: The ability to produce new individual organisms, either asexually from a single parent organism, or sexually from two parent organisms.

Proposed

To reflect the minimum phenomena required, some have proposed other biological definitions of life:^[18]

• A network of inferior negative feedbacks (regulatory mechanisms) subordinated to a superior positive feedback (potential of expansion, reproduction).^[19]
• A systemic definition of life is that living things are self-organizing and autopoietic (self-producing). Variations of this definition include Stuart Kauffman's definition as an autonomous agent or a multi-agent system capable of reproducing itself or themselves, and of completing at least one thermodynamic work cycle.^[20]
• Living beings are thermodynamic systems that have an organized molecular structure.^[21]
• Things with the capacity for metabolism and motion.^[15]
• Life is a delay of the spontaneous diffusion or dispersion of the internal energy of the biomolecules towards more potential microstates.^[21]
• Life is a way to "hydrogenate carbon dioxide," at least at its very beginnings, according to physicist Sean Carroll.^[22]
• Life is a self-sustained chemical system capable of undergoing Darwinian evolution.^[23]
• Life is matter that can reproduce itself and evolve as survival dictates.^[24][25]
• Life is self-reproduction "with variations."^[26][27]
• Life is self-reproduction "with an error rate below the sustainability threshold."^[27]

Viruses

Electron micrograph of icosahedral adenovirus

Viruses are most often considered replicators rather than forms of life. They have been described as "organisms at the edge of life,"^[28] since they possess genes, evolve by natural selection,^[29] and replicate by creating multiple copies of themselves through self-assembly. However, viruses do not metabolize and require a host cell to make new products. Virus self-assembly within host cells has implications for the study of the origin of life, as it may support the hypothesis that life could have started as self-assembling organic molecules.^[30][31]

Biophysics

Biophysicists have also commented on the nature and qualities of life forms—notably that they function on negative entropy.^[32][33] In more detail, according to physicists such as John Bernal, Erwin Schrödinger, Eugene Wigner, and John Avery, life is a member of the class of phenomena which are open or continuous systems able to decrease their internal entropy at the expense of substances or free energy taken in from the environment and subsequently rejected in a degraded form (see: entropy and life).^[34][35][36]

Living systems theories

Some scientists have proposed in the last few decades that a general living systems theory is required to explain the nature of life.^[37] Such a general theory, arising out of the ecological and biological sciences, attempts to map general principles for how all living systems work. Instead of examining phenomena by attempting to break things down into component parts, a general living systems theory explores phenomena in terms of dynamic patterns of the relationships of organisms with their environment.^[38]

Gaia hypothesis

The idea that the Earth is alive is probably as old as humankind, but the first public expression of it as a fact of science was by a Scottish scientist, James Hutton. In 1785 he stated that the Earth was a superorganism and that its proper study should be physiology. Hutton is rightly remembered as the father of geology, but his idea of a living Earth was forgotten in the intense reductionism of the 19th century.^[39] The Gaia hypothesis, originally proposed in the 1960s by scientist James Lovelock,^[40][41] explores the idea that the life on Earth functions as a single organism which defines and maintains environmental conditions necessary for its survival.^[42]

Nonfractionability

Robert Rosen (1991) built on the assumption that the explanatory powers of the mechanistic worldview cannot help understand the realm of living systems. One of several important clarifications he made was to define a system component as "a unit of organization; a part with a function, i.e., a definite relation between part and whole." From this and other starting concepts, he developed a "relational theory of systems" that attempts to explain the special properties of life. Specifically, he identified the "nonfractionability of components in an organism" as the fundamental difference between living systems and "biological machines."^[43]

Life as a property of ecosystems

A systems view of life treats environmental fluxes and biological fluxes together as a "reciprocity of influence",^[44] and a reciprocal relation with environment is arguably as important for understanding life as it is for understanding ecosystems. As Harold J. Morowitz (1992) explains it, life is a property of an ecological system rather than a single organism or species.^[45] He argues that an ecosystemic definition of life is preferable to a strictly biochemical or physical one. Robert Ulanowicz (2009) also highlights mutualism as the key to understand the systemic, order-generating behavior of life and ecosystems.^[46]

Origin

Main article: Origin of life

For religious beliefs about the creation of life, see Creation myth.

Evidence suggests that life on Earth has existed for about 3.7 billion years,^[47] with the oldest traces of life found in fossils dating back 3.4 billion years.^[48] All known life forms share fundamental molecular mechanisms, and based on these observations, theories on the origin of life attempt to find a mechanism explaining the formation of a primordial single cell organism from which all life originates. There are many different hypotheses regarding the path that might have been taken from simple organic molecules via pre-cellular life to protocells and metabolism. Many models fall into the "genes-first" category or the "metabolism-first" category, but a recent trend is the emergence of hybrid models that combine both categories.^[49]

There is no scientific consensus as to how life originated and all proposed theories are highly speculative. However, most currently accepted scientific models build in one way or another on the following hypotheses:

• The Miller-Urey experiment, and the work of Sidney Fox, suggest that conditions on the primitive Earth may have favored chemical reactions that synthesized some amino acids and other organic compounds from inorganic precursors.
• Phospholipids spontaneously form lipid bilayers, the basic structure of a cell membrane.

Life as we know it today synthesizes proteins, which are polymers of amino acids using instructions encoded by cellular genes—which are polymers of deoxyribonucleic acid (DNA). Protein synthesis also entails intermediary ribonucleic acid (RNA) polymers. One possibility is that genes came first and then proteins.^[50] Another possibility is that proteins came first and then genes.^[51] However, because genes are required to make proteins, and proteins are required to make genes, the problem of considering which came first is like that of the chicken or the egg. Most scientists have adopted the hypothesis that because DNA and proteins function together so intimately, it's unlikely that they arose independently.^[52] Therefore, many scientists consider the possibility, apparently first suggested by Francis Crick,^[53] that the first life was based on the DNA-protein intermediary: RNA.^[52] In fact, RNA has the DNA-like properties of information storage and replication and the catalytic properties of some proteins. Crick and others actually favored the RNA-first hypothesis^[54] even before the catalytic properties of RNA had been demonstrated by Thomas Cech.^[55]

A significant issue with the RNA-first hypothesis is that experiments designed to synthesize RNA from simple precursors have not been nearly as successful as the Miller-Urey experiments that synthesized other organic molecules from inorganic precursors. One reason for the failure to create RNA in the laboratory is that RNA precursors are very stable and do not react with each other under ambient conditions. However, the successful synthesis of certain RNA molecules under conditions hypothesized to exist prior to life on Earth has been achieved by adding alternative precursors in a specified order with the precursor phosphate present throughout the reaction.^[56] This study makes the RNA-first hypothesis more plausible to many scientists.^[57]

Recent experiments have demonstrated true Darwinian evolution of unique RNA enzymes (ribozymes) made up of two separate catalytic components that replicate each other in vitro.^[58] In describing this work from his laboratory, Gerald Joyce stated: "This is the first example, outside of biology, of evolutionary adaptation in a molecular genetic system."^[59] Such experiments make the possibility of a primordial RNA World even more attractive to many scientists.

Recent findings by NASA, based on studies with meteorites found on Earth, suggests DNA and RNA components (adenine, guanine and related organic molecules) may also be formed extraterrestrially in outer space.^{[60][61][62][63]}

Conditions for life

Cyanobacteria dramatically changed the composition of life forms on Earth by stimulating biodiversity and leading to the near-extinction of oxygen-intolerant organisms.

