I don’t think the wheel was ever really invented. I think it can only be described as being discovered. There are naturally occurring round things in the world, and they certainly are involved in natural processes that involve rolling across or down various surfaces. These processes were certainly observed by humans, which led to the development of a variety of round objects including the wheel.
I think there is an interesting difference between what is invented and what has been discovered and yet is still considered invented. Just as I find it interesting that two people can discover or invent something in different places or in different times without it lessening the magnitude of their discovery/invention. America is still a pretty good place and a pretty important discovery for the Europeans, even though the Asians had also discovered it some 12,000 years earlier on their own. Radio is a pretty neat little technology that just happenned to be invented by no less than three people within ten years of each other, none of them knowing what the others were doing. Each person who “invented” radio made an equally important technological contribution, regardless of whether they were first, because they developed a technology that was not available or known in their region.
In the modern world, disemination of ideas has two paths, and one is like the old way, but faster. Within fifteen years of the invention of the radio, it was already changing the way the whole world communicated. Now when something groundbreaking is invented, the whole world knows about it even before it is ready to be built, and it can come into widespread use in as little as 6-18 months. The other path is not really new, but the way it is being handled has not been as extreme since the dark ages. Companies around the world spend money of R&D, and they come up with hudreds of thousands of good, new ideas every year. IBM registers so many patents every year that it boggles my mind; they must register literally hundreds of patents every day of the year. Yet what was the last groundbreaking thing to actually come out of IBM besides the sheer volume of patents itself? Deep Blue? The upcoming Blue Gene (a computer so powerful it puts Deep Blue to shame; it will be used to model complex protein behaviors that we barely understand)? The NetVista? Where is all their invention going? It isn’t changing the world. This second path is (unfortunately) the more common one today; carefully hide and protect your invention instead of sharing it with the world.
I want to say two more things (because I think that if I try for any more, I’ll descend into incoherent babbling): First, the second path I describe is what is wrong with copyright today. A recent law passed congress extending copyright to 90 years (from 70). (I hear that Disney was a big player behind this, trying to extend its ownership of Mickey Mouse, which would otherwise have run out next year.) Now, when IBM invents something useful that could change the way the world works and make life better for everyone, they can sit on it for longer than anyone at IBM today will be alive before it becomes public domain. If accounting or management or even the legal department at IBM decides a particular discovery or invention wouldn’t be safe or profitable or wouldn’t fit Big Blue’s corporate vision, it could be shelved indefinitely, only to begin to effect the world positively nearly a century later at the earliest. When the first copyright law was passed in the US, it made the copyright period 14 years. This was probably the most reasonable copyright law ever passed in the US. This allows a reasonable amount of time for a company to make a profit from a discovery or invention before it becomes public domain, but does not excessively slow down the progress that can be made when a technology can be adapted and improved and spread by the common man.
Second, I don’t think things that can be logically considered discoveries more than inventions should be patentable at all. If you invent a unique way of putting together resources to make something new and useful, sure, you invented it and should be able to patent/copyright it for a decade or two so you have the opportunity to reasonably control and profit from your creation. If you notice that a particular number sure is handy when encrypting things digitally, you shouldn’t be able to patent or copyright that number (There is a man who holds the international patents on two different numbers. Seriously.) If you notice that a particular chemical modification of glass transmits data a little faster than regular fiber optics, you should be able to effectively own the idea for chemically treating glass. Now, if you build a machine that performs this treatment on glass, you should be able to patent that machine, but not the fact that certain impure types of glass happen to transmit light faster than others. If someone genetically engineers a specific piece of genetic code that will give you a prehensile tail, they should be able to patent the specific code that they worked hard to put together, but not the idea of a prehensile tail, and not if they just discovered the code in use somewhere else and copied it themselves.