Life For other uses, see Life (disambiguation). Life (Biota / Vitae / Eobionti) Life on Earth: * (unranked) Non-cellular life^[note 1] * (unranked) Cellular life Life is a characteristic distinguishing physical entities having as inanimate.^[3]^[4]^[5] Various forms of life exist such as plants, potential artificial life as living. Biology is the primary science concerned with the study of life, although many other sciences are The smallest contiguous unit of life is called an organism. Organisms Abiogenesis is the natural process of life arising from non-living matter such as simple organic compounds. The earliest life on Earth Eon. The earliest physical evidence of life on Earth is biogenic theories such as the Late Heavy Bombardment theory suggest that life on mechanism by which life began on Earth is unknown, although many hypotheses have been formulated. Since emerging, life has evolved into taxa. Life can survive and thrive in a wide range of conditions. The chemistry leading to life may have begun shortly after the Big the panspermia hypothesis, microscopic life—distributed by meteoroids, universe.^[21] Though life is confirmed only on the Earth, many think that extraterrestrial life is not only plausible, but probable or been examined for evidence of having once supported simple life, and The meaning of life—its significance, origin, purpose, and ultimate philosophy and religion have offered interpretations as to how life life stance, purpose, conception of a god or gods, a soul or an afterlife. Different cultures throughout history have had widely * 7 Extraterrestrial life * 9 Artificial life Some of the earliest theories of life were materialist, holding that all that exists is matter, and that life is merely a complex form or forms of life are caused by an appropriate mixture of elements.^[24] Democritus (460 BC) thought that the essential characteristic of life because of the apparent connection between life and heat, and because theory in biological science encouraged this view. The evolutionary extant writings. In this view, all things in the material universe have This account is consistent with teleological explanations of life, Vitalism is the belief that the life-principle is non-material. This hypothetical vital force or life force.^[35] It is a challenge for scientists and philosophers to define life in unequivocal terms.^[36]^[37]^[38] This is difficult partly because life sufficiently broad to encompass all life with which we are familiar, and must be sufficiently general to include life that may be fundamentally different from life on Earth.^[41]^[42]^[43] Some may even consider that life is not real at all, but a concept instead.^[44] Since there is no unequivocal definition of life, the current understanding is descriptive. Life is considered a characteristic of the basic units of life. phenomena associated with life.^[42] control mechanisms that are essential to maintaining life. See also: Entropy and life of life have been proposed,^[49] many of these are based upon chemical viewed as a delay of the spontaneous diffusion or dispersion of the Bernal, Erwin Schrödinger, Eugene Wigner, and John Avery, life is a That is, life is matter that can reproduce itself and evolve as survival dictates.^[56]^[57] Hence, life is a self-sustained chemical Others take a systemic viewpoint that does not necessarily depend on molecular chemistry. One systemic definition of life is that living life. They have been described as "organisms at the edge of life,"^[60] 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 that life on Earth functions as a single organism that defines and nature of life was in 1978, by American biologist James Grier life. Specifically, he identified the "nonfractionability of components A systems view of life treats environmental fluxes and biological life as it is for understanding ecosystems. As Harold J. Morowitz (1992) explains it, life is a property of an ecological system rather definition of life is preferable to a strictly biochemical or physical understand the systemic, order-generating behavior of life and emergence of complexity in functional organisms from the viewpoint of biology and aims to understand the most fundamental aspects of life. A biology,^[77]^[78] is concerned mainly with understanding life 'life is a general term for the presence of the typical closures found at least as complex as the cell.^[83]^[84]^[85]^[86] Life can also be Evidence suggests that life on Earth has existed for at least life dating back 3.7 billion years.^[9]^[10]^[11] All known life forms descent; based on these observations, hypotheses on the origin of life common ancestor, from simple organic molecules via pre-cellular life to There is no current scientific consensus as to how life originated. possibility for how life began is that genes originated first, followed that the first life was based on RNA,^[93] which has the DNA-like RNA molecules under the conditions that existed prior to life on Earth Cyanobacteria dramatically changed the composition of life forms on The diversity of life on Earth is a result of the dynamic interplay thereby affecting the path of evolution of subsequent life.