Every now and again, I meet a Biblical literalist who decides that they are going to try to show me what a house of cards evolution is. Typically this involves making statements that indicate a rather stunning ignorance of the fossil record, DNA, mutation, and the basic scientific method, and more often than not a strange misunderstunding of the second law of thermodynamics. Not typically, but often enough that I have taken notice, I will be presented with the example of the Piltdown Hoax, an episode in anthropology's history that is apparently supposed to make me feel like scientists don't know what they're doing and therefore all of their results are invalid.
For those who don't know, the Piltdown hoax occured at the village of Piltdown in England. In 1912, Charles Dawson claimed to have been given fragments of a skull by workmen at the Piltdown Gravel pit, who he said told them that they had dug it out of the pit. The cranial vault (the part that forms the part of the head where are brains are) and face were those of modern humans, but the jaw was that of an ape. Many of the early paleoanthropologists* were won over and thought that this was an example of an early human in Europe - someone who was not quite a modern human but was well on his way to being such. Four decades later, advances in microscopes and other lab tools, as well as a much fuller understanding of the homonid fossil record, led to the skull being shown to be a fake - a human skull and an orangutan jawbone that had been carved, ground, and stained to make them look as if they belonged together. The identity of the hoaxer was never entirely determined (though many people have their own pet theories as to who it was), but the supporters of the skull as a part of the fossil record were forced to concede.
The implication that the creationists often give is, essentially, if anthropologists/paleontologists could be fooled by a hoax then all of their results must be false. Putting aside the logical problems here (proving one result false doesn't necessarilly prove another result false, and even if evolution were proven false, that doesn't prove Biblical creationism true), the fact of the matter is that this still doesn't work to show the folly of evolutionary scientists because it was the evolutionary scientists who demonstrated that this was a hoax and who revised their views based on the demonstration of thsi fact.
However, the thing that is most interesting to me about the times when the Piltdown Hoax has been brought up is that it is treated as a "gotcha' moment" by the people bringing it up, I have been told, each time, some variation on "Well, you don't know the true history of the study of evolution, because the Piltdown Hoax has been hidden from you!" These people are always shocked, and a bit confused, when I inform them that not only has the Piltdown Hoax not been hidden from me or anyone else who has studied human evolution, but every single introudctory paleoanthropology, archaeology, and physical anthropology book I used as an undergraduate discussed the Piltdown Hoax at length. It's a great instructive tale - it tells us about how enthusiasm can lead someone to the wrong conclusions (and therefore why we should be cautious in examining data) and it tells us about how a decades-old conslusion can be reversed by new information. It's good both as a cautionary tale and as a description of how science corrects itself over time. So, um, no, this wasn't hidden from us. In general, science doesn't try to hide it's dirty laundry, but instead scientists try to learn from it (otherwise, no scientist working now would ever have heard of the ether, hyper-diffusionism, phrenology, or any of a number of other things that we have all heard of).
In order to understand Piltdown a bit better, it is necessary to understand not only the nature of the hoax, but also the context in which it occured. By the early 20th century, most biologists and paleontologists had accepted evolution (remember, the theory of evolution by descent with modification was, at the time that the Piltdown Hoax occured, only around 50 years old). Human ancestors were being found throughout Europe, and Germany had one in the Neanderthal and France had one in the Cro Magnon. While these species represented by these finds would eventually be found throughout Europe, Africa, and Asia, they were for some time thought to be endemic to those regions in which the fossils were found. Even after it was discovered that they were spread more widely, there was astill a certain amount of national pride tied up in the "first find" of each.
To this end, the British very much wanted an "early man" of their own. When the Piltdown skull was found, it was just what they wanted: early man, but with the cranial vault (and hence the brain) more modern (or as they would think it, "more developed") than those found in France or Germany. This was in keeping with the British ideal of themselves as intellectual leaders. So, at least a portion of the early belief in Piltdown resulted from wishful thinking on the part of the British scientists examining it. Some of it also probably was due to, frankly, novelty. These pre-modern homonids were a new discovery, and were just beginning to really be appreciated. So, just as nationalistic wishful thinking likely led some to accept the hoax as real, so too did the excitement of finding another example of "early man."
