In the Arenal Region of Costa Rica, Professor Sheets studies the human impacts on the landscape; namely, how their repetitive use of specific areas affects landscapes.
- Using remote sensing imagery from NASA (aircraft and satellite), Professor Sheets and his team discovered ancient foot paths that linked villages with cemeteries from about 500 BC until AD 1300.
- After centuries of people making regular pilgrimages in a single file, paths were formed. Where the path traversed land sloping more than five degrees the path was incised by erosion. In some places the path was incised over 6 meters deep. On these deeply incised paths a cultural value developed indicating this was an entrance to a special place.
- When chiefdoms developed to the east of Arenal, the chiefs had large sunken entryways constructed, to make that cultural standard “writ large.” The Arenal paths were not constructed in any way but were simply eroded by sustained use.
Of all the ancient societies Professor Sheets has studied in Mexico and Central America that were impacted by explosive volcanic eruptions, the Arenal people were the most resilient, and recovered from the repetitive disasters more rapidly and more thoroughly. They were egalitarian, and thus decision making (emergency evacuations) was at the household or village level, in contrast to hierarchical complex societies. They relied on agriculture for only a fraction of their diet, and thus could rely on wild foods in refuge areas. And they were not at war with nearby groups, making refugee migrations more feasible.