In historical linguistics, betacism is a sound change in which [b] (the voiced bilabial plosive, like in bane) shifts to [v] (the voiced labiodental fricative, like in English vane). Betacism is a fairly common phenomenon; it has taken place in Greek, Hebrew, and Spanish, among others.

In Classical Greek, the letter beta <β> denoted [b]. As a result of betacism, it has come to denote [v] in Modern Greek. (Modern Greek uses the digraph <μπ> to represent [b].) Indeed, this is the origin of the word betacism.

Perhaps the best known example of betacism is in the Romance languages. The first traces of betacism in Latin can be found in the third century C.E. The results of the shift are most widespread in the Western Romance languages, especially in Spanish, where the letters <b> and <v> are now both pronounced [β] (the voiced bilabial fricative, which is similar to [v]) except phrase-initially and after [m] when they are pronounced [b]; the two sounds ([β] and [b]) are now allophones. A similar phenomenon takes place in Persian in casual speech.^{[citation needed]} Another example is in Neapolitan, or in Maceratese (dialect of Macerata) which uses <v> to denote betacism-produced [v], such that Italian bocca corresponds to Neapolitan voccaand to Maceratese "vocca", Italian albero to arvero, and barba to Neapolitan varva and Maceratese "varba".

Clinton Richard Dawkins, FRS, FRSL (born 26 March 1941), known as Richard Dawkins, is a British ethologist, evolutionary biologist and author. He is an emeritus fellow of New College, Oxford, and was the University of Oxford's Professor for Public Understanding of Science from 1995 until 2008.

Dawkins came to prominence with his 1976 book The Selfish Gene, which popularised the gene-centered view of evolution and introduced the term meme. In 1982 he introduced an influential concept into evolutionary biology, presented in his book The Extended Phenotype, that the phenotypic effects of a gene are not necessarily limited to an organism's body, but can stretch far into the environment, including the bodies of other organisms.

Dawkins is an atheist, a vice president of the British Humanist Association, and a supporter of the Brights movement. He is well known for his criticism of creationism and intelligent design. In his 1986 book The Blind Watchmaker, he argued against the watchmaker analogy, an argument for the existence of a supernatural creator based upon the complexity of living organisms. Instead, he described evolutionary processes as analogous to a blind watchmaker. He has since written several popular science books, and makes regular television and radio appearances, predominantly discussing these topics. In his 2006 book The God Delusion, Dawkins contends that a supernatural creator almost certainly does not exist and that religious faith is a delusion—"a fixed false belief." As of January 2010 the English-language version has sold more than two million copies and had been translated into 31 languages.