In early 1921, an article in Good Housekeeping signaled the coming of a law that makes President Trump’s campaign for immigration restriction seem mild by comparison. “Biological laws tell us that certain divergent people will not mix or blend,” it read. “The dead weight of alien accretion stifles national progress.” The author was Calvin Coolidge, about to be sworn in as vice president of the United States. Three years later, the most severe immigration law in American history entered the statute books, shepherded by believers in those “biological laws.”

The anti-immigrant fervor at the heart of current White House policymaking is not a new phenomenon, nor is the xenophobia that has infected the political mainstream. In fact, race-based nativism comes with an exalted pedigree — and that pedigree is something we all should remember as the Trump administration continues its assault on immigrants of specific nationalities. The scientific arguments Coolidge invoked were advanced by men bearing imposing credentials. Some were highly regarded scholars from Harvard, Princeton, Yale and Stanford. One ran the nation’s foremost genetics laboratory. Another was America’s leading environmentalist at the time. Yet another was the director of the country’s most respected natural history museum.

Together, they popularized “racial eugenics,” a junk science that made ethnically based racism respectable. “The day of the sociologist is passing,” said the Harvard professor Robert DeCourcy Ward, “and the day of the biologist has come.” The biologists and their publicists achieved what their political allies had failed to accomplish for 30 years: enactment of a law stemming the influx of Jews, Italians, Greeks and other eastern and southern Europeans. “The need of restriction is manifest,” The New York Times declared in an editorial, for “American institutions are menaced” by “swarms of aliens.”

Keeping people out of the country because of their nationality was hardly a novel idea. The Chinese Exclusion Act of 1882 was avowedly racist. In 1923 a unanimous Supreme Court declared that immigrants from India could be barred from citizenship strictly on racial grounds.

What was different about the new, putatively scientific campaign was that even whiteness was no ticket to entry.

Writing about Slavic immigrants, the sociologist Edward A. Ross of the University of Wisconsin — later the national chairman of the American Civil Liberties Union — declared, they “are immune to certain kinds of dirt. They can stand what would kill a white man.” The president of Massachusetts Institute of Technology said newcomers from eastern and southern Europe were “vast masses of filth” who were “living like swine.”

The Washington Post editorialized that 90 percent of Italians coming to the United States were “the degenerate spawn” of “Asiatic hordes.” A Boston philanthropist, Joseph Lee, his city’s leading supporter of progressive causes, explained to friends why he became the single largest financial backer of the anti-immigrant campaign: His concern, he wrote, was that without a restriction law, Europe would be “drained of Jews — to its benefit no doubt but not to ours.”

The “biological” justifications for this nativism were first developed in Cold Spring Harbor, on Long Island, in laboratories financed by the widow of the railroad baron E.H. Harriman. (One of her goals, Mary Harriman said, was preventing “the decay of the American race.”) The laboratory’s head, the zoologist Charles B. Davenport, took the ideas of the British gentleman scientist Francis Galton — who had coined the word “eugenics” in 1883 — welded them to a gross misunderstanding of the genetic discoveries of Gregor Mendel, and concluded that the makeup of the nation’s population could be improved by the careful control of human breeding. One of the first steps, he believed, was to impose new controls on open immigration.

At first, Davenport wished to bar the immigration only of people afflicted by specific disorders — epileptics, the “feebleminded” and others of similarly troublesome (to Davenport) disability. But soon he was caught up in a racialist whirlwind initiated by “The Passing of the Great Race,” a book by Madison Grant, the founder of the Bronx Zoo and the era’s most prominent conservationist. A bilious stew of dubious history, bogus anthropology and completely unfounded genetic theory, Grant’s work persuaded Davenport and others that the American bloodstream was threatened not by suspect individuals, but by entire ethnic groups.

First published in 1916 and reissued in a series of revisions over the next eight years — all of them brought into print by Maxwell Perkins, the celebrated editor of F. Scott Fitzgerald and Ernest Hemingway — “The Passing of the Great Race” savagely denigrated the peoples of eastern and southern Europe while exalting the “Nordics” of northwestern Europe. With the presumed authority of scholarship, he summarized the essential argument of racial eugenics.

“Whether we like to admit it or not,” Grant wrote, “the result of the mixture of two races, in the long run, gives us a race reverting” to the “lower type.” Lower than Nordics were the questionable “Alpines.” Lower than the “Alpines” were the woeful “Mediterraneans.” And, he concluded, “the cross between any of the three European races and a Jew is a Jew.”

Grant was not an actual scientist. But Henry Fairfield Osborn, a world-famous paleontologist and his closest friend, definitely was. Osborn, who once expressed his opposition to the extension of the Westchester Parkway near his country estate because it would bring thousands of “East Side Jews” to the area, presided over the American Museum of Natural History for 25 years, and made that institution the beating heart of the combined eugenics and anti-immigration movement. “I am convinced,” said Osborn, that the “spiritual, physical, moral and intellectual structure” of individuals is “based on racial characteristics.” It wasn’t a matter of ethnic bias, he said — it was “cold-blooded” science.

Other scholars rallied to the cause. Robert M. Yerkes — his name immortalized today at the Yerkes National Primate Research Center in Atlanta — conducted a severely flawed series of tests of American servicemen purporting to establish the intellectual inferiority of eastern and southern Europeans. Charles W. Gould, a lawyer in New York, sponsored “A Study of American Intelligence,” by Carl C. Brigham, a young Princeton psychologist (and later the inventor of the SAT). Brigham’s conclusion: “There can be no doubt that recent history has shown a movement of inferior peoples or inferior representatives of peoples to this country.”

At the same time, Perkins and his colleagues at Charles Scribner’s Sons published a raft of books promoting racialized eugenics. Scribner publicists wrote in one promotion piece: “The inrush of lower races is threatening the very blood of our country.” Perkins’s authors were echoed in the country’s leading magazine, The Saturday Evening Post. “Race character is as fixed a fact as race color,” the Post declared. “Thirty years ago,” the magazine insisted in another article, “science had not perhaps sufficiently advanced to make us fully aware” of the danger of open immigration. Now it had.

Daniel Okrent

Mr. Okrent is the author of a forthcoming book on the history of immigration and race in America.

Daniel Okrent

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