The diversity of life on Earth today is a result of the dynamic interplay between genetic opportunity, metabolic capability, environmental challenges,^[64] and symbiosis.^[65][66][67] For most of its existence, Earth's habitable environment has been dominated by microorganisms and subjected to their metabolism and evolution. As a consequence of such microbial activities on a geologic time scale, the physical-chemical environment on Earth has been changing, thereby determining the path of evolution of subsequent life.^[64] For example, the release of molecular oxygen by cyanobacteria as a by-product of photosynthesis induced fundamental, global changes in the Earth's environment. The altered environment, in turn, posed novel evolutionary challenges to the organisms present, which ultimately resulted in the formation of our planet's major animal and plant species. Therefore this "co-evolution" between organisms and their environment is apparently an inherent feature of living systems.^[64]

Range of tolerance

The inert components of an ecosystem are the physical and chemical factors necessary for life—energy (sunlight or chemical energy), water, temperature, atmosphere, gravity, nutrients, and ultraviolet solar radiation protection.^[68] In most ecosystems the conditions vary during the day and often shift from one season to the next. To live in most ecosystems, then, organisms must be able to survive a range of conditions, called "range of tolerance."^[69] Outside of that are the "zones of physiological stress," where the survival and reproduction are possible but not optimal. Outside of these zones are the "zones of intolerance," where life for that organism is implausible. It has been determined that organisms that have a wide range of tolerance are more widely distributed than organisms with a narrow range of tolerance.^[69]

Extremophiles

Deinococcus radiodurans can resist radiation exposure.

Main article: Extremophile

To survive, some microorganisms can assume forms that enable them to withstand freezing, complete desiccation, starvation, high-levels of radiation exposure, and other physical or chemical challenges. Furthermore, some microorganisms can survive exposure to such conditions for weeks, months, years, or even centuries.^[64] Extremophiles are microbial life forms that thrive outside the ranges life is commonly found in. They also excel at exploiting uncommon sources of energy. While all organisms are composed of nearly identical molecules, evolution has enabled such microbes to cope with this wide range of physical and chemical conditions. Characterization of the structure and metabolic diversity of microbial communities in such extreme environments is ongoing. An understanding of the tenacity and versatility of life on Earth, as well as an understanding of the molecular systems that some organisms utilize to survive such extremes, will provide a critical foundation for the search for life beyond Earth.^[64] In this regard, on 26 April 2012, scientists reported that lichen survived and showed remarkable results on the adaptation capacity of photosynthetic activity within the simulation time of 34 days under Martian conditions in the Mars Simulation Laboratory (MSL) maintained by the German Aerospace Center (DLR).^[70][71]

Chemical element requirements

All life forms require certain core chemical elements needed for biochemical functioning. These include carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur— the elemental macronutrients for all organisms^[72] — often represented by the acronym CHNOPS. Together these make up nucleic acids, proteins and lipids, the bulk of living matter.

Alternative hypothetical types of biochemistry have been proposed which eliminate one or more of these elements, swap out an element for one not on the list, or change required chiralities or other chemical properties.

Classification of life

Main article: Biological classification

The hierarchy of biological classification's eight major taxonomic ranks, which is an example of definition by genus and differentia. Life is divided into domains, which are subdivided into further groups. Intermediate minor rankings are not shown.

Traditionally, people have divided organisms into the classes of plants and animals, based mainly on their ability of movement. The first known attempt to classify organisms was conducted by the Greek philosopher Aristotle (384–322 BC). He classified all living organisms known at that time as either a plant or an animal. Aristotle distinguished animals with blood from animals without blood (or at least without red blood), which can be compared with the concepts of vertebrates and invertebrates respectively. He divided the blooded animals into five groups: viviparous quadrupeds (mammals), birds, oviparous quadrupeds (reptiles and amphibians), fishes and whales. The bloodless animals were also divided into five groups: cephalopods, crustaceans, insects (which also included the spiders, scorpions, and centipedes, in addition to what we now define as insects), shelled animals (such as most molluscs and echinoderms) and "zoophytes." Though Aristotle's work in zoology was not without errors, it was the grandest biological synthesis of the time and remained the ultimate authority for many centuries after his death.^[73]

The exploration of the American continent revealed large numbers of new plants and animals that needed descriptions and classification. In the latter part of the 16th century and the beginning of the 17th, careful study of animals commenced and was gradually extended until it formed a sufficient body of knowledge to serve as an anatomical basis for classification.

In the late 1740s, Carolus Linnaeus introduced his method, still used, to formulate the scientific name of every species.^[74] Linnaeus took every effort to improve the composition and reduce the length of the many-worded names by abolishing unnecessary rhetoric, introducing new descriptive terms and defining their meaning with an unprecedented precision. By consistently using his system, Linnaeus separated nomenclature from taxonomy. This convention for naming species is referred to as binomial nomenclature.

The fungi were originally treated as plants. For a short period Linnaeus had placed them in the taxon Vermes in Animalia. He later placed them back in Plantae. Copeland classified the Fungi in his Protoctista, thus partially avoiding the problem but acknowledged their special status.^[75] The problem was eventually solved by Whittaker, when he gave them their own kingdom in his five-kingdom system. As it turned out, the fungi are more closely related to animals than to plants.^[76]

As new discoveries enabled us to study cells and microorganisms, new groups of life were revealed, and the fields of cell biology and microbiology were created. These new organisms were originally described separately in protozoa as animals and protophyta/thallophyta as plants, but were united by Haeckel in his kingdom protista, later the group of prokaryotes were split off in the kingdom Monera, eventually this kingdom would be divided in two separate groups, the Bacteria and the Archaea, leading to the six-kingdom system and eventually to the current three-domain system.^[77] The classification of eukaryotes is still controversial, with protist taxonomy especially problematic.^[78]

As microbiology, molecular biology and virology developed, non-cellular reproducing agents were discovered, such as viruses and viroids. Sometimes these entities are considered to be alive but others argue that viruses are not living organisms since they lack characteristics such as cell membrane, metabolism and do not grow or respond to their environments. Viruses can however be classed into "species" based on their biology and genetics but many aspects of such a classification remain controversial.^[79]

Since the 1960s a trend called cladistics has emerged, arranging taxa in an evolutionary or phylogenetic tree. It is unclear, should this be implemented, how the different codes will coexist.^[80]

Linnaeus 1735[81] 2 kingdoms	Haeckel 1866[82] 3 kingdoms	Chatton 1925[83][84] 2 empires	Copeland 1938[75][85] 4 kingdoms	Whittaker 1969[86] 5 kingdoms	Woese et al. 1977[87][88] 6 kingdoms	Woese et al. 1990[77] 3 domains	Cavalier-Smith 2004[89] 6 kingdoms
(not treated)	Protista	Prokaryota	Monera	Monera	Eubacteria	Bacteria	Bacteria
					Archaebacteria	Archaea
		Eukaryota	Protoctista	Protista	Protista	Eukarya	Protozoa
							Chromista
Vegetabilia	Plantae		Plantae	Plantae	Plantae		Plantae
			Protoctista	Fungi	Fungi		Fungi
Animalia	Animalia		Animalia	Animalia	Animalia		Animalia

Extraterrestrial life

Main articles: Extraterrestrial life and astrobiology

Panspermia hypothesis

Earth is the only planet known to harbor life. The Drake equation, which relates the number of extraterrestrial civilizations in our galaxy with which we might come in contact, has been used to discuss the probability of life elsewhere, but scientists disagree on many of the values of variables in this equation. Depending on those values, the equation may either suggest that life arises frequently or infrequently.

