Common descent

Common descent describes how, in evolutionary biology, a group of organisms share a most recent common ancestor. There is massive evidence of common descent of all life on Earth from the last universal common ancestor (LUCA). In July 2016, scientists reported identifying a set of 355 genes from the LUCA by comparing the genomes of the three domains of life, archaea, bacteria, and eukaryotes.There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.May we not say that, in the fortuitous combination of the productions of Nature, since only those creatures could survive in whose organizations a certain degree of adaptation was present, there is nothing extraordinary in the fact that such adaptation is actually found in all these species which now exist? Chance, one might say, turned out a vast number of individuals; a small proportion of these were organized in such a manner that the animals' organs could satisfy their needs. A much greater number showed neither adaptation nor order; these last have all perished.... Thus the species which we see today are but a small part of all those that a blind destiny has produced.ould it be too bold to imagine, that in the great length of time, since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind, would it be too bold to imagine, that all warm-blooded animals have arisen from one living filament, which .mw-parser-output .smallcaps{font-variant:small-caps}the great First Cause endued with animality, with the power of acquiring new parts attended with new propensities, directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down those improvements by generation to its posterity, world without end?Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed.'We do not know all the possible transitional gradations between the simplest and the most perfect organs; it cannot be pretended that we know all the varied means of Distribution during the long lapse of years, or that we know how imperfect the Geological Record is. Grave as these several difficulties are, in my judgment they do not overthrow the theory of descent from a few created forms with subsequent modification'. No reliable observation has ever been found to contradict the general notion of common descent. It should come as no surprise, then, that the scientific community at large has accepted evolutionary descent as a historical reality since Darwin’s time and considers it among the most reliably established and fundamentally important facts in all of science. Common descent describes how, in evolutionary biology, a group of organisms share a most recent common ancestor. There is massive evidence of common descent of all life on Earth from the last universal common ancestor (LUCA). In July 2016, scientists reported identifying a set of 355 genes from the LUCA by comparing the genomes of the three domains of life, archaea, bacteria, and eukaryotes. Common ancestry between organisms of different species arises during speciation, in which new species are established from a single ancestral population. Organisms which share a more-recent common ancestor are more closely related. The most recent common ancestor of all currently living organisms is the last universal ancestor, which lived about 3.9 billion years ago. The two earliest evidences for life on Earth are graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in western Greenland and microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. All currently living organisms on Earth share a common genetic heritage, though the suggestion of substantial horizontal gene transfer during early evolution has led to questions about the monophyly (single ancestry) of life. 6,331 groups of genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived 650 million years ago in the Precambrian. Universal common descent through an evolutionary process was first proposed by the British naturalist Charles Darwin in the concluding sentence of his 1859 book On the Origin of Species: In the 1740s, the French mathematician Pierre Louis Maupertuis made the first known suggestion that all organisms had a common ancestor, and had diverged through random variation and natural selection. In Essai de cosmologie (1750), Maupertuis noted: In 1790, the philosopher Immanuel Kant wrote in Kritik der Urteilskraft (Critique of Judgement) that the similarity of animal forms implies a common original type, and thus a common parent. In 1794, Charles Darwin's grandfather, Erasmus Darwin asked: Charles Darwin's views about common descent, as expressed in On the Origin of Species, were that it was probable that there was only one progenitor for all life forms: But he precedes that remark by, 'Analogy would lead me one step further, namely, to the belief that all animals and plants have descended from some one prototype. But analogy may be a deceitful guide.' And in the subsequent edition , he asserts rather, Common descent was widely accepted amongst the scientific community after Darwin's publication. In 1907, Vernon Kellogg commented that 'practically no naturalists of position and recognized attainment doubt the theory of descent.'