Some researchers assume that since Mixe-Zoquan is spoken in the Olmec heartland today, this language was spoken by the ancient inhabitants of Olman: the Olmecs, in ancient times.
But the location of Mixe-Zoquan speakers in this region today does not mean it was spoken in the region in the past. Today it is spoken in the Tuxtla Mountains.The Otomanguean family include Zapotec, Mixtec and Otomi to name a few.
The hypothesis that the Olmec spoke an Otomanguean language is not supported by the contemporary spatial distribution of the languages spoken in the Tabasco/Veracruz area.Thomas Lee in R.J. Sharer and D. C. Grove (Eds.), Regional Perspectives on the Olmecs , New York: Cambridge University Press (1989, 223) noted that
"...closely Mixe, Zoque and Popoluca languages are spoken in numerous villages in a mixed manner having little or no apparent semblance of linguistic or spatial unity. The general assumption made by the few investigators who have considered the situation, is that the modern linguistic pattern is a result of the disruption of an Old homogeneous language group by more powerful neighbors or invaders...."
If this linguistic evidence is correct, many of the languages in the Otomanguean family are spoken by people who may have only recently settled in the Olmec heartland, and may not reflect the people that invented the culture we call Olmecs today.
Moreover if the Olmec had spoken a Mixe-Zoquean language and gave the Maya writing they should have influenced the Mayan language. This is not the case.
Brown has suggested that the Mayan term for writing c'ib' diffused from the Cholan and Yucatecan Maya to the other Mayan speakers. This term is not derived from Mixe-Zoque. If the Maya had got writing from the Mixe-Zoque, the term for writing would Probably be found in a Mixe-Zoque language. The research indicates that no word for writing exist in this language family.
Mixe tradition also suggest that another people lived in the Olmec heartland when they arrived in the area. In "The Mixe of Oaxaca: Religion, Ritual, and Healing", by Frank J. Lipp it is noted that:
"The elders say that there was a people who possessed considerable knowledge and science and that they could make children sick by simply looking at them. At one time they came from a part of Veracruz and took up residence here. However, they spoke a different language. Clearly, they were also Mixe but their language was very modified, and we did not understand the words they spoke"(p.77).
This group was probably the Mande speaking Olmec.Finally, the Mixe hypothesis is not supported by the evidence for the origin of the Mayan term for writing. The Mayan term for writing is not related to Zoque.
In summary Mayan tradition makes it clear that they got writing from another Meso-American group. Landa noted that the Yucatec Maya claimed that they got writing from a group of foreigners called Tutul Xiu from Nonoulco (Tozzer, 1941). Xiu is not the name for the Zoque. Brown has suggested that the Mayan term c'ib' diffused from the Cholan and nYucatecan Maya to the other Mayan speakers. This term is not derived from Mixe-Zoque. If the Maya had got writing from the Mixe-Zoque, the term for writing would Probably be found in a Mixe-Zoque language.
The fact that there is no evidence that 1)the Zoque were in the ancient Olmec land 3200 years ago, 2)there is no Zoque substrate language in Mayan, and 3) there is no such thing as "pre-Proto-Zoque" falsifies the hypothesis that the Mixe were the Olmec people. This evidence makes it clear that the Olmec were called Xiu, and they did not speak Mixe languages.
Due to the lack of evidence for a Mixe origin of the Olmec writing Houston and Coe believe that that the Olmec must of spoken another language. They suggest that the language may have been Huastec .
The Huastec hypothesis is not supported by the linguistic evidence. Swadesh provides linguistic evidence that suggest that around 1200 B.C., when the Olmec arrived in the Gulf, region of Mexico a non-Maya speaking group wedged itself between the Huastecs and Maya.This linguistic evidence is supplemented by Amerindian traditions regarding the landing of colonist from across the Atlantic in Huasteca .