The region around a main sequence star that could support Earth-like life on an Earth-like planet is known as the habitable zone. The inner and outer radii of this zone vary with the luminosity of the star, as does the time interval during which the zone will survive. Stars more massive than the Sun have a larger habitable zone, but will remain on the main sequence for a shorter time interval during which life can evolve. Small red dwarf stars have the opposite problem, compounded with higher levels of magnetic activity and the effects of tidal locking from close orbits. Hence, stars in the intermediate mass range such as the Sun may possess the optimal conditions for Earth-like life to develop. The location of the star within a galaxy may also have an impact on the likelihood of life forming.^{[citation needed]}

Panspermia, also called exogenesis, is a hypothesis proposing that life originated elsewhere in the universe and was subsequently transferred to Earth in the form of spores perhaps via meteorites, comets or cosmic dust. In October 2011, scientists found that the cosmic dust permeating the universe contains complex organic matter ("amorphous organic solids with a mixed aromatic-aliphatic structure") that could be created naturally, and rapidly, by stars.^[90][91][92] As one of the scientists noted, "Coal and kerogen are products of life and it took a long time for them to form ... How do stars make such complicated organics under seemingly unfavorable conditions and [do] it so rapidly?"^[90] Further, the scientist suggested that these compounds may have been related to the development of life on earth and said that, "If this is the case, life on Earth may have had an easier time getting started as these organics can serve as basic ingredients for life."^[90]

Death

Main article: Death

Death is the permanent termination of all vital functions or life processes in an organism or cell.^[93][94] After death, the remains of an organism become part of the biogeochemical cycle. Organisms may be consumed by a predator or a scavenger and leftover organic material may then be further decomposed by detritivores, organisms which recycle detritus, returning it to the environment for reuse in the food chain.

One of the challenges in defining death is in distinguishing it from life. Death would seem to refer to either the moment at which life ends, or when the state that follows life begins.^[95] However, determining when death has occurred requires drawing precise conceptual boundaries between life and death. This is problematic, however, because there is little consensus over how to define life. The nature of death has for millennia been a central concern of the world's religious traditions and of philosophical inquiry. Many religions maintain faith in either some kind of afterlife or reincarnation for the soul, or resurrection of the body at a later date.

Extinction

Main article: Extinction

Extinction is the gradual process by which a group of taxa or species dies out, reducing biodiversity.^[96] The moment of extinction is generally considered to be the death of the last individual of that species. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively after a period of apparent absence. Species become extinct when they are no longer able to survive in changing habitat or against superior competition. Over the history of the Earth, over 99% of all the species that have ever lived have gone extinct;^[97] however, mass extinctions may have accelerated evolution by providing opportunities for new groups of organisms to diversify.^[98]

Fossils

Main article: Fossil

Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossil-containing rock formations and sedimentary layers (strata) is known as the fossil record. Such a preserved specimen is called a "fossil" if it is older than the arbitrary date of 10,000 years ago.^[99] Hence, fossils range in age from the youngest at the start of the Holocene Epoch to the oldest from the Archaean Eon, up to 3.4 billion years old.^[100][101]

See also

Alpha taxonomy Artificial life Biological immortality Biology—the study of life Biomarker Biosignature Carbon-based life Cell Conway's Game of Life End of Life Entropy and life Evolutionary history of life Extraterrestrial life Extremophile Gaia hypothesis Genetics Genetic engineering

Hierarchy of life Kingdom (biology) Life on Mars Meaning of life Nature Non-cellular life Organic life Organism Origin of life Personal life Phylogenetics Prehistoric life Prion Quality of life Silicon-based life Synthetic life

Notes

1. ^ The 'evolution' of viruses and other similar forms is still uncertain. Therefore, this classification may be paraphyletic because cellular life might have evolved from non-cellular life, or polyphyletic because the most recent common ancestor might not be included.

