Can you tell who a criminal is just by looking at them? No you can’t, but that didn’t stop the idea from gaining traction in the late 19th century. Early criminologists in the U.S. and Europe seriously debated whether criminals have certain identifying facial features separating them from non-criminals. And even though there is no scientific data to support this false premise of a “born criminal,” it played a role in shaping the field we now know as criminology.

This idea first struck Cesare Lombroso, the so-called “father of criminology,” in the early 1870s. While examining the dead body of Giuseppe Villella, a man who’d gone to prison for theft and arson, the Italian professor made what he considered a great discovery: Villella had an indentation on the back of his skull that Lombroso thought resembled those found on ape skulls.

“At the sight of that skull, I seemed to see all of a sudden…the problem of the nature of the criminal—an atavistic being who reproduces in his person the ferocious instincts of primitive humanity and the inferior animals,” he wrote in his 1876 book Criminal Man (which he expanded in four subsequent editions).

“Thus were explained anatomically the enormous jaws, high cheek bones” and other features “found in criminals, savages and apes,” he continued. These features corresponded, he argued, to a “love of orgies and the irresistible craving for evil for its own sake, the desire not only to extinguish life in the victim, but to mutilate the corpse, tear its flesh, and drink its blood.”

Lombroso’s ideas led to a major shift in how western scholars and authorities viewed crime. Previously, many Enlightenment thinkers believed humans made choices about breaking the law of their own free will. But Lombroso theorized that a good portion of criminals have an innate criminality that is difficult for them to resist. Followers of this new school of thought placed an emphasis on removing “born criminals” from society rather than seeking to reform them. Though the specific premise that physical features correspond to criminality has been debunked, its influence is still felt in modern debates about the role of nature vs. nurture, and even in the surprise after Ted Bundy’s arrest because the handsome law student “didn’t look like” a serial killer.

What Lombroso was doing was combining phrenology and physiognomy, two types of pseudoscience that purported to explain a person’s personality and behavior based on his skull and facial features, respectively. White men before him had used these pseudosciences to advance racist theories, and now Lombroso was using them to develop the field of “criminal anthropology.”

Like his predecessors, Lombroso also relied on racist stereotypes. “Oblique eyelids, a Mongolian characteristic” and “the projection of the lower face and jaws (prognathism) found in negroes” were some of the features he singled out as indicative of criminality. Lombroso also laid out what types of facial features he thought corresponded to specific kinds of crime.

“In general, thieves are notable for their expressive faces and manual dexterity, small wandering eyes that are often oblique in form, thick and close eyebrows, distorted or squashed noses, thin beards and hair, and sloping foreheads,” he wrote in Criminal Man. “Like rapists, they often have jug ears. Rapists, however, nearly always have sparkling eyes, delicate features, and swollen lips and eyelids. Most of them are frail; some are hunchbacked.”

Before publishing Criminal Man, Lombroso had taught psychiatry, nervous pathology and anthropology at the University of Pavia and directed the insane asylum of Pesaro from 1871 to 1873. After the book, he became a professor of forensic medicine at the University of Turin. To law enforcement figures at the time, he was considered an authority.

“He was tremendously influential,” says Diana Bretherick, a retired criminal lawyer with a PhD in criminology. “He was the first person to make crime and criminals a specific area of study, so that’s why he’s called the father of modern criminology." He was also the first person to write about female crime, she explains.

As an expert, Lombroso sometimes provided advice in criminal cases. In a case in which a man sexually assaulted and infected a three-year-old girl, Lombroso bragged that he singled out the perpetrator from among six suspects based on his appearance. “I picked out immediately one among them who had obscene tattooing upon his arm, a sinister physiognomy, irregularities of the field of vision, and also traces of a recent attack of syphilis,” he wrote in his 1899 book, Crime, Its Causes and Remedies. “Later this individual confessed to his crime.”

Translated versions of Lombroso’s books spread his ideas throughout Europe and the U.S. as Social Darwinism—a warped version of Charles Darwin’s theory of evolution—took hold in the late 19th and early 20th centuries. One of the scholars who subscribed to his theories was leading American sociologist Charles A. Ellwood, who became president of the American Sociological Society in 1924.

“The publication of Lombroso's works in English should mark an epoch in the development of criminological science in America,” Ellwood gushed in a 1912 issue of the Journal of Criminal Law and Criminology, where he was an associate editor. Ellwood felt “Lombroso has demonstrated beyond a doubt that crime has biological roots,” and that his books “should be found in the library of every judge of a criminal court, every criminal lawyer and every student of criminology and penology.”

Lombroso also inspired others to perform studies of criminals in order to determine the “criminal type.” Earnest A. Hooton, an anthropologist at Harvard University, measured more than 17,000 people in the 1930s and concluded that “criminals are inferior to civilians in nearly all of their bodily measurements.” Francis Galton, the racist British anthropologist who coined the term “eugenics,” created composite images of “The Jewish Type” and influenced Nazi thinking, also tried and failed to come up with his own catalogue of criminal features.

Not everyone agreed with these ideas. After Russian novelist Leo Tolstoy met Lombroso, he ridiculed his theories in the 1899 novel Resurrection. And while Alphonse Bertillon—the French policeman who pioneered the mug shot and a system for measuring criminals—thought physical features could disadvantage a person, thus making her more likely to turn to crime, he disagreed that those features were directly linked to criminality.

Still, Lombroso’s ideas about the “criminal type” outlasted him. When casting M, a 1931 movie about a child-killer in Berlin, filmmaker Fritz Lang said “my idea was to cast the murderer aside from what Lombroso has said what a murderer is: big eyebrows, big shoulders, you know, the famous Lombroso picture of a murderer.”

Modern facial-recognition technology—which is more likely to mis-identify people of color—has again raised the spectre of Lombroso’s “criminal type.” In 2016, two researchers at China’s Shanghai Jiao Tong University published a paper arguing that they had used facial-recognition technology to pinpoint features that corresponded to criminality. One of the study’s flaws, critics pointed out, was its assumption that the population of people convicted of crimes accurately reflects the population of people who commit them.

Early criminologists couldn’t have predicted modern facial-recognition technology, but even scholars before them could foresee the moral problems it raises. In the 18th-century, the German physicist Georg Christoph Lichtenberg warned about the dangers of taking “physiognomy” seriously: “one will hang children before they have done the deeds that merit the gallows.” One might also overlook Ted Bundy, with his symmetrical features and clean-cut looks, as a potential suspect.