Around 10,000 years ago. A group of hunter-gatherers near China’s Yangtze River started to grow rice.
Archaeologists discovered this at a site called Shangshan. When they began their excavation they found evidence of a rice-dependent diet – rice husks buried in pottery and stone tools that could have been used for milling. They also found phytoliths.
Phytoliths are microscopic pieces of silica that are found in the leaf cells of rice. They don’t burn, digest or decompose.
The team went through the time-consuming process of sifting the phytoliths from the dirt. They then washed and sieved the mixture until they ended up with pure phytolith. They carbon dated them and found the oldest were 9,400 years old.
The researchers then examined them under a microscope. They noted that the scale-like patterns that appear on them had changed over time – the older samples had fewer of these patterns than the newer samples.
This indicates that the rice had originally grown in swampy conditions (which is where wild rice grows). It would have gotten plenty of water. When the rice was domesticated, it was grown in less swampy areas so the leaves would have needed to curl more often to capture rainwater. It’s the curling that creates the scale-like patterns.
The change in the patterns shows that rice the people cultivated at Shangshan 9,400 years ago were not like the rice we eat today. The grains were likely small and thin, which means they would have blown easily in the wind for propogation.
However, years of domestication transformed the rice into fat, starchy grains that cling to the stalks for easy harvest. The changes in the phytoliths over time show this gradual transformation.
There is other evidence that Shangshan was the first place rice was cultivated and this discovery adds to that. However, genetic evidence points to perhaps more than one domestication over time. This explains the different varieties of rice we have today.
I imagine that the early cultivators of rice had no idea it would become a staple food for half of the modern world.