    Sentence 4: What was Norman Cantor's  theery about the plague?    Sentence 2: Archaeologist Barney Sloane has  argued that there is insufftcient evidence of  the extinction of a large number of rats in  the archaeological record of the medieval]  waterfront in London and that the plague  spread too quickly to support the thesis that  fhe Y. pestis was spread ftom fleas on rats;