Recursion was a good candidate for a universal grammar rule because it can take many forms. However, in 2005 linguists published findings on an Amazonian language called Piraha, which doesn't appear to have any recursive structures.

递归是通用语法规则的一个很好的候选者， 因为它可以采用多种形式。然而，2005 年语言学家发表了关于一种名为 Piraha 的亚马逊语言的研究结果， 该语言似乎没有任何递归结构。