TULUM.- More than 10 thousand years ago, on the peninsula of Yucatan, very different from the one we now know: with a cold climates and extensive prairies similar to those of the British islands or the Cantabrian coast of Spain, the first humans of America already interacted with the wild environment, leaving traces that today are being discovered and studied from archaeology and science.

This is the case of a new investigation, endorsed by the National Institute of Anthropology and History (INAH), whose results are made public as part of the campaign "Contigo en la Distancia" – “With You by Long Distance” of the Ministry of Culture, and published in the most recent issue of the journal Geoarchaeology, which verifies -for the first time in an underwater context- that hunter-gatherers lit and used fire in the space today known as the “Cámara de los Ancestros”– “Chamber of Ancestors”, formation located in the cave system of the cenote Aktun Ha, in Quintana Roo.

This is corroborated by 14 prehistoric bonfires, whose samples -obtained between 2017 and 2018- were subjected to laboratory studies: controlled heating, petrography, Taphonomy, nuclear magnetic resonance spectroscopy and Carbon Dating 14, and demonstrated two key points:

The first, explains archaeologist Luis Alberto Martos López, of the Department of Archaeological Studies (DEA) of the INAH, relating to an antiquity that ranges between 10,750 and 10,250 years before the present. This is the oldest time period reported through charcoal with human association in a cenote of the peninsula, coinciding with the end of the last glaciation, occurring during the Pleistocene to Holocene period.

The second and even more important is the confirmation that these fires, some of which reached temperatures of 600 ºC, had an anthropogenic origin in situ, meaning, that the remains of coal arriving through the natural action of water after the rise of the sea level on Earth is discarded.

After confirming that these results were crucial to understand the populating of the American continent and the Yucatan peninsula, Martos explained that the project was authorized by the Council of Archaeology of the INAH, and carried out under the coordination of researchers Octavio del Río Lara and Rafael López Martínez, as well as with the participation of Adriana Velázquez Morlet, who in 2018 was the Director of the INAH Quintana Roo Center.

The Chamber of Ancestors has been investigated three times. The first in 1990, when two speleodivers by the name of Coke and Young made a tour of it, the second by the INAH in 1998 and again in 2002.

The cenote Aktun Ha thus became the first flooded cave, nationally, that showed temporary prehistoric human occupation, possibly as a room, shelter maybe for ritualistic purposes. Other notable discoveries verified by the INAH in similar contexts are those of Naharon, Las Palmas and Hoyo Negro, with ancient human remains, also located in the labyrinthine subsoil that surrounds Tulum.

The Chamber of Ancestors is located 150 meters from the entrance of the cenote and 26 meters deep. It is a space of about 20 square meters by 5 or 6 meters high. Its morphology -recorded in plans and in a 3D reconstruction- was propitious for the ventilation of smoke from the burning of the fires, as the hot air rose and left the cave easily.

The ‘Car Wash’ cenote in prehistoric times
Aktun Ha is colloquially known by the name ‘Car Wash’ in English. This is because in the years prior to its revaluation as a heritage site it was common for taxi drivers from the Tulum area to take advantage of its proximity to the road and wash their cars there.

Now, the cenote, of which part is open to tourism, is well preserved by the local authorities, who simultaneously ban all access to the areas that lead to the Chamber of Ancestors.

In prehistoric times it was different. Luis Alberto Martos describes that the Chamber of Ancestors back then was a dry cavern only 80 centimeters high that today, when completely flooded, is dangerous to traverse even for trained underwater archaeologists.

"This small tunnel, hidden behind a mound of rocks richly bedecked with stalactites, stalagmites and columns that could serve as an access sign," was crawl space only, which no doubt provided protection to its access, avoiding the infiltration of the great predators of that era as were the saber-toothed tigers and bears, or other bands of hunter-gatherers.

In addition to its being a refuge, the cave also provided fresh water, since at the bottom of the Chamber of Ancestors there was a natural well, whose existence was verified by analyzing zeolite mineral remains.

Also noteworthy is that the project involved the participation of a multidisciplinary panel of experts, coordinated by Octavio del Río, of the Nautical Archaeology Society and who has been a collaborator of INAH, and by Rafael López, of the Institute of Geology (IGL) of UNAM.

Luis Alberto Martos and Adriana Velázquez, from the DEA and the INAH Quintana Roo Center, respectively; Elizabeth Solleiro Rebolledo and Jaime Díaz Ortega, from the IGL; Bruno Chávez Vergara, from the National Geochemistry and Mineralogy Laboratory of the UNAM; Agustín Merino, from the Polytechnic of Santiago de Compostela; Alejandro Terrazas Mata, from the Anthropological Research Institute of the UNAM; Felipe Trabanino García, from the Postdoctoral Scholarship Program of the UNAM, and Eugenio Acevez, Director of the Museum of Prehistory in Quintana Roo.