Number of words: 395<\/p>\n\n\n\n
Thanks to the heroic efforts of Tina Tang, who scoured texts for examples, we were able to study the evolution of 177 irregular verbs over the past 1,200 years, from Beowulf to The Canterbury Tales to Harry Potter. We grasped something that no one thought could be measured and obtained striking results. Of the seven rules for conjugating the past tense in Old English, only one has survived. That single extant rule adds an -ed suffix to simple past and past participle forms. Just as genes and organisms undergo natural selection, words\u2014 specifically, irregular verbs such as \u201cholp\u201d that do not take an -ed ending in the past tense\u2014are subject to powerful pressure to \u201cregularize\u201d as the language develops.<\/p>\n\n\n\n
Of the 177 verbs that were irregular 1,200 years ago, 145 stayed irregular in Middle English. Only 98 or so remain irregular today, following the regularization over the centuries of such verbs as \u201chelp,\u201d \u201claugh,\u201d \u201creach,\u201d \u201cwalk,\u201d and \u201cwork.\u201d What\u2019s striking is that the \u201cdecay of an irregular word\u201d followed a very clear trend with remarkably small error bars. The mathematical function explaining this decay says that a verb used 100 times less frequently will regularize 10 times as fast. To put it another way, verbs evolve at a rate inversely proportional to the square-root of their prevalence in the English language. An irregular verb that occurs less often will be forgotten faster. In this way, irregular verbs behave in just the same way as radioactive atoms and have half-lives. We can calculate the half-life of irregular verbs depending on their frequency.<\/p>\n\n\n\n
The present tense of \u201cI know\u201d has the irregular past tense \u201cI knew.\u201d Although little kids might apply the logic of language to say\u2014quite understandably\u2014\u201cI knowed,\u201d this verb hasn\u2019t regularized yet. \u201cI know\u201d is so common that it resists change. Children also start out by saying \u201cgrowed\u201d before they learn the -ew rule. Or \u201chitted\u201d instead of \u201chit\u201d\u2014the basis of that old joke\u2014Child: \u201cMummy, Bobby hitted me. Mother: \u201cBobby hit me.\u201d Child: \u201cYou too? Boy, that kid is in trouble.\u201d<\/p>\n\n\n\n
Children need to hear the irregular form often enough to memorize it. As a corollary of this, relatively less popular words are more likely to succumb to change. And all modern verbs, such as \u201cto google,\u201d are regular.<\/p>\n\n\n\n