Here, the Olmec constructed permanent city-temple complexes at San Lorenzo Tenochtitlán, La Venta, Tres Zapotes, and Laguna de los Cerros.

Past finds of Olmec remains ritually deposited at the shrine El Manatí near the triple archaeological sites known collectively as San Lorenzo Tenochtitlán moved this back to at least 1600–1500 BCE.

The rise of civilization was assisted by the local ecology of well-watered alluvial soil, as well as by the transportation network provided by the Coatzacoalcos river basin.

[15] Many of these luxury artifacts were made from materials such as jade, obsidian, and magnetite, which came from distant locations and suggest that early Olmec elites had access to an extensive trading network in Mesoamerica.

[37] Infused with individuality, no two heads are alike and the helmet-like headdresses are adorned with distinctive elements, suggesting personal or group symbols.

The Tres Zapotes heads, for example, were sculpted from basalt found at the summit of Cerro el Vigía, at the western end of the Tuxtlas.

The San Lorenzo and La Venta heads, on the other hand, were probably carved from the basalt of Cerro Cintepec, on the southeastern side,[42] perhaps at the nearby Llano del Jicaro workshop, and dragged or floated to their final destination dozens of miles away.

Others note that in addition to the broad noses and thick lips, the eyes of the heads often show the epicanthic fold, and that all these characteristics can still be found in modern Mesoamerican Indians.

For instance, in the 1940s, the artist/art historian Miguel Covarrubias published a series of photos of Olmec artwork and of the faces of modern Mexican Indians with very similar facial characteristics.

[49] Richard Diehl wrote "There can be no doubt that the heads depict the American Indian physical type still seen on the streets of Soteapan, Acayucan, and other towns in the region.

[38] Before radiocarbon dating could tell the exact age of Olmec pieces, archaeologists and art historians noticed the unique "Olmec-style" in a variety of artifacts.

[54] Olmec-style artifacts, designs, figurines, monuments and iconography have been found in the archaeological records of sites hundreds of kilometres outside the Olmec heartland.

For example, numerous natural and ceramic stingray spikes and maguey thorns have been found at Olmec sites,[63] and certain artifacts have been identified as bloodletters.

[65] At El Manatí, disarticulated skulls and femurs, as well as the complete skeletons of newborns or fetuses, have been discovered amidst the other offerings, leading to speculation concerning infant sacrifice.

[66] Some authors have associated infant sacrifice with Olmec ritual art showing limp werejaguar babies, most famously in La Venta's Altar 5 (on the right) or Las Limas figure.

[78] A dozen rubber balls dating to 1600 BCE or earlier have been found in El Manatí, a bog 10 km (6 mi) east of San Lorenzo Tenochtitlan.

[82] Campbell and Kaufman proposed that the presence of these core loanwords indicated that the Olmec – generally regarded as the first "highly civilized" Mesoamerican society – spoke a language ancestral to Mixe–Zoquean.

[87] As no documentations of Olmec religious narratives and figures comparable to the Popol Vuh has been left or found, any interpretation of Olmec religious narratives and figures must be based on interpretations of surviving monumental and portable art (such as the Señor de Las Limas statue at the Xalapa Museum), and comparisons with other seemingly similar elements found throughout nearby Mesoamerican cultures.

[90] This evidence of geographic and demographic centralization leads archaeologists to propose that Olmec society itself was hierarchical, concentrated first at San Lorenzo and then at La Venta, with an elite that was able to use their control over materials such as water and monumental stone to exert command and legitimize their regime.

[94] Studies of the Sierra de los Tuxtlas settlements, some 60 km (35 mi) away, indicate that this area was composed of more or less egalitarian communities outside the control of lowland centers.

Based on archaeological studies of two villages in the Tuxtlas Mountains, it is known that maize cultivation became increasingly important to the Olmec over time, although the diet remained fairly diverse.

[101] Despite the wide range of hunting and fishing available, midden surveys in San Lorenzo have found that the domesticated dog was the single most plentiful source of animal protein.

In 1869, the Mexican antiquarian traveller José Melgar y Serrano published a description of the first Olmec monument to have been found in situ.

Hearing about the curious find while travelling through the region, Melgar y Serrano first visited the site in 1862 to see for himself and complete the partially exposed sculpture's excavation.

[104] In the latter half of the 19th century, Olmec artifacts such as the Kunz Axe (right) came to light and were subsequently recognized as belonging to a unique artistic tradition.

[106] In counterpoint to Stirling, Covarrubias, and Alfonso Caso, however, Mayanists J. Eric Thompson and Sylvanus Morley argued for Classic-era dates for the Olmec artifacts.

[107] Shortly after the conference, radiocarbon dating proved the antiquity of the Olmec civilization, although the "mother culture" question generated considerable debate even 60 years later.

The bone consistency in two of them allowed the study of their mitochondrial DNA to be carried out successfully, as part of an investigation that proposes the comparative analysis of the genetic information of the Olmecs with that obtained from subjects from other Mesoamerican societies under the advice of the specialists Dr. María de Lourdes Muñoz Moreno and Miguel Moreno Galeana, both at CINVESTAV in Mexico.

This pioneering study of mitochondrial DNA in 2018 was carried out on two Olmec individuals, one from San Lorenzo and the other from Loma del Zapote, resulted, in both cases, in the unequivocal presence of the distinctive mutations of the haplogroup A maternal lineage.

[115] As of 2018, mitochondrial DNA studies carried out on Olmec remains, one from San Lorenzo and the other from Loma del Zapote, resulted, in both cases, in the “unequivocal presence of the distinctive mutations of the “A” maternal lineage.