Recent essays such as “Bad for the Jews, Bad for America” (Huffington Post, May 26, 2015) and “US Jewish Numbers No Longer Declining, but Demographic Worries Persist” (Washington Post, June 12, 2015) raise concerns for the future of Jews in America and the world. They cite drops in the membership of “mainline” Jewish denominations, relentless and growing rates of assimilation and intermarriage, plus dramatic growth of haredi (ultra-Orthodox) populations in the US and Israel.This, plus surges in Islamic extremism and worldwide anti-Semitism, as well as Iran’s nuclear aspirations and stated intention to destroy Israel, are much in the public eye.One would have to be blind not to understand the existential fears of a people whose total worldwide population is smaller than that of greater Los Angeles.A rhetorical query to Jewish colleagues was: “Can the center hold?” Namely, can Modern Orthodox, Conservative, Reform and other mainline denominations plus committed secular Jews survive and thrive? The insightful response from one was that American Jewry is “leaking at both ends.” At the liberal end, he said, assimilation and intermarriage increasingly pull Jews away from mainline Jewish denominations while, at the conservative end, dramatic growth of the haredi sector means an ever smaller proportion of Jews will emulate the cultural values that spurred disproportionate Jewish secular achievements.Historians Raphael Patai, Paul Johnson and others made the case for The Enlightenment, Haskalah, Reform Judaism, Napoleon’s Grand Sanhedrin and Jewish Emancipation as the driving forces that Patai called “nothing short of astounding.”This “as the huge reservoir of Jewish talent dammed up behind the wall of Talmudic learning was suddenly released to spill over into all fields of Gentile cultural activity.”Johnson, in turn, referred to a “shift” of Jewish “output” around 1800 that “unleashed a significant and ever growing proportion of Jews into secular life.” It was, he said, “an event of shattering importance in world history.” Some years ago I explored the early 19th century beginnings and ever growing later torrent of disproportionate Jewish secular achievements over the past two centuries.This has been “the golden age of Jewish achievement.”Today I fear the “leaking at both ends” portends an inexorable decline of that golden age and with it, ever less commitment to the cultural values that drove the performance.It will be a significant loss.Jewish achievements have benefited us all. Think for example of Salk and Sabin conquering polio and the important discoveries of the 200 Jewish Nobel laureates since 1901.At the end of World War II and the Holocaust, Jews were four-tenths of one percent of the world’s population.Today, they are two-tenths of 1%. They sustain that level only because the remarkable growth of the haredim offsets the declines of secular, Conservative, Reform, other mainline Jewish groups and denominations, likely including the Modern Orthodox.Through 2007, the astonishing history of disproportionate Jewish achievement showed that Jews had won: 23% of all Nobel Prizes, 100 times their percentage of the world’s population; 51% of Pulitzer Prizes for Non-Fiction, 25 times their US numbers; 31% of the Forbes 400, 15 times their numbers; and 38% of Business Week’s Most Philanthropic People, 19 times their numbers. This is just the tiniest sample of their achievements. Jews led or shaped every major Hollywood studio. They did the same in American broadcast radio and television (NBC, ABC and CBS) and today they are a third of the US Supreme Court. In 624 pages, The Golden Age of Jewish Achievement described the range and depth of those accomplishments. Recently as I focused on why Jews are such high achievers, I evaluated 11 major theories, most of which involve nature (genetics) or nurture (culture). In doing that, I also updated results in several domains to see if the disproportionate performance still continues.I looked at Nobel Prizes since 2007 and found 27% of them have gone to Jews. In entrepreneurship and philanthropy, Forbes’ March 23, 2015 issue listed the world’s 50 wealthiest people. Of them, 22 inherited their wealth or inherited great wealth and then made even more. None of them were Jews.The other 28 are all self-made and of them 10 (36%) are Jews. Sergey Brin, Larry Ellison, Mark Zuckerberg, Michael Dell and Michael Bloomberg are just a few of those who also donate generously to philanthropic causes.One major reason for the record of disproportionate Jewish achievement is the cultural premium Jews place on education. Two thousand years ago, rabbinic Judaism made education mandatory. In 2011, the Pew Charitable Trust documented college graduation rates among America’s major religious denominations.Reform Jews with ~65% and Conservative Jews with ~59% were two of the top three. Other sources indicate ~65% of Modern Orthodox Jews are also college grads. America’s average is ~28%.Yet, while Jews continue to be disproportionately admitted to Ivy League schools (e.g. 26% at Harvard and Yale), it is ever less explained by their prior academic performance.In 2012, Ron Unz detailed surprising recent declines in Jewish academic results. In the 1970s, Jews were 40% of those chosen for the annual Math Olympiad; since 2000 they have dropped to 2.5%.From the 1950s to the ‘80s, Jews were ~23% of the participants in America’s Science Talent Search; in 2010 they were 7%. And since 1987, Jewish National Merit Finalists have declined by 35%. Unz provides extensive further data to prove his case adding that in California, where by law admissions are based more on academic merit, Jews are only 5.5% of Cal Tech’s enrollment (vs. 39% for Asians) and at the University of California’s five most selective campuses, Jews are 8% of the students.This is consistent with declining Jewish attendance at medical schools where they were once the largest single ethnic group. Now they are eclipsed by East Indians, Chinese and other Asians. I rarely see a Jewish resident or fellow when I am at the University of California San Francisco Medical School campus.Originally, I felt religion was probably the major force driving Jewish culture and that rising secularism would threaten disproportionate achievement. The data, however, changed my mind. Secular Jews have phenomenal rates of disproportionate achievement. I concluded secularism was not a major threat so long as the core cultural values I associate with most Jews remain strongly held.As a lapsed Presbyterian, I am the last person who should engage in a detailed discussion of doctrinal differences between the various Jewish denominations. But here too, my efforts yielded useful insights about the role of culture in human achievement.Haredi genetics are the same as their mostly Ashkenazi brethren, with both groups containing a small constituent of Sephardi genes.Any differences in values, life style and secular achievements can only arise because of cultural differences shaped mostly by religious convictions (nurture). A telling example is the value placed on secular education.The college graduation rate for haredi Jews is only 25%.A 2012 New York Times story by Joseph Berger reported on the 10-year rise in the numbers of Jews in Greater New York after many years of decline. Berger’s data showed the growth was fueled largely by 230,000 Russian immigrant Jews (a one-time event) and the 115,000 increase in the haredi population.Meanwhile, the 80,000 drop in the Conservative and Reform Jews was more than offset by the 127,000 rise in “nondenominational Jews.”It was startling for me to learn that because of high fertility rates among the haredim, today 74% of New York’s Jewish kids are Orthodox – most of them haredim. Berger’s story went on to say the “Hasidic population in Brooklyn, where college degrees are rare, poverty rates now reach 43 percent.”I worry that for an ever growing proportion of America’s Jews, the Enlightenment will have “never happened” or will be seen as heresy.Haskalah will not shape their values and there will be ever diminishing inclination toward great secular achievements with ever less potential for philanthropy.I hope the center holds, but today’s demographics provide no basis for optimism.The writer is the author of The Golden Age of Jewish Achievement as well as his more recent book, The Debate Over Jewish Achievement.