By Richard Morin

Sunday, December 19, 2004; Page B05

For years, demographers have asked themselves this question: Why do adult Hispanics living in the United States live so long and never seem to get sick? Demographers call it the "Hispanic Paradox": Hispanics, who tend to be poorer and have fewer advantages than non-Latino whites, nonetheless seem to live longer and have healthier lives, on average, than their Anglo counterparts.

The disparity in life expectancy is large, report demographers Alberto Palloni of the University of Wisconsin and Elizabeth Arias of the National Center for Health Statistics. They found the overall adult mortality rate was a whopping 30 to 50 percent lower for Hispanics than for whites. Those differences "translate into five to eight years of additional life expectancy at age 45" for Hispanics living in the United States, Arias and Palloni reported in a recent issue of the journal Demography.

Moreover, "these large differences persist even after we controlled for factors associated with longevity," Palloni said. The gap is large enough to prompt researchers to wonder, "Is this true? Is this real?" he said.

To find out, Arias and Palloni examined health and demographic data collected annually by the federal government on approximately 130,000 individuals between 1985 and 1994.

They used a data file that contained matched records from the survey and death records. The file allowed them to determine who subsequently died and from what causes during the study period.

The first thing they found is that not all Hispanics in the United States live longer, healthier lives than Anglos. There was no difference between the mortality rates of non-Hispanic whites and Latinos born in Puerto Rico or Cuba. But among foreign-born Hispanics other than Cubans or Puerto Ricans, the paradox held. "They died later, and didn't get sick as often," Palloni said.

But why?

One clue came when they saw that the mortality gap was particularly large among men and women born in Mexico who lived in states closest to the Mexican border. Digging deeper into the data, they found the answer: The ill and infirm apparently returned home to die and thus didn't appear in U.S. vital statistics data, while healthy Mexican immigrants remained in the United States. It's called the "salmon effect," Palloni laughed.

But the puzzle wasn't completely solved. Hispanics living in the United States who were born in foreign countries other than Mexico also lived longer and healthier lives, despite the absence of a salmon effect.

Some evidence suggests this finding may just be the result of bad or incomplete data, Palloni said. Then again, he suspects there might be something about the people who choose to come to the United States. Studies conducted in other countries have yielded this curious finding: "Migrants who come into a country generally fare better than the natives in terms of health. The reason is that in order to be a migrant, you have to be in pretty good health, so it is a select group of people," he said. "But we don't have the data to know for sure."

One thing he does know: The apparent health benefits that seem to accrue to foreign-born Latinos soon vanishes. "When you look at the first generation, the sons and daughters of migrants aren't as healthy . . . whatever advantage the parents had crumbles later on."

Marc Abrahams is the silliest smart person we know. It was Abrahams who gave the world the Ig Nobel Awards, which are bestowed annually at a raucous ceremony at Harvard University that always includes a few actual Nobel laureates. The awards honor ignominious accomplishments in science, such as this year's prize in engineering to the father-and-son team who patented the hair comb-over (U.S. Patent No. 4,022,227 -- you can look it up).

Speaking of hair and brains, Abrahams also founded the Luxuriant Flowing Hair Club for Scientists (LFHCfS), which last week announced its annual awards to male and female scientists with spectacular heads of hair.

This year's winners came in threes. The Men-of-the-Year award went jointly to Falk Schuch, Andreas Linsner and Kai Jung, chemists and colleagues at a research company in Frankfurt, Germany. The trio posed for the Busby Berkeleyesque group photo shown here, in which their heads form the spokes of a hairy pinwheel (sort of, if you squint). Your Unconventional Wiz prefers a more conventional photo that featured them standing in a row (because it reminded him of every dissolute hair band of the 1980s).

The LFHCfS Women-of-the-Year honorees were the Bobrow sisters: Johanna, staff biologist at the MIT Lincoln Laboratory; Laurel, an MIT student majoring in brain and cognitive science, and engineer Elisabeth. "Between them, the three Bobrow sisters have more than seven feet of hair," Abrahams reported in a release that officially ushered the winners into the ranks of "Outstanding Heads of Science."

Abrahams said the LFHCfS was inspired by his wife's dream -- and by star psychologist Steven Pinker of Harvard, whose formidable follicles produce curly hair in wild abundance.

"My wife, Robin, who is a psychology professor, had a dream that she would be editing a special issue of a psychology journal, and that the one editorial rule she was given was that every article had to mention Steven Pinker's luxuriant, flowing hair. Robin told me about that dream, and thus was born the LFHCfS," Abrahams said in an e-mail. "Pinker in fact became the first member."

Changing Their Minds, Down Under

It's hard enough for pollsters in the United States to predict with accuracy the U.S. presidential election. Think about what it must be like to do political surveys in New Zealand, where one out of six voters changes his or her mind on Election Day, according to a Canadian political scientist.

Andre Blais of the Universite de Montreal reports in the journal PS that 30 percent of all New Zealanders typically change their minds about their choice for prime minister in the last 30 days of the national campaign and 16 percent switch preferences on the day they vote.

In contrast, on average, only 4 percent of all voters in the United States and 7 percent in Great Britain change their voting preference on Election Day, according to his cross-country analysis of voting patterns in 27 election surveys conducted between 1952 and 2001 in New Zealand, Great Britain, Canada, the Netherlands and the United States.

Why are New Zealanders more fickle? Blais doesn't hazard a guess. Sounds like a good topic for another survey.

morinr@washpost.com