Buzz
Scientific theories are never absolute. They are constantly open to verification and refutation. This is why, when we explore history, we uncover a collection of outlandish ideas that were once widely regarded as true.
For instance, there was a time when people thought the characteristics of a woman’s former partner could influence the traits of her child with a new partner. Could anything be more astonishing? And that’s just the beginning. Below are nine additional theories that were once considered factual.
10. Maternal Impression
Up until the early 1900s, it was widely believed that a pregnant woman’s experiences could physically affect her unborn child. This concept, known as maternal impression, suggested that events like hearing loud noises could result in a child being born deaf.
It was also thought that a mother’s visual experiences could influence her unborn child. For example, if a pregnant woman encountered a blind person, it was believed her child might be born blind. To prevent such outcomes, doctors often recommended that expectant mothers spend time in serene environments like art galleries or music concerts.
In 1726, a servant named Mary Toft took advantage of the maternal impression theory by convincing doctors she had given birth to rabbits. The physicians attributed this to her diet, dreams, and habit of chasing rabbits, concluding these factors caused her babies to transform into rabbits.
Joseph Merrick, widely known as the Elephant Man, was thought to be a result of maternal impression. Many believed his deformities were caused by his mother being frightened by an elephant while pregnant. Modern science, however, attributes his condition to neurofibromatosis and/or Proteus syndrome.
9. Preformationism
In the 17th and 18th centuries, scientists and doctors thought that human sperm or eggs contained tiny preformed humans that simply grew larger in the womb. This idea, known as preformationism, also applied to animals and insects. Some researchers even claimed to have spotted tiny winged beings inside chicken embryos.
Preformationism was eventually debunked with the invention of advanced microscopes. By examining human and animal eggs, sperm, and embryos, scientists found no evidence of miniature creatures. This led to the theory being replaced by epigenesis.
8. Spontaneous Generation
Spontaneous generation was the idea that living organisms could arise from nonliving materials. For example, people once thought mice emerged from stored food and maggots formed from rotting meat. This theory dates back to ancient Roman times.
The concept of spontaneous generation stemmed from observations. People saw maggots appearing on decaying meat and mice seemingly materializing in bread and cheese stored in dark, damp places. A 17th-century account even described creating mice by wrapping wheat husks in a sweaty cloth and leaving it in an open jar for three weeks.
Over the years, many scientists challenged the idea of spontaneous generation, but none conducted conclusive experiments to definitively disprove it. Supporters of the theory often manipulated experimental results to uphold their beliefs. It wasn’t until 1859 that Louis Pasteur delivered the final blow to the theory.
7. Telegony
Telegony was the notion that characteristics from a woman’s previous sexual partner could influence the traits of her child with a new partner. This idea was introduced by the renowned Greek philosopher and scientist, Aristotle.
Although debunked today, telegony was widely accepted in its time. This belief explains why Greek heroes often had dual fathers—one mortal and one divine. It also influenced the British monarchy, where kings were forbidden from marrying previously married women. A notable example occurred in the 14th century when the British monarchy tried to block the marriage between Edward the Black Prince and Joan of Kent, a divorcee. (Edward died before ascending the throne.)
Telegony was discredited in the 19th century when scientists established that genetics dictate an offspring’s traits. However, in 2014, researchers at the University of New South Wales found that telegony does occur in fruit flies. The first male a female mates with influences the size of her offspring, even if she mates with other males later.
6. Tooth Worm
Thousands of years ago, it was widely believed that toothaches were caused by a worm residing inside the tooth. This mythical creature was referred to as the tooth worm, with its first recorded mention dating back to around 5000 BC.
The tooth worm theory persisted until the 18th century, when scientists discovered that bacteria, not worms, were responsible for tooth decay. Before this revelation, it was thought that the tooth worm lurked at the tooth’s root, causing pain when it moved and relief when it rested.
The theory gained traction because the nerve at the base of the tooth bore a resemblance to a worm. However, there was no consensus on the worm’s appearance. British scientists described it as eel-like, while German scientists compared it to a maggot.
Even after the tooth worm theory was debunked in the 18th century, some scientists refused to accept its nonexistence. They clung to the idea that tooth worms were the cause of toothaches well into the 1900s.
5. Miasma Theory
During the Middle Ages, doctors attributed diseases to a harmful vapor in the air known as miasma. This belief was so widespread that malaria derived its name from the Italian words mala (“bad”) and aria (“air”), reflecting the idea that the illness was caused by foul air.