References

1. ^ ^{a b} Koshland Jr, Daniel E. (March 22, 2002). "The Seven Pillars of Life". Science 295 (5563): 2215–2216. doi:10.1126/science.1068489. PMID 11910092. http://www.sciencemag.org/cgi/content/full/295/5563/2215. Retrieved 2009-05-25. 
2. ^ The American Heritage Dictionary of the English Language, 4th edition, published by Houghton Mifflin Company, via Answers.com:
   • "The property or quality that distinguishes living organisms from dead organisms and inanimate matter, manifested in functions such as metabolism, growth, reproduction, and response to stimuli or adaptation to the environment originating from within the organism."
   • "The characteristic state or condition of a living organism."
3. ^ Definition of inanimate. WordNet Search by Princeton University.
4. ^ "Merriam-Webster Dictionary". Merriam-Webster Dictionary. http://www.merriam-webster.com/dictionary/life. Retrieved 2009-06-21. 
5. ^ "organism". Chambers 21st Century Dictionary (online ed.). 1999. 
6. ^ SEP
7. ^ SEP
8. ^ Ibidem
9. ^ Aristotle, De Anima, Book II
10. ^ Introduction to Ancient Philosophy, Don Marietta, p. 104.
11. ^ Friedrich Wöhler (1828). "Ueber künstliche Bildung des Harnstoffs". Annalen der Physik und Chemie 88 (2): 253–256. Bibcode 1828AnP....88..253W. doi:10.1002/andp.18280880206. http://gallica.bnf.fr/ark:/12148/bpt6k15097k/f261.chemindefer. 
12. ^ Defining Life : Astrobiology Magazine – earth science – evolution distribution Origin of life universe – life beyond
13. ^ Defining Life, Explaining Emergence
14. ^ "Can We Define Life". Colorado Arts & Sciences. 2009. http://artsandsciences.colorado.edu/magazine/2009/03/can-we-define-life/. Retrieved 2009-06-22. 
15. ^ ^{a b c} McKay, Chris P. (September 14, 2004). "What Is Life—and How Do We Search for It in Other Worlds?". PLoS Biol. 2 (2(9)): 302. doi:10.1371/journal.pbio.0020302. PMC 516796. PMID 15367939. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=516796. Retrieved 2010-02-02. 
16. ^ Nealson KH, Conrad PG (December 1999). "Life: past, present and future". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 354 (1392): 1923–39. doi:10.1098/rstb.1999.0532. PMC 1692713. PMID 10670014. http://journals.royalsociety.org/content/7r10hqn3rp1g1vag/fulltext.pdf. 
17. ^ Davison, Paul G.. "How to Define Life". The University of North Alabama. http://www2.una.edu/pdavis/BI%20101/Overview%20Fall%202004.htm. Retrieved 2008-10-17. 
18. ^ Popa, Radu (March 2004). Between Necessity and Probability: Searching for the Definition and Origin of Life (Advances in Astrobiology and Biogeophysics). Springer. ISBN 3-540-20490-3. http://www.amazon.com/Between-Necessity-Probability-Astrobiology-Biogeophysics/dp/3540204903. 
19. ^ Korzeniewski, Bernard (2001). "Cybernetic formulation of the definition of life". Journal of Theoretical Biology. 2001 April 7. 209 (3) pp. 275–86.
20. ^ 2004, "Autonomous Agents", in John D. Barrow, P.C.W. Davies, and C.L. Harper Jr., eds., Science and Ultimate Reality: Quantum Theory, Cosmology, and Complexity, Cambridge University Press.
21. ^ ^{a b} "Astrobiology". Biology Cabinet. September 26, 2006. http://biocab.org/Astrobiology.html. Retrieved 2011-01-17. 
22. ^ Musser, George (23 September 2011). "How Life Arose on Earth, and How a Singularity Might Bring It Down". Scientific American. http://blogs.scientificamerican.com/observations/2011/09/23/how-life-arose-on-earth-and-how-a-singularity-might-bring-it-down/. Retrieved 2011-09-24. 
23. ^ Gerald Francis Joyce, "The RNA World: Life Before DNA and Protein".
24. ^ Luttermoser, Donald G.. "ASTR-1020: Astronomy II Course Lecture Notes Section XII" (PDF). East Tennessee State University. http://www.etsu.edu/physics/lutter/courses/astr1020/a1020chap12.pdf. Retrieved 2011-08-28. 
25. ^ Luttermoser, Donald G. (Spring 2008). "Physics 2028: Great Ideas in Science: The Exobiology Module" (PDF). East Tennessee State University. http://www.etsu.edu/physics/lutter/courses/phys2028/p2028exobnotes.pdf. Retrieved 2011-08-28. 
26. ^ Trifonov, Edward N.. "Definition of Life: Navigation through Uncertainties". Journal of Biomolecular Structure & Dynamics (Adenine Press) 29 (4): 647–650. ISSN 0739-1102. http://www.jbsdonline.com/mc_images/category/4317/21-trifonov-jbsd_29_4_2012.pdf. Retrieved 2012-01-12. 
27. ^ ^{a b} Zimmer, Carl (11 January 2012). "Can scientists define 'life' ... using just three words?". MSN. http://www.msnbc.msn.com/id/45963181/ns/technology_and_science/. Retrieved 2012-01-12. 
28. ^ Rybicki, EP (1990). "The classification of organisms at the edge of life, or problems with virus systematics". S Aft J Sci 86: 182–186. 
29. ^ Holmes EC (October 2007). "Viral evolution in the genomic age". PLoS Biol. 5 (10): e278. doi:10.1371/journal.pbio.0050278. PMC 1994994. PMID 17914905. http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0050278. Retrieved 2008-09-13. 
30. ^ Koonin EV, Senkevich TG, Dolja VV (2006). "The ancient Virus World and evolution of cells". Biol. Direct 1: 29. doi:10.1186/1745-6150-1-29. PMC 1594570. PMID 16984643. http://www.biology-direct.com/content/1//29. Retrieved 2008-09-14. 
31. ^ Rybicki, Ed (November 1997). "Origins of Viruses". http://www.mcb.uct.ac.za/tutorial/virorig.html#Virus%20Origins. Retrieved 2009-04-12. 
32. ^ Schrödinger, Erwin (1944). What is Life?. Cambridge University Press. ISBN 0-521-42708-8. 
33. ^ Margulis, Lynn; Sagan, Dorion (1995). What is Life?. University of California Press. ISBN 0-520-22021-8. 
34. ^ Lovelock, James (2000). Gaia – a New Look at Life on Earth. Oxford University Press. ISBN 0-19-286218-9. 
35. ^ Avery, John (2003). Information Theory and Evolution. World Scientific. ISBN 981-238-399-9. 
36. ^ "BIOPHYSICS: DEFINITION OF LIFE AND BRIEF EXPLANATION OF EACH TERM". Biology Cabinet. September 29, 2006. http://biocab.org/Exobiology.html#anchor_41. Retrieved 2009-07-22. 
37. ^ Woodruff, T. Sullivan; John Baross (October 8, 2007). Planets and Life: The Emerging Science of Astrobiology. Cambridge University Press.  Cleland and Chyba wrote a chapter in Planets and Life: "In the absence of such a theory, we are in a position analogous to that of a 16th-century investigator trying to define 'water' in the absence of molecular theory." [...] "Without access to living things having a different historical origin, it is difficult and perhaps ultimately impossible to formulate an adequately general theory of the nature of living systems".
38. ^ "Patterns, Flows, and Interrelationship". 2002. http://www.mollyyoungbrown.com/systems_article.htm. Retrieved 2009-06-27. 
39. ^ GAIA – A new look at life on Earth. James Lovelock 1979. pp. 10. Oxford University Press. ISBN 0-19-286030-5.
40. ^ Lovelock, J.E. (1965). "A physical basis for life detection experiments". Nature 207 (7): 568–570. Bibcode 1965Natur.207..568L. doi:10.1038/207568a0. PMID 5883628. 
41. ^ Geophysiology
42. ^ GAIA – A new look at life on Earth. James Lovelock. 1979. Oxford University Press. ISBN 0-19-286030-5.
43. ^ Life Itself: A Comprehensive Inquiry into the Nature, Origin, and Fabrication of Life. Rosen, Robert. November, 1991. ISBN 978-0-231-07565-7
44. ^ "The Ecosystemic Life Hypothesis". Bulletin of the Ecological Society of America. April 2002. http://www.calresco.org/fiscus/esl.htm. Retrieved 2009-08-28. 
45. ^ Morowitz, Harold J. (1992) "Beginnings of Cellular Life: Metabolism Recapitulates Biogenesis". Yale University Press. ISBN 0-300-05483-1
46. ^ A Third Window: Natural Life Beyond Newton and Darwin, Templeton Foundation Press (2009) ISBN 1-59947-154-X
47. ^ "History of life through time". University of California Museum of Paleontology.
48. ^ Dean, Tim. "World’s oldest fossils reveal earliest life on Earth", Australian Life Scientist, 23 August 2011. Retrieved on 2011-08-23.
49. ^ Coveney, Peter V.; Philip W. Fowler. "Modelling biological complexity: a physical scientist's perspective". Journal of the Royal Society Interface. 2005. 2 (4) pp. 267–280. doi:10.1098/rsif.2005.0045
50. ^ Senapathy, Periannan, Independent Birth of Organisms, Madison, WI. Genome Press, 1994.
51. ^ Eigen, Manfred, Steps Towards Life: A Perspective on Evolution (German edition, 1987), Oxford University Press, 1992. p 31.
52. ^ ^{a b} Barazesh, Solmaz, How RNA Got Started: Scientists Look for the Origins of Life, Science News, May 13, 2009.
53. ^ Watson, James D., Prologue: Early Speculations and Facts about RNA Templates, p. xv–xxiii, The RNA World, R.F. Gesteland and J.F. Atkins, Eds., Cold Spring Harbor Laboratory Press, 1993.
54. ^ Gilbert, Walter, The RNA world, p 618 v 319, Nature, 1986.
55. ^ Cech, Thomas R., A model for the RNA-catalyzed replication of RNA, p 4360-4363 v 83, Proc. Nat. Acad. Sci., USA, 1986.
