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Timeline of selected archaeological, geological and genetic evidence
|40,000 B.C. – 25,000 B.C.
- Paleolithic people move into Beringia across the Bering Land Bridge into western Alaska.
- Bison (buffalo), mammoths, and mastodons are thought to have migrated from Asia to America about this time. This would imply a land bridge between the continents that would have had a food supply.
|30,000–20,000 years ago:
(Note: The dates given for the Old Crow and Topper digs have not been completely accepted by the archaeology community.)
(Note: The conclusions reached in Alberta on dates have not been accepted by the entire archaeology community.)
- Cambridge DNA Services estimates humans entered the Americas around 25,000 years ago. Other geneticists have variously estimated that peoples of Asia and the Americas were part of the same population from about 21,000 to 42,000 years ago.
- Siberian mammoth hunters were believed to have penetrated far into the Arctic where ice-free corridors north during the time are believed found. Theory first introduced by geologists in the late 1970s when core samples indicate the ice is no older than 17,000 years old.
|23,000–16,500 years ago:
- The Ice Age entombs the northern hemisphere in glaciers, cutting off routes from Siberia to the south.
- 2002 the presence of the X haplogroup was found in a small percentage of modern indigenous Americans that is known to exist in a few locations in Europe and the Middle East. Subsequent research indicated that this DNA was not the result of genetic mixing after Columbus. However, the time estimates on haplogroup X entering Americas is around 15,000 to 20,000 years ago.
- Genetic evidence (2007–2009) suggests the Beringia population's first genetic diversification from Asian populations occurred. An article in the American Journal of Human Genetics states "Here we show, by using 86 complete mitochondrial genomes, that all Native Americanhaplogroups, including haplogroup X, were part of a single founding population.
|16,500–13,000 years ago:
- Receding glaciers reopened an ice-free corridor through Canada between Alaska and the rest of the Americas. Massive flooding would have created large lakes covering vast areas of north America with glacial waters.
- Age estimates based on Y-chromosome micro-satellite place diversity of the so called "American Haplo" Q1a3a1 at around 10,000 to 15,000 years ago.
- Mass extinction of large fauna begins due to climate change and perhaps hunting. The Dire Wolf, Smilodon, Cave Lion, Giant beaver, Ground sloth, Mammoth, American Mastodon, American Camel, American Equine, and American lion all become extinct by 11,000 years ago.
- Pre-Clovis sites uncovered from 1973 to 1978 Meadowcroft Rockshelter in Pennsylvania site indicated occupancy as early as 16,000 years ago and possibly as long as 19,000 years ago. Dates in excess of 19,000 years have been claimed for the deepest occupation layer uncovered.
- pre-Clovis sites found in Monte Verde, located along Chinchihuapi Creek, in Chile. A crew of eighty people, led by Tom Dillehay of the University of Kentucky, excavated the site from 1977 to 1985. A coastal migration could explain how people arrived in Monte Verde.
- 2000, archaeologists say people were living at Cactus Hill, Virginia where stone tools and charcoal from a fire pit are found.
|15,000–13,000 years ago:
- The Taima Taima mastodon kill/butchering site in Falcon, Venezuela was first excavated by J.M. Cruxent in the 1960s and 1970s. It is one of the earliest archaeological sites that is pre-Clovis. In 1976 a broken El Jobo point (red arrow) was found inside the pubic cavity of a partially disarticulated and butchered young mastodon whose bones had been cut, with a jasper flake found near the left ulna of the animal.
- Peñon women found by an ancient lake bed near Mexico City in 1959.
- El Abra sites located in the valley east of the city of Zipaquirá, Colombia. First excavated by Gonzalo Correal and associates in the late 1970s and early 1980s. 3,072 pieces found indicate it was inhabited continuously for over 7,000 years.
- At Paisley Caves in the Cascade Range of Oregon, archaeologists find a scattering of human coprolites, or fossil feces in 2003. The mitochondrial DNA extracted from coprolites linked the cave dwellers to two genetic groups of early Americans that arose 14,000 to 18,000 years ago. These two genetic groups were the founding Paleo-Indians and later Na-Dené migration.
|13,500–12,000 years ago:
- The Ice Age is ending, melting glaciers have raised sea levels 120 meters and submerged the land bridge between Alaska and Siberia. Geologic evidence indicates that by 11,500 years ago, the Cordilleran and Laurentide ice sheets had retreated far enough to open a habitable ice-free corridor between them. The exposed land was dry and probably restored enough to support plants and animals, which the migrating hunter-gatherer followed.
- Clovis theory – People were living near Clovis, New Mexico where tools from this era were found in the 1930s. This find gave rise to the widely held "Clovis First" theory that people spread through the Americas only after the Ice Age. The Clovis culture was believed replaced by several more localized regional cultures, such as the Folsom tradition, from the time of the Younger Dryas cold climate period.
- Peru coastal region inhabitants fished with nets and bone hooks, collecting seafood such as crabs and sea urchins.
|12,000–10,000 years ago:
- Ice age over, climate similar to present temperatures. Old migration theories believe first widespread migration in South America and subsequently a dramatic rise in population all over the Americas, introduced in the 1930s.
- The Maritimes of Canada are settled by Paleo-Indians. Sites in and around Belmont, Nova Scotia have evidence indicating small seasonal hunting camps, perhaps re-visited over many generations.
- Luzia Woman's skull and other bones excavated in the Lagoa Santa, Brazil area by French archaeologist Annette Laming-Emperaire in the 1970s. By 2006, Lagoa Santa sites had produced no fewer than 75 well-preserved ancient skulls.
- 1994, University of California, Riverside anthropologist R. Erv Taylor examined seventeen of the Spirit Cave artifacts near Fallon, Nevada from the 1940s using mass spectrometry. The results indicated that a mummy was approximately 9,400–10,200 years old — older than any previously known North American mummy.
- Unique markers found in DNA recovered from an Alaskan tooth were found in specific coastal tribes, and were rare in any of the otherindigenous peoples in the Americas. This finding lends substantial credence to a migration theory that at least one set of early peoples moved south along the west coast of the Americas in boats.
|9,000–8,000 years ago:
- Remains, known as Kennewick Man, are found in 1996 on the Columbia River near Kennewick, Washington. A skull and more than 300 bones and bone fragments were found at the site, making up among the oldest, best preserved, and most complete human remains ever found in North America. Initial radiocarbon dating indicated the remains were between 7,000 and 9,500 years old. A leaf-shaped projectile found on the body was long, broad and had serrated edges, all fitting the definition of a Cascade point. This type of point is a feature of the Cascade phase, occurring in the archaeological record from roughly 6,000 to over 8,500 years ago.
- 1930s-1990s no major Central American archaeological sites that go back more than 9,000 years have been found. Isolated finds of stone tools in Belize, Nicaragua and Costa Rica indicate that such sites almost certainly exist. Lack of funding for exploration in the areas has postponed likely finds.
- Tehuacan Valley of Mexico – people are living in rock shelters and using stone cooking pots, which were left in the center of the hearth. Maize was cultivated to be used in the same valley between 7,000–6,000 years ago.
While it is perhaps all but indisputable that land migration occurred over the Bering Strait, it is not conclusive that this path was the first or the only means of migration to the Americas. There are incongruities in the archaeological record when North and South America are compared. There are South American sites, including Monte Verde, which predate the North American Clovis remains by at least 1,000 years (Dillehay 1999 http://www.archaeology.or.../clovis/). These findings lend support to what has been argued to be