His discussion of New Guineans is used to directly refute the claim that Eurasians were more advanced due to intelligence - New Guineans are just as intelligent

His discussion of New Guineans is used to directly refute the claim that Eurasians were more advanced due to intelligence - New Guineans are just as intelligent (or more intelligent in his opinion) as Europeans, but did not develop advanced technology, thus intelligence cannot be the determining factor in technological development. He rejects intelligence as a determining factor, and spends the rest of the book after the preface explaining how influence of geography is much more convincing causal factor. How you reach the conclusion that this reinforces racist thinking, particularly when he explicitly states that the geographic explanation he offers in Guns, Germs, and Steel is meant as a refutation to race-based explanations, is beyond me.