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. This viewpoint is echoed by a minority of other researchers including art historian Caterina Magni who nonetheless agrees that the Olmecs bequeathed a rich heritage to later cultures. However, Magni does not agree that what is presently labelled as Olmec culture was first and foremost the product of the heartland. "Contrary to [this] generally accepted idea, the brilliant [Olmec] culture did not originate in the Gulf coast of Veracruz and Tabasco. In truth, the varied and voluminous archaeological data shows a much more complex reality; [instead] Olmec religious and political centers emerged simultaneously throughout a vast part of Mesoamerica: from Mexico to Costa Rica." Magni attributes these concepts to noted archaeologist Christine Niederberger. Olmec-style pottery analysis In an effort to address questions concerning the geographic origins of Olmec artifacts — with implications concerning the geographic origins of Olmec culture — in March 2005 a team of archaeologists used instrumental neutron