Take a deep breath: Believe it or not, scientists are not always right. We really put them up on a pedestal, though, don't we? We quote scientists as experts, buy things if they're "scientifically proven" to work better … but scientists are human, too. It's just not fair to expect perfection out of them, is it? But come on, can't we at least ask for a reasonable level of competency?
1: The Circulatory System
You don't have to be a doctor to know how important the heart is…but back in ancient Greece, you could be a doctor and STILL have no idea how important the heart is.
Back then, doctors like second-century Greek physician Galen believed (no kidding) that the liver (not the heart) circulated blood (along with some bile and phlegm), while the heart (really) circulated "vital spirit"(whatever that is).
How could they be so wrong? It gets worse.
Galen hypothesized that the blood moved in a back-and-forth motion and was consumed by the organs as fuel. What's more, these ideas stuck around for a very long time. How long?
It wasn't until 1628 that English physician William Harvey let us in on our heart's big secret. His "An Anatomical Study of the Motion of the Heart and of the Blood in Animals" took a while to catch on, but a few hundred years later, it seems beyond common sense -- perhaps the ultimate compliment for a scientific idea.
2: The Earth Is the Center of the Universe
Chalk it up to humanity's collectively huge ego. Second-century astronomer Ptolemy's (blatantly wrong) Earth-centered model of the solar system didn't just stay in vogue for 20 or 30 years; it stuck around for a millennium and then some.
It wasn't until almost 1,400 years later that Copernicus published his heliocentric (sun-centered) model in 1543. Copernicus wasn't the first to suggest that the we orbited the sun, but his theory was the first to gain traction.
Ninety years after its publication, the Catholic Church was still clinging to the idea that we were at the center of it all and duking it out with Galileo over his defense of the Copernican view. Old habits die hard.
3: Germs in Surgery
Laugh or cry (take your pick), but up until the late 19th century, doctors didn't really see the need to wash their hands before picking up a scalpel.
The result? A lot of gangrene. Most early-19th century doctors tended to attribute contagion to "bad air" and blamed disease on imbalances of the "four humors" (that's blood, phlegm, yellow bile and black bile, in case you weren't familiar).
"Germ theory" (the revolutionary idea that germs cause disease) had been around for a while, but it wasn't till Louis Pasteur got behind it in the 1860s that people started listening. It took a while, but doctors like Joseph Lister eventually connected the dots and realized that hospitals and doctors had the potential to pass on life-threatening germs to patients.
Lister went on to pioneer the idea of actually cleaning wounds and using disinfectant. Remember him next time you reach for the Purell.
4: DNA: Not So Important
DNA was discovered in 1869, but for a long time, it was kind of the unappreciated assistant: doing all the work with none of the credit, always overshadowed by its flashier protein counterparts.
Even after experiments in the middle part of the 20th century offered proof that DNA was indeed the genetic material, many scientists held firmly that proteins, not DNA, were the key to heredity. DNA, they thought, was just too simple to carry so much information.
It wasn't until Watson and Crick published their all-important double-helical model of the structure of DNA in 1953 that biologists finally started to understand how such a simple molecule could do so much. Perhaps they were confusing simplicity with elegance.
5: The Atom Is the Smallest Particle in Existence
Believe it or not, we weren't actually all that stupid in ancient times. The idea that matter was composed of smaller, individual units (atoms) has been around for thousands of years -- but the idea that there was something smaller than that was a bit harder to come by.
It wasn't until the early 20th century, when physicists like J.J. Thompson, Ernest Rutherford, James Chadwick and Neils Bohr came along, that we started to sort out the basics of particle physics: protons, neutrons and electrons and how they make an atom what it is. Since then, we've come a long way: on to charmed quarks and Higgs bosons, anti-electrons and muon neutrinos. Let's hope it doesn't get too much more complicated than that.
