Science is constantly improving and teaching us amazing things about ourselves and the world around us. Our understanding of the sciences bends and shapes over time and is influenced by the people who study them. And humans are, well, humans—which means that while we can make amazing discoveries, we’re also prone to making mistakes. We carry with us biases that can lead to bad science. Here are five cases where scientists are completely wrong.
1. Humoral theory / 5 Times Science Goes Wrong
(Credit: Book Illustration in ‘Quinta Essentia’ by Leonhart Thurneisser zum Thurn/ Public Domain, via Wikimedia Commons) {{PD-US}}
We have come a long way in understanding the human body. For almost two thousand years, the physical health of the body was based on humoral theory, a belief that greatly influenced both Western and Eastern medicine. The theory holds that four fluids—blood, cholera (yellow bile), phlegm, and black bile—make up the body and must be kept in balance for good health. Each temperament had characteristics that reflected one’s personality.
According to Folger Shakespeare Library“[s]Anginics were considered ruddy and cheerful, Phlegmatics pale and apathetic, Cholerics jaundiced and angry, and Melancholics dark and sad (but often creative).”
2. Eugenics / 5 Times Science Goes Wrong
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Eugenics is nothing but scientific racism. It is based on the inaccurate principle that a population can be improved by selective breeding of certain ethnic and racial populations.
Unfortunately, by the time it was popularized in the 19th century, it was not a fringe movement, but rather widely accepted among scientists. The theory posits that science can create a perfect population that will elevate the white Western European race above other races by using “involuntary sterilization, segregation, and social exclusion,” according to the NIH’s National Genome Research Institute.
3. The age of the Earth
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We now think the Earth is about 4.54 billion years old, a number calculated from radiometric dating, or the dating of the oldest rocks on Earth and the Moon. But this theory is relatively new. Before the 19th century, we still believed that the Earth was round 6000 years based on the Bible. However, scientists began to question the biblical theory because it would not have allowed Earth’s species to evolve long enough.
Read more: How old is the oldest thing in the solar system?
4. Phlogiston theory
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The phlogiston theory states that a fire-like element called phlogiston causes combustion. First proposed by Johann Joachim Becher in 1669, the theory was intended to explain the chemical process of rusting and oxidation. Rusting is actually caused by combining iron, oxygen and water and causing an electrochemical reaction. But the phlogiston theory wasn’t so bad because the experiments done to prove it would later lead to the discovery of oxygen.
5. The great dinosaur dies
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Even 40 years ago, we thought that the dinosaurs were extinct due to a giant volcanic explosion. Other scientists believed that a great plague caused the extinction of the dinosaurs, or that they gradually died out because their brains were too small for their massive bodies. But in 1980, a group of scientists reported a “special sedimentary clay layer” that existed around the time of the dinosaurs’ extinction. It contained a thick layer of a rare element called iridium, which is found in meteorites. A decade later, scientists discovered the massive Chicxulub Crater, which crashed into Earth and ended the age of dinosaurs 66 million years ago.
Read more: Two asteroids may have wiped out the dinosaurs
Science has fixed many things. And it’s amazing how far we’ve come. But we’ve also seen our share of big missteps along the way. While science can guide us, there are times when we must question it.