dating of the antiquity of human use of wild rice and the appearance of the plant itself in lakes and streams have been the subjects of continuing academic debates. These disputes may be framed around these questions: When did wild rice first appear in various areas of the region? When was it plentiful enough to be harvested in quantities to be a significant food source? What is the relationship of wild rice to the introduction of pottery and to increases in indigenous populations in the past 2,000 years? "The use of wild rice by and its influence on prehistoric people in northeast Minnesota has led to much argument among archaeologists and paleoecologists". As an example, archaeologists divide human occupation of northeast Minnesota into numerous time periods. They are: the Paleo-Indian period from 7,000 years ago (5000 BC) extending back to an uncertain time after the glaciers receded from the last Ice Age; the Archaic period from 2,500 to 7,000 years ago (5000–500 BC); the Initial Woodland period from 2,500 to 1,300 years ago (500 BC–700 AD); the Terminal Woodland period from 1,300 to 400 years ago (700–1600 AD); and the historical period after that time. These rough dates are open to debate and vary by location in the state. In general, two lines of inquiry have focused on archaeological wild rice: 1) The radiocarbon dating of charred wild rice seeds or the associated charcoal left behind during the parching stage of rice production, and 2) Examination of preserved wild rice seeds associated with specific prehistoric pottery styles found in excavations of processing sites. Different pottery styles in northern Minnesota are linked to certain times in the Initial and Terminal Woodland periods stretching from around 500 BC to the time of contact between indigenous peoples and Europeans. To place this in context, "Although ceramics may have appeared as early as 2,000 BC in the southeastern United States, it is about 1,500 years later that they became evident in the Midwest". After European contact, indigenous wild rice processors generally abandoned ceramic vessels in favor of metal kettles. Woodland period The Initial Woodland period in northeast Minnesota marks the beginning of the use of pottery and burial mound building in the archaeological record. The Initial Woodland also experienced an increase in indigenous population. One hypothesis is that wild rice as a food source was related to these three developments. An example of a