From subterranean Martians to female hysteria, people have been known to believe some pretty bizarre things. What does it take to make a believable scientific hypothesis out of a strange idea like Hollow Earth theory, what suspension of believe is needed to agree with the Intelligent Design nutjobs? Apparently, not much. Here are five of the strangest examples and who knows what people will find hilariously untrue from our era in 50 years? Everyone will no doubt have other ideas for what the world’s weirdest theories are so give it a shot in the comments below!

1. Trepanation

Ouch. In one of the oldest known medical interventions, a hole is drilled in the skull of a patient who is suffering from defects such as seizures or migraine headaches. The idea was to relieve pressure in the head which was believed to be causing the ailment. Today, trepanation is used on a very limited basis as a mechanism to access the brain for necessary surgery. Some people practice recreational or spiritual trepanation, presumably because they need modern medicine like they need a hole in the head.

2. Female hysteria

Women in the Victorian age were said to be suffering from female hysteria when they were moody or a little more “difficult” than usual. Fortunately for them, the treatment was something called pelvic massage. We can’t laugh too hard at this one, though. Many years later, it directly caused vibrating devices to be widely available for, um, home treatment.

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3. Expanding Earth

As bizarre theories go, this one doesn’t sound that far-fetched. Expanding Earth is the idea that the planet was once a lot smaller and completely covered in one continent. If you mentally shrink the globe and try to fit the continents together like a puzzle, you could almost start to believe this theory – after all, the galaxy is said to be expanding, right? However, the Expanding Earth theory has been discredited by nearly all of Earth’s scientists.

4. Phrenology

Would you believe me if I told you that I could tell you how likely you are to commit a crime in the future without talking to you? What if I could do it just by rubbing my grubby hands all over your noggin? Phrenology was on the cutting edge of Victorian-era medical science. Practitioners claimed to be able to determine your personality, propensity for crime, and intelligence from the size and shape of your skull. Although it’s been discredited by modern medicine, there is a small but dedicated community of people who still believe that phrenology is a useful science. Yes, seriously.

5. The Island of California

The idea that California was an island separated from North America by the Gulf of California was actually a cartographic error that was blown way out of proportion. In the 16th century, Spanish explorers mistook what we now know as California for a legendary Atlantis-like paradise island. Despite being disproved by subsequent explorers, many people continued to believe in the Californian island paradise. Something tells me that even without accurate maps, you wouldn’t get many people to believe that legend these days. Other theories like Quantum Evolution may explain everything or might equally well be just as funny as these five in fifty years.