I had never heard of rice culture before:

Now, another theory is emerging: Communities that grow and eat rice are more interdependent, while those that farm wheat are more independent. A new study published in the magazineScience claims that rice-planting breeds collectivism that’s passed on through generations, creating what the researchers call a “rice culture.”

Planting rice requires social coordination. Because rice is grown in standing water it requires elaborate irrigation systems, where one farmer’s water usage directly affects another’s. Building, dredging, and draining a rice paddy often requires the work of an entire village; the labor, says the study, is typically twice as much as that of farming wheat, which doesn’t necessarily need irrigation. (Rain falls on wheat farmers’ fields whether they cooperate with each other or not, the researchers note.)

To study this theory, Thomas Talhelm, a researcher from the University of Virginia surveyed 1,162 university students in China, home to two distinct rice and wheat regions. Rice is grown mostly in the south while wheat is raised and eaten in the north.