Merritt Ruhlen (May 10, 1944 – January 29, 2021) was an American linguist who worked on the classification of languages and what this reveals about the origin and evolution of modern humans.

Subsequently, Ruhlen worked for several years as a research assistant on the Stanford Universals Project, directed by Joseph Greenberg and Charles Ferguson.

[2] From 2005, Ruhlen was on the advisory board of the Genographic Project and held appointment as a visiting professor at the City University of Hong Kong.

Ruhlen has been in the forefront of attempts to coordinate the results of historical linguistics and other human sciences, such as genetics and archaeology.

It involves comparing selected elements of the morphology and basic vocabulary of the languages being investigated, examining them for similarities in sound and meaning, and formulating a hypothesis of classification based on these.

[8] As an example, Ruhlen mentions Delbrück (1842–1922), who considered Indo-European to have been proved by the time of Bopp at the beginning of the 19th century; the basis for this proof was the "juxtaposition of words and forms of similar meaning.

[25] Ruhlen stresses the importance of the three-way i / u / a (i.e. masculine / feminine / neutral) ablaut in such forms as t'ina / t'una / t'ana ("son / daughter / child") as well as of the general American pronominal pattern na / ma (i.e. "I / you"), first noted by Alfredo Trombetti in 1905.

[31] They adduce: The following table shows similarities between the pronominal systems of several languages claimed to belong to the Indo-Pacific family.

... We do not deal here with reconstruction, and these [semantic and phonetic] glosses are intended merely to characterize the most general meaning and phonological shape of each root.