> The architect of the Great Pyramid of Giza used
> the Royal Cubit.
> Therefore, if we knew who (i.e. a people not an
> individual) invented the Royal Cubit, then we
> would know the earliest the Great Pyramid could
> have been designed.
I think you are asking the wrong question.
For arguments sake, let's choose a group of people, say, the pre-dynastic Egyptians of Naqada I period. Plugging this data into your question would have us suppose the pyramids of Giza could have been designed c.4400-3500 BCE.
There are a couple of problems with this approach.
First, the answer may imply the design phase is contemporary with the building phase. This leaves us with showing the people of Naqada I built the Giza pyramids.
Second, what's not to say a Naqada I development of the cubit was merely passed down? Do we see any employment of the cubit (or even cubit rods) during the Naqada I period? How about any other period?
Third, what about the pyramids built before Giza (Saqqara, Dashur; why focus on not only Giza, but just the GP)?
Lastly, how could anyone possibly dare to answer the question without it being 100% speculation? How could anyone substantiate their answer?
I just can't see how your query would be able to resolve itself. 'Who' invented it cannot tell us anything about time frame. 'When' it was invented cannot tell us anything about Giza (or any other OK pyramids).
How about Cro-Magnon? How about prehistoric Chin? Tribal Mugumbu of the Congo? Scottish Picts? Even if a cubit rod was found in these remote areas at remote dates, there is no way to tell when any ancient Egyptian pyramid was designed or built.
So you can either flesh out your question by providing the reasoning behind how a cubit inception would be connected to a certain time frame for pyramid design/construction, or perhaps drop the proposal in favor of a different question.
Have you already thought of a candidate to fit your idea? Where are you going with this?
Yours in curiousity,