Tests on skulls found in Mexico suggest they are almost 13,000 years old - and shed fresh light on how humans colonised the Americas.
The human skulls are the oldest tested so far from the continent, and their shape is set to inflame further a controversy over native American burial rights. Mexico appears to have been a crossroads for people spreading across the Americas.
The skulls were analysed by a scientist from John Moores University in Liverpool, UK, with help from teams in Oxford and Mexico itself. They came from a collection of 27 skeletons of early humans kept at the National Museum of Anthropology in Mexico City. These were originally discovered more than 100 years ago in the area surrounding the city.
The latest radiocarbon dating techniques allow dating to be carried out on tiny quantities of bone, although the process is expensive. Dr Silvia Gonzalez, who dated the skulls, said:
"The museum knew that the remains were of significant historical value but they hadn't been scientifically dated. "I decided to analyse small bone samples from five skeletons using the latest carbon-dating techniques," she told BBC News Online. "I think everybody was amazed at how old they were." The earliest human remains tested prior to this had been dated at approximately 12,000 years ago. Domestic tools dated at 14,500 years have been found in Chile - but with no associated human remains. The latest dating is not only confirmation that humans were present in the Americas much earlier than 12,000 years ago, but also that they were not related to early native Americans.
The two oldest skulls were "dolichocephalic" - that is, long and narrow-headed. Other, more recent skulls were a different shape - short and broad, like those from native American remains. This suggests that humans dispersed within Mexico in two distinct waves, and that a race of long and narrow-headed humans may have lived in North America prior to the American Indians. Traditionally, American Indians were thought to have been the first to arrive on the continent, crossing from Asia on a land bridge.
Dr Gonzalez told BBC News Online: "We believe that the older race may have come from what is now Japan, via the Pacific islands and perhaps the California coast. "Our next project is to examine remains found in the Baha peninsula of California, and look at their DNA to see if they are related.
Chile: Monte Verde, Chile: is a boggy stream-bed in which mastodon bones and wet preserved plant remains were found with a few stone tools, including three bi-pointed points and a crude bi-face. Monte Verde which was occupied some 14,500 years ago, provides a slightly different view of life for the early inhabitants of South America.
Due to the quality of preservation at Monte Verde, natural materials such as wood, fiber, and cordage remain. Even a human footprint has been found there. This range of artifacts crafted from perishable materials is typically lost to archaeologists.
Their preservation due to the extremely wet conditions at Monte Verde indicate that baskets, fishing nets, and tents made from hides were among the range of belongings used by the thirty or so people who lived there. These campers were likely able fishermen and gatherers of wild plants, which would have supplemented their diet of hunted animals.
They also crafted exquisite leaf-shaped spearpoints. These weapons and hunting tools are not dissimilar from the examples from Fell's Cave, which suggests that the two sites, while separated in time by more than 4,000 years, were part of a long-standing and connected tradition of thriving in the new world.
Venezuela: At Taima Taima, an oil field site in northern Venezuela, fragmentary tools were found with cut mastodon bones in a spring where cultural and natural materials had become mixed.
One tool is a bi-pointed style point. The ancient habitat was swampy, wooded, and subtropical.
The radiocarbon dates range too widely for comfort - from about 41,000 to 12,000 B.P. Late Pleistocene people may have killed mastodon there, but exactly when is not certain.
In nearby Colombia, early pre-pottery sites have also been found, notably at El Jobo in Falcón, that date to about 14,920 B.C.E. There carved stone was used for such objects as small pendants: shell and bone are also known to have been used. Some of these sites contain triangular points, while others have ground-stone tools. Food remains are tropical forest fruits and nuts. In the Andes highlands of Peru, early work had uncovered possible big-game kill sites dating to as early as 20,000 years ago, but these had no clear association with humans.
Sites with triangular and sometimes stemmed points and diverse modern fauna and flora, date to between 11,500 and 8,500 years ago. The first secure evidence of early Paleo-indians on the Pacific coast was from two south Peruvian sites with beginning dates between 11,100 and 10,700 years ago. At the sites Quebrada and Jaguay, the ancient hearths contained carbonized fragments of stone tools and remains of shellfish, small fish, and birds, but no large game.
