New Research Solves Ancient Papua New Guinea Mysteries

A new study co-authored by Archaeology Professor from the University of Otago, Glenn Summerhayes, is now recognized to have solved decades-long mysteries on what ancient Papua New Guineans eat and how they processed food.

For several decades, there have been academic speculations on how ancient Papua New Guineans used recovered ground stone bowls called mortars and other tools that have been manufactured. The findings also showed a variety of starchy plants processed in the area and were once widely eaten.

The site in the Ivane Valley, referred to as "Joe's Garden" in the highlands of New Guinea, has finally filled in the blanks and finally solved several archaeological mysteries.

Archaeologists have recovered formally manufactured ground stone bowls or mortars in various parts of New Guinea.

However, there is limited information on their age or purpose. Most of the mortars collected or dug by local New Guineans while gardening, which they have re-used, and only a few have been excavated for archaeological purposes. The research shows an excavated mortar dating back 4,400 years ago from the Ivane Valley of Papua New Guinea.

Extraordinary evidence for ground stone artifacts and implements is reported in the study. Microscopic starch grains adhered to the recovered stone tools, which were identified as starch from Castanopsis acumeninatissma, a type of tree nut, and Pueraria lobata, a kind of tuber. Since the mid-60s, these vegetation have been identified as everyday staples in these regions.

Ground stone technology, such as what was employed for processing starchy plant foods in the Ivane Valley context, has origins dating in the late Pleistocene to early Holocene. During this time, the resulting intensification and change in the ground stone technology happened simultaneously.

Analysis of the use and residue of the mortar fragments shows that it was utilized to process nuts and tubers, which are starch-rich plants. This finding also gives relevant insight into the subsistence patterns of the past, which are quite rare, especially since these happened more than four thousand years ago.

The study also contributes to other researches that confirm that the microfossils of starchy residues are resilient, as seen in their long-term survival in a montane setting and located 2000 meters above sea level. Professor Summerhayes previously co-authored a 2010 study on how humans lived and adapted, particularly on their plant use in the highlands of New Guinea.

They have discovered that ancient settlers in Papua New Guinea highlands exploited another type of endemic nut called a Pandanus. Also, they fashioned stone tools that suggest the ancestors cleared patches of forest and took down trees to grow useful agricultural plants.

Summerhayes also added that for the past 300 years, numerous starchy vegetations were abandoned due to the predominance of sweet potato for cultivation and subsistence. Previous studies have shown that settlers grew taros, bananas, and yams.

However, this new research shows that the Castanopsis had played a crucial role, especially in the highland diets and subsistence. The discovery on the ground stone tool technology employed by ancient New Guineans confirm previous speculations on what food was widespread in the past.