History is rife with intellectual debate over the most fundamental aspects of existence—but sometimes, those feuds got a little out of hand. Here are 20 of the most outrageous scientific throwdowns.

1. Isaac Newton vs. Gottfried Wilhelm Leibniz on the Invention of Calculus

Despite what most people are taught, Isaac Newton wasn’t the sole inventor of calculus. That is an honor he shares with philosopher Gottfried Wilhelm Leibniz—whether he wanted to or not. Existing evidence [PDF] shows that Newton developed his ideas for calculus before Leibniz, but Leibniz only became somewhat aware of Newton’s developments after he had been working on his own. Leibniz published his paper on calculus first, and Newton was convinced that Leibniz plagiarized him. Both men and their supporters traded insults and smears over who deserved priority of invention, with both sides resorting to personal attacks. Leibniz appealed to the Royal Society to make a final ruling in the dispute. The Royal Society (RS) ruled in favor of Newton, but that’s not surprising considering that Newton was president of the RS, picked reviewers who would support his case, and authored the final report. The dispute lasted for years until Leibniz’s death in 1716.

2. Thomas Edison vs. Nikola Tesla and George Westinghouse on AC/DC

When Nikola Tesla left Thomas Edison’s employ in 1885, he took his invention of an alternating current (AC) electricity system with him. Edison believed his invention of direct current (DC) would herald an electrified future, but he found competition when Tesla sold his AC patents to industrialist George Westinghouse. With Westinghouse’s backing, AC threatened DC’s dominance, so Edison undertook a smear campaign against Tesla and Westinghouse, embroiling the three men in the near decade long “War of the Currents.” Edison tried to discredit AC by arguing it was dangerous and went so far to prove it that he had animals publicly electrocuted with AC. He found the perfect opportunity to showcase AC’s alleged volatility when a death-row inmate was up for execution, and Edison suggested New York use an AC electrocution as the most humane way to deliver capital punishment. He had an inside man illegally buy a Westinghouse AC generator for the execution, which was reportedly “an awful spectacle.” Despite Edison’s underhanded efforts, Westinghouse and Tesla won the war, and AC became the dominant system in the U.S.

3. Derek Freeman vs. Margaret Mead on Margaret Mead

In the 1980s, anthropologist Derek Freeman made the interesting career move toward trashing a deceased Margaret Mead for a living. In her book Coming of Age in Samoa, Mead chronicled the commonplace casual premarital sex of young Samoans. She argued that sexual mores were predicated by society, and people in the West could choose to live freer lives by breaking free from its rigid rules around sexuality. Many couldn’t abide Mead’s progressive views on sexuality, and Freeman became their champion when he published his first anti-Mead book in 1983 and his second in 1998. He claimed Mead ignored key evidence and presented a false image of sexuality. Mead had her defenders, but Freeman cast enough doubt on Mead that her reputation was irreparably damaged. As it turns out, Freeman was the one who falsified and misrepresented data to smear Mead. Anthropologist Paul Shankman has tried to set the record straight and published evidence suggesting Freeman made every misstep he accused Mead of doing in her field work. Mead wasn’t alive to defend her integrity.

4. Edward Drinker Cope vs. Othniel Charles Marsh on the Bone Wars

Othniel Charles Marsh (left) and Edward Drinker CopeMathew Brady or Levin Corbin Handy (Marsh) and Frederick Gutekunst (Cope), Wikimedia Commons // Public Domain

In the 19th century, friends-turned-arch-enemies Edward Drinker Cope and Othniel Charles Marsh kicked off the “Bone Wars.” The feud between the paleontologists began in 1868 when Cope invited Marsh to tour his fossil quarry, during which Marsh made a secret agreement with the miners to send any fossils they found to him at Yale. The relationship then dissolved, and the “Bone Wars” was on, each trying to collect more fossils and publish more papers than the other. They sent spies to the other’s fossil quarries, their crews brawled with each other, and they blew up their own quarries to prevent the other from finding any fossils that might have been missed. The rivalry dominated their lives and careers, but it also provided the foundation of American paleontology by fueling their massive collections of fossils that were left to the Smithsonian and Peabody Museum of Natural History upon their deaths for further study by generations of paleontologists.

