In the list of darker experiments that once launched in Spain there is one that continues to remain in the top positions. It happened at the end of the 1930s inside an architecture that today is historical heritage, A abbey trapped on the outskirts of Burgos. The basis for carrying out the study started from a premise as simple as Martian: The communist, is born or done?
In search of the “red” gene. Between 1938 and 1939, In full Spanish Civil Warthe Franco regime undertook one of the most sinister experiments in its history. Under the direction of Psychiatrist Antonio Vallejo-NájeraHead of the psychiatric services of Franco’s army, a study that sought to find a biological predisposition to Marxism, what he called the Marxist fanaticism biopsiquism.
The purpose of this research was to demonstrate that communism and democratic ideologies were not the result of a conscious choice, but rather of A hereditary biopsychic tara, a mental inferiority that could be identified.
Context: The regime psychiatrist. Vallejo-Nájera (1889-1960) was One of the most influential figures of Franco’s psychiatry. With training in Germany, where he came into contact with Nazi psychiatry, he developed a racial and genetic theory applied to the Spanish context, arguing that Marxism was the result of mental inferiority and that it should be eradicated from the root.
In 1938, Franco assigned him the direction of the Psychiatric Services of the Francoist Armywhat allowed him to lead A pseudoscientific program based on eugenics, xenophobic psychology and coercive psychiatry. San Pedro de Cardeña became its experimentation laboratory, where international republican prisoners and brigades were subjected to evidence in order to “decipher” the communist psyche.


Facade of the monastery
The excuse. The study, financed and approved by Franco, It was developed for ten months, analyzing those prisoners of war through psychological testsanthropomorphic measurements and behavioral evaluations.
Your conclusionspublished in the Spanish magazine of Medicine and War Surgery, would serve as justification for one of the most brutal policies of Franco: the systematic separation of the children of Republicans of their families to avoid their “ideological contagion”, the segregation of prisoners and The consolidation of a dictatorship that relied on scientific manipulation to eradicate dissent.
The “study.” The epicenter of the investigation, as we said before, was the then concentration camp of San Pedro de Cardeñaan old monastery in Burgos that was converted into a detention center for Republican prisoners and International Brigades Members. The Vallejo-Nájera study divided prisoners into five large groupseach analyzed with preconceived hypothesis about their “biological degeneration.” Namely:
- International Brigadistas: It was sought to contrast their characteristics with those of Spanish prisoners to identify differences in the “origin of Marxism.”
- Spanish Republican prisoners: considered key to finding the “red gene.”
- Republican dams: it was claimed that their political participation responded to uncontrolled sexual impulses.
- Catalan prisoners: analyzed as “doubly dangerous” for their “Marxist fanaticism” and “antispañolism”.
- Basque prisoners: considered an “anomalous” group, as they were Catholics, but “contaminated by the revolutionary element.”
Plus: the analysis included cranial measurements, facial studies and personality tests, all with the intention of finding common physical and psychological features between The Marxists. The results were not only biased, obvious, but served as an ideological basis for justifying the persecution and extermination of Republicans.


Pseudoscientific conclusions. After months of “research”, Vallejo-Nájera He published his conclusions in the Spanish Magazine of Medicine and War Surgery. Among its most aberrant and extreme postulates, there were assertions such as Marxism is linked to mental inferiority. According to the psychiatrist, the communists were mostly “antisocial psychopaths” and His segregation from childhood would prevent society from “suffering its plague”.
He also stressed that Democracies promote resentment. In his vision, democratic regimes allowed the “social failed” to triumph through public policies, in contrast to authoritarian regimes, which favored the most suitable. I also thought that Marxism was a racial phenomenon. Influenced by Nazi ideology, man proposed the need for “racial purification” to eradicate the elements considered “dangerous” to Spain.
For all this, he indicated that The militarization of society was the only solution. In other words, he defended a model in which military discipline had to permeate all institutions, from school to the theater, to guarantee the “superiority of the Spanish race.”
The role of women. Another of the darkest aspects of his study was the characterization of republican women as An “irrational” and “dangerous” being. According to Vallejo-Nájera Women participated in politics only for uncontrolled sexual impulsesand Marxism in women was a consequence of their “weak mental balance”, which made them more prone to cruelty. In fact and as we said, I thought that religion was the only one that could act as a brake to avoid its moral “corruption.”
These ideas were also used as a justification to restrict women’s participation in public life and to establish a model of a woman submissive to the service of the homeland.
The theft of children: applying the study. We indicate it at the beginning. One of the most abominable legacies of Vallejo-Nájera’s theories was The implementation of a forced separation system of the children of Republicans. His theory suggested that Children from Marxist families had to be separated from their parents to avoid its “ideological contamination.”
What happened? That The reasoning resulted in the systematic theft of babiesa practice that continued even after Franco. In fact, it is estimated that thousands of children were taken from their families and delivered to institutions or families related to the regime, in what is considered one of the greatest crimes of Franco.
Gestapo and Nazism. The San Pedro de Cardeña experiment was not carried out in isolation, but It was attended by members of the Gestapo and German scientists who conducted tests in Republican prisoners. This collaboration reflected the ideological and methodological links between Franco and Nazism, especially in the use of psychiatry as a tool of political repression.
(Re) discovering the experiment. The truth is that, for decades, Vallejo-Nájera’s investigations were forgotten, protected by the silence imposed by Franco. So it was until 1996, when Researchers Rafael Llavona and Javier Bandrés published psychology in Franco’s concentration campsrevealing with greater depth what happened in San Pedro de Cardeña.
The work revealed the most obvious: that The experiment was a total failuresince he failed to demonstrate any biological base for Marxism. But above this, he revealed that Its effects were devastating: he legitimated repression, justified the separation of families and perpetuated a racist and classist vision of society. That “biopsychism of Marxist fanaticism” was one of the most perverse experiments of Franco, a combination of pseudoscience, racism and political repression that served as an ideological basis for the persecution of Republicans.
If you want also, a reminder of how science It can be manipulated to justify oppression, and the importance of rescuing from oblivion the darkest episodes in history.
Image | Cassawary, X20106301, JTSPOTAU
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