56. ^ Powner, Matthew W., Béatrice Gerland and John D. Sutherland, Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions, Nature 459, 239–242 (14 May 2009).
57. ^ Szostak, Jack W., Origins of life: Systems chemistry on early Earth, Nature 459, 171–172 (14 May 2009).
58. ^ Lincoln, Tracey A. and Gerald F. Joyce, Self-Sustained Replication of an RNA Enzyme, Science 27 February 2009: Vol. 323, No. 5918, pp. 1229–1232, DOI: 10.1126/science.1167856.
59. ^ Joyce, Gerald F., Evolution in an RNA World, Cold Spring Harb Symp Quant Biol sqb.2009.74.004; Published in Advance August 10, 2009, doi:10.1101/sqb.2009.74.004.
60. ^ Callahan; Smith, K.E.; Cleaves, H.J.; Ruzica, J.; Stern, J.C.; Glavin, D.P.; House, C.H.; Dworkin, J.P. (11 August 2011). "Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases". PNAS. doi:10.1073/pnas.1106493108. http://www.pnas.org/content/early/2011/08/10/1106493108. Retrieved 2011-08-15. 
61. ^ Steigerwald, John (8 August 2011). "NASA Researchers: DNA Building Blocks Can Be Made in Space". NASA. http://www.nasa.gov/topics/solarsystem/features/dna-meteorites.html. Retrieved 2011-08-10. 
62. ^ ScienceDaily Staff (9 August 2011). "DNA Building Blocks Can Be Made in Space, NASA Evidence Suggests". ScienceDaily. http://www.sciencedaily.com/releases/2011/08/110808220659.htm. Retrieved 2011-08-09. 
63. ^ Gallori, Enzo (November 2010). "Astrochemistry and the origin of genetic material". Rendiconti Lincei 22 (2): 113–118. doi:10.1007/s12210-011-0118-4. http://www.springerlink.com/content/x332837483630g24/. Retrieved 2011-08-11. 
64. ^ ^{a b c d e} Rothschild, Lynn (September, 2003). "Understand the evolutionary mechanisms and environmental limits of life". NASA. http://astrobiology.arc.nasa.gov/roadmap/g5.html. Retrieved 2009-07-13. 
65. ^ King, G.A.M. (April, 1977). "Symbiosis and the origin of life". Origins of Life and Evolution of Biospheres 8 (1): 39–53. Bibcode 1977OrLi....8...39K. doi:10.1007/BF00930938. http://www.springerlink.com/content/n10p775113175l67/. Retrieved 2010-02-22. 
66. ^ Margulis, Lynn (2001). The Symbiotic Planet: A New Look at Evolution. London, England: Orion Books Ltd.. ISBN 0-7538-0785-8. 
67. ^ Douglas J. Futuyma; Janis Antonovics (1992). Oxford surveys in evolutionary biology: Symbiosis in evolution. 8. London, England: Oxford University Press. pp. 347–374. ISBN 0-19-507623-0. 
68. ^ "Essential requirements for life". CMEX-NASA. http://cmapsnasacmex.ihmc.us/servlet/SBReadResourceServlet?rid=1025200161109_2045745605_1714&partName=htmltext. Retrieved 2009-07-14. 
69. ^ ^{a b} Chiras, Daniel C. (2009). Environmental Science – Creating a Sustainable Future. 
70. ^ Baldwin, Emily (26 April 2012). "Lichen survives harsh Mars environment". Skymania News. http://www.skymania.com/wp/2012/04/lichen-survives-harsh-martian-setting.html. Retrieved 27 April 2012. 
71. ^ de Vera, J.-P.; Kohler, Ulrich (26 April 2012). "The adaptation potential of extremophiles to Martian surface conditions and its implication for the habitability of Mars". European Geosciences Union. http://media.egu2012.eu/media/filer_public/2012/04/05/10_solarsystem_devera.pdf. Retrieved 27 April 2012. 
72. ^ New Link in Chain of Life, Wall Street Journal, 2010-12-03, accessed 2010-12-05. "Until now, however, they were all thought to share the same biochemistry, based on the Big Six, to build proteins, fats and DNA."
73. ^ "Aristotle -biography". University of California Museum of Paleontology. http://www.ucmp.berkeley.edu/history/aristotle.html. Retrieved 2008-10-20. 
74. ^ Knapp S, Lamas G, Lughadha EN, Novarino G (April 2004). "Stability or stasis in the names of organisms: the evolving codes of nomenclature". Philosophical transactions of the Royal Society of London. Series B, Biological sciences 359 (1444): 611–22. doi:10.1098/rstb.2003.1445. PMC 1693349. PMID 15253348. http://journals.royalsociety.org/openurl.asp?genre=article&issn=0962-8436&volume=359&issue=1444&spage=611. 
75. ^ ^{a b} Copeland, H.F. (1938). "The Kingdoms of Organisms". Quarterly Review of Biology 13 (4): 383. doi:10.1086/394568. JSTOR 2808554. 
76. ^ Whittaker RH (January 1969). "New concepts of kingdoms or organisms. Evolutionary relations are better represented by new classifications than by the traditional two kingdoms". Science 163 (3863): 150–60. Bibcode 1969Sci...163..150W. doi:10.1126/science.163.3863.150. PMID 5762760. 
77. ^ ^{a b} Woese C, Kandler O, Wheelis M (1990). "Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya.". Proc Natl Acad Sci U S A 87 (12): 4576–9. Bibcode 1990PNAS...87.4576W. doi:10.1073/pnas.87.12.4576. PMC 54159. PMID 2112744. http://www.pnas.org/cgi/reprint/87/12/4576. 
78. ^ Adl SM, Simpson AG, Farmer MA, et al. (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". J. Eukaryot. Microbiol. 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x. PMID 16248873. 
79. ^ Van Regenmortel MH (January 2007). "Virus species and virus identification: past and current controversies". Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 7 (1): 133–44. doi:10.1016/j.meegid.2006.04.002. PMID 16713373. 
80. ^ Pennisi E (March 2001). "Taxonomy. Linnaeus's last stand?". Science (New York, N.Y.) 291 (5512): 2304–7. doi:10.1126/science.291.5512.2304. PMID 11269295. http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=11269295. 
81. ^ C. Linnaeus (1735). Systemae Naturae, sive regna tria naturae, systematics proposita per classes, ordines, genera & species. 
82. ^ E. Haeckel (1866). Generelle Morphologie der Organismen. Reimer, Berlin. 
83. ^ É. Chatton (1925). "Pansporella perplexa. Réflexions sur la biologie et la phylogénie des protozoaires". Ann. Sci. Nat. Zool 10-VII: 1–84. 
84. ^ É. Chatton (1937). Titres et Travaux Scientifiques (1906–1937). Sette, Sottano, Italy. 
85. ^ H. F. Copeland (1956). The Classification of Lower Organisms. Palo Alto: Pacific Books. 
86. ^ Whittaker RH (January 1969). "New concepts of kingdoms of organisms". Science 163 (3863): 150–60. doi:10.1126/science.163.3863.150. PMID 5762760. 
87. ^ C. R. Woese, W. E. Balch, L. J. Magrum, G. E. Fox and R. S. Wolfe (August 1977). "An ancient divergence among the bacteria". Journal of Molecular Evolution 9 (4): 305–311. doi:10.1007/BF01796092. PMID 408502. 
88. ^ Woese CR, Fox GE (November 1977). "Phylogenetic structure of the prokaryotic domain: the primary kingdoms". Proc. Natl. Acad. Sci. U.S.A. 74 (11): 5088–90. doi:10.1073/pnas.74.11.5088. PMC 432104. PMID 270744. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=432104. 
89. ^ Cavalier-Smith, T. (2004), "Only six kingdoms of life", Proc. R. Soc. Lond. B 271: 1251–62, doi:10.1098/rspb.2004.2705, PMC 1691724, PMID 15306349, http://www.cladocera.de/protozoa/cavalier-smith_2004_prs.pdf, retrieved 2010-04-29 
90. ^ ^{a b c} Chow, Denise (26 October 2011). "Discovery: Cosmic Dust Contains Organic Matter from Stars". Space.com. http://www.space.com/13401-cosmic-star-dust-complex-organic-compounds.html. Retrieved 2011-10-26. 
91. ^ ScienceDaily Staff (26 October 2011). "Astronomers Discover Complex Organic Matter Exists Throughout the Universe". ScienceDaily. http://www.sciencedaily.com/releases/2011/10/111026143721.htm. Retrieved 2011-10-27. 
92. ^ Kwok, Sun; Zhang, Yong (26 October 2011). "Mixed aromatic–aliphatic organic nanoparticles as carriers of unidentified infrared emission features". Nature. Bibcode 2011Natur.479...80K. doi:10.1038/nature10542. 
93. ^ "Definition of death". Definition of death. Archived from the original on 2009-10-31. http://www.webcitation.org/5kwsdvU8f. 
94. ^ Defining of death.
95. ^ Encyclopedia of Death and Dying
96. ^ "Extinction – definition". Extinction – definition. Archived from the original on 2009-10-31. http://www.webcitation.org/5kwseRB80. 
97. ^ What is an extinction?
98. ^ Van Valkenburgh, B. (1999). "Major patterns in the history of carnivorous mammals". Annual Review of Earth and Planetary Sciences 27: 463–493. Bibcode 1999AREPS..27..463V. doi:10.1146/annurev.earth.27.1.463. http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.earth.27.1.463. 
99. ^ FAQs – San Diego Natural History Museum
100. ^ "Oldest ‘microfossils’ raise hopes for life on Mars". The Washington Post. 21 August 2011. http://www.washingtonpost.com/national/health-science/oldest-microfossils-hail-from-34-billion-years-ago-raise-hopes-for-life-on-mars/2011/08/19/gIQAHK8UUJ_story.html?hpid=z3. Retrieved 2011-08-21. 
101. ^ Wade, Nicholas (21 August 2011). "Geological Team Lays Claim to Oldest Known Fossils". The New York Times. http://www.nytimes.com/2011/08/22/science/earth/22fossil.html?_r=1&partner=rss&emc=rss&src=ig. Retrieved 2011-08-21. 