^[107] For environment. Since oxygen was toxic to most life on Earth at the time, All life forms require certain core chemical elements needed for factors necessary for life — energy (sunlight or chemical energy), life forms that thrive outside the ranges where life is commonly found. life forms thrive in the Mariana Trench, the deepest spot on the Investigation of the tenacity and versatility of life on Earth, as well utilize to survive such extremes, is important for the search for life ranks. Life is divided into domains, which are subdivided into further new groups of life were revealed, and the fields of cell biology and lack characteristics of life such as cell membranes, metabolism and the Extraterrestrial life Main articles: Extraterrestrial life, Astrobiology, Astroecology and Life in the solar system Earth is the only planet known to harbor life. Other locations within the Solar System that may host life include subsurface Mars, the life on an Earth-like planet is known as the habitable zone. The inner the Sun may have a greater likelihood for Earth-like life to an impact on the likelihood of life forming. Stars in regions with a greater abundance of heavier elements that can form planets, in with complex life.^[148] Panspermia, also called exogenesis, is the hypothesis that life Conversely, terrestrial life may be seeded in other solar systems through directed panspermia, to secure and expand some terrestrial life elements and may be fertile soils for microbial, algal and plant life, for past and future life in our and other solar systems.^[149] the formation of early life on Earth—in a nebula, by necessity they chemical building-blocks of life (the amino acid glycine) in a comet Fullerenes have been implicated in the origin of life; according to outer space provided seeds for life on Earth."^[154] organic molecules), building blocks for life as we know it, may be serve as basic ingredients for life due to their surface-catalytic 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 for life."^[155] formed planets with the chemical precursors for life.^[166] evidence of ancient life, including a biosphere based on autotrophic, formation of life. PAHs seem to have been formed shortly after the Big Death is the permanent termination of all vital functions or life life. Death would seem to refer to either the moment life ends, or when the state that follows life begins.^[173] However, determining when between life and death. This is problematic, however, because there is little consensus over how to define life. The nature of death has for kind of afterlife or reincarnation for the soul, or resurrection of the Artificial life Main articles: Artificial life and Synthetic biology Artificial life is a field of study that examines systems related to life, its processes, and its evolution through simulations using artificial life imitates traditional biology by recreating some aspects information processing that defines such systems. 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"Alien Life 'Inevitable': makes life's existence elsewhere "inevitable" over billions of life: how evolutionary theory undermines everything you thought you knew of life. Cambridge University Press. pp. 193–194. 36. ^ Mullen, Leslie (June 19, 2002). "Defining Life". Origin & Evolution of Life. Astrobiology. Retrieved 2012-05-25. 37. ^ Emmeche, Claus (1997). "Defining Life, Explaining Emergence". 38. ^ "Can We Define Life". Colorado Arts & Sciences. 2009. Retrieved 40. ^ ^a ^b Mautner, Michael N. (2000). Seeding the Universe with Life: 41. ^ Nealson, K. H.; Conrad, P. G. (December 1999). "Life: past, 42. ^ ^a ^b ^c McKay, Chris P. (September 14, 2004). "What Is Life—and 43. ^ ^a ^b Mautner, Michael N. (2009). "Life-centered ethics, and the 45. ^ Davison, Paul G. "How to Define Life". The University of North 46. ^ "Habitability and Biology: What are the Properties of Life?". 47. ^ Trifonov, Edward N. (2012). "Definition of Life: Navigation 'life' ... using just three words?". MSN. 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Jupiter may have conditions needed for life". The University of beyond Earth: extraterrestrial life and society. Berghahn Series. 147. ^ Selis, Frank (2006). "Habitability: the point of view of an complex life in the Milky Way". Science 303 (5654): 59–62. 152. ^ Staff (18 August 2009). "'Life chemical' detected in comet". Mimic Life's Origins". Space.com. Retrieved September 22, 2012. carnivorous mammals". Annual Review of Earth and Planetary Sciences hopes for life on Mars". The Washington Post. Retrieved 181. ^ Chopra, Paras; Akhil Kamma. "Engineering life through Synthetic * Seeding the Universe With Life Legacy Books, Washington D. C., * Walker, Martin G. LIFE! Why We Exist...And What We Must Do to * Adrian Bejan, Sylvie Lorente, The constructal law and the evolution of design in nature, Physics of Life Reviews, Volume 8, Issue 3, Life Look up life or living in Wiktionary, the free dictionary. * Wikispecies – a free directory of life * Resources for life in the Solar System and in galaxy, and the potential scope of life in the cosmological future * The Kingdoms of Life Life Hierarchy of life * 5: Abiogenesis and evolution of life * Evolutionary history of life * Life + Life cycles/nuclear phases * Gene-centered view Life * Wildlife * Extraterrestrial life * Life "http://en.wikipedia.org/w/index.php?title=Life&oldid=641970020" * Life Views * View source * View history * Latviešu * Mobile view