Unmarked transitive verbs in Melanesian Pidgin

Although all four major varieties of Melanesian Pidgin mark transitivity by a verbal suffix of the form <-Vm>, there is a small group of verbs in each of them which are unmarked when used transitively—more in Bislama and Broken than in Tok Pisin and Pijin. I will show that there are different kinds of explanations for different cases of zero-marking involving the origin, function, or form of the verb.