Further reading

• Kauffman, Stuart. The Adjacent Possible: A Talk with Stuart Kauffman
• Nealson KH, Conrad PG (December 1999). "Life: past, present and future". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 354 (1392): 1923–39. doi:10.1098/rstb.1999.0532. PMC 1692713. PMID 10670014. http://journals.royalsociety.org/content/7r10hqn3rp1g1vag/. 
• Walker, Martin G. LIFE! Why We Exist...And What We Must Do to Survive Dog Ear Publishing, 2006, ISBN 1-59858-243-7

External links

Wikimedia Commons has media related to: Tree of life

Wikiquote has a collection of quotations related to: Life

Look up life or living in Wiktionary, the free dictionary.

Wikispecies has information related to: The Taxonomy of Life

• Wikispecies – a free directory of life
• "The Adjacent Possible: A Talk with Stuart Kauffman"
• Stanford Encyclopedia of Philosophy entry
• Life under extreme conditions An in depth look at how life can form under the most extreme conditions and circumstaces.

v t e Elements of nature Universe Space Time Matter Energy Earth Earth science Future of the Earth Geological history of Earth Geology History of the Earth Plate tectonics Structure of the Earth Weather Atmosphere of Earth Climate Meteorology Environment Ecology Ecosystem Wilderness Life Biology Eukaryota Plants/Flora Animals/Fauna Fungi Protista Evolutionary history of life Hierarchy of life Life on Earth Origin of life Prokaryotes Archaea Bacteria Viruses Category Portal

v t e Hierarchy of life Biosphere >  Ecosystem > Community (Biocoenosis) > Population >  Organism > Organ system > Organ > Tissue > Cell > Organelle > Molecule (Macromolecule · Biomolecule) > Atom

v t e Basic topics in evolutionary biology Evidence of common descent Processes of evolution Adaptation Macroevolution Microevolution Speciation Population genetic mechanisms Genetic drift Gene flow Mutation Natural selection Evolutionary developmental biology (Evo-devo) concepts Canalisation Inversion Modularity Phenotypic plasticity Evolution of organs and biological processes Aging Avian flight Cellular DNA Eye Flagella Hair Human intelligence Mammalian auditory ossicles Mosaic evolution Multicellular Nervous Systems Sex Taxa evolution Birds Butterflies Cats Cephalopods Dinosaurs Dogs Dolphins and whales Fish Fungi Horses Humans Influenza Insects Lemur Life Mammals Molluscs Plants Reptiles Sea cows Spiders Viruses Modes of speciation Anagenesis Catagenesis Cladogenesis History of evolutionary thought Charles Darwin On the Origin of Species Modern evolutionary synthesis Gene-centered view of evolution Life (classification trees) Other subfields Ecological genetics Molecular evolution Phylogenetics Systematics List of evolutionary biology topics Timeline of evolution

v t e Taxonomic ranks
				Magnorder
Domain/Superkingdom	Superphylum/Superdivision	Superclass		Superorder	Superfamily	Supertribe		Superspecies
Kingdom	Phylum/Division	Class	Legion	Order	Family	Tribe	Genus	Species
Subkingdom	Subphylum	Subclass	Cohort	Suborder	Subfamily	Subtribe	Subgenus	Subspecies
Infrakingdom/Branch	Infraphylum	Infraclass		Infraorder			Section	Infraspecies
	Microphylum	Parvclass		Parvorder			Series	Variety
								Form

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Common misspelling(s) of life

• lief

Dansk (Danish)
n. - liv, livet, levevis, livsførelse, levned, tilværelse, levnedsløb, livsløb, menneskeliv, levnedsbeskrivelse, biografi

idioms:

• be in someone's life    have et forhold til nogen
• come to life    komme til live igen, komme til sig selv igen
• for dear life    for livet, om det så gjaldt livet, som om det gjaldt livet, af alle livsens kræfter
• for life    for livet, for bestandig, på livstid
• for the life of me    for min død
• Get a life    gør dog noget, kom i gang
• have a life    mor dig
• life after death    livet efter døden
• life and death    liv og død
• life assurance    livsforsikring
• life belt    redningsbælte
• life buoy    redningsbøje, redningskrans
• life cycle    livscyklus
• life expectancy    forventet levealder, levesandsynlighed
• life experience    livserfaring
• life form    livsform
• life goes on    livet går videre
• life imprisonment    livsvarigt fængsel, livstid
• life insurance    livsforsikring
• life jacket    redningsvest
• life member    livsvarigt medlem, livslangt medlemskab
• life peer    livsvarigt overhusmedlem hvis titel ikke går i arv
• life preserver    totenschlæger, redningsvest, redningskrans
• life raft    redningsflåde
• life science    videnskab der beskæftiger sig med levende organismer (biologo, zoologi osv)
• life sentence    idømmelse af livsvarigt fængsel
• life span    levetid
• life to come    livet efter døden
• life to the full    leve fuldt ud
• life work    livsværk
• take one's life in one's own hands    vove pelsen, vove sit skind, sætte livet på spil
• take someone's life    tage livet af en, slå ihjel
• the life and soul of    midtpunktet
• What a life    sikke et liv, sikke et hundeliv

Nederlands (Dutch)
leven, leefwijze, (recht van) bestaan, levensduur, draaglijk leven, animus, wezen, organisme, levenskans, animerende kracht, kabaal, (auto)biografie, levenslang aanslaan (motor), plotseling beginnen te werken

Français (French)
n. - vie, durée, vivant (de qn), plein de vie/d'entrain, boute-en-train, plein d'animation
adj. - à vie, vital

idioms:

• be in someone's life    faire partie de la vie de qn
• come to life    donner des signes de vie, s'animer
• for dear life    de toutes mes/etc forces
• for life    à vie, pour la vie
• for one's life    pour sa vie
• for the life of me    même avec les plus grands efforts
• Get a life    fais quelque chose de ta vie (excl)
• have a life    s'amuser
• life after death    (croire) à la vie après la mort
• life and death    (une affaire) de vie ou de mort, désespérée (une lutte)
• life assurance    assurance-vie
• life belt    ceinture de sauvetage
• life buoy    bouée de sauvetage
• life cycle    cycle de vie
• life expectancy    espérance de vie
• life experience    expérience de la vie
• life form    être vivant
• life goes on    la vie continue
• life imprisonment    réclusion à perpétuité
• life insurance    assurance-vie
• life jacket    gilet de sauvetage
• life member    membre à vie
• life peer    (GB, Pol) pair à vie
• life preserver    gilet de sauvetage
• life raft    radeau de sauvetage
• life science    sciences de la vie
• life sentence    (Jur) condamnation à perpétuité
• life span    durée de vie
• life to come    la vie future
• life to the full    vivre pleinement
• life work    l'¯uvre de toute une vie
• not on your life    jamais de la vie (excl)
• take one's life in one's own hands    mettre sa vie en danger
• take someone's life    donner la mort à qn
• that's life    c'est la vie (excl)
• the life and soul of    le boute-en-train de
• this is the life    voilà, ce que j'appelle vivre (excl)
• to the life    exactement, réplique exacte
• What a life    Quelle vie!

