The mid holocene occupation of the Pearl Islands: A case of unusual insular adaptations on the Pacific Coast of Panama

A survey of the Pearl Island archipelago discovered a Preceramic shell-bearing midden on the island of Pedro Gonz?alez located in Panama Bay in the eastern tropical Pacific Ocean. This occupation dates between ca. 6200 and 5600 cal yr BP, and revealed a mixed marine and terrestrial economy including the exploitation of sea and terrestrial turtles, snakes, iguanas, dolphins, and land mammals such as dwarf deer. Test excavations in 2007?2010 provided well-preserved invertebrate and vertebrate samples, which were considerably more diverse taxonomically for fish than for other vertebrate categories. At that time, only boa among a large snake sample was identified to species. A 7 ? 4 m pit dug in 2015 increased the faunal sample but added little to diversity. Development of the ophidian comparative collection, augmented by on-line research, enhanced snake diversity and highlighted the dietary importance of snakes. Two marine turtle species ? hawksbill and Pacific green? remain the only ones exploited. Improvements in stratigraphic sectioning have fine-tuned chronological fluctuations of faunal populations as in the case of green iguana and terrestrial mammals. Birds have experienced the greatest increase in diversity, but not as much as expected on the basis of the present-day island avifauna. Only two terrestrial mammal genera ? squirrel, and rabbit ? were added to the inventory inferred during 2007?2010, which comprised deer, opossum, monkey, agouti, paca, spiny rat, furry spiny rat, and probable capybara. The occupants of Pedro Gonz?alez took advantage of the abundant agate nodules eroding from the island?s volcanic bedrock. This latest study reveals the presence of a substantial microlithic component that relied on the specialized heat treatment of whole nodules of lithic raw materials. As an idea to be explored further, we suggest that these microliths may have been produced by women for the manufacture and maintenance of composite cutting and/or grating tools used for the preparation of various foods. Ongoing analyses from the 2015 excavations are providing new information on the impact of these early colonists on the local fauna and have demonstrated how the physical properties of the island?s lithic raw materials influenced their reduction strategies.

Automated summary

The study on the Preceramic shell-bearing midden in the Pearl Island archipelago revealed the occupation activities on Pedro Gonz?alez Island between ca. 6200 and 5600 cal yr BP, showing the exploitation of both marine and terrestrial resources and the dietary importance of snakes in the local ecosystem.