5. Alice Lee vs. the Anatomical Society on the Size of Women’s Brains

Bigger brains are better brains, or so 19th century medical men thought. Many anatomists believed that cranial capacity determined intelligence, and since women’s skulls and brains were smaller than men’s, they were naturally less intelligent than men. Alice Lee, a Ph.D. student at the University of London, put this theory to test, formulating a statistical analysis [PDF] to measure the skulls of living people, and her first test subjects were the men of the Anatomical Society. She measured all 35 members’ skulls, compared them to the skulls of women students, and delivered surprising results: Some of the most renowned male anatomists had the smallest skulls of the test group! Overall, skull size varied dramatically across all subjects. Those who adhered to “bigger is better” either had to accept they weren’t as smart as they thought they were, or that brain size had nothing to do with intelligence. Unsurprisingly, they chose the latter.

6. Barry Marshall vs. Gastroenterology on Stomach Ulcers

In 2005, internist Barry Marshall and pathologist Robin Warren won the Nobel Prize in Physiology or Medicine for discovering the bacterium Helicobacter pylori as a cause of peptic ulcer disease. For Marshall, it was a (literally) painful road to the Nobel. In 1979, Warren discovered that H. pylori could overrun a person’s gut, and Marshall went further by culturing the bacteria from ulcer patients. He found that ulcers and stomach cancer can be attributed to this bacterium; therefore, the cure was simple—antibiotics. Marshall and Warren tried to spread the word about their discovery, presenting at conferences and writing letters to medical journals. Yet, gastroenterologists insisted ulcers were caused by stress and rejected Marshall’s discovery outright. To prove them wrong, he made himself a guinea pig: He put the bacteria in beef broth and drank it himself. As he predicted, he became quite ill with symptoms leading to ulcers. He then biopsied his own stomach and cultured H. pylori, proving beyond a shadow of a doubt that the bacteria cause peptic ulcer disease.

7. Zelia Nuttall vs. Leopoldo Batres on La Isla de Sacrificios

Hell hath no fury like an intelligent woman whose discoveries were stolen by incompetent men, or so it was for Zelia Nuttall when Leopoldo Batres took credit for her archeological discovery. In 1909, Nuttall explored a small island called La Isla de Sacrificios and found ancient structural remains and frescos. The Mexican government agreed to fund her excavation of the site and made Batres her supervisor. Before Nuttall could begin, Batres secretly went to the island to investigate the frescoes on his own, and when he returned, he took credit for the entire discovery. In a fury, Nuttall resigned as honorary professor of the National Museum in Mexico and then published an article [PDF] detailing her discovery and excoriating Batres as incompetent and for trafficking antiquities. In response, Batres published his own pamphlet on their battle, alleging Nuttall’s accusations were nothing but “feminine hysteria.” Compared to Nuttall’s well-written scientific article, Batres’s pamphlet was seen as combative and petty. After Nuttall died, another archaeologist joked about the controversy saying, “Batres fought with all the world ... Doña Celia tambien.” (Mrs. Zelia also.)

8. Ignaz Semmelweis vs. the Medical Community on Washing Your Hands

Ignaz Semmelweis, handwashing proponentWikimedia Commons // Public Domain

Before the world knew about germ theory, Dr. Ignaz Semmelweis ordered his hospital staff to wash their hands—and the medical community wasn’t having it. In hospitals across Europe, new mothers were dying of puerperal fever in the maternity ward, and Semmelweis suspected that medical workers were transferring what he called “decomposing animal organic matter” from corpses to patients and making them sick. After he mandated handwashing in his hospital, the mortality rate immensely declined. He tried to get other hospitals to do the same, but the medical community rejected his hand-washing theory, holding fast to the idea that “bad air” spread infections. An obstetrician named Charles Meigs washed his hands (ahem) of any responsibility in patient illness, saying, “Doctors are gentlemen and a gentleman’s hands are clean.” Semmelweis couldn’t find acceptance anywhere. As he grew more desperate to be heard, he started writing letters to obstetricians, accusing them of committing massacre by not washing their hands. Semmelweis’s behavior became more volatile and he was eventually committed to an asylum.

