Some 140 years after the samurai gave up their swords, their descendants still enjoy an edge in Japanese society.

That's according to a new study, which finds that people carrying surnames associated with Japan's feudal ruling class tend to be overrepresented among those high up on the social ladder today.

The study by Gregory Clark of the University of California, Davis, and graduate student Tatsuya Ishii could be a bit of a disappointment for Japan's millions of Satos and Suzukis. It suggests people with common surnames have less chance of making it to the upper echelons of society compared to people with more uncommon surnames like Shinmi or Sugieda.

Those two names were among those listed in an 1812 genealogy of samurai families compiled by bureaucrats under the Tokugawa shoguns, the hereditary military rulers who led Japan from 1603 to 1867. Under the rigid class barriers of the Tokugawa era, the samurai ruling elite was closed in principle to the sons of other classes.

Prof. Clark's book, "The Son Also Rises," uses surnames from across the world to track intergenerational status changes. He said he found to his surprise that people's fortunes today depend in part on what their ancestors were doing several hundred years ago.

Samurai and other nobility long ago lost their privileges in Japan, and under the nation's postwar constitution, all people are legally equal. Nonetheless, "Japan fit right in with other societies" in terms of slow mobility among generations, said Mr. Ishii, the graduate student who helped with the Japan portion of Prof. Clark's work.

The Japan study picked out surnames from the 1812 records and looked for those that have a frequency of 10 per million people or fewer in a modern Internet database called the World Names Profiler. The researchers figured that anyone carrying those rare samurai surnames today is likely to be a samurai progeny.

They then compared the names with lists of doctors, lawyers, corporate managers, university professors and those with scholarly publications and found in each case that the samurai names were overrepresented.

Conventional wisdom would suggest that dramatic societal shifts such as Japan's Meiji Restoration in 1868, which ended the feudal class system, and the country's defeat in World War II would spur social mobility.

Prof. Clark's studies show otherwise. In fact, even the Communist revolution in China failed to have a significant impact on social mobility, according to his research.

In Japan, a group of class analysts have been conducting what they call the Social Stratification and Social Mobility study every decade since 1955, providing a trove of data on social status and class consciousness.

But Satoshi Miwa, a board member of the project and an associate professor at Tohoku University's Graduate School of Education, said he wasn't aware of any class studies focused specifically on surnames.

He said he found the results of the UC Davis research persuasive. "There was a study around 50 years ago which focused on descendants of the samurai, and it showed that in terms of education and social status, they tend to fare better than the general population," he said. Nonetheless, he added, "I'm surprised that such trends can still be observed in the present age."

The Internet database on which Prof. Clark and Mr. Ishii relied lists Sato and Suzuki as the two most common Japanese surnames, with 14,392 Satos and 12,906 Suzukis per population of one million. That's roughly 1.8 million Satos and 1.6 million Suzukis in Japan's total population of 127 million.In contrast, there are only around 17 Shinmis and 169 Sugiedas in the entire population.

What about Mr. Ishii's name? "As you can imagine, 'Ishii' is quite a common surname so I believe there is nothing special that can be said about it," he said.