Skull in Underwater Cave May Be Earliest Trace of First Americans

National Geographic: Skull in Underwater Cave May Be Earliest Trace of First Americans
By Fabio Esteban Amador

Explorers have discovered what might be the oldest evidence of humans in the Americas.

Alex Alvarez, Franco Attolini, and Alberto (Beto) Nava are members of PET (Projecto Espeleológico de Tulum), an organization that specializes in the exploration and survey of underwater caves on the Yucatan Peninsula in Mexico.

Alex, Franco and Beto have surveyed tens of thousands of feet of mazelike cave passages in the state of Quintana Roo. The team's relatively recent explorations of a large pit named Hoyo Negro (Black Hole, in Spanish), deep within a flooded cave, resulted in their breathtaking and once-in-a-lifetime discovery of the remains of an Ice Age mastodon and a human skull at the very bottom of the black abyss.

Beto recalls the amazing day of the discovery of Hoyo Negro.

"We started the exploration while following the main tunnel and progressed relatively fast by using scooters to cover more terrain.

"After about 1,500 feet [450 meters] we began to see the light of another entrance, so we headed towards it and surfaced.

"After taking a moment to chat and laugh about what a great dive we were having, we dropped down to continue the work.

"After about 400 feet [120 meters] the tunnel narrowed to form a circular shape, almost like a huge cement pipe. I made one tie-off and, while waiting for Franco to complete his surveying effort, I took a good look at the strangely shaped tunnel.

"All I could see was the whiteness of the cave walls along the sides, and beyond that it was all black. I thought to myself that this is either the largest tunnel I have seen or there is something unusual at the end of it.

"After Franco caught up, we continued for another 200 feet [60 meters] and eventually reached the end of the tube-shaped tunnel. To our surprise the floor disappeared and all we could see was blackness in all directions. It felt like we had reached a big drop-off or the edge of a canyon wall.

"We tried to slow down our heart rates as we were not really sure of what to do next."

The Aktun-Hu cave system, where Hoyo Negro is located, is completely filled with water and is fully decorated with speleothems.

Where is Hoyo Negro?

Hoyo Negro was reached by the PET team after the divers travelled more than 4,000 feet [1,200 meters] through underwater passages using underwater propulsion vehicles, or scooters, which enabled them to cover long distances in the flooded cave system.

Once they reached the pit, they began to survey and document its dimensions. The pit is approximately 200 feet [60 meters] deep and 120 feet [36 meters] in diameter and is located inside the Aktun-Hu cave system in the state of Quintana Roo, Mexico.

Submerged cave systems in Quintana Roo have been systematically surveyed and mapped by teams of highly specialized divers. The PET team is affiliated with Global Underwater Explorers, as is the Mexico Cave Exploration Project.

"The immense size of Hoyo Negro is difficult to comprehend. Once you enter the pit you cannot see the floor below, and all that can be seen in front of you is a black void -- an inviting entrance to the abyss, " recalls Franco.

The team of explorers touched bottom at 197 feet [57 meters], where they made their incredible discovery.

How Did the Tunnels Form?

The Yucatan Peninsula's geology is almost entirely limestone -- a karstic shelf that is easily dissolved by rainwater, forming caves and sinkholes.

Approximately 12,000 years ago, at the end of the Pleistocene epoch, Earth experienced great climatic changes. The melting of the ice caps caused a dramatic rise in global sea levels, which flooded low lying coastal landscapes and cave systems. Many of the subterranean spaces that once provided people and animals with water and shelter became inundated and lost until the advent of cave diving.

Ironically, the Yucatan Peninsula does not have any major rivers or lakes; however, there are many underground rivers and water-filled caves or sinkholes known as cenotes (a Spanish word derived from the Maya dzonot).

What Was Found at the Bottom of the Black Hole?

While the team of explorers conducted various dives for the purpose of mapping and surveying of this newly discovered pit, they noticed some peculiar bones sitting on the bottom. They first came across several megafauna remains and what was clearly a mastodon bone, while subsequent dives proved even more exciting when they spotted a human skull resting upside down with other nearby remains at about 140 feet [43 meters] depth.

"I was searching for more of the mastodon remains, when I saw what looked like a human skull. I had thought we already had a great discovery after finding the remains of several Pleistocene animals...but finding a human skull was totally amazing for us. All of our efforts... walking through the jungle, carrying all the gear, securing the helium required to do such a deep dive, laying thousands of feet of exploration line... paid off at that moment. This is the Holy Grail of underwater cave exploration," Alex said.

"This is the Holy Grail of underwater cave exploration."

Soon after the discovery, the team contacted Guillermo de Anda, an archaeologist from the University of Yucatan in Merida (UADY) who has also been documenting Pleistocene megafauna sites and who helped in the identification of the Hoyo Negro discovery.

