Talk:Evolution

A1: This is essentially mandated by Wikipedia's official neutral point of view policy. This policy requires that articles treat views on various subjects proportionally to those views' mainstream acceptance in the appropriate academic field. For example, if two contradictory views in physics are held by roughly an equal number of physicists, then Wikipedia should give those views "equal time". On the other hand, if one view is held by 99% of physicists and the other by 1%, then Wikipedia should favor the former view throughout its physics articles; the latter view should receive little, if any, coverage. To do otherwise would require, for example, that we treat belief in a Flat Earth as being equal to other viewpoints on the figure of the Earth.

Due to the enormous mainstream scientific consensus in support of modern evolutionary theory, and pursuant to Wikipedia's aforementioned policies, the Evolution article references evolution as an observable natural process and as the valid explanation for the diversity of life on Earth. Although there are indeed opposing views to evolution, such as Creationism, none of these views have any support in the relevant field (biology), and therefore Wikipedia cannot, and should not, treat these opposing views as being significant to the science of evolution. On the other hand, they may be very significant to sociological articles on the effects of evolutionary theory on religious and cultural beliefs; this is why sociological and historical articles such as Rejection of evolution by religious groups give major coverage to these opposing views, while biological articles such as Evolution do not.

A2: As noted above, evolution is at best only controversial in social areas like politics and religion. The fact that evolution occurs and the ability of modern evolutionary theory to explain why it occurs are not controversial amongst biologists. Indeed, numerous respectable scientific societies, such as the American Association for the Advancement of Science and the National Academy of Sciences, have issued statements supporting evolution and denouncing creationism and/or ID.^[1] In 1987 only about 0.15% of American Earth and life scientists supported creationism.^[2]

Thus, as a consequence of Wikipedia's policies, it is necessary to treat evolution as mainstream scientific consensus treats it: an uncontroversial fact that has an uncontested and accurate explanation in evolutionary theory. There are no scientifically supported "alternatives" for this view.

A3: That depends on if you use the words evolution, theory, and fact in their scientific or their colloquial sense. Unfortunately, all of these words have at least two meanings. For example, evolution can either refer to an observed process (covered at evolution), or, as a shorthand for evolutionary theory, to the explanation for that process (covered at modern evolutionary synthesis). To avoid confusion between these two meanings, when the theory of evolution, rather than the process/fact of evolution, is being discussed, this will usually be noted by explicitly using the word theory.

Evolution is not a theory in the sense used on Evolution; rather, it is a fact. This is because the word evolution is used here to refer to the observed process of the genetic composition of populations changing over successive generations. Because this is simply an observation, it is considered a fact.

A4: Once again, this depends on how one is defining the terms proof and proven. Proof has two meanings: in logic and mathematics, it refers to an argument or demonstration showing that a proposition is completely certain and logically necessary; in other uses, proof refers to the establishment and accumulation of experimental evidence to a degree at which it lends overwhelming support to a proposition. Therefore, a proven proposition in the mathematical sense is one which is formally known to be true, while a proven proposition in the more general sense is one which is widely held to be true because the evidence strongly indicates that this is so ("beyond all reasonable doubt", in legal language).

In the first sense, the whole of evolutionary theory is not proven with absolute certainty, but there are mathematical proofs in evolutionary theory. However, nothing in the natural sciences can be proven in the first sense: empirical claims such as those in science cannot ever be absolutely certain, because they always depend on a finite set of facts that have been studied relative to the unproven assumptions of things stirring in the infinite complexity of the world around us. Evolutionary science pushes the threshold of discovery into the unknown. To call evolution "unproven" in this sense is technically correct, but meaningless, because propositions like "the Earth revolves around the Sun" and even "the Earth exists" are equally unproven. Absolute proof is only possible for a priori propositions like "1 + 1 = 2" or "all bachelors are unmarried men", which do not depend on any experience or evidence, but rather on definition.

A5: Evolution, as a fact, is the gradual change in forms of life over several billion years. In contrast, the field of evolutionary biology is less than 200 years old. So it is not surprising that scientists did not directly observe, for example, the gradual change over tens of millions of years of land mammals to whales.^[3] However, there are other ways to "observe" evolution in action.

Scientists have directly observed and tested small changes in forms of life in laboratories, particularly in organisms that breed rapidly, such as bacteria and fruit flies.^[4] A famous experiment was developed in 1992 that traced bacterial evolution with precision in a lab. This experiment has subsequently been used to test the accuracy and robustness of methods used in reconstructing the evolutionary history of other organisms with great success.^[5][6] Evolution has also been observed in the field, such as in the plant Oenothera lamarckiana which gave rise to the new species Oenothera gigas,^[7] in the Italian Wall Lizard,^[8] and in Darwin's finches.^[9]

A6: The article doesn't equate the two, but merely recognizes that they are largely or entirely the same process, just on different timescales. The great majority of modern evolutionary biologists consider macroevolution to simply be microevolution on a larger timescale; all fields of science accept that small ("micro") changes can accumulate to produce large ("macro") differences, given enough time. Most of the topics covered in the evolution article are basic enough to not require an appeal to the micro/macro distinction. Consequently, the two terms are not equated, but simply not dealt with much.

A more nuanced version of the claim that evolution has never been observed is to claim that microevolution has been directly observed, while macroevolution has not. However, that is not the case, as speciations, which are generally seen as the benchmark for macroevolution, have been observed in a number of instances.

A7: To be frank, there isn't any. Most claimed "evidence against evolution" is either a distortion of the actual facts of the matter, or an example of something that hasn't been explained yet. The former is erroneous, as it is based on incorrect claims. The latter, on the other hand, even when accurate, is irrelevant. The fact that not everything is fully understood doesn't make a certain proposition false; that is an example of the argument from ignorance logical fallacy. Examples of claimed evidence against evolution:

1. There aren't any transitional fossils, or there aren't enough.

   There are many transitional fossils, including Archaeopteryx (earliest and most primitive bird known), Thrinaxodon (a cat-sized mammal-like "reptile"), Tiktaalik (fish with many features akin to those of four-legged animals), Acanthostega (first vertebrate animal to have recognizable limbs), and Ambulocetus (early whale that could walk as well as swim). See also List of transitional fossils. That there are not more is explained by the rarity of fossilization and by punctuated equilibrium. Furthermore, technically all fossils are transitional fossils, because no species is fixed and unchanging. For example, you can argue that Homo erectus is a transitional fossil between Homo sapiens and Homo habilis. But in the same line of thought, you can say Homo habilis is a transitional fossil between A. afarensis and Homo erectus, and so on.^[10][11]

A8: If by "arise", one means "develop from non-organic matter through abiogenesis", then this is a question that is not answered by evolutionary theory. Evolution only deals with the development of pre-existing life, not with how that life first came to be. The fact that life evolves is not dependent upon the origin of life any more than the fact that objects gravitate towards other objects is dependent upon the Big Bang.

On the other hand, if by "arise" one means "evolve into the organisms alive today", then the simple answer is: it didn't. Evolution does not occur "by chance". Rather, evolution occurs through natural selection, which is a non-random process. Although mutation is random, natural selection favors mutations that have specific properties—the selection is therefore not random. Natural selection occurs because organisms with favored characteristics survive and reproduce more than ones without favored characteristics, and if these characteristics are heritable they will mechanically increase in frequency over generations. Although some evolutionary phenomena, such as genetic drift, are indeed random, these processes do not produce adaptations in organisms.