The notion that we are imperiled by the size of the human population has been around since Anglican priest Thomas Malthus first postulated it in the late 18th century. In regard to famine, immorality, war and human misery of all sorts, Malthus maintained that there is "one great cause," preventing "improvement of society," and that is "the constant tendency in all animated life to increase beyond the nourishment prepared for it." If the size of the human population were to go unchecked, Malthus' demographics suggested that people would soon outrun global food supplies. Yup, that tired notion has been around...