"The findings of Hoyo Negro are a once-in-a-lifetime discovery. The skull looks pre-Maya, which could make it one of the oldest set of human remains in the area. Gaining an understanding of how this human and these animals entered the site will reveal an immense amount of knowledge from that time. Therefore, protecting and learning the secrets of Hoyo Negro should be one of the main priorities for the archaeologists in the region," Guillermo told News Watch in an interview.

The PET team formally announced the discovery at Hoyo Negro to Pilar Luna Erreguerena, Director of Underwater Archaeology for Mexico's National Institute for Archaeology and History (INAH). Pilar is the founder of underwater archaeology in Latin America and has been instrumental in protecting Mexico's submerged cultural heritage.

"This discovery is extremely important and confirms the cultural diversity and richness that can be found in the Yucatan Peninsula," said Pilar Luna. "INAH's division of underwater archaeology is preparing a multidisciplinary project together with discoverers of the site. This team work will allow us to scientifically recover the data and the evidence in its own context, so that experts may really get to know the true value of this discovery and turn it into a deeper knowledge or understanding of the prehistoric era in this part of Mexico."

At present, the entrance to the site is limited to INAH's research team since they are responsible for maintaining the integrity of the site.

Studies in the Tulum area, similar to those currently being planned for Hoyo Negro, were accomplished for the very first time by Pilar Luna's collaborators, namely Arturo González, Carmen Rojas, Octavio Del Río, Eugenio Aceves, and Jerónimo Avilés, with the support of Adriana Velázquez, Director of Centro INAH Quintana Roo.

What is the Significance of the Discovery of Hoyo Negro?

The human found with the megafauna remains in Hoyo Negro could represent the oldest evidence of humans yet discovered in the Americas.

Archaeological and genetic data have long supported a northeast Asia origin for the populations that first settled North and South America. The so-called "First Americans" or Paleoindian peoples likely entered into these new lands sometime between 15,000 and 20,000 years ago.

Although a number of early archaeological sites have been excavated, only few sets of Paleoindian remains have been found. A detailed analysis of the human skeletal remains from Hoyo Negro can help us to better understand who these First Americans were and when they arrived here, which is one of the greatest mysteries in American archaeology.

Radiometric dating of the human bones from Hoyo Negro will have to wait for now, but its location within the cave, and its position relative to the mastodon remains, are suggestive of its antiquity.

Waitt Institute archaeologist and New World cave expert, Dominique Rissolo, offers a compelling argument for the importance of this site and similar discoveries. "The cenotes of Quintana Roo, Mexico, have emerged as one of the most promising frontiers for Paleoindian studies in the Americas.

"Recent discoveries of human remains deep within the region's flooded caverns, as well the bones of mastodons and other extinct species of Pleistocene megafauna, offer an extraordinarily rare glimpse into a period that witnessed the peopling of the New World.

"During the Late Pleistocene, these caves were dry. The first people to occupy what is now the Caribbean coast of Mexico wandered into these caves, where some ultimately met their demise.

"As the last glacial maximum came to end, the melting of the polar ice caps and continental ice sheets raised sea levels worldwide. The caves of the Yucatan Peninsula filled with water and the First Americans were hidden for millennia -- only to be discovered by underwater cave explorers

"It is within these dark reaches that cave explorers are discovering and documenting the oldest human skeletons yet found in the Western Hemisphere," Rissolo said.

Future Research at Hoyo Negro

In the summer of 2010, Pilar Luna organized a Nautical Archaeology Society training course for the Hoyo Negro team. The course, which was funded by National Geographic Magazine thanks to Chris Sloan, a magazine editor, covered the essentials of underwater archaeological site recording.

In collaboration with INAH, the team hopes to continue their exploration of Hoyo Negro and to thoroughly document the findings at the site.

Perhaps this is a turning point in scientific exploration in the region, where successful research will depend upon the knowledge and experience of a multidisciplinary team that includes underwater archaeologists, geologists, and paleontologists working side by side with highly skilled divers.

The National Geographic/Waitt Grants Program has funded similar research in the past by supporting GUE diver, Sam Meacham, in his cave exploration and water conservation work in Quintana Roo.

National Geographic has been active in featuring similar discoveries made by cave divers on the Yucatan peninsula. In 2008 National Geographic Daily News published the discovery of the Eve of Naharon, a female skeleton dated to 13,600 years old, which was also found in an underwater cave in Quintana Roo. (Oldest Skeleton in Americas Found in Underwater Cave? )

More recently in 2010, National Geographic Daily News published an article on the Young Man of Chan Hol, a possible ritual burial from 10,000 years ago. (Undersea Cave Yields One of Oldest Skeletons in Americas)

In addition to the latest extraordinary expedition and amazing discovery, Robbie Schmittner connected the Aktun-Hu cave system (where Hoyo Negro is located) to the Sac Actun cave system. Together they may now represent the longest underwater cave system in the world.

Future investigations in Hoyo Negro will no doubt reveal new clues about the peopling of the New World.