Independent and individualistic cultures, like those in the West, can thank the cultivation of a certain plant for the way they are: wheat.

Cultures that farm rice are just the opposite -- interdependent and cooperative -- a new study from the journal Science reported today.

The "rice theory" was created by Thomas Talhelm, a University of Virginia Ph.D. student in cultural psychology and the study's lead author.

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While teaching English in China, both in the wheat-growing north of the country and the rice-farming south, Talhelm noticed differences between people in the two parts of the country. Northerners were more direct and less concerned with social conformity than Southerners, who were more "interdependent, holistic-thinking and fiercely loyal to their friends," according to a U.Va. press release.

"This has sometimes been attributed to different climates -- warmer in the south, colder in the north -- which certainly affects agriculture, but it appears to be more related to what Chinese people have been growing for thousands of years," Talhelm said.

Psychological testing in other rice-growing nations, such as Japan and Korea, show a similar mindset to the southern Chinese.

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For the study, Talhelm and his collegues in China interviewed 1,162 Han Chinese college students in the north and the south to see how they thought. They also tested students living in areas just on opposite sides of the north-south divide of the Yangtze River.

They found that the students from the north -- even just north of the river -- displayed more analytical thinking. Those from the south were more community oriented.

"I think the rice theory provides some insight to why the rice-growing regions of East Asia are less individualistic than the Western world or northern China, even with their wealth and modernization," Talhelm said in the press release.

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What makes rice farmers more interdependent? Rice farming requires much more time and is much more labor intensive than wheat farming. Rice fields must be irrigated, which requires the sharing of water. Rice paddies are bordered by dikes and canals that require frequent maintenance, so farmers have to work together constantly and share resources.

Wheat is grown on land and wheat farmers rely on the weather and their own skills, not each other, for success.

"The data suggests that legacies of farming are continuing to affect people in the modern world," Talhelm said. "It has resulted in two distinct cultural psychologies that mirror the differences between East Asia and the West."