Noun classes are advantageous. Gender happens to be a useful way to categorize nouns because mostly we like to talk about other people. Gender (and animacy -- "

Noun classes are advantageous. Gender happens to be a useful way to categorize nouns because mostly we like to talk about other people. Gender (and animacy -- "it" versus "s/he") split things up efficiently for many conversations, where, say, paper versus non-paper wouldn't.