Criminal Endocrinology

That certain men “have too much testosterone” and that is why they hit, dominate and lay waste is an intuition as old as it is popular. Criminal endocrinology, the study of the role of hormones in aggression and antisocial behavior, takes that intuition to the laboratory and dismantles the cliché. Yes, there is a relationship between testosterone and aggressive behavior, but not the one common sense imagines. The hormone does not “cause” crime; it is associated above all with the pursuit of dominance and status, the relationship is correlational and bidirectional, and its effect is small and depends on the social context. Biology can tip the scales without ever deciding the game.

// BackgroundPende and classical criminal endocrinology

Before testosterone, criminal endocrinology was a current of interwar positivist criminology, heir to Lombroso: to the physical stigmata of the born criminal it added chemical, or hormonal, stigmata, those of the glands of internal secretion. Its central figure was the Italian physician Nicola Pende, who in 1921 published his first paper on the subject, on endocrinology and psychology, and linked behavioural deviations to endocrine disorders: hyperthyroid and hyperadrenal types would predominate among violent and impulsive offenders; hyperpituitary types, among cold-blooded murderers. In the United States, Louis Berman published The Glands Regulating Personality that same year, and Max Schlapp and Edward Smith called their 1928 book on the chemical causes of abnormal behaviour The New Criminology.

Pende's biotypology was especially influential in Latin America from 1930 onwards, above all in Argentina and Brazil, and served as scientific support for Italian fascism. The counterweight came from the Spanish endocrinologist Gregorio Marañón: in a 1936 essay on endocrinology and penal science he warned that the glands bear an important but only partial responsibility for behaviour, and that the social and physical environment weighs on which reactions are awakened and which lie dormant. That is, in essence, the conclusion modern research on testosterone has reached.

// OriginDabbs and the inmates with high hormone levels

The modern field has a name of its own: James M. Dabbs, a psychologist at Georgia State University who devoted his career to measuring testosterone in saliva and cross-referencing it with behavior. In a series of studies in the 90s, Dabbs measured the hormone levels of hundreds of inmates and found a pattern: prisoners with higher testosterone tended to have committed more violent crimes, to break prison rules more often and to project more dominance. In the general population the pattern was attenuated: men with high levels appeared more often in risky and confrontational professions, with more divorces and more antisocial behavior. Dabbs summarized his work in Heroes, Rogues and Lovers: Testosterone and Behavior (2000), whose title already holds the decisive nuance: the same hormone that pushes the “villain” also pushes the “hero” and the “lover”. It is not a molecule of evil; it is a molecule of drive.

The sociologist Alan Booth showed, with Dabbs and others, how testosterone relates to marital instability, leadership and competition, and how that relationship is modulated by the environment: a high level in a stable setting with consolidated status is not the same as one amid precariousness and constant provocation. The field thus moved from pure biology to a biosocial model. And from comparative biology came the piece that ordered the picture: the challenge hypothesis of John Wingfield.

// The theoryThe challenge hypothesis: a hormone of status, not of blood

John Wingfield, studying birds in 1990, observed that males’ testosterone levels did not remain fixed: they rose when there was a need to compete for territory or rank (a rival, a challenge) and fell in seasons of breeding and cooperation. Thus was born the “challenge hypothesis”: testosterone mobilizes dominance behavior when status is at stake, not gratuitous aggression. In human beings, what the hormone pushes toward is winning rank, and physical aggression is only one path to it, often the least effective. An aggressive executive in a negotiation, an elite athlete and a thug may ride the same hormonal wave, with different outcomes because the context channels the drive.

The hypothesis also explains the most revealing finding: the winner effect. Winning a competition (a tennis match, an election, or simply watching one's team triumph, in the case of fans) raises testosterone; losing lowers it. The relationship is bidirectional: the hormone influences dominance behavior, and dominance behavior raises the hormone. This breaks the deterministic reading at its root, because a high level may be both antecedent and consequence of the person’s own history of dominance.

// In fictionEmperors, tyrants and mercenaries: the dominance drive

Fiction distills the dominance drive into impossible bodies. El Emperador, the Emperor of Mortal Kombat, is testosterone turned into cosmology: a being who fights not for money or ideas but for absolute rank, the pursuit of status taken to the domination of entire worlds. Dictador, the dictator of Street Fighter, raises that drive to an imperial project: a tyrant who aspires to subdue the entire world and whose will, fueled by “Psycho Power”, has no goal other than to impose his rank over everything. And —, the tiger of The Jungle Book, gives the most literary version: a sovereign who demands submission by right, the dominance that does not need to shout.

Cain Marko, Cain Marko, makes the drive unstoppable: a man who literally cannot be stopped once he charges, impulse with no off switch. And —, the mercenary of Mortal Kombat, shows dominance channeled by cold greed: high testosterone and, one would say, low cortisol (no fear, no guilt) in the service of self-interest, the social predator who dominates for sport and for profit. Fiction exaggerates into caricature what science measures timidly, and every one of them chooses how to channel the drive.

SK

Mortal Kombat · Video games

Shao Kahn

MB

Street Fighter · Video games

M. Bison

SK

The Jungle Book · Literature

Shere Khan

JU

X-Men · Comics

Juggernaut

KA

Mortal Kombat · Video games

Kano

From the conquering emperor to the fearless mercenary: the dominance drive in its different forms. Tap to open their case file.

// Today’s nuanceA small, social and two-way effect

Behavioral endocrinology has learned to distrust its own headline. Modern meta-analyses confirm that the association between testosterone and aggression in humans exists, but it is weak (much looser than in rodents) and heavily conditioned by context. Controlled administration studies show something subtler: giving testosterone to volunteers does not simply make them more aggressive, but increases their sensitivity to status; they become fairer when fairness confers prestige, and harsher when harshness does. The hormone amplifies whatever behavior grants rank in each situation. That is why the same high level produces an ambitious surgeon or a gang member depending on whether the environment offers legitimate ladders of status.

The highest-risk profile, high testosterone plus low cortisol, describes a minority, not men in general. Criminal endocrinology thus matures toward a biosocial model: the hormone is one input among many, modulated by social class, provocation, the culture of honor, opportunities and choices.

// The crackHormonal determinism and its alibi

The crack in this theory is also its most dangerous temptation: turning correlation into destiny and destiny into excuse. “He just has a lot of testosterone” has served as an alibi to exculpate aggressors (“he couldn’t help it, it’s his nature”) and to stigmatize entire populations of men, singularly poor and racialized ones, as biological time bombs. Both uses are junk science. The real effect is small, correlational, bidirectional and mediated by context; none of that authorizes saying that a hormone “makes” someone kill. At most, in a specific brain and environment, testosterone tilts the probability a little toward dominance responses. Between that tilt and a crime lie the prefrontal cortex that brakes, values, the available alternatives and, above all, the decision.

Hormonal biology is a risk factor, not a sentence. Forgetting it repeats the error of all biological criminology: confusing “influences” with “determines”, and “determines” with “excuses”.

// Why it mattersReading a biological factor with seriousness and limits

Criminal endocrinology offers the cleanest example of how a biological factor of crime should be read: with seriousness and with limits. Seriousness, because denying that hormones influence temperament would be as unscientific as claiming they dictate everything. Limits, because the dominance drive is raw material that each person and each society mold. Understanding it has practical consequences, from treatments that reduce testosterone in certain high-risk sexual aggressors to the design of environments that offer non-violent paths to status for the young people with the most drive.