The causes and degree of Olmec influences on Mesoamerican cultures has been a subject of debate over many decades. Although the Olmecs are considered to be perhaps the earliest Mesoamerican civilization, there are questions concerning how and how much the Olmecs influenced cultures outside the Olmec heartland. This debate is succinctly, if simplistically, framed by the title of a 2005 The New York Times article: “Mother Culture, or Only a Sister?”.
Olmec heartland
Nearly all researchers agree on a number of specific issues concerning the Olmec and the Olmec Heartland:
The forebears of the Olmecs were indigenous to the Olmec heartland, and developed their civilization independent of other civilizations. The Olmec civilization arose in the Olmec heartland with the flowering of San Lorenzo Tenochtitlán in the centuries before 1200 BCE.
Beyond the heartland
While some of the hallmarks of Olmec culture, such as colossal heads or other sculptures, earthen platforms, and monolithic "altars", are to be found only within the heartland, many Olmec-style artifacts, designs, figurines, monuments, and motifs can be found in the archaeological records of sites hundreds of kilometers/miles distant. The most prominent of these sites are:
Tlatilco and Tlapacoya, major centers of the Tlatilco culture in the Valley of Mexico, where artifacts include hollow baby-face motif figurines and Olmec designs on ceramics. Chalcatzingo, in the Valley of Morelos, which features Olmec-style reliefs on monuments and exposed rock. Teopantecuanitlan, in Guerrero, which also features Olmec-style reliefs as well as city plans with distinctive Olmec features. San José Mogote, in Oaxaca, which features Olmec-style pottery. San Jose Mogote is, like the larger Olmec site of La Venta, oriented 8° west of north.
Other sites showing Olmec influence include Takalik Abaj and Monte Alto in Guatemala, Las Bocas in Puebla, and Zazacatla. In all these cases, the archaeological record shows Olmec-influenced objects existing alongside objects in the local tradition. Often, for example at Las Bocas, Olmec inconography will even appear on objects created in the local tradition.
The Olmec influences in these sites all post-date San Lorenzo and the cultural pathways almost exclusively flow from the Olmec heartland to these distant sites, and not in the other direction (from, say, Chalcatzingo to San Lorenzo Tenochtitlan). This apparent one-way flow has led most researchers to declare Olmecs to be the "mother culture" of Mesoamerica.
To quote perhaps the most prominent of Mesoamerican archaeologists, Michael D. Coe, "There is now little doubt that all later civilizations in Mesoamerica, whether Mexican or Maya, ultimately rest on an Olmec base." To this, Coe's student archaeologist Richard Diehl adds "While not every archaeologist agrees with Coe, ... mounting evidence ... has convinced everyone but the most die-hard opponents".
Mother culture
The concept of the Olmecs as a mother culture was first formally raised by Alfonso Caso at a 1942 conference on the "Olmec problem" in Tuxtla Gutiérrez where he argued that the Olmec were the "cultura madre" of Mesoamerica.
The proponents of the "mother culture" do not argue that the Olmec were the only contributors, but that the Olmecs first developed many of the features adopted by later Mesoamerican civilizations.
They argue that it was in San Lorenzo and the Olmec heartland that the hallmarks of the Olmec culture were first established, hallmarks that include the patio/plaza concept, monumental sculpture, Olmec iconography, archetypical Olmec figurines, and other portable art.
Sister culture
The "sister culture" proponents, on the other hand, state that Mesoamerican cultures evolved more or less simultaneously. Major proponents of this theory include Joyce Marcus and Kent V. Flannery, who argue that the Olmec were merely the first among equals, rather than the wellspring of cultural change.
"It is the adaptive autonomy and frequent competitive interaction of such chiefdoms that speed up evolution and eventually make useful technologies and sociopolitical strategies available to all regions.".
In a subsequent paper, they imply, for example, that Olmec iconography may have originated in the early Tlatilco culture.