The deadly plague was also thought to be caused by bad air. During the Great Plague of London, doctors treating plague patients wore masks filled with flowers to ward off the supposed miasma. While this did little to prevent the plague, the fear of miasma had some positive effects.
The mistaken belief that miasma arose from decaying matter led doctors to advocate for cleaner environments. Florence Nightingale, a pioneer of modern nursing, emphasized the importance of cleanliness and proper ventilation in hospitals.
In England, people inadvertently shielded themselves from diseases by cleaning the streets of the waste they believed produced miasma. While the filth was indeed causing illness, it wasn’t through the mechanism they imagined. This lack of understanding was a significant setback for medical progress.
Doctors often neglected to wash their hands when treating patients, unknowingly spreading diseases among them. The miasma theory began to lose credibility in the 1800s when scientists identified microorganisms like bacteria as the true cause of illnesses. This led to the germ theory, which remains foundational in medicine today.
4. Caloric Fluid Theory
Today, we understand that heat is a type of energy. Like other energy forms, it cannot be created or destroyed but can be converted from one form to another. Centuries ago, this was unknown. In 1787, French chemist Antoine Lavoisier proposed that heat was a fluid, which he named caloric fluid.
Lavoisier proposed that heat moved from a warmer object to a cooler one through caloric fluid. As the cooler object absorbed more of this fluid, it would heat up. This theory became the standard explanation for various heat-related phenomena during that era.
For example, scientists argued that the rise in temperature during compression occurred because caloric fluids were forced into a smaller area. Essentially, more caloric fluids equated to greater heat. This theory was eventually disproven years after its introduction.
3. Geocentric Model Of The Universe
The geocentric model of the universe is among the oldest astronomical theories. It posited that the Earth stood at the center of the universe, with all celestial bodies, including the Sun, Moon, and planets, orbiting around it. While this holds true for the Moon, it does not apply to the Sun or other celestial objects.
The geocentric model was first introduced by the ancient Greek philosopher Anaximander in the sixth century BC. He described the Earth as a cylinder, with all celestial bodies orbiting around it. Later, philosophers like Plato, Pythagoras, and Aristotle agreed the Earth was spherical but maintained it was the universe’s center.
Over the centuries, many astronomers questioned the geocentric model, particularly between the 10th and 12th centuries, but their ideas were dismissed. This shifted in the 16th century when Nicolaus Copernicus argued that the Earth was not the center of the universe.
Copernicus documented his discoveries in his book, De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres). Aware of its controversial nature, he delayed its publication until he was near death. The geocentric model was ultimately discredited in the 17th century.
2. Humoral Theory
The humoral theory posited that every individual possesses four humors: blood, phlegm, black bile, and yellow bile. Each humor corresponded to one of the four elements—air, earth, water, and fire—and was also tied to a specific season. It was believed that an excess of any humor during its associated season could disrupt the body’s balance, which was essential for proper functioning. For example, blood was thought to be most abundant in spring, potentially leading to health issues.
Historically, doctors treated patients for humor imbalances using various methods. Depending on the diagnosis, treatments included exercise, specific diets, or medications. In some cases, doctors resorted to extreme measures like cauterizing the skin to create blisters or administering laxatives to purge the body. In severe situations, they would directly remove the excess humor. The humoral theory was ultimately discredited in the 19th century.
1. Hollow Earth
The Hollow Earth theory stands apart from the other theories discussed here. Unlike the others, it was never widely accepted by the scientific community. Despite this, some individuals still consider it true, even though there is no evidence to support it, and all known facts about the Earth contradict its claims.
The Hollow Earth theory was introduced in 1692 by Edmund Halley, the namesake of Halley’s Comet. Halley suggested that the Earth was hollow after observing fluctuations in our planet’s magnetic field. He theorized that these changes occurred because the Earth possessed multiple magnetic fields.
Halley proposed that the Earth is composed of four concentric spheres. The outermost sphere is the largest and represents the Earth as we know it, while the three inner spheres decrease in size the deeper they lie. This means the innermost sphere is the smallest, and the outermost is the largest.
Many scientists backed Halley’s theory, with some adding their own interpretations. Leonhard Euler suggested that a sun inside the Earth illuminated the inhabitants of the inner spheres, while Sir John Leslie proposed the existence of two inner suns. Despite being disproven, the theory still has its believers.