So, the story does work well as a cautionary tale against assuming that all scientific conclusions are correct - and in that the creationists who have pointed me to it have a small point, though their overgeneralization that this dismisses all science (or at least all science that disagrees with their assumptions) is foolish. It also works well as a description of how science can be self-correcting, which is ultimately one of the great strengths of science, and one that is lacking from any system of belief where the subscribers assume that they know the answer before they start gathering evidence.
When the Piltdown Hoax gets brought up, I usually try to contrast it with the Cardiff Giant.
In 1869, a farmer named Stub Newell, in Cardiff, New York sent a group of laborers to dig a well behind his barn. They had only dug a few feet when they hit stone. Digging a bit around the stone, it rapidly became clear that they had hit a large, stone man. Although the laborers report that Newell was annoyed and suggested re-burying the figure, it was only a short time later that a tent was erected and people were charged admission to come and see the Cardiff Giant. And people came by the thousands, making Newell rather wealthy in a very short time. The businessmen of Syracuse, the nearest large city, even bought a 3/4 interest in the giant for $30,000 (which amounts to several million when converted to modern currency) in order to ensure that it stayed in the local area and kept the money rolling in to Syracuse.
The hoax was, of course, eventually uncovered. Harvard's professor of paleontology, Othniel Marsh (and you think you have problems, look at that guy's name!) was asked to examine it, and proclaimed it a fake based on it being a soft stone that wouldn't preserve well for long in the local soils, and the little fact that there were tool marks obvious on the "giant." People in town began to talk, and it came out that a large heavy container had been moved by wagon to Newell's farm the previous year, and that Newell had been heard bragging about the hoax to family members.
Finally, late in 1869, George Hull, a friend and distant relative of Newell's, confessed that he and Newell had created the hoax. And with that, the Cardiff Giant became one of the better known hoaxes of American history.
Okay, so why do I bring this up when others bring up Piltdown? Simple: it's the same basic thing, but from the creationist side. The Bible states flatly that there were giants on Earth in the early days, the most famous of which was, of course, Goliath. Now, it needs to be remembered that Darwin's On the Origin of Species was published ten years earlier in 1859, and while it hadn't quite reached complete scientific acceptance, it was at least seriously considered by most scientists and accepted by many. Contrary to popular belief, the concept of evolution existed well before Charles Darwin, but it was a concept that was hard to grasp and even harder to test scientifically, until Darwin had the insights that solved the puzzle. For the first time, creationism had a strong cultural competitor, and one that explained more while requiring less assumptions, and was supported by all physical evidence**.
So, people flocked to see the Cardiff Giant in part because of the simple novelty and spectacle of it, and in large part because it seemed to provide physical evidence for the truth of the Bible. Where the evidence proving the hoax was visible, wishful thinking wiped it from the public's minds. Sermons were written, visitors were moved, and it was all a hoax. However, while scientists teach the younger generation about Piltdown, I've not yet heard of a creationist church telling it's memberships about the giant, and in fact I often hear members of such churches claiming other known hoaxes as evidence for the truth of the Book of Genesis.
So, no, the Piltdown Man hoax doesn't disprove evolution, and the Cardiff Giant demonstrates that those on the other side can be just as ready to accept a hoax as truth.
*Though, contrary to many claims, far from all. This was a period in which such hoaxes were not uncommon, and so there were many who suspected the skull from the start.
**this may seem to some like an over-statement, but it must be taken into account that both paleontology and general biology had been recognize similarities between animals both living and extinct for a couple of centuries, and so the notion of evolution was very strongly supported by the state of the observable world, but there was no plausible causal mechanism known, so many people dismissed it out of hand. That is what Darwin changed - he didn't introduce the idea of evolution, he just introduced a mechanism that explained all of the evidence for evolution in a way that was testable and could predict further evidence, which has been consistently found.