Human syntactic structures are usually represented as graphs. Much research has focused on the mapping between such graphs and linguistic sequences, but less attention has been paid to the shapes of the graphs themselves: their topologies. This study investigates how the topologies of syntactic graphs reveal traces of the processes that led to their emergence. I report a new universal regularity in syntactic structures: Their topology is communicatively efficient above chance. The pattern holds, without exception, for all 124 languages studied, across linguistic families and modalities (spoken, written, and signed). This pattern can arise from a process optimizing for communicative efficiency or, alternatively, by construction, as a by-effect of a sublinear preferential attachment process reflecting language production mechanisms known from psycholinguistics. This dual explanation shows how communicative efficiency, per se, does not require optimization. Among the two options, efficiency without optimization offers the better explanation for the new pattern.

翻译：人类句法结构通常以图的形式呈现。已有研究大多关注这类图与语言序列之间的映射关系，但鲜有研究探讨图本身的形状——即其拓扑结构。本研究考察句法图的拓扑如何揭示其形成过程的痕迹。报告发现句法结构存在一项新的普适规律：其拓扑在统计上显著高于随机水平的交际效率。这一规律毫无例外地适用于所有124种研究语言，跨越不同语系和模态（口语、书面语及手语）。该规律既可能源于追求交际效率的优化过程，也可能作为次线性优先依附过程的副产物而形成——后者反映了心理语言学已知的语言产出机制。这种双重解释表明，交际效率本身并不需要优化过程。在这两种可能性中，"无需优化的效率"为这一新规律提供了更优的解释。