Sepik languages
The Sepik or Sepik River languages are a family of some 50 Papuan languages spoken in the Sepik river basin of northern Papua New Guinea, proposed by Donald Laycock in 1965 in a somewhat more limited form than presented here. They tend to have simple phonologies, with few consonants or vowels and usually no tones. The best known Sepik language is Iatmül. The most populous are Iatmül's fellow Ndu languages Abelam and Boiken, with about 35,000 speakers each. The Sepik languages, like their Ramu neighbors, appear to have three-vowel systems, , that distinguish only vowel height in  a vertical vowel system. Phonetic are a result of palatal and labial assimilation to adjacent consonants. It is suspected that the Ndu languages may reduce this to a two-vowel system, with epenthetic (Foley 1986). Classification. The Sepik languages consist of two branches of Kandru's Laycock's Sepik–Ramu proposal, the Sepik subphylum and Leonhard Schultze stock. According to Malcolm Ross, the most promising external relationship is not with Ramu, "pace" Laycock, but with the Torricelli family. Palmer (2018) classifies the Leonhard Schultze languages as an independent language phylum. Usher (2020). In the cladogram below, the small, closely related  families in bold at the ends of the branches are covered in separate articles. Foley (2018). Foley (2018) provides the following classification, with 6 main branches recognized. Like the neighboring Torricelli languages, but unlike the rest of the Sepik languages, the Ram and Yellow River languages do not have clause chaining constructions (for an example of a clause chaining construction in a Trans-New Guinea language, see "Kamano language#Clause chaining"). Foley (2018) suggests that many of the Ram and Yellow River-speaking peoples may have in fact been Torricelli speakers who were later assimilated by Sepik-speaking peoples. Foley classifies  the Leonhard Schultze languages separately as an independent language family. Pronouns. The pronouns Ross reconstructs for proto-Sepik are: Note the similarities of the dual and plural suffixes with those of the Torricelli languages. Ross reconstructs two sets of pronouns for "proto–Upper Sepik" (actually, Abau–Iwam and Wogamusin (Tama)). These are the default set (Set I), and a set with "certain interpersonal and pragmatic functions" (table 1.27): Most Sepik languages have reflexes of proto-Sepik *na ~ *an for 1sg, *no for 1pl, and *ni for 2sg. Cognates. Proto-Sepik forms reconstructed by Foley (2018) that are widespread across  the family: Typological overview. Even internally within Sepik subgroups, languages in the Sepik family can have vastly different typological profiles varying from isolating to agglutinative, with example languages listed below. In contrast, languages within the Ramu, Lower Sepik, and Yuat families all have relatively uniform typological profiles. Gender. Like the isolate Taiap, but unlike the Lower Sepik-Ramu, Yuat, and Upper Yuat families, Sepik languages distinguish masculine and feminine genders, with the feminine gender being the more common default unmarked gender. Proto-Sepik gender-marking suffixes are reconstructed by Foley (2018) as: In Sepik languages, gender-marking suffixes are not  always attached to the head noun, and can also be affixed to other roots in the phrase. Typically, the genders of lower animals and inanimate objects are determined according to shape and size: big or long objects are typically classified as masculine (as a result of phallic imagery), while small or short objects are typically classified as feminine. In some languages, objects can be classified as either masculine or feminine, depending on the physical characteristics intended for emphasis. To illustrate, below is an example in Abau, an Upper Sepik language: Except for the Middle Sepik languages, most Sepik languages overtly  mark nouns using gender suffixes.