Jason Richwine, the young conservative scholar who co-authored the Heritage Foundation report on the long-term costs of the amnesty bill backed by the "Gang of Eight," is gone from Heritage.

He was purged after The Washington Post unearthed his doctoral dissertation at the JFK School of Government.

Richwine's thesis:

IQ tests fairly measure mental ability. The average IQ of immigrants is well below that of white Americans. This difference in IQ is likely to persist through several generations.

And the potential consequences of this?

"A lack of socioeconomic assimilation among low IQ immigrant groups, more underclass behavior, less social trust and an increase in the proportion of unskilled workers in the American labor market."

Richwine defended his 166-page thesis before Harvard's George Borjas, Richard Zeckhauser and Christopher Jencks, who once edited The New Republic. But while his thesis was acceptable at Harvard—it earned Richwine a Ph.D.—it has scandalized the Potomac priesthood.

Our elites appear unanimous: Richwine's view that intelligence is not equally distributed among ethnic and racial groups, and is partly inherited, is rankest heresy. Yet no one seems to want to prove him wrong.

Consider Richwine's contention that differences in mental ability exist and seem to persist among racial and ethnic groups.

In The Wall Street Journal last month, Warren Kozak noted that 28,000 students in America's citadel of diversity, New York City, took the eighth-grade exam to enter Stuyvesant, the Bronx School of Science and Brooklyn Tech, the city's most elite high schools. Students are admitted solely on their entrance test scores.

Of the 830 students who will be entering Stuyvesant as freshmen this fall, 1 percent are black, 3 percent are Hispanic, 21 percent are white—and 75 percent are Asian.

Now, blacks and Hispanics far outnumber Asians in New York. But at Stuyvesant, Asians will outnumber blacks and Hispanics together 19-to-1.

Is this the result of racially biased tests at Stuyvesant?

At Berkeley, crown jewel of the California university system, Hispanics, 40 percent of California's population and an even larger share of California's young, are 12 percent of the freshman class. Asians, outnumbered almost 3-to-1 by Hispanics in California, have almost four times as many slots as Hispanics in the freshman class. Another example of racial bias?

The 2009 Programme for International Student Assessment, PISA, which measures the academic ability of 15-year-olds worldwide, found the U.S.A. falling to 17th in reading, 23rd in science, 31st in math.

Yet, Spain aside, not one Hispanic nation, from which a plurality of our immigrants come, was among the top 40 in reading, science or math.

But these folks are going to come here and make us No. 1 again?

Is there greater "underclass behavior" among Hispanics?

The crime rate among Hispanics is about three times that of white Americans, while the Asian crime rate is about a third that of whites.

Among white folks, the recent illegitimacy rate was 28 percent; among Hispanics, 53 percent. According to one study a few years back, Hispanics were 19 times as likely as whites to join gangs.

What about Richwine's point regarding "social trust"?

Six years ago, in "E Pluribus Unum: Diversity and Community in the Twenty-first Century," [PDF] Robert Putnam, author of "Bowling Alone," wrote that after 30,000 interviews he found that ethnic and racial diversity can be devastating to communities and destructive of community values.

In racially mixed communities, Putnam wrote, not only do people not trust strangers, they do not even trust their own kind.

"People living in ethnically diverse settings appear to 'hunker down,' that is, to pull in like a turtle ... (to) withdraw even from close friends, to expect the worst from their community and its leaders, to volunteer less, give less to charity and work on community projects less often, to register to vote less, to agitate for social reform more but have less faith they can actually make a difference, and to huddle unhappily in front of the television."

With the immigration bill granting amnesty to 12 million illegals, an open door to their dependents and a million new immigrants each year, almost all from the Third World, America in 2040 is going to look like Los Angeles today. Yet, it was in L.A. that Putnam found social capital at its most depleted and exhausted.

If Richwine is right, America in 2040 will be a country with whites and Asians dominating the professions, and 100 million Hispanics concentrated in semiskilled work and manual labor.

The issues Richwine raises go to the question of whether we shall survive as one nation and one people.

If our huge bloc of Hispanics, already America's largest minority at 53 million, is fed by constant new immigration, but fails for a couple of generations to reach the middle-class status that Irish, Germans, Jews, Italians and Poles attained after two generations, what becomes of our "indivisible" nation?

Rather than face this question, better to purge and silence the Harvard extremist who dared to raise it.