Life (cf. biota Biota is the total collection of organisms of a geographic region or a time period, from local geographic scales and instantaneous temporal scales all the way up to whole-planet and whole-timescale spatiotemporal scales. The biota of the Earth lives in the biosphere. Commonly, humans are not categorized as biota) is a characteristic that distinguishes objects In physics, a physical body or physical object is a collection of masses, taken to be one. For example, a cricket ball can be considered an object but the ball also consists of many particles (pieces of matter) that have signaling and self-sustaining processes A biological process is a process of a living organism. Biological processes are made up of any number of chemical reactions or other events that results in a transformation (biology) from those that do not,[1][2] either because such functions have ceased (death Death is the termination of the biological functions that sustain a living organism. The word refers both to the particular processes of life's cessation as well as to the condition or state of a formerly-living body), or else because they lack such functions and are classified as inanimate.[3]
In biology Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy, the science of living organisms, life is the condition which distinguishes active organisms In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole. An organism may either be unicellular (single-celled) or be composed of, as in humans, many trillions of cells grouped into from inorganic matter Traditionally, inorganic compounds are considered to be of a mineral, not biological, origin. Complementarily, most organic compounds are traditionally viewed as being of biological origin. Over the past century, the precise classification of inorganic vs organic compounds has become less important to scientists, primarily because the majority of.[4] Living organisms undergo metabolism Metabolism is the set of chemical reactions that happen in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter, for example to harvest energy in cellular, maintain homeostasis Homeostasis is the property of a system, either open or closed, that regulates its internal environment and tends to maintain a stable, constant condition. Typically used to refer to a living organism, the concept came from that of milieu interieur that was created by Claude Bernard and published in 1865. Multiple dynamic equilibrium adjustment, possess a capacity to grow The term cell growth is used in the contexts of cell development and cell division When used in the context of cell division, it refers to growth of cell populations, where one cell (the "mother cell") grows and divides to produce two "daughter cells", respond to stimuli In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity. When a stimulus is applied to a sensory receptor, it elicits or influences a reflex via stimulus transduction. A stimulus is often the first component of a homeostatic, reproduce Reproduction is the biological process by which new "offspring" individual organisms are produced from their "parents". Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. The known methods of reproduction are broadly grouped into two main types: sexual and and, through natural selection Natural selection is a natural law by which genetically heritable traits become more or less common in a population over successive generations. This selection in interaction with the production of variation, the possible genetic fixation process and possibly, in several cases, whith little epigenetic process determine the evolution of the species, 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 The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth. From the broadest biophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, hydrosphere and atmosphere. The on Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet,[note 6] or by its Latin name, Terra.[note 7], and the properties common to these organisms—plants Plants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants, bryophytes, ferns and fern allies. As of 2004,, animals Animals are a major group of mostly multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and independently. All animals are also, fungi A fungus ) is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi (pronounced /ˈfʌndʒaɪ/ or /ˈfʌŋɡaɪ/), that is separate from plants, animals and bacteria. One major difference is that fungal, protists Protists are a diverse group of eukaryotic microorganisms. which include mostly unicellular organisms that do not fit into the other kingdoms. Historically, protists were treated as the kingdom Protista, which includes mostly unicellular organisms that do not fit into the other kingdoms, but this group is contested in modern taxonomy. Instead, it, archaea The Archaea (/ɑrˈkiːə/ ar-KEE-ə) are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon (sometimes spelled "archeon"). They have no cell nucleus or any other organelles within their cells. In the past they were viewed as an unusual group of bacteria and named archaebacteria, and bacteria The bacteria ( [bækˈtɪəriə] ; singular: bacterium)[α] are a large group of single-celled, prokaryote microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste,—are a carbon Carbon forms the backbone of biology for all life on Earth. Complex molecules are made up of carbon bonded with other elements, especially oxygen, hydrogen and nitrogen, and carbon is able to bond with all of these because of its four valence electrons. It is often assumed in astrobiology that if life exists somewhere else in the universe, it will- and water Water is a chemical substance with the chemical formula H2O. Its molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state, water vapor or steam-based cellular The cell is the functional basic unit of life. It was discovered by Robert Hooke and is the functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. Some organisms, such as most bacteria, are unicellular . Other organisms, such as humans, form with complex organization An organization is a social arrangement which pursues collective goals, controls its own performance, and has a boundary separating it from its environment. The word itself is derived from the Greek word organon, itself derived from the better-known word ergon and heritable genetic A gene is a unit of heredity in a living organism. It is normally a stretch of DNA that codes for a type of protein or for an RNA chain that has a function in the organism. All living things depend on genes, as they specify all proteins and functional RNA chains. Genes hold the information to build and maintain an organism's cells and pass genetic information.