Luzia: Several studies concerning the extra-continental morphological affinities of Paleo-Indian skeletons, carried out independently in South and North America, have indicated that the Americas were first occupied by non-Mongoloids that made their way to the New World through the Bering Strait in ancient times.
The first South Americans show a clear resemblance to modern South Pacific and African populations. In none of these analyses the first Americans show any resemblance to either northeast Asians or modern native Americans.
So far, these studies have included affirmed and putative early skeletons thought to date between 8,000 and 10,000 years B.P. In this work the extra-continental morphological affinities of a Paleo-Indian skeleton well dated between 11,000 and 11,500 years B.P.
(Lapa Vermelha IV Hominid 1,"Luzia") is investigated, using as comparative samples Howells' (1989) world-wide modern series and Habgood's (1985) Old World Late. The results obtained clearly confirm the idea that the Americas were first colonized by a generalized Homo sapiens population which inhabited East Asia in the Late Pleistocene, before the definition of the classic Mongoloid morphology.
Above: A skull belonging to a roughly 20 year old Australoid woman that was unearthed in Brazil by the French archaeologist Annette Amperaire in 1971, nicknamed “Luzia”. Since Luzia's discovery, at least 50 similarly un-mongoloid Palaeoamerican remains have been found in the Lagoa Santa area near where "Luzia" herself was found. They all seem to have been buried within a small area that may have been a cemetery. This raises the intriguing question of whether the Lagoa Santa population at this early time, was perhaps already settled in a specific area and perhaps were even no longer just hunter-gatherers.
Deep inside an underwater cave in Mexico, archaeologists may have discovered the oldest human skeleton ever found in the Americas. Dubbed Eva de Naharon, or Eve of Naharon, the female skeleton has been dated at 13,600 years old. If that age is accurate, the skeleton—along with three others found in
underwater caves along the Caribbean coast of the Yucatán Peninsula.
Arturo Gonzalez, Eve of Naharon, Eva, Native American
The remains have been excavated over the past four years near the town of Tulum, about 80 miles southwest of Cancún, by a team of scientists led by Arturo González, director of the Desert Museum in Saltillo, Mexico.
Clues from the skeletons'
skulls hint that the people may not be of northern Asian descent, which would contradict the dominant theory of New World settlement.
That theory holds that ancient humans first came to North America from northern Asia via a now submerged land bridge across the Bering Sea.
"The shape of the skulls
has led us to believe that Eva and the others have more of an affinity with people from South Asia than North Asia," González explained.
The three other skeletons excavated in the caves have been given a date range of 11,000 to 14,000 years ago, based on radiocarbon dating.
The remains were found some 50 feet (15 meters) below sea level in the caves off Tulum. But at the time Eve of Naharon is believed to have lived there, sea levels were 200 feet (60
meters) lower, and the Yucatán Peninsula was a wide, dry prairie.
The polar ice caps melted dramatically 8,000 to 9,000
years ago, causing sea levels to rise hundreds of feet and
submerging the burial grounds of the skeletons.
Stalactites and stalagmites then grew around the remains, preventing them
from being washed out to sea. González has also found remains of elephants, giant sloths, and other ancient fauna in the caves.
Fell's Cave is a rock shelter in the valley of the Chico
River, not far from the Strait of Magellan in the Chilean part of the Tierra del Fuego Archipelago.
It was initially occupied
by hunters around 10,000 B.C.E. who left behind an impressive layer of refuse which was sealed by hundreds of pounds of
debris from the fall of the shelter overhang.
The hunter's refuse included firepots with the broken bones of native
horse, sloth, and guanaco, as well as stone and bone tools.
Among the stone tools were fishtail spearpoints, a form of stone point found in many places in South America.
Fishtail points are flaked bifacially (that is, worked on both sides) and have pronounced shoulders above a clearly shaped stem.
Some are fluted with small channels removed from the bottom.
In 1936-37, the discoveries in Fell's Cave represented the first evidence of early humans in South America. Since then, older sites such as Monte Verde have been identified.