Otmar von Verschuer had spent much of his professional life investigating the mutability of human characteristics when, in 1945, he embarked upon his greatest act of metamorphosis.
With millions dead and his country in ruins, Verschuer – a German geneticist, eugenicist and Nazi — adopted the posture of a humble scientist untainted by anti-Semitism.
"I have always kept away from politics, with the result that I had many hardships during the Nazi days," Verschuer wrote to a colleague.
"Jealous former colleagues from my old Kaiser-Wilhelm Institute at Dahlem have, for purely selfish reasons, maligned me and denounced me politically.
"False reports have thus been put out about me."
These weren't the only flagrant fabrications peddled by Verschuer during this time, but they were the ones he chose to tell Sir Ronald Aylmer Fisher, a man lauded as one of the greatest biologists of the 20th century.
The correspondence between Verschuer and Fisher is kept at the University of Adelaide, the city where the English-born Fisher died in 1962.
In recent years, Fisher has himself generated posthumous controversy — not only did he share Verschuer's interest in eugenics, but he dedicated his final years to promoting the view that cigarette smoking was safe.
As a consequence, a stained-glass window commemorating his work was removed from the University of Cambridge in 2020.
"Fisher was less unsympathetic to Nazi eugenics than most of his British colleagues were," historian Richard J. Evans wrote in the New Statesman at the time of the Cambridge quarrel.
"In the mid-1930s he campaigned for the legalisation of eugenic sterilisation, especially of the 'mentally defective'."
Fisher's correspondence with Verschuer spanned several decades and extended to more than 60 letters.
For Stanford University science historian Robert Proctor, their exchange provides insight into one of history's darker episodes of scientific corruption and collusion.
"They're horrific scientific criminals, basically," Professor Proctor said.
"You have Verschuer, who's one of the top Nazi racial theorists – and the thesis advisor of [infamous Auschwitz doctor] Josef Mengele – corresponding with a top eugenicist, RA Fisher, who was also a total apologist for the tobacco industry.
"These two people were heavily involved in the criminal denial of cigarettes causing cancer.
"The eugenics and the tobacco denialism are intimately linked — and that's the story that's never been told."
The Nazi corruption of medicine
When Verschuer and Fisher first became penpals several years before the war, the idea that humanity should be genetically improved by selective breeding – eugenics – was popular in academic circles.
Verschuer's letters bear evidence of this.
Several are stamped with the German word "rassenhygiene", meaning "racial hygiene", a subject that flourished during the Third Reich.
Professor Proctor's book, Racial Hygiene: Medicine Under the Nazis extensively demonstrates that Verschuer, whose special interest was twins, was far from alone in his enthusiasm.
Collectively, German doctors seemed unusually susceptible to Nazism, diagnosing it not as a mortal threat to humanity, but as the very embodiment of providence.
"Medicine achieved higher political power and political authority in the Nazi period than at any other time in history," Professor Proctor said.
"Doctors joined the Nazi Party in greater numbers than any other profession — 45 per cent joined the party, and 7 per cent joined the SS, which is extremely high."
The full extent of Verschuer's wartime criminality remains obscured by the fact that he apparently destroyed records of his activities and was thus never prosecuted.
But several historians have written that during Verschuer's directorship the Kaiser Wilhelm Institute for Anthropology in Berlin received human samples from Auschwitz — including eyes collected by Mengele, the so-called "Angel of Death" who became notorious for his human experimentation.
Was Fisher aware of these horrors? Would he have cared?
"I don't think Fisher would have known details about Mengele," Professor Proctor said.
"[But] I'm sure that Fisher knew that Verschuer was a Nazi sympathiser, and was sympathetic to the goal of breeding a 'superior Nordic race'.
"I'm sure Fisher thought that that was a great idea."
The tobacco war
During the 1950s, when Fisher became fixated with the idea that tobacco smoke wasn't toxic, he conscripted Verschuer to his cause.
"Fisher thought that it wasn't true that smoking causes cancer — [he thought] cancer causes smoking," Professor Proctor said.
"He put that forward in a number of articles in the 1950s and then he was hired by the tobacco industry in the United States to help with litigation to exonerate cigarettes.
"That's where Verschuer comes in.
"Verschuer had this extensive twin data that was useful in trying to say whether you get sick or not is really just a genetic predisposition."
In a letter to Verschuer from 1958, Fisher stated his views plainly, describing the evidence for an "association between lung cancer and cigarette-smoking" as having been "forcibly propagandised".
Four years later, Fisher — a persistent pipe smoker — died after an operation for colon cancer at Adelaide's Queen Elizabeth Hospital.
Verschuer was killed in a car accident in 1969.
Like dozens of other Nazi scientists complicit in the Holocaust, he was untroubled by his past.
His experiment in moral deception had been a success.
