"life arises from a different, unrelated form, such as tapeworms from the bodies of their hosts. In the years following Louis Pasteur's 1859 experiment, the term ""spontaneous generation"" fell increasingly out of favor. Experimentalists used a variety of terms for the study of the origin of life from nonliving materials. ""Heterogenesis"" was applied to the generation of living things from once-living organic matter (such as boiled broths), and Henry Charlton Bastian proposed the term ""archebiosis"" for life originating from inorganic materials. Disliking the randomness and unpredictability implied by the term ""'spontaneous' generation,"" in 1870 Bastian coined the term ""biogenesis"" to"
"continuously created as a result of chance events. The term ""biogenesis"" is usually credited to either Henry Charlton Bastian or to Thomas Henry Huxley. Bastian used the term around 1869 in an unpublished exchange with John Tyndall to mean ""life-origination or commencement"". In 1870, Huxley, as new president of the British Association for the Advancement of Science, delivered an address entitled ""Biogenesis and Abiogenesis"". In it he introduced the term ""biogenesis"" (with an opposite meaning to Bastian's) as well as ""abiogenesis"": Subsequently, in the preface to Bastian's 1871 book, ""The Modes of Origin of Lowest Organisms"", Bastian referred to the"
"substance of life. Huxley's principal contribution was to establish protoplasm as incompatible with a vitalistic theory of life. Attempts to investigate the origin of life through the creation of synthetic ""protoplasm"" in the laboratory were not successful. The idea that protoplasm of eukaryotes is simply divisible into a ground substance called ""cytoplasm"" and a structural body called the cell nucleus reflects the more primitive knowledge of cell structure that preceded the development of electron microscopy, when it seemed that cytoplasm was a homogeneous fluid and the existence of most sub-cellular compartments, or how cells maintain their shape, was unknown. Today,"
"energy is derived from the condensed products of the chemical reactions taking place in the cooling nebula. Abiogenesis Abiogenesis, or informally the origin of life, is the natural process by which life arises from non-living matter, such as simple organic compounds. The transition from non-living to living entities was not a single event, but a gradual process of increasing complexity that involved molecular self-replication, self-assembly, autocatalysis and cell membranes. Although the occurrence of abiogenesis is uncontroversial among scientists, there is no single, generally accepted model for the origin of life, and this article presents several principles and hypotheses for ""how"""
"Abiogenesis Abiogenesis, or informally the origin of life, is the natural process by which life arises from non-living matter, such as simple organic compounds. The transition from non-living to living entities was not a single event, but a gradual process of increasing complexity that involved molecular self-replication, self-assembly, autocatalysis and cell membranes. Although the occurrence of abiogenesis is uncontroversial among scientists, there is no single, generally accepted model for the origin of life, and this article presents several principles and hypotheses for ""how"" abiogenesis could have occurred. Researchers study abiogenesis through a combination of molecular biology, paleontology, astrobiology, oceanography, biophysics,"
"and adaptation to the environment. Vitalism holds that living organisms differ from other things in containing something non-physical, such as a fluid or vital spirit, that makes them live. The theory dates to ancient Egypt. Since Early Modern times, vitalism stood in contrast to the mechanistic explanation of biological systems started by Descartes. Nineteenth century chemists set out to disprove the claim that forming organic compounds required vitalist influence. In 1828, Friedrich Wöhler showed that urea could be made entirely from inorganic chemicals. Louis Pasteur believed that fermentation required whole organisms, which he supposed carried out chemical reactions found only"
"Bathybius haeckelii In 1868 Huxley studied an old sample of mud from the Atlantic seafloor taken in 1857. When he first examined it, he had found only protozoan cells and placed the sample into a jar of alcohol to preserve it. Now he noticed that the sample contained an albuminous slime that appeared to be criss-crossed with veins. Huxley thought he had discovered a new organic substance and named it ""Bathybius haeckelii"", in honor of German biologist Ernst Haeckel. Haeckel had theorized about ""Urschleim"" (""primordial slime""), a protoplasm from which all life had originated. Huxley thought ""Bathybius"" could be that"
"Preformationism In the history of biology, preformationism (or preformism) is a formerly-popular theory that organisms develop from miniature versions of themselves. Instead of assembly from parts, preformationists believed that the form of living things exist, in real terms, prior to their development. It suggests that all organisms were created at the same time, and that succeeding generations grow from homunculi, or animalcules, that have existed since the beginning of creation. Epigenesis (or neoformism), then, in this context, is the denial of preformationism: the idea that, in some sense, the form of living things comes into existence. As opposed to ""strict"""