6: The Earth Is Only 6,000 Years Old
Once upon a time, the Bible was considered a scientific work. Really. People just kind of assumed it was accurate, even when it didn't make much sense.
Take the age of the planet, for example.
Back in the 17th century, a religious scholar took a hard look at the Bible and estimated that creation happened around 4004 B.C. (you know, approximately). Add in nearly 2,000 more years to get to the 18th century, when Western, Bible-reading geologists started to realize that the Earth was constantly shifting and changing, and you get about 6,000 years.
Hmm ... those biblical scholars may have been a bit off. Current estimates, based on radioactive dating, place the age of the planet at around, oh, 4.5 BILLION years.
By the 19th century, geologists started putting the pieces together to realize that if geologic change was happening as slowly as they thought it was, and if this Darwin guy was at all right about evolution (which was also a slow process), the Earth had to be WAY older than they had thought. The emergence of radioactive dating in the early 20th century would eventually prove them right.
7: The Rain Follows the Plow
If only it were so easy. It's actually kind of shocking that humanity held on to the idea that land would become fertile through farming for so long. Didn't anyone look around and see that all this farming of arid land wasn't doing much?
So much for observation.
In reality, this quite erroneous theory (popular during the American and Australian expansions) may have stayed alive in part because it did sometimes work -- or at least it seemed to work.
What we know now is that the plow wasn't actually bringing the rain; long-term weather patterns were. Arid regions (like the American West, for example) go through long-term cyclical droughts, followed by cycles of wetter years. Wait long enough and you'll get a few wet ones.
There's just one problem: wait a few more years and all the rain just goes away - only now, you've got a civilization to support.
What? You've never heard of phlogiston? Well, don't beat yourself up about it, because it's not real.
Phlogiston, proposed in 1667 by Johann Joachim Becher, was another element to add to the list (earth, water, air, fire and sometimes ether); it wasn't fire itself, but the stuff fire was made of. All combustible objects contained this stuff, Becher insisted, and they released it when they burned.
Scientists bought into the theory and used it to explain a few things about fire and burning: why things burned out (must have run out of phlogiston), why fire needed air to burn (air must absorb phlogiston), why we breathe (to get rid of phlogiston in the body).
Today, we know that we breathe to get oxygen to support cellular respiration, that objects need oxygen (or an oxidizing agent) to burn and that phlogiston just doesn't exist.
9: Heavier Objects Fall Faster
OK, trick question: do heavier objects fall faster than lighter ones? Today, we all know that they don't, but it's understandable how Aristotle could've gotten this one wrong.
It wasn't until Galileo came along in the late 16th century that anyone really tested this out. Though he most likely did not, as legend holds, drop weights from the tower of Pisa, Galileo did perform experiments to back up his theory that gravity accelerated all objects at the same rate. In the 17th century, Isaac Newton took us a step further, describing gravity as the attraction between two objects: on Earth, the most important being the attraction between one very massive object (our planet) and everything on it.
A couple of hundred years later, Albert Einstein's work would take us in a whole new direction, viewing gravity as the curvature that objects cause in space-time. And it's not over. To this day, physicists are ironing out the kinks and trying to find a theory that works equally well for the macroscopic, microscopic and even subatomic. Good luck with that.
The idea of morphing lead into gold may seem a little crazy these days, but take a step back and pretend you live in ancient or medieval times.
Pretend you never took high-school chemistry and know nothing about elements or atomic numbers or the periodic table. What you do know is that you've seen chemical reactions that seemed pretty impressive: substances change colors, spark, explode, evaporate, grow, shrink, make strange smells - all before your eyes.
Now, if chemistry can do all that, it seems pretty reasonable that it might be able to turn a dull, drab, gray metal into a bright, shiny yellow one, right? In the hopes of getting that job done, alchemists sought out the mythical "philosopher's stone," a substance that they believed would amplify their alchemical powers.
They also spent a lot of time looking for the "elixir of life." Never found that, either.