Research press release




言語と遺伝子は、いずれも1つの世代から次の世代へ伝播し、各段階で、ランダムな揺らぎと自然選択という2つの機構によって変化することがある。今回、Joshua Plotkinたちは、デジタル化された注釈付き文例を集めた膨大な言語資料を解析し、英語文法の3つのよく知られた変遷に着目して、言語の進化における上記2機構の相対的寄与を評価した。3つの変遷とは、動詞の過去形の規則化と迂言的な‘do’の使用(例えば‘do you know?’という語句)と動詞の否定文の変遷であった。



An analysis of large bodies of digitised texts dating from the 12th to 21st centuries provides new insights into the evolution of the English language, a Nature paper reports.

Both languages and genes are transmitted between generations, and are subject to change at each step as a result of random fluctuation and natural selection. Joshua Plotkin and colleagues have assessed the relative contributions of these two mechanisms in language evolution by analysing large corpora of digitally annotated texts. They studied three well-known grammatical changes in the English language: the regularisation of past-tense verbs, the use of the periphrastic ‘do’ (such as is found in the phrase, ‘do you know?’), and variation in verbal negation.

They find that both evolutionary mechanisms are operating in English. Random drift is stronger in rare words than in common words, which could explain why rare words are more likely than common words to be replaced in a language. However, selection for the irregular forms of some past-tense verbs (such as ‘lit’ being favoured over ‘lighted’ and ‘dove’ over ‘dived’) seems to buck this trend. The authors suggest that this might be driven by changes in rhyming patterns over time; the increased selection for ‘dove’ coincides with a marked increase in the use of the irregular past-tense form ‘drove’, for example.

The findings demonstrate how combining large digital corpora with inferences from population genetics can yield valuable clues into the forces that drive language evolution.

doi: 10.1038/nature24455

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