The Yam languages, also known as the Morehead River languages, are a family of Papuan languages. They include many of the languages south and west of the Fly River in Papua New Guinea and Indonesian West Papua.

The names Morehead and Upper Maro River or Morehead-Maro refer to the area around the Morehead and Maro rivers. Most of the languages are found between these rivers, but the Nambu subgroup are spoken east of the Morehead. Evans (2012) refers to the family instead with the more compact name Yam. This name is motivated by a number of linguistic and cultural items of significance: yam (and cognates) means "custom, tradition"; yəm (and cognates) means "is"; and yam tubers are the local staple and of central cultural importance.

Ross (2005) tentatively includes the Yam languages in the proposed Trans-Fly – Bulaka River family. More recently (Evans 2012) has argued that this is not justified and more data has to be gathered. Evans (2018) classifies the Pahoturi River languages as an independent language family.^[1]

Yam languages have also been in intensive contact with Marind and Suki speakers, who had historically expanded into Yam-speaking territories via headhunting raids and other expansionary migrations.^[1]

Internal classification of the Yam languages:^[2]

• Yei
• Tonda languages (a dialect chain)
• Nambu languages (a dialect chain)

Wichmann (2013) did not find a connection between the branches in his automated comparison.^[3]

Yam languages are spoken by up to 3,000 people on both sides of the border in Papua New Guinea and Indonesia. In Papua New Guinea, Yam languages are spoken in Morehead Rural LLG, Western Province. In Papua, Indonesia, Yam languages are spoken in Merauke Regency.^[1]

Yam languages and respective demographic information listed by Evans (2018) are provided below.^[1] Geographical coordinates are also provided for some villages.^[4]

See also: Districts of Papua (Indonesian Wikipedia)

The pronouns Ross (2005) reconstructs for the family are,

Proto-Yam (Proto–Morehead – Upper Maro)

I/we	*ni
you	*bu
s/he/they	*be

Many Yam languages display vowel harmony, including in Nambu and Tonda languages.^[1]

• Carroll, Matthew J., Nicholas Evans, I Wayan Arka, Christian Döhler, Eri Kashima, Volker Gast, Tina Gregor, Julia Miller, Emil Mittag, Bruno Olsson, Dineke Schokkin, Jeff Siegel, Charlotte van Tongeren & Kyla Quinn. 2016. Yamfinder: Southern New Guinea Lexical Database.
• Döhler, Christian (2018) A grammar of Komnzo. (Studies in Diversity Linguistics 22). Berlin: Language Science Press. doi:10.5281/zenodo.1477799. ISBN 978-3-96110-125-2. Accessed on 2019-11-12.
• Evans, Nicholas, I Wayan Arka, Matthew Carroll, Christian Döhler, Eri Kashima, Emil Mittag, Kyla Quinn, Jeff Siegel, Philip Tama & Charlotte van Tongeren. 2017. The languages of Southern New Guinea. In Bill Palmer (ed.), The languages and linguistics of the New Guinea area, 641–774. Berlin; Boston: Walter de Gruyter. ISBN 978-3-11-029525-2. Accessed on 2019-11-12.
• Kaiping, Gereon A. & Edwards, Owen & Klamer, Marian (eds.). 2019. LexiRumah 2.2.3. Leiden: Leiden University Centre for Linguistics. Available online at https://lexirumah.model-ling.eu/lexirumah/. Accessed on 2019-09-14.
• Greenhill et al., 2008. In: Kaiping, Gereon A. & Edwards, Owen & Klamer, Marian (eds.). 2019. LexiRumah 2.2.3. Leiden: Leiden University Centre for Linguistics. Available online at https://lexirumah.model-ling.eu/lexirumah/. Accessed on 2019-09-14.