How does grammatical gender differ between Nilo-Saharan and neighboring Afro-Asiatic languages?

Grammatical gender distinctions between masculine and feminine nouns are a widespread, fundamental feature of the Afro-Asiatic languages, whereas such systems are generally absent in the Nilo-Saharan languages.

In Afro-Asiatic languages, gender is often a pervasive inflectional category affecting nouns, pronouns, and verb conjugations. These languages frequently exhibit "gender stability," where common nouns share the same gender across the phylum, and some branches utilize "gender polarity," where a noun’s gender changes when shifting from singular to plural.1

Conversely, Nilo-Saharan languages typically lack these gender distinctions, with only a few exceptions. While some Nilotic languages—a subgroup of Nilo-Saharan—do exhibit gender, this is often attributed to typological influence from neighboring Afro-Asiatic groups rather than a shared genetic origin. In Southern and Western Nilotic languages, gender functions as a derivational property, while in Eastern Nilotic languages, it has developed into a fully inflectional system where nouns are inherently masculine, feminine, or occasionally neuter.2