"the Great Oxidation Event might be a consequence of eukaryogenesis and its impact on the export and burial of organic carbon. Symbiogenesis Symbiogenesis, or endosymbiotic theory, is an evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms, first articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by Lynn Margulis in 1967. It holds that the organelles distinguishing eukaryote cells evolved through symbiosis of individual single-celled prokaryotes (bacteria and archaea). The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells represent formerly free-living"
"of how the origin of life produced reproducing organisms from non-reproducing elements is called abiogenesis. Whether or not there were several independent abiogenetic events, biologists believe that the last universal ancestor to all present life on Earth lived about 3.5 billion years ago. Scientists have speculated about the possibility of creating life non-reproductively in the laboratory. Several scientists have succeeded in producing simple viruses from entirely non-living materials. However, viruses are often regarded as not alive. Being nothing more than a bit of RNA or DNA in a protein capsule, they have no metabolism and can only replicate with the"
"types), compared with 10–20 in plants, fungi, and protoctista. Cell theory In biology, cell theory is the historic scientific theory, now universally accepted, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells. Cells are the basic unit of structure in all organisms and also the basic unit of reproduction. With continual improvements made to microscopes over time, magnification technology advanced enough to discover cells in the 17th century. This discovery is largely attributed to Robert Hooke, and began the scientific study of cells,"
"Epigenesis (biology) In biology, epigenesis (or, in contrast to preformationism, neoformationism) is the process by which plants, animals and fungi develop from a seed, spore or egg through a sequence of steps in which cells differentiate and organs form. Aristotle first published the theory of epigenesis in his book ""On the Generation of Animals."" Although epigenesis appears to be an obvious fact in today's genetic age, historically creationist theories of life's origins hindered its acceptance. However, during the late 18th century an extended and controversial debate among biologists finally led epigenesis to eclipse the long-established preformationist view. The embryologist Caspar"
"Cell theory In biology, cell theory is the historic scientific theory, now universally accepted, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells. Cells are the basic unit of structure in all organisms and also the basic unit of reproduction. With continual improvements made to microscopes over time, magnification technology advanced enough to discover cells in the 17th century. This discovery is largely attributed to Robert Hooke, and began the scientific study of cells, also known as cell biology. Over a century later,"
"materialism of Huxley. In 1880, term protoplast was proposed by Hanstein (1880) for the entire cell, excluding the cell wall, and some authors like Julius von Sachs (1882) preferred that name instead of cell. In 1965, lardy introduced the term ""cytosol"", later redefined to refer to the liquid inside cell. By the time Huxley wrote, a long-standing debate was largely settled over the fundamental unit of life: was it the cell or was it protoplasm? By the late 1860s, the debate was largely settled in favor of protoplasm. The cell was a container for protoplasm, the fundamental and universal material"
"redefined the term (also named as ""Primordialschlauch"", ""primordial utricle"") to refer to the ""tough, slimy, granular, semi-fluid"" substance within plant cells, to distinguish this from the cell wall and the cell sap (""Zellsaft"") within the vacuole. Thomas Huxley (1869) later referred to it as the ""physical basis of life"" and considered that the property of life resulted from the distribution of molecules within this substance. The protoplasm became an ""epistemic thing"". Its composition, however, was mysterious and there was much controversy over what sort of substance it was. In 1872, Beale created the vitalist term ""bioplasm"", to contrast with the"
"Evolutionary biology Evolutionary biology is the subfield of biology that studies the evolutionary processes that produced the diversity of life on Earth, starting from a single common ancestor. These processes include natural selection, common descent, and speciation. The discipline emerged through what Julian Huxley called the modern synthesis (of the 1930s) of understanding from several previously unrelated fields of biological research, including genetics, ecology, systematics, and paleontology. Current research has widened to cover the genetic architecture of adaptation, molecular evolution, and the different forces that contribute to evolution including sexual selection, genetic drift and biogeography. The newer field of evolutionary"