Deutsch (German)
n. - Leben, Lebensbeschreibung, Lebensdauer, (ugs.) lebenslängliche Freiheitsstrafe
adj. - lebens-

idioms:

• be in someone's life    eine Beziehung mit jmdm. haben
• come to life    lebendig werden
• for dear life    um sein Leben (rennen)
• for life    auf Lebenszeit
• for one's life    um sein Leben rennen usw.
• for the life of me    trotz jds. Bemühungen
• Get a life    Mach was Interessantes
• have a life    Interessen haben, die das Leben bereichern
• life after death    Leben nach dem Tod
• life and death    leben und Tod
• life assurance    Lebensversicherung
• life belt    Rettungsgürtel
• life buoy    Rettungsring
• life cycle    Lebenszyklus
• life expectancy    Lebenserwartung
• life experience    Lebenserfahrung
• life form    Lebensform
• life goes on    das Leben geht weiter
• life imprisonment    lebenslängliche Haft
• life insurance    Lebensversicherung
• life jacket    Schwimmweste
• life member    Mitglied auf Lebenszeit
• life peer    Peer auf Lebenszeit
• life preserver    Schwimmweste, Totschläger
• life raft    Rettungsfloß
• life science    Biowissenschaft
• life sentence    lebenslängliche Freiheitsstrafe
• life span    Lebenserwartung, Lebensdauer
• life to come    zukünftiges Leben
• life to the full    das Leben voll genießen
• life work    Lebenswerk
• not on your life    nie im Leben! (ugs.)
• take one's life in one's own hands    sein Leben riskieren
• take someone's life    jmdn. töten, jmdn. ermorden
• that's life    so ist das Leben [nun mal]
• the life and soul of    der Mittelpunkt von etwas
• this is the life    so läßt sich's leben!
• to the life    lebensgetreu
• What a life    So eine elende Existenz!

Ελληνική (Greek)
n. - ζωή, βίος, βιογραφία, ζωντάνια, (μτφ.) ισόβια κάθειρξη
adj. - ζωής, σωσίβιος, ζωικός

idioms:

• be in someone's life    είμαι μέρος της ζωής κάποιου
• come to life    ζωντανεύω, ξυπνώ, ενεργοποιούμαι
• for dear life    να γλιτώσω
• for life    δια βίου
• for the life of me    με τίποτα, με κανένα τρόπο
• Get a life    Βγες να ζήσεις, Βρες να κάνεις κάτι καλύτερο
• have a life    έχω να ζήσω τη ζωή μου, έχω κι άλλα πράγματα να κάνω
• high life    κοσμική ή μεγάλη ζωή
• lay down one's life    είμαι έτοιμος να θυσιάσω ακόμα και τη ζωή μου
• life after death    μετά θάνατο ζωή
• life and death    ζωής και θανάτου
• life assurance    (οικον.) ασφάλεια ζωής
• life belt    σωσίβια ζώνη
• life buoy    σωσίβιο σε σχήμα κουλούρας
• life cycle    (βιολ.) βιολογικός κύκλος ζωής
• life expectancy    πιθανή διάρκεια ζωής, προσδόκιμο ζωής
• life experience    πείρα ζωής
• life form    ζωντανός οργανισμός
• life goes on    η ζωή συνεχίζεται
• life imprisonment    ισόβια
• life insurance    ασφάλεια ζωής
• life jacket    περιστήθιο σωσίβιο, σωσίβιο-χιτώνας
• life member    ισόβιο μέλος
• life peer    ισόβιος λόρδος
• life preserver    σωσίβιο, (Βρετ.) ρόπαλο
• life raft    σωσίβια σχεδία, ναυαγοσωστική σχεδία
• life science    επιστημονική εξέταση ζωντανών οργανισμών
• life sentence    ισόβια κάθειρξη
• life span    (μέγιστη) διάρκεια ζωής, μέσος όρος ζωής
• life to come    μέλλουσα ζωή
• life to the full    (ζω τη) ζωή με τα όλα της
• life work    έργο (ολόκληρης) ζωής
• take one's life in one's own hands    παίρνω τη ζωή μου στα χέρια μου
• take someone's life    αφαιρώ τη ζωή κάποιου
• the life and soul of    η "ψυχή" (της παρέας)
• What a life    Ζωή κι αυτή!

Italiano (Italian)
vita, modo di vivere, chiasso, perpetuo

idioms:

• a new life    una nuova vita
• be in someone's life    avere un romanzo con
• bring to life    far rinvenire
• come to life    animarsi
• for dear life    assolutamente
• for life    a vita
• for the life of    per nulla al mondo
• Get a life!    Svegliati!
• have a life    avere una vita
• larger than life    esagerato, esuberante
• lay down one's life    mettersi a repentaglio
• life after death    vita eterna
• life assurance    assicurazione sulla vita
• life buoy    salvagente
• life cycle    ciclo vitale
• life expectancy    durata di vita
• life experience    esperienza di vita
• life form    forma di vita
• life goes on    la vita continua
• life imprisonment    prigione a vita
• life insurance    assicurazione sulla vita
• life jacket    salvagente
• life member    membro vitalizio
• life peer    lord a vita
• life preserver    salvagente
• life raft    zattera salvagente
• life science    scienze naturali
• life sentence    condanna a vita
• life span    durata di vita
• life to the full    vita intensa
• life work    capolavoro
• life's work    capolavoro
• life-support machine/system    sistema di sopravvivenza
• live one's own life    vivere la propria vita
• not (able to) do something to save someone's life    inetto a salvarsi
• rule someone's life    spadroneggiarsi su
• spring to/roar into life    rinascere
• start/begin life    nascere
• take life    prendere vita
• take one's life in one's own hands    mettersi a repentaglio
• the life and soul of    lo spirito di
• What a life!    che vita!

Português (Portuguese)
n. - vida (f), vivacidade (f), duração (f), vigência (f)
adj. - de vida, perpétuo, permanente

idioms:

• be in someone's life    estar na vida de alguém
• come to life    trazer à vida
• for dear life    fazer o possível para se viver bem
• for life    por toda a vida
• for the life of me/them etc.    pela minha vida/deles
• Get a life!    Vá se danar!
• have a life    levar uma vida
• life assurance    garantia (f) de vida
• life buoy    bóia (f) salva-vidas
• life cycle    ciclo (m) de vida
• life expectancy    expectativa (f) de vida
• life experience    experiência (f) de vida
• life form    forma (f) de vida
• life goes on    a vida continua
• life imprisonment    prisão (f) perpétua (Jur.)
• life insurance    seguro (m) de vida
• life jacket    colete (m) salva-vidas
• life member    membro da família
• life peer    pessoa que recebeu título de lorde
• life preserver    colete (m) salva-vidas
• life raft    balsa (f) salva-vidas
• life science    ciência da vida
• life sentence    pena (f) de prisão perpétua (Jur.)
• life span    duração
• life to come    vida após a morte
• life to the full    vida por inteiro
• life work    trabalhar duro
• spring to/roar into life    despertar para a vida
• start/begin life    começar a vida
• take life    levar a vida
• take one's life in one's own hands    ter a vida de alguém nas próprias mãos
• the life and soul of    vida e alma de algum lugar
• What a life!    que vida!, que droga!

Русский (Russian)
жизнь, живые существа, образ жизни, жизненный

idioms:

• be in someone's life    вмешиваться в чью-л. жизнь
• come to life    появиться на свет, прийти в себя
• for dear life    изо всех сил
• for life    на всю оставшуюся жизнь
• for the life of    ни за что на свете!
• Get a life!    начните жить по-настоящему!, займитесь серьезным делом
• have a life    начать жить по-настоящему, заняться серьезным делом
• life assurance    страхование жизни
• life buoy    спасательный круг
• life cycle    жизненный цикл, биография
• life expectancy    ожидаемая продолжительность жизни
• life experience    жизненный опыт
• life form    формы жизни
• life goes on    жизнь продолжается
• life imprisonment    пожизненное заключение
• life insurance    страхование жизни
• life jacket    спасательный жилет
• life member    пожизненный член
• life peer    титул пэра, который не может быть передан по наследству
• life preserver    спасательный пояс, кастет
• life raft    спасательный плот
• life science    научные дисциплины, занимающиеся живыми организмами
• life sentence    приговор пожизненного заключения
• life span    продолжительность жизни
• life to come    после смерти
• life to the full    жить полной жизнью
• life work    труд всей жизни
• spring to/roar into life    включить двигатель, нажать на газ
• start/begin life    родиться, начать жить
• take life    убить кого-л.
• take one's life in one's own hands    распорядиться собственной жизнью
• the life and soul of    вдохновитель чего-л.
• What a life!    "что за жизнь..." (выражение неудовольствия)

