다음 빈칸에 들어갈 말로 가장 적절한 것을 고르시오. [3점]
Both the acquisition and subsequent rejection of agriculture are becoming increasingly recognized as adaptive strategies to local conditions that may have occurred repeatedly over the past ten millennia. For example, in a recent study of the Mlabri, a modern hunter-gatherer group from northern Thailand, it was found that these people had previously been farmers, but had abandoned agriculture about 500 years ago. This raises the interesting question as to how many of the diminishing band of contemporary hunter-gatherer cultures are in fact the descendents of farmers who have only secondarily readopted huntergathering as a more useful lifestyle, perhaps after suffering from crop failures, dietary deficiencies, or climatic changes. Therefore, the process of what may be termed the ‘agriculturalization’ of human societies was ____________________________, at least on a local level. Hunter-gatherer cultures across the world, from midwestern Amerindians to !Kung in the African Kalahari, have adopted and subsequently discarded agriculture, possibly on several occasions over their history, in response to factors such as game abundance, climatic change, and so on.