Is it all quackery? I'm not qualified to judge. I know, however, that he anticipates arguments in several of the "cutting edge" books I have recently read on similar subjects.
Huntington divides the "mainsprings" into:
1. Physical inheritance: The selective, Darwinian process. Huntington's focus, which is unique among the sociobiologists I have read, is more on the effects of migration than anything else, and he places great emphasis on how Puritans, Icelanders, and other migrant groups were winnowed by their journeys. This is partly a function of the importance, in his mind, of physical energy to the creation of civilization. But it is struggle, either in Jews facing persecution, Junkers taming the slavic east, or Arab tribesmen robbing each other of cattle, that in his mind makes kiths strong.
2. Environment: Huntington's reputation, which although perhaps appropriate to earlier phases of his career now seems undeserved, is as a climactic determinist. Diet is also considered, but the main factors are seasons, temperatures, and storms. He claims, for instance, that mental activity is best produced in a fairly stormy environment with fairly strong seasonal variation. The influence of different temperatures on physical energy, and on religious creeds, is another worthwhile discussion. The climatic cycles and the "ozone" hypothesis are not very convincing.
His understanding of race is far ahead, in my view, of both the racists and anti-racists of our contemporary scene. His understanding of climate's influence on history, claims David Hackett Fischer, is quite unjustly neglected.
"We are confronted by possibilities which may be of the first importance, but so slight is our knowledge that most historians have never even thought of them, and many dismiss them as not worth pursuing."