Ancient grains: oldest rice in Pacific found in remote cave 

The discovery of ancient traces of rice in a cave in Guam has changed what we know about the lives of the region’s early inhabitants, according to experts from The Australian National University (ANU).  

The remains of rice husks, which were found on pottery, are the earliest evidence of rice in the Remote Pacific, dating back 3,500 years.  

Dr Hsiao-chun Hung, a researcher from the ANU School of Culture, History and Language, says the findings offer new clues about ancient migration and culture. 

“Until now, archaeological evidence has revealed only rare traces of rice in the remote Pacific dating back perhaps 1,000 to 700 years ago – so the evidence we’ve found pushes that timeline back significantly,” she says.   

The rice remains were excavated from Ritidian Beach Cave in northern Guam, a site that still holds cultural significance today. 

“While rice was a daily staple in many ancient Asian societies, this discovery indicates that in the remote Pacific it was treated as a precious commodity, reserved for ritual use rather than being consumed daily,” Hung says. 

“We haven’t found any evidence of ancient rice fields, irrigation systems or harvesting tools in Guam. Our findings support the idea that the first Pacific Islanders transported rice with them from the Philippines across 2,300 kilometres of open water – the longest known ocean voyage of the time. 

“It demonstrates not only their advanced navigation skills but also their foresight in preserving and transporting precious resources across vast distances. It highlights how important rice must have been.” 

The Ritidian Beach Cave provides a unique insight into the lives of the first inhabitants of the area, as most other cave sites in Guam were disturbed during and after the Second World War.  

“Despite many years of work at open-air sites we found no evidence of early rice use until now,” Hung says. 

“This discovery points to a deep and enduring connection to ancestral traditions and an Asian homeland.” 

The rice husks were found in the site’s oldest cultural layer and were dated using a series of advanced techniques, including radiocarbon dating of surrounding human rubbish mounds – known as middens.  

“People probably cooked the rice elsewhere, away from the cave, as grain processing and cooking undoubtedly would have left behind other traces,” Hung says.   

“A damp cave environment would have been unsuitable for storing unprocessed rice in pots. The ancient rice remains were found only on the surfaces of the pottery, ruling out ordinary food storage.”