9. John James Audubon vs. Charles Waterton on Vultures’ Sense of Smell

In the 19th century, a war raged in the world of ornithology between Nosarians and Anti-Nosarians [PDF]. Charles Waterton recruited Nosarians to support his view that vultures use their sense of smell to find dead prey, while John James Audubon’s Anti-Nosarians argued that vultures use only their sight. A vulture’s sense of smell doesn’t seem like something that would ignite a flame war, but they turned a scientific squabble into what Waterton’s biographer called “a civil war amongst naturalists.” Waterton believed so strongly in the vulture’s olfactory abilities that he wrote in a letter to his supporters that the Anti-Nosarians “ought to be whipped.” Audubon’s followers staged experiments for members of the public, who in turn had to sign a document vouching for the vulture’s lack of smell. Audubon ultimately won his 19th century audience, but lost it in the 20th century, when ornithologists proved Audubon was wrong. It turns out that Audubon probably was studying the black vulture (which hunts by sight), not the turkey buzzard or vulture (which hunts by smell)—two entirely different species.

10. Domenico Scandella vs. the Inquisition on Cheese and Worms

Domenico Scandella, known as Mennochio, was a poor miller when he went before the Inquisition in Italy for his unusual views about the cosmos. Menocchio claimed the cosmos was like cheese formed from milk and that God and the angels were the worms that sprang from it. Menocchio formed his cosmology by weaving together various poems and philosophies with myths that he picked up from agrarian cults, all leading him to reinterpret the Bible and the cosmos in this way. On the urging of his family Menocchio recanted, but when he returned home, he just couldn't stop telling people about his theory. He was brought before the Inquisition again, and this time he was sentenced to burn at the stake by Pope Clement VIII in 1599. Carlo Ginzburg documents the ordeal in his 1976 book The Cheese and the Worms.

11. Grover Krantz vs. Other Anthropologists on Bigfoot

When anthropologist Grover Krantz saw the famous 1967 film of Bigfoot walking through the woods, he became convinced Bigfoot was real. After observing various fossil evidence, he posited the creature was an extinct primate from Asia that had crossed the Bering Strait to North America. He went so far to prove he was right by hunting it, hoping to serve up a Bigfoot body for evidence. Krantz’s students loved him, but the faculty didn’t and wouldn’t support him for full professorship. According to a former student, it wasn’t so much his belief in sasquatches that held back his career as his tendency to fall for hoaxes and unwillingness to let go when evidence didn’t support his theories. The same student tried to prove this point by faking a Bigfoot cast and presenting it to Krantz, who examined and formed theories about its origin. The student told Krantz what he had done, but Krantz was undeterred and continued to look for evidence of Bigfoot until his death in 2002.

12. Elizabeth Blackwell vs. Medical Schools on Admitting Women

Elizabeth Blackwell, first female physician in the U.S.Schlesinger Library on the History of Women in America, Flickr // No Known Copyright Restrictions

In the 1840s, Elizabeth Blackwell applied to every medical school in New York and Philadelphia, plus a dozen more in the northeast U.S., before she found one that would accept a woman. When Geneva Medical College received her application, the all-male faculty made public sport of her by putting her admission up for vote to its all-male student body, confident none of the students would accept her. The student body, however, thought the vote was a literal joke, and they all voted “yes” on acceptance. Backed into a corner of their own making, the college accepted Blackwell in 1847, and when she graduated two years later, she became the first licensed female physician in the country. Her younger sister Emily followed in her footsteps, becoming the third woman to graduate from medical school in the U.S. in 1854. The Blackwell sisters and a colleague went on to open the New York Infirmary for Women and Children in 1857, the first such hospital in the country, which was also managed by a female staff. And after the humiliation they both suffered in male-dominated medical schools, the Blackwells founded the Women's Medical College of the New York Infirmary in 1868, specifically for women who weren't welcome at existing schools. As the motivational poster saying goes, “success is the best revenge.”

