Tree model

"‘The Tree Model presupposes a flawed understanding of language diversification processes. In a nutshell, cladistic (tree-based) representations are entirely based on the fiction that the main reason why new languages emerge is the abrupt division of a language community into separate social groups. Trees fail to capture the very common situation in which linguistic diversification results from the fragmenta- tion of a language into a network of dialects which remained in contact with each other for an extended period of time’ (François 2014, p. 162)."

"Almost all literature on language spreads assumes, at least implicitly, either demographic expansion or migration as basic mechanism, but in fact language shift is the most conservative assumption and should be the default assumption. There is no reason to believe that the mechanism of spread has any impact on the linguistic geography of the spread … simple phylogenetic descent [i.e., the tree model] is insufficient for tracing the origin and dispersal of the world’s languages and peoples."