Español (Spanish)
n. - existencia, ser, vida, duración, manera de vivir, animación, vitalidad, biografía, vigencia, validez
adj. - de la vida, vitalicio, vital

idioms:

• be in someone's life    tener una relación amorosa
• come to life    animarse, cobrar vida, recobrar los sentidos, volver en sí
• for dear life    como para salvar la vida, desesperadamente
• for life    de por vida
• for one's life    desesperadamente, para salvar la vida
• for the life of me    que me maten si..., a fe mía, aunque me fuera la vida en ello
• Get a life    ¡es tiempo ya que se dediquen a algo!, haz tu vida!
• have a life    disfrutar de actividades placenteras, tener una vida de
• life after death    vida después de la muerte
• life and death    vida o muerte
• life assurance    seguro de vida
• life belt    cinturón salvavidas
• life buoy    salvavidas, guindola
• life cycle    ciclo vital
• life expectancy    esperanza o expectativas de vida
• life experience    las enseñanzas de la vida
• life form    forma de vida
• life goes on    la vida continúa
• life imprisonment    prisión a perpetuidad
• life insurance    seguro de vida
• life jacket    chaleco salvavidas
• life member    miembro o socio vitalicio
• life peer    (GB) persona a la que se le da el título de "Lord" para toda su vida pero que no lo puede pasar a otras generaciones
• life preserver    chaleco salvavidas, vergajo
• life raft    balsa salvavidas
• life science    ciencias biológicas
• life sentence    cadena perpetua
• life span    duración de la vida, longevidad
• life to come    la vida que vendrá, el futuro
• life to the full    vivir la vida al máximo
• life work    trabajo de toda una vida
• not on your life    ciertamente no!
• take one's life in one's own hands    jugarse la vida
• take someone's life    quitar la vida, matar
• that's life    esto es vida!
• the life and soul of    ser el alma de
• this is the life    así es la vida
• to the life    copiado exactamente
• What a life    ¡que vida ésta!, Qué vida! (ingrata, asquerosa, etc.)

Svenska (Swedish)
n. - liv, livstid, livslängd, levnad, levnadslopp, varaktighet, bestånd, löptid, tillvaro, levnadssätt, leverne, livsföring, liv (och rörelse), (i kricket) "liv", chans, levnadsteckning, levnadsbeskrivning, biografi, (konst.) natur, verklighet, levande modell, naturlig storlek
adj. - liv-

中文（简体）(Chinese (Simplified))
生活, 人生, 生命

idioms:

• be in someone's life    在某人的生活中
• come to life    苏醒过来, 显得逼真, 变得活跃
• for dear life    拼命地
• for life    终身, 为逃命
• for the life of me    一点头绪也没有
• Get a life    过活泼一点的生活
• have a life    有好的社交生活
• life after death    死后的生活, 来世
• life and death    生死攸关的, 重大的
• life assurance    人寿保险
• life belt    安全带
• life buoy    救生圈, 救生衣
• life cycle    生命周期, 盛衰周期
• life expectancy    平均寿命
• life experience    身世
• life form    生物, 活物
• life goes on    生命还是要继续
• life imprisonment    无期徒刑, 终身监禁
• life insurance    人寿保险
• life jacket    救生衣
• life member    终身成员
• life peer    终身贵族
• life preserver    救生用具, 保命用具
• life raft    救生艇
• life science    生命科学
• life sentence    无期徒刑之判决
• life span    生命的源泉
• life to come    来世
• life to the full    经历丰富的生活
• life work    一生的工作, 毕生的事业
• take one's life in one's own hands    把握自己的命运, 冒生命危险
• take someone's life    杀掉某人
• the life and soul of    ...的生命, 中心人物, 最活跃有趣的人
• What a life    瞧这种生活, 人生太苦

中文（繁體）(Chinese (Traditional))
n. - 生活, 人生, 生命

idioms:

• be in someone's life    在某人的生活中
• come to life    甦醒過來, 顯得逼真, 變得活躍
• for dear life    拼命地
• for life    終身, 為逃命
• for the life of me    一點頭緒也沒有
• Get a life    過活潑一點的生活
• have a life    有好的社交生活
• life after death    死後的生活, 來世
• life and death    生死攸關的, 重大的
• life assurance    人壽保險
• life belt    安全帶
• life buoy    救生圈, 救生衣
• life cycle    生命周期, 盛衰周期
• life expectancy    平均壽命
• life experience    身世
• life form    生物, 活物
• life goes on    生命還是要繼續
• life imprisonment    無期徒刑, 終身監禁
• life insurance    人壽保險
• life jacket    救生衣
• life member    終身成員
• life peer    終身貴族
• life preserver    救生用具, 保命用具
• life raft    救生艇
• life science    生命科學
• life sentence    無期徒刑之判決
• life span    生命的源泉
• life to come    來世
• life to the full    經歷豐富的生活
• life work    一生的工作, 畢生的事業
• take one's life in one's own hands    把握自己的命運, 冒生命危險
• take someone's life    殺掉某人
• the life and soul of    ...的生命, 中心人物, 最活躍有趣的人
• What a life    瞧這種生活, 人生太苦

한국어 (Korean)
n. - 생명, 수명, 생물, 생활 방식, 인생

idioms:

• be in someone's life    다른 사람의 입장이 되어보다
• come to life    의식을 되찾다, 정신이 들다
• Get a life    새롭게 시작하다
• have a life    삶을 시작하다
• life goes on    세월이 가다
• take one's life in one's own hands    일부러 목숨을 건 모험을 하다
• take someone's life    누군가를 죽이다
• the life and soul of    활력소
• What a life    무슨 놈의 인생이 이래

日本語 (Japanese)
n. - 生命, 生存, 一生, 寿命, 人生, 世間, 生物, 伝記, 生活, 実物, 実物大, 活気, 救い, 被保険者, 新鮮さ
int. - これは驚いた

idioms:

• be in someone's life    一生で
• come to life    生き返る, 活気づく
• for life    一生
• for the life of    どうしても
• frighten the life out of    生活をおびやかす
• have a life    寿命がある
• life after death    死後の世界
• life and death    死活問題
• life assurance    生命保険
• life belt    救命帯, 安全ベルト
• life buoy    救命浮標
• life cycle    生活環, ライフサイクル
• life expectancy    平均余命
• life experience    人生経験
• life form    生物形態
• life goes on    時間が経つ
• life imprisonment    終身刑, 終身懲役
• life insurance    生命保険
• life jacket    救命胴着, ライフジャケット
• life member    終身会員
• life peer    一代貴族
• life preserver    救命具, こん棒
• life raft    救命いかだ
• life science    ライフサイエンス
• life sentence    終身刑
• life span    寿命
• life to come    後世
• life to the full    充実した人生
• life work    一生の仕事, ライフワーク
• start/begin life    この世に生をうける, 生まれる
• take life    殺す
• take one's life in one's own hands    命を賭ける
• the life and soul of    花形

العربيه (Arabic)
‏(الاسم) حياة, عيشه, سيرة ترجمه حيه, عمر, معيشه رزق, كائن حي وبخاصه شخص, مبدأ أو قوة محييه, حيويه, روح, فرصه أخرى تمنح لشخص محتمل أن يخسر (صفه) ذو علاقه بكائن حي, دائم مدى الحياة, مستعمل نموذجا حيا في تعليم الرسم, متعلق بالتأمين على الحياة, نابض بالحياة, شديد الشبه بالأصل‏

עברית (Hebrew)
n. - ‮חיים, נפש, חיות, מודל חי (בציור), פעילות, מאסר עולם, נוכחות או פעילות של יצורים חיים, תקופת החיים, דרך חיים‬

If you are unable to view some languages clearly, click here.