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A variety of reasons have been advanced to explain the loss of fur in humans and why they differ in this way from all other primates. None of these reasons has become generally accepted as the explanation for the absence of functionally effective thermally insulating fur. The hypotheses previously advanced have not satisfactorily explained why humans are the unique naked ape. This paper proposes a new hypothesis; that Homo sapiens ancestors use of fire created the initial selection pressure leading to fur loss in humans.