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.

研究人类句法结构展现为图形表示后发现，其拓扑图形自身便符合有效沟通机制，而非优化沟通效率而来，此定论同时说明了语言沟通效率自身不一定优化。