Rice served as a fundamental crop in the Austronesian region, which includes the ancestors of Taiwan and the islands of Southeast Asia. However, it was largely unknown in the Pacific Islands during their initial encounters with Europeans, with the exceptions of Guam and the Mariana Islands. A recent study conducted by scientists from Guam, China, and Australia highlights the discovery of abundant rice husks and leafy plant oils associated with red melted pottery found in the Litidian Beach Caves in Guam, dating back between 3,500 and 3,100 years ago.

The presence of early rice in Pacific Island settlements is part of a broader narrative about rice as a staple in the diet of ancient Austronesian speakers, who formed the world’s most extensive language family prior to the onset of global colonial expansions.

Austronesian communities cultivated rice in Taiwan no less than 4,800 years ago, but cultivation of rice among populations in eastern Indonesia seems to have been carried over into the more remote Pacific Islands. The Austronesian ancestors migrated from Taiwan across the Asia-Pacific region approximately 4,200 years ago.

These early islanders introduced domesticated rice from Taiwan and returned to the Yangtze River Basin in mainland China, the source of these resources.

In this context, rice’s significance in the Mariana Islands in Guam and western Micronesia has garnered significant interest, as it was the sole island in the distant Pacific where rice cultivation occurred, as evidenced by historical records from the 1500s and 1600s.

“These findings provide fresh insights into ancient migration and culture,” states Dr. Hsiao-Chun Hung, an archaeologist at the Australian National University.

“To this point, archaeological records only showed traces of rare rice in the remote Pacific Ocean, dating back perhaps 1,000 to 700 years ago. The evidence we have found pushes that timeline significantly forward.”

Rice cultivation from excavations at Litidian Beach Cave in Guam. Scale bar – 10μm. Image credits: Carson et al. , doi: 10.1126/sciadv.adw3591.

Dr. Hung and her team discovered ancient rice remnants in a cave at Ritidian Beach in northern Guam.

“Rice served as a daily staple in many ancient Asian societies, yet this discovery reveals that, in the remote Pacific Ocean, it was regarded as a valuable item reserved for rituals rather than regular consumption,” Dr. Hung remarked.

“Our investigations found no signs of ancient rice paddies, irrigation systems, or harvesting tools in Guam.”

“Our findings bolster the hypothesis that the first Pacific Islanders transported rice from the Philippines over 2,300 km of open ocean.

“This indicates not just their exceptional navigation abilities but also their foresight in storing and carrying essential resources across vast distances.

“The caves at Ritidian Beach offer unique insights into the lives of early inhabitants in the region, especially given that most other cave sites in Guam were affected during World War II.”

“Despite extensive exploration of outdoor sites, evidence of early rice usage had not been uncovered until this point.”

“This discovery highlights a profound and enduring connection between our ancestral heritage and our Asian roots.”

“Rice husks were found in the oldest cultural layer of this site, dated through a range of advanced methods including radiocarbon analyses of nearby human waste deposits.

“It is likely that rice was prepared and cooked elsewhere, as the grain processing would have left different kinds of evidence.”

“The humid cave conditions were not suitable for storing raw rice in a pot.”

“Ancient residues were only located on ceramic surfaces, ruling out conventional food storage options.”

Details of these findings are documented in a study published in the journal Advances in Science.

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Mike T. Carson et al. 2025. The earliest evidence of rice cultivation in remote Oceania: ritual use by the first islanders of the Marianas 3,500 years ago. Advances in Science 11 (26); doi:10.1126/sciadv.adw3591