For these studies, Barzilai has assembled a cohort of some 540 people over the age of 95 who, like the Kahns, reached that milestone having never experienced the so-called big four: cardiovascular disease, cancer, diabetes, and cognitive decline. He theorized that these “SuperAgers,” as he calls them, must have something that protects them from all four conditions. Otherwise, when they didn’t have a heart attack, say, at 78, they’d have succumbed quickly to the next thing on their body’s inscrutable list. So instead of looking, as most genetic studies do, for pieces of DNA that correlate with the likelihood of getting diseases, Barzilai looked for the opposite: genes that correlate with the likelihood of not getting them—and thus with longevity.
The top correlate for longevity is one that requires no blood test to discover: having a SuperAger in your family already. ... Barzilai has so far identified, or corroborated, at least seven associative markers. The most significant is the Cholesterol Ester Transfer Protein gene, or CETP, which in one unusual form correlates with slower memory decline, lower risk for dementia, and strongly increased protection against heart disease. (Among other things, it increases the amount and size of “good” cholesterol.) Only about 9 percent of control subjects have two copies (one from each parent) of the protective form of CETP, while 24 percent of the centenarians do, including all four Kahn siblings.
There’s evidence, as well, that small stature among the SuperAgers (Irving is now about five foot two) may reflect the influence of a protective factor seen throughout nature; ponies live longer than horses. ...
But the Einstein project is fascinating for a major reason beyond its science: Its main test group consists entirely of Ashkenazim—that is, Jews who descend, as more than 80 percent of American Jews do, from communities in the Pale of Settlement of Eastern Europe. In longevity news, the spotlight frequently passes from one group to another: Georgian yogurt eaters, Japanese pensioners, the Pennsylvania Dutch. But 540 Jews in a New York–based study of extreme old age is too delicious. The mind cramps with the possibility of jokes.
... Barzilai centered his studies on Ashkenazim not because they live longer or produce more centenarians than other ethnic groups. They don’t. It’s that their unusual development as a homogeneous community makes them easier to study at the level of DNA. Genetic research done by Barzilai’s Einstein colleague Gil Atzmon suggests that Ashkenazim branched off from other Jews around the time of the destruction of the First Temple, 2,500 years ago. They flourished during the Roman Empire but then went through a “severe bottleneck” as they dispersed, reducing a population of several million to just 400 families who left Northern Italy around the year 1000 for Central and eventually Eastern Europe. Though their numbers increased dramatically once there, to some 18 million before the Holocaust, studies suggest that 40 percent of today’s Ashkenazim descend from just four Jewish mothers. How proud those mothers would be to know that the reason their mishpocheh has remained far more genetically alike than a random population—Barzilai says by a factor of at least 30—is that until recently their sons almost never married outside the clan.
As I've pointed out, "white guilt" is guilt over being too ethnocentric, "Jewish guilt" is is guilt over being not ethnocentric enough.
That likeness means that small genetic differences—as small as one “letter” of DNA code—are more easily spotted on Ashkenazi genes than on those of, say, Presbyterians. Icelanders are good, too: They are all descendants, Barzilai says, of five Viking men and four Irish women. But they are a tiny population, with proportionately fewer centenarians, and aren’t so easy to find in New York. Ashkenazim are plentiful. And because they are also fairly similar in their educational and economic status, some of the variables that can muddy the picture are already controlled.
Others are controlled more explicitly. An Einstein study published in August asked whether the SuperAgers, over the course of their lives, had better health habits than the general population.
The answer was no; their habits were, if anything, worse. They smoked as much or more than others and were no better about diet or exercise.