In philosophy Philosophy is the study of general and fundamental problems concerning matters such as existence, knowledge, values, reason, mind, and language. It is distinguished from other ways of addressing fundamental questions by its critical, generally systematic approach and its reliance on rational argument. The word "philosophy" comes from the and religion Religion is the belief in and worship of a god or gods, or a set of beliefs concerning the origin and purpose of the universe. It is commonly regarded as consisting of a person’s relation to God or to gods or spirits. Many religions have narratives, symbols, traditions and sacred histories associated with their deity or deities, that are, the conception A concept is a cognitive unit of meaning—an abstract idea or a mental symbol sometimes defined as a "unit of knowledge," built from other units which act as a concept's characteristics. A concept is typically associated with a corresponding representation in a language or symbology[citation needed] such as a single meaning of a term of life and its nature varies. Both offer interpretations as to how life relates to existence In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity conditions for objects and properties. Philosophers and consciousness Consciousness is variously defined as subjective experience, awareness, the ability to experience "feeling", wakefulness, or the executive control system of the mind. It is an umbrella term that may refer to a variety of mental phenomena. Although humans realize what everyday experiences are, consciousness refuses to be defined,, and both touch on many related issues, including life stance A person's life stance or lifestance is their relation with what they accept as being of ultimate importance, the presuppositions and theory of this, and the commitments and practice of working it out in living, purpose Purpose is a result, end, mean, aim, or goal of an action intentionally undertaken, or of an object being brought into use or existence, whether or not the purpose was a primary or secondary effect. It is possible that an intentional act may have multiple purposes, only one of which is a primary intention while the remainder are secondary, conception of a god or gods The God of monotheism, pantheism or panentheism, or the supreme deity of henotheistic religions, may be conceived of in various degrees of abstraction:, a soul A soul is the supposed incorporeal essence of a person or living thing. Many philosophical and spiritual systems teach humans are souls; some attribute souls to all living things and even inanimate objects ; this belief is commonly called animism. The soul is often believed to exit the body and live on after a person’s death, and some religions or an afterlife The afterlife is the idea that consciousness or the mind continues after the death of the body occurs, by natural or supernatural means. In many popular views, this continued existence often takes place in an immaterial or spiritual realm. Major views on the afterlife derive from religion, esotericism and metaphysics.
Contents |
Early theories about life
Materialism
Some of the earliest theories of life were materialist In philosophy, the theory of materialism holds that the only thing that exists is matter; that all things are composed of material and all phenomena are the result of material interactions. In other words, matter is the only substance. As a theory, materialism is a form of physicalism and belongs to the class of monist ontology. As such, it is, holding that all that exists is matter, and that all life is merely a complex form or arrangement of matter. Empedocles Empedocles was a Greek pre-Socratic philosopher and a citizen of Agrigentum, a Greek city in Sicily. Empedocles' philosophy is best known for being the originator of the cosmogenic theory of the four Classical elements. He also proposed powers called Love and Strife which would act as forces to bring about the mixture and separation of the (430 B.C.) argued that every thing in the universe is made up of a combination of four eternal 'elements' Many philosophies and worldviews have a set of classical elements believed to reflect the simplest essential parts and principles of which anything consists or upon which the constitution and fundamental powers of anything are based. Most frequently, classical elements refer to ancient beliefs inspired by natural observation of the phases of 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 Democritus (ca. 460 BC – ca. 370 BC) was an Ancient Greek philosopher born in Abdera, Thrace, Greece. He was an influential pre-Socratic philosopher and pupil of Leucippus, who formulated an atomic theory for the cosmos (460 B.C.), the disciple of Leucippus Leucippus or Leukippos was the first Greek to develop the theory of atomism — the idea that everything is composed entirely of various imperishable, indivisible elements called atoms — which was elaborated in far greater detail by his pupil and successor, Democritus, thought that the essential characteristic of life is having a soul (psychê). 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 seventeenth century In the history of science, the scientific revolution was a period when new ideas in physics, astronomy, biology, human anatomy, chemistry, and other sciences led to a rejection of doctrines that had prevailed starting in Ancient Greece and continuing through the Middle Ages, and laid the foundation of modern science. According to a majority of, mechanistic ideas were revived by philosophers like Descartes René Descartes (Latinized form: Renatus Cartesius; adjectival form: "Cartesian"), was a French philosopher, mathematician, physicist, and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the "Father of Modern Philosophy", and much of subsequent Western philosophy is a response to his writings,.
Hylomorphism
Hylomorphism Hylomorphism is a philosophical theory developed by Aristotle, which analyzes substance into matter and form. More precisely, substances are conceived of as forms inhering in matter is the theory (originating with Aristotle Aristotle (384 BC – 322 BC) was a Greek philosopher, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, politics, government, ethics, biology, and zoology. Together with Plato and Socrates (Plato's teacher), Aristotle is one of the most (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 A soul is the supposed incorporeal essence of a person or living thing. Many philosophical and spiritual systems teach humans are souls; some attribute souls to all living things and even inanimate objects ; this belief is commonly called animism. The soul is often believed to exit the body and live on after a person’s death, and some religions (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 nineteenth 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 Wöhler prepared urea from inorganic materials. This so-called Wöhler synthesis is considered the starting point of modern organic chemistry. It is of great 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.[11][12][13] Defining life is difficult —in part— because life is a process, not a pure substance.[14] 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 earthly life.[15]
|
Thu, 19 Aug 2010 16:16:19 GMT+00:00
of Heidi Montag Plastic Surgeon ... Associated Content At 7:10 pm on Aug. 16, celebrity plastic surgeon Frank Ryan tweeted a picture he'd just taken of his border collie Jill, "surveying the view from atop the ... Plastic Surgeon to the Celebrities Fatal Crash Most Likely Caused by Texting ... Associated Content
admin
Wed, 01 Sep 2010 20:23:42 GM
Looking for the Cheapest . Life. Insurance and Other Online Insurance Quotes When looking for a . life. insurance, you should consider the amount of.