"of molecular biology. Though the term usually refers strictly to biological evolution, creationists have appropriated it to refer to the origin of life, and it has even been applied to concepts of cosmic evolution, both of which have no connection to Darwin's work. It is therefore considered the belief and acceptance of Darwin's and of his predecessors' work—in place of other theories, including divine design and extraterrestrial origins. English biologist Thomas Henry Huxley coined the term ""Darwinism"" in April 1860. It was used to describe evolutionary concepts in general, including earlier concepts published by English philosopher Herbert Spencer. Many of"
"and appointed a commission to judge the winner. Spontaneous generation Spontaneous generation refers to an obsolete body of thought on the ordinary formation of living organisms without descent from similar organisms. The theory of spontaneous generation held that living creatures could arise from nonliving matter and that such processes were commonplace and regular. For instance, it was hypothesized that certain forms such as fleas could arise from inanimate matter such as dust, or that maggots could arise from dead flesh. A variant idea was that of equivocal generation, in which species such as tapeworms arose from unrelated living organisms, now"
"in heterogenesis, i.e., that one form of life derived from a different form (e.g., bees from flowers). Classical notions of spontaneous generation held that certain complex, living organisms are generated by decaying organic substances. According to Aristotle, it was a readily observable truth that aphids arise from the dew that falls on plants, flies from putrid matter, mice from dirty hay, crocodiles from rotting logs at the bottom of bodies of water, and so on. In the 17th century, people began to question such assumptions. In 1646, Sir Thomas Browne published his ""Pseudodoxia Epidemica"" (subtitled ""Enquiries into Very many Received"
"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. Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction. Life may also be said to be simply the characteristic state of organisms. In biology, the science of living organisms, ""life"" is the condition which distinguishes active organisms from inorganic matter, including"
"Zoology"". New York: Viking Press. Bathybius haeckelii In 1868 Huxley studied an old sample of mud from the Atlantic seafloor taken in 1857. When he first examined it, he had found only protozoan cells and placed the sample into a jar of alcohol to preserve it. Now he noticed that the sample contained an albuminous slime that appeared to be criss-crossed with veins. Huxley thought he had discovered a new organic substance and named it ""Bathybius haeckelii"", in honor of German biologist Ernst Haeckel. Haeckel had theorized about ""Urschleim"" (""primordial slime""), a protoplasm from which all life had originated. Huxley"
"to spontaneous generation. He experimentally showed that organisms (microbes) can not grow in a sterilised water, unless it is exposed to air. The experiment won him the Alhumbert Prize in 1862 from the French Academy of Sciences, and he concluded: Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment. Evolutionary biologists believed that a kind of spontaneous generation, but different from the simple Aristotelian doctrine, must have worked for the emergence of life. French biologist Jean-Baptiste de Lamarck had speculated that the first life form started from non-living materials. """"Nature, by means of"
"Spontaneous generation Spontaneous generation refers to an obsolete body of thought on the ordinary formation of living organisms without descent from similar organisms. The theory of spontaneous generation held that living creatures could arise from nonliving matter and that such processes were commonplace and regular. For instance, it was hypothesized that certain forms such as fleas could arise from inanimate matter such as dust, or that maggots could arise from dead flesh. A variant idea was that of equivocal generation, in which species such as tapeworms arose from unrelated living organisms, now understood to be their hosts. The idea of"
"Primordial soup Primordial soup, or prebiotic soup (also sometimes referred as prebiotic broth), is the hypothetical set of conditions present on the Earth around 4.2 to 4.0 billions of years ago. It is a fundamental aspect to the heterotrophic theory of the origin of life, first proposed by Alexander Oparin and John Burdon Sanderson Haldane in the 1920s. The notion that living beings originated from inanimate materials comes from the Ancient Greeks—the theory known as spontaneous generation. Aristotle in the 4th century BCE gave a proper explanation, writing: Aristotle also states that it is not only that animals originate from"
"process known as ""Generatio spontanea"". Aristotle disagreed, but he still believed that creatures could arise from dissimilar organisms or from soil. Variations of this concept of spontaneous generation still existed as late as the 17th century, but towards the end of the 17th century, a series of observations and arguments began that eventually discredited such ideas. This advance in scientific understanding was met with much opposition, with personal beliefs and individual prejudices often obscuring the facts. William Harvey (1578–1657) was an early proponent of all life beginning from an egg, ""omne vivum ex ovo"". Francesco Redi, an Italian physician, proved"