13. Alfred Wegener vs. Geologists on Continental Drift

Meteorologist Alfred Wegener started a war against geologists when he cut the continents out of an atlas and put them together like a puzzle. Wegener’s spontaneous experiment in 1910 was the beginning of his theory for continental drift, the notion that the continents once formed one super continent and had drifted apart. This flew in the face of the accepted belief that the continents and oceans were static and unmoving on solid earth.

The reaction from geologists was swift and fierce: Wegener's work was called “Germanic pseudo-science,” a “fairy tale,” and “delirious ravings,” and at academic conferences in Britain and America, his ideas were treated with hostility. Geologists even discouraged young researchers from pursuing continental drift theory, saying it would be career suicide. This backlash ultimately served to delay scientific progress because, in the end, Wegener was right. He wouldn’t be vindicated until the 1960s as the old guard of geology died and younger scientists took the possibility of continental drift seriously.

14. Antoine Lavoisier vs. Jean-Paul Marat on Animal Magnetism 

While most scientific feuds involve name-calling and humiliation, only one includes a beheading. The beef in question was between the father of modern chemistry Antoine Lavoisier and animal magnetism enthusiast Jean-Paul Marat. Marat applied to the prestigious Academy of Sciences for his experiments on the supposed energy behind animal magnetism, which he said he observed leaking from heated rocks and the head of Benjamin Franklin. Lavoisier wasn’t convinced by Marat’s experiments, and his application to the academy was publicly rejected. A humiliated Marat used his position as a French revolutionary leader to turn the public against Lavoisier. Marat was stabbed to death in his bathtub during the revolution by a political rival, but his allies carried out his vendetta and had Lavoisier arrested and his laboratory equipment seized. Lavoisier was tried, convicted of fraud, and executed by guillotine on May 8, 1794.

15. Thomas H. Huxley vs. Samuel Wilberforce on Natural Selection 

Bill Nye and Ken Ham made headlines in 2014 with their televised debate of evolution versus intelligent design, but their public argument on this topic wasn’t the first, and certainly not the most rowdy. In 1860, Bishop Samuel Wilberforce and Thomas H. Huxley, a.k.a. Darwin’s Bulldog, took the stage in front of 500 people for what is now known as the Great Debate. Huxley was an ardent supporter of Darwin’s theory of natural selection, and Wilberforce defended creationism. During their debate, Wilberforce asked Huxley if he descended from an ape through his grandmother or grandfather, and Huxley replied that he’d rather descend from an ape than an ignorant man, meaning Wilberforce. The crowd was so shocked by Huxley’s response that a woman fainted, and others jumped to their feet. After the debate, the relationship between the two never really cooled. When Wilberforce died from falling off a horse, Huxley joked to another scientist, “For once, reality and his brain came into contact and the result was fatal.”

16. Percival Lowell vs. Astronomers on Martian Canals

Percival Lowell's drawings of Martian canalsWikimedia Commons // Public Domain

In 1877, Italian astronomer Giovanni Schiaparelli observed deep winding trenches on the surface of Mars, which he called canali, Italian for “grooves.” But American astronomer Percival Lowell took the word canali to literally mean canals. For Lowell, water-carrying canals hinted at intelligent life capable of constructing waterways. He was so obsessed with this idea that he built his own observatory in Flagstaff, Arizona, with the express purpose to study life on Mars. Even though Lowell had his followers, largely in popular culture, astronomers and scientists from other fields thought the theory was nonsense. Astronomer William Huggins called Lowell’s observations “pseudo-ones,” and joked about becoming rich on Martian fish. Biologist Alfred Russel Wallace, co-developer of natural selection, published two books discrediting Lowell’s theories, concluding the Martian atmosphere made it impossible for water to exist in a liquid state. Lowell’s detractors were right; there are no Martians building infrastructure on Mars, which was conclusively proven by NASA’s Viking Program in the 1970s.

