Data from: New evidence from linguistic phylogenetics identifies limits to punctuational change

Since the early 1970s, biologists have debated whether evolution is punctuated by speciation events with bursts of cladogenetic changes, or whether evolution tends to be of a more gradual, anagenetic nature. A similar discussion among linguists has barely begun, but the present results suggest that there is also room for controversy over this issue in linguistics. The only previous study correlated the number of nodes in linguistic phylogenies with branch lengths and found support for punctuated equilibrium. We replicate this result for branch lengths, but find no support for punctuated equilibrium using a different, automated measure of linguistic divergence and a much larger data set. With the automated measure, segments of trees containing more nodes show no greater divergence from an outgroup than segments containing fewer nodes.自20世纪70年代初以来，生物学界始终围绕演化模式持续争论：演化究竟会因伴随分支演化（cladogenetic）爆发式变化的物种形成事件而被间断，还是更倾向于渐进式的前进演化（anagenetic）路径。语言学家群体中类似的讨论才刚刚起步，但本次研究结果表明，语言学领域内该议题同样存在争议空间。此前仅有一项研究将语言系统发育树（linguistic phylogenies）中的节点数量与分支长度进行关联分析，并为间断平衡（punctuated equilibrium）假说提供了支持证据。我们针对分支长度重复了该研究的结果，但采用一种全新的自动化语言分化（linguistic divergence）度量方法，结合规模更大的数据集开展分析后，并未发现支持间断平衡假说的证据。采用该自动化度量方法时，包含更多节点的树段与外类群（outgroup）之间的分化程度，并不比包含更少节点的树段更高。