Mesoamerican writing was used to keep genealogies and to falsify them when necessary. So it's a close integration of myth and history to form a seamless, unbroken narrative. For Mesoamerican cultures, the important distinction was not between myth, history, and propaganda, but between what "noble" speech was and what "commoner" speech had to offer. Noble speech was by definition true, no matter how improbable. Commoner speech was regarded as confused, uninformed, full of falsehoods. The hieroglyphic writing was commissioned by educated nobles, and that writing was the visible form of this true speech, or this noble speech. Writing, then, is a political tool used to disseminate myth, history, and propaganda about the ruler, the ruling family, and the nobility in general.
Mesoamerican rulers linked their reigns to mythical ones when gods and ancestors--mythical ancestors--supposedly ruled. By a process known as "euhemerism," noble ancestors turned gradually into heroes, then semi-divine intermediaries, and sometimes actual deities. While even a clever propagandist might not be able to deceive his contemporaries about his immediate ancestors, it is very clear that the ancient Maya, the Aztec, and other groups sometimes borrowed distant ancestors (including deified ancestors) just to legitimize their claim to the throne. In fact, some of the most spectacular genealogical displays we have may have been the work of nobles who were not really in the direct line of succession.
Propaganda?
One of the things that I think has confused some of my colleagues is: What does the word "propaganda" mean? Propaganda involves slanting the truth to put the ruler in the best possible light and affecting a target audience. Two primary types of propaganda, the two broadest categories, are "vertical" and "horizontal." The "vertical" propaganda, as a I define it, is hierarchic. The rulers want to influence the beliefs of commoners. Huge monuments erected in public plazas would be examples of vertical propaganda. On the other hand, "horizontal" propaganda involves nobles who want to influence other nobles. That is their target audience. Codices, for instance, tomb murals, small lintels, things that you have to approach very closely in order to be able to read, these are examples of horizontal propaganda. Such writing is not on public display and we can surmise that the audience was probably restricted to nobles.
In sum, then, the skillful manipulation of propaganda, myth, and history is probably as old as the first politician. In the Maya, the Aztec, the Mixtec, the Zapotec, all of these groups knew how to keep genealogies, and to falsify them when necessary, and to alter the nature of events, in order to delete those things that did not conform to what their current political needs were.
Literacy?
In general, Mesoamerican societies were not literate. Literacy was not even their goal. They want to restrict access to knowledge, and to reading, and to writing, to the nobles so that they can maintain this significant gulf between a commoner stratum and an upper stratum of nobles and royalty. How I think the vertical propaganda was actually disseminated to commoners if they couldn't read is that there are readers. There are interpreters. There are guides to the main plaza, in effect, where you have someone who would literally sing or chant out loud the content of the inscription. And [that] would be another way of controlling the content of what the commoners got out of that vertical propaganda.
Well, if you believe that anything that the ruler says is true and the texts are commissioned by the ruler, then everything he writes and records in stone is the true record of events. Once written, it is that record unless subsequent rulers (and we do have cases of this) take those monuments out of circulation--destroy them, bury them or whatever, deface them. I think the simplest strategy is usually to just bury it--break it and then bury it in some other building and reuse it as the fill within a larger pyramid, so that you can ensure that it really will not be used again or read again.
Hidden in Stone?
In some ways, our goal is not only to confirm or find out exactly what the truth is. Even if [we] find out a ruler was not conveying the truth all the time, we learn a great deal about his strategy, his manipulation, and how he got to the throne. Our job doesn't end with reading a particular text. You always want to see how many other lines of information you can recover that seem to confirm or lend support to a particular text. I do believe that we will never make the field archaeologist irrelevant because the primary data that we need to evaluate all of these texts--their context, their veracity, their value--lies within the excavations of those very cities, palaces, temples, households, and so forth.
When I was working with the Quirigua and Copan texts I discovered that Quirigua had a ruler who claimed victory over Copan. With excavations at Copan we have no physical evidence that Copan is in any way affected. In fact, it goes on to a flurry of construction. So if its ruler was actually taken in a raid and perhaps decapitated, perhaps killed, Copan shows no effect. This makes us look at the archaeological data and the texts in a dynamic way, not really using the texts to just simply give us the gospel on what happened.
So I would say that for the Maya these texts become sincere and consistent even if they include mythology or untruths or delete other kinds of information. We know that one of the few sources of what we might call objective evidence is the physical remains resulting from excavation. It's how we evaluate that. We now know, I think, that the Aztec, the Mixtec, the Zapotec, and the Maya have biased records. They have a political purpose in mind and we are beginning to see that not all records of conquest are textbook history. We now see, I think, that these Mesoamerican accounts are self-serving attempts to show each ruler or each lineage or each ethnic group in a particular light.
