Human settlement has often centered around coastal areas and waterways. Until recently, however, archaeologists believed that marine economies did not develop until the end of the Pleistocene, when the archaeological record begins to have evidence of marine life as part of the human diet. This has long been interpreted as a postglacial adaptation, due to the rise in sea level and subsequent decrease in terrestrial resources. Coastal resources, particularly mollusks, were viewed as fallback resources, which people resorted to only when terrestrial resources were scarce, included only as part of a more complex diet. Recent research has significantly altered this understanding, known as the Broad Spectrum