Working with the limited scientific knowledge they had, the ancient Greek and Roman civilizations cooked up a handful of theories about the human body. While a few hit the mark, most missed spectacularly. In this roundup of 10 incorrect ancient ideas, we’ll see how doctors, philosophers, and curious minds got hilariously wrong.
10 Incorrect Ancient Theories About the Body
10 Food Was Changed Into Blood By The Liver
Galen, arguably the most celebrated Roman‑era physician (though of Greek descent), penned countless treatises on anatomy and physiology. Among his many correct observations, he also championed the notion that food, after being broken down in the stomach, traveled to the liver where it was magically transformed into blood. This error stemmed largely from the fact that human dissection was forbidden in his time, leaving him to infer from animal work. Galen’s teachings dominated medical curricula for centuries, persisting unquestioned until the 16th‑century anatomist Andreas Vesalius began to challenge his authority.
9 Lambs Grew From Trees
Megasthenes, a Greek explorer who returned from India with a vivid travelogue, described cotton plants as “trees on which grew wool.” Misreading this, later scholars assumed that actual lambs sprouted from branches. This fantastical idea spread through the works of Theophrastus and Pliny the Elder, who both mentioned ‘wool‑bearing trees.’ The myth lingered well into the 1700s and 1800s, inspiring books and even expeditions seeking the elusive plant that supposedly bore lambs.
8 Light Came From The Eye
Plato, one of the towering philosophers of antiquity, ventured into optics with a bold claim: a stream of light or fire emanated from the eye, struck objects, and then merged with sunlight to produce sight. He further argued that colors were merely “flame particles” shed by objects. This view held sway until the 11th century, when the Persian scholar Ibn al‑Haytham demonstrated in his Book of Optics that the eye functions as a passive receptor, not a light emitter.
7 Veins Carried Blood, Arteries Carried Air
Praxagoras, an early Greek physician whose works have not survived, is credited with distinguishing veins from arteries for the first time. Yet he insisted that arteries conveyed air, not blood, reasoning that blood leaked from arteries after death while air filled them. He explained bleeding by suggesting that exposed arteries attracted blood from surrounding tissue when in contact with air. This misconception persisted for many centuries.
6 Sleep Occurs When Blood Flows Away From The Surface
Alcmaeon of Croton, a pioneering Greek thinker who first argued that the brain, not the heart, was the seat of intellect, also proposed that sleep arose when blood retreated from the body’s surface to deeper vessels. He further claimed that death ensued if all blood sank inward. While his insights into brain function were groundbreaking, his circulatory theory missed the mark.
5 The Brain Was Just A Cooling Device
Aristotle, the legendary philosopher‑scientist, placed the heart at the center of cognition and sensation, relegating the brain to a mere cooling organ for the heart and a repository for ‘spirit.’ He dismissed earlier neuro‑centric ideas from Plato and Alcmaeon as fallacious, and even asserted that women’s brains were smaller than men’s—a claim that lingered for centuries.
4 Hemorrhoids Could Be Cured In Weird Ways
Pliny the Elder, author of the encyclopedic Naturalis Historia, recorded a bewildering array of remedies for hemorrhoids. Treatments ranged from inserting an onion as a suppository to consuming garlic with wine only to vomit it back out. Another prescription involved rubbing fresh rosemary root on the afflicted area, while a particularly odd cure mixed pig lard with rust scraped from a chariot wheel.
3 Light Traveled Through The Ether
Aristotle also posited that the cosmos was suffused with an invisible substance he called ‘ether,’ arguing that light could not traverse a true vacuum. This ether theory endured for over two millennia, only being dismantled in 1910 when Albert Einstein’s special relativity showed that light propagates without any medium.
2 The Testicles Determined A Person’s Voice
Aristotle further claimed that the testicles dictated vocal pitch, observing that boys’ voices deepened as their testicles descended during puberty. He noted that castrated males retained a higher, “ladylike” timbre, extrapolating that the testes must control voice. Modern anatomy, however, places the larynx and its vocal folds at the heart of pitch regulation.
1 The Womb Roamed Around A Woman’s Body
Hippocrates, hailed as the father of Western medicine, championed the humoral theory of four bodily fluids, yet his most outlandish belief was the ‘wandering womb.’ He argued that a woman’s uterus craved warmth and moisture, and if she abstained from sexual activity, the organ would become bored and drift throughout her body, causing a host of ailments, including hysteria. This notion persisted well into the Middle Ages.