Directional Processes in Language Evolution

In language evolution there are a lot of well-known and well-investigated processes with a strong directional tendency, including sound change, semantic change, and grammatical change. Although linguists know these processes very well and use them frequently to make inferences, they are rarely used in computational approaches to phylogenetic reconstruction. I discuss this question in more detail in a new blogpost I wrote for David Morrison's blog The Genealogical World of Phylogenetic Networks and which you may find here.