Ever since we realized that there's more to life than sitting in a tree making frat boy noises and picking fleas off each other, our species has been defined by a profound curiosity about the world around us. Sadly, the fact that our stupid brains are still unable to fully comprehend the vastness of the universe (or even our own planet, for that matter) means that many of our scientific fields are, at best, mostly guesswork. Take archaeology: Despite its bull whip-swinging reputation in popular culture, the field is largely slow-paced "What the hell is this shit?" guesswork, where even the foremost experts can make hilarious mistakes by mislabeling a single bone. Then, years later, some other guy points out the mistake, and BOOM! Half the stuff you've ever read about dinosaurs is obsolete.
As one would expect, the unpredictability of such fields has been noticed by people who indulge in the third human base need -- the desire to get an assload of money without working for it too hard. Which is why history is teeming with stupid forgeries such as ...
Remember that time you needed to make a fast profit and, for reasons that made perfect sense at the time (say, you were staring too hard at the pile of ribs you ordered while getting wasted on tequila), your chosen method of monetary advancement was to create a straight-up archaeological forgery? Don't be ashamed, man -- we've all been there. The point is that whatever hoaxing method you chose, chances are skulls weren't even on the list. They're not exactly easy to fake -- in the time it takes to gain the necessary skill set to manufacture a convincing one, you can sew herring tails on dozens of monkey carcasses and P.T. Barnum your way into drunken glory, or at least a number of interesting watch lists.
Calling your Fiji Mermaid "Carny Aquaman" probably didn't help matters.
Still, there are plenty of people who are fully prepared to give forgin' face bones a go, judging by how often they pop up in the annals of accurate-ish archaeology. Some of these fakes, like crystal skulls and the Piltdown Man, have been decent enough to fool people for a while.
And then there is the Calaveras skull.
Brought to light in 1866 by Josiah Whitney, a well-respected Californian geologist, this significant head bone was found buried beneath million-year-old volcanic layers by gold miners. When presented with the skull, Whitney realized it could belong to the oldest known human being at the time and immediately started writing all the academic papers. The scientific community promptly shat a brick, as they are wont to do in such situations, and set out to investigate further ... only to find out that the skull actually belonged to a very specific creature called "just some random fucking dude." It was an old, fossilized Native American skull that had been planted in the mine as a practical joke.
"And then we sold him one of those mermaids Butch is always making."
Gold Rush California was a tough place, with way too few PS4s and other sources of entertainment to go around. To occupy their time, a bunch of dudes developed an equally hard sense of humor and devised a complicated prank at the expense of Whitney (whom I strongly suspect had been sleeping with someone's wife to deserve such an Ocean's Eleven treatment). The skull was planted in the mine, and a miner "found" it and presented it to Whitney. Add some friendly nudges in the right direction by shopkeepers and academics who were also in on the joke, and voila -- Whitney was soon called out and thoroughly shamed by the scientific community.
A note to all aspiring academics: Although your Wild West survival instinct is correct in not contesting the words of a man emerging from underground waving a pickax and screaming about ancient skulls, please realize that this doesn't mean you should instantly publicize everything he says.
4Etruscan Terracotta Warriors
The Etruscan people manned the Italian peninsula before the Roman Empire came along, and while they did leave archaeological proof of their existence, a whole bunch of the remainders of their culture is almost completely covered in vomitoriums, aqueducts, and wine jugs with pictures of orgies. This is why the three Etruscan terracotta statues the New York Metropolitan Museum of Art acquired between 1915 and 1921 were such a big deal. Not only were all three in excellent condition, but their location and certain other circumstances seemed to cast suspicion on large chunks of what we knew about Roman history at the time.
So of course they were fake as balls.
"What, this? Just, uh, just experimenting with a clay pizza."
The statues that would eventually be known as the Etruscan Terracotta Warriors were actually crafted by Pio and Alfonso Riccardi, two notable Italian art forgers who specialized in Etruscan techniques. Through their art dealer accomplice, they had already littered the world with an impressive amount of fake historical artifacts, including a massive "Etruscan" bronze chariot they managed to sell to the British Museum. Then they grew greedier and enlisted the help of a sculptor friend to create the Etruscan warriors.
When several valuable, near-pristine artifacts from an extinct culture that has been almost completely covered in a heaping helping of the motherfucking Roman Empire emerge in the span of a few years and the same guys are selling each and every one of them, most people would immediately call bullshit. To the credit of archaeologist John Marshall, the Met's liaison in Rome, the thought did occur to him. Largely thanks to Marshall, the pieces were subjected to a thorough investigation (the museum was bonering over the statues so hard, they wanted to exhibit them right away). Too bad said investigation presumably consisted of a bunch of dudes looking at the statues real hard and saying: "Yep, those are statues, all right," since in 1933 they were eventually put up on exhibit anyway.
"Don't blame us. They were all very clearly stamped 'Made in Italy.'"
It wasn't until the 1960s, following three straight decades of constant screams of "Fake!" by art historians, that someone noticed that the chemical composition in the glaze of the statues wasn't accurate, and shenanigans were called.