Deep beneath the tropical forests of the Yucatán Peninsula, the submerged cave system known as Hoyo Negro is revealing secrets from the Ice Age. This vast underground realm, part of the second-largest cave system in the Mexican state of Quintana Roo, has remained largely untouched for millennia. Researchers, including divers and scientists from the National Institute of Anthropology and History (INAH), are uncovering a wealth of fossils and evidence of ancient human activity that date back as far as 12,970 years.
Hoyo Negro, discovered by divers Alejandro Alvarez, Franco Attolini, and Alberto Nava Blank in 2007, gained international attention after the remains of Naia, one of the oldest known human skeletons in the Americas, were found within its depths. The Hoyo Negro Underwater Archaeological Project, initiated by INAH in 2010, has since facilitated the exploration of this submerged wonder, allowing scientists to piece together its historical significance.
Diving into the Unknown
Exploratory dives into the cave system are fraught with challenges. Roberto Chávez Arce, co-director of the project, has been navigating these treacherous tunnels since 2011. His remarkable underwater photography has provided a glimpse into the subterranean world. Initially, divers relied on basic tools like compasses and measuring tapes to map the cave, but advancements have led to the use of structure-from-motion (SfM) photogrammetry, creating detailed 3D representations of Hoyo Negro.
Accessing the site has become more efficient over time. Previously, divers had to enter through a cenote located 3,000 feet (914 meters) away, requiring nearly an hour of swimming. Now, a newly discovered cenote just 250 to 300 feet (76 to 91 meters) from the pit and the use of motorized scooters have significantly decreased travel time.
Evidence of Life in the Ice Age
The cave’s history reveals that it was once dry and accessible. Sediment analyses indicate that water levels fluctuated dramatically over millennia, with the cave reaching its current underwater state approximately 6,000 years ago. This flooding coincided with the rising sea levels, making Hoyo Negro a unique archaeological site.
During the Late Pleistocene, the region was vastly different, resembling a savanna rather than the lush jungle seen today. The cave’s freshwater sources would have attracted both humans and animals. Evidence of human activity includes tools and ochre mining, a mineral used for various cultural practices. The ochre found in the Yucatán, noted for its high arsenic content, raises questions about its use in lice control and other purposes.
Among the notable discoveries are the remains of Naia, who was around 15 to 17 years old at the time of her death. Her skeletal analysis suggests she suffered a fatal injury after falling into the pit, providing insights into the dangers faced by ancient people in this environment. Dr. James Chatters, another co-director of the project, emphasized the significance of Naia’s find in understanding early human life in the Americas.
Fossils of various extinct species have also been recovered, including short-faced bears and ground sloths, alongside evidence of their interactions with the environment. The discovery of Protocyon troglodytes and gomphotheres in the cave system expands knowledge about these animals’ habitats during the Pleistocene.
As the research continues, the findings from Hoyo Negro are anticipated to contribute significantly to understanding the Great American Biotic Interchange. This period of migration between North and South America holds critical implications for evolutionary studies and climate change impacts.
The ongoing project at Hoyo Negro is poised to unveil more about the intricate tapestry of life that existed in this submerged cave. Researchers hope to present further findings at future academic conferences, reinforcing the cave’s status as a vital resource for paleontological discovery. As Chávez Arce aptly stated, the exploratory work in Hoyo Negro allows us to “travel back in time” and gain a deeper understanding of the Earth’s ancient ecosystems.