17. Leta Hollingworth vs. Edward Thorndike on the Variability Hypothesis

Edward Thorndike likely didn’t know what he was getting into when he took on Leta Hollingworth as a doctoral psychology student. Thorndike advocated for the Variability Hypothesis, which purported that men exhibit a high range of physical and psychological traits while women remained static and unable to excel to the same levels as men. Hollingworth called this theory “armchair dogma” [PDF] and dedicated her research to striking Thorndike down. After comparing the physical traits of 2000 male and female newborns, she found, contrary to Thorndike’s theory, that female babies exhibit greater physical and psychological range. If anything stunted the abilities of women, she said, it was the environment, not nature. She followed her study with two papers, each launching a point-by-point assault on Thorndike’s work. Hollingworth took a big risk when she challenged the field of psychology and the man who held her future career in his hands. But Thorndike couldn’t deny the validity of her research, and not only did she pass her doctoral study with him, he offered her a job.

18. Donald Johanson vs. Richard Leakey on “Lucy”

For 30 years, Donald Johanson and Richard Leakey fought over Lucy, a 3.2-million-year-old woman. “Lucy” was the name of the skeleton Johanson unearthed in Ethiopia, which he claimed was the direct ancestor of humans. Leakey, however, maintained that she wasn’t, and the direct ancestor had yet to be found. What was largely an academic debate spilled into public view when the two men appeared on a 1981 episode of the TV show Cronkite’s Universe. From the way events unfolded, it seems Leakey was unknowingly lured into debate, thinking it would be an educational conversation. But from the get-go, Cronkite set it up as a face-off, and Johanson came prepared with a cast of Lucy’s skull and other evidence while Leakey came with nothing. They both humiliated each other, and after recording, Leakey cut off communication with Johanson. In later publications, Johanson continued criticizing Leakey. Finally, in 2011, the two men mended fences for their first public meeting since the Cronkite incident for an educational event. Scientists are still debating whether Lucy's species, Australopithecus afarensis, is an ancestor of Homo sapiens.

19. Thomas Hobbes vs. John Wallis on Squaring a Circle 

When Thomas Hobbes claimed that a circle can be squared, he was a philosopher, not a mathematician—a fact that didn’t go unnoticed by actual mathematician John Wallis. Wallis was angry that a philosopher was dabbling in his field and said that Hobbes’s arrogance in mathematics would “vomit poison and filth upon us.” With an edge of schadenfreude, Wallis said Hobbes needed to be shown “how little he understands this mathematics (from which he takes his courage).” In turn, Hobbes called Wallis’s work “mere ignorance and gibberish.” The rivalry spanned 24 years [PDF], from 1655 until Hobbes’s death in 1679. Hobbes would never be vindicated because it is, indeed, impossible to square a circle.

20. Gerta Keller vs. Everyone on What Killed the Dinosaurs

Since the 1980s, most people have been taught that an asteroid brought about the mass extinction event that killed the dinosaurs, but for Gerta Keller, the case is not closed. Keller argues that a series of colossal volcanic eruptions in India precipitated the extinction. This questioning of the asteroid extinction has put Keller at the center of what The Atlantic called “the nastiest feud in science,” which has involved attempts to ruin her career, threats, and name-calling. Keller’s opponents have no qualms about going on the record, calling her “fringe,” “dishonest,” “and a “crybaby.” Keller likewise accuses her opponents of ignoring evidence and being unscientific, and she dismisses those who try to bridge the two sides with an asteroid-and-volcano scenario. Many of these scientists, including Keller, are still working to promote their theories and fighting with each other, and it doesn’t seem like any side will be waving the white flag of peace any time soon.