"for natural selection, which explains the consequence in terms of a prior cause. Biological features are explained not by looking at future optimal results, but by looking at the past evolutionary history of a species, which led to the natural selection of the features in question. Spontaneous generation was the belief that living organisms can form without descent from similar organisms. Typically, the idea was that certain forms such as fleas could arise from inanimate matter such as dust or the supposed seasonal generation of mice and insects from mud or garbage. The theory of spontaneous generation was proposed by"
"and other ancient marine invertebrates. Inspired by Darwin's manifesto, Thomas Henry Huxley emphatically cited embryologic and fossil evidence for the evolution of ""higher"" invertebrates from ""lower"" cnidarians, worms and mollusks, thereby elaborating what he concluded was ""Man's Place in Nature"" (1863). Another Darwinist, Ernst Haeckel, proposed a Protozoa-Metazoa theory of animal origins, while arguing that embryonic ""ontogeny recapitulates phylogeny"" throughout organic prehistory. Haeckel popularized his paleozoologic ideas with majestic genealogical trees of the Animal Kingdom in his ""General Morphology of Organisms"" (1866). A half-century later, the genetic conclusions of Gregor Mendel (1822 to 1884) were revived by ""The Mutation Theory"""
"protoplasm, a missing link (in modern terms) between inorganic matter and organic life. Huxley published a description of ""Bathybius"" and also wrote to Haeckel to tell him about it. Haeckel was impressed and flattered and procured a sample for himself. In the next edition of his textbook ""The History of Creation"" Haeckel suggested that the substance was constantly coming into being at the bottom of the sea. Huxley did not agree but speculated that ""Bathybius"" formed a continuous mat of living protoplasm that covered the whole ocean floor. Other scientists were less enthusiastic. Charles Wyville Thomson examined some samples in"
"within the quickly flowing circulatory system. The German pathologist Rudolf Virchow brought forward the idea that not only does life arise from cells, but every cell comes from another cell; """"Omnis cellula e cellula"""". Until now, most attempts to create an artificial cell have only created a package that can mimic certain tasks of the cell. Advances in cell-free transcription and translation reactions allow the expression of many genes, but these efforts are far from producing a fully operational cell. The future is in the creation of a protocell, or a cell which has all the minimum requirements for life."
"several organs functioning as an organ system such as the reproductive system, and digestive system. Many multicellular organisms consist of several organ systems, which coordinate to allow for life. The cell theory, first developed in 1839 by Schleiden and Schwann, states that all organisms are composed of one or more cells; all cells come from preexisting cells; and cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells. There are two types of cells, eukaryotic and prokaryotic. Prokaryotic cells are usually singletons, while eukaryotic cells are usually found in multicellular"
"355 genes from the Last Universal Common Ancestor (LUCA) of all organisms living on Earth. All known life forms share fundamental molecular mechanisms, reflecting their common descent; based on these observations, hypotheses on the origin of life attempt to find a mechanism explaining the formation of a universal common ancestor, from simple organic molecules via pre-cellular life to protocells and metabolism. Models have been divided into ""genes-first"" and ""metabolism-first"" categories, but a recent trend is the emergence of hybrid models that combine both categories. There is no current scientific consensus as to how life originated. However, most accepted scientific models"
"that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve. However, several other biological definitions have been proposed, and there are some borderline cases of life, such as viruses or viroids. In the past, there have been many attempts to define what is meant by ""life"" through obsolete concepts such as odic force, hylomorphism, spontaneous generation and vitalism, that have now been disproved by biological discoveries. Abiogenesis describes the natural process of life arising from non-living matter, such as simple"
"early lifeforms evolved into the complex ecosystem that we see today. Based on the similarities between all present-day organisms, all life on Earth is assumed to have originated through common descent from a last universal ancestor from which all known species have diverged through the process of evolution. All individuals have hereditary material in the form of genes received from their parents, which they pass on to any offspring. Among offspring there are variations of genes due to the introduction of new genes via random changes called mutations or via reshuffling of existing genes during sexual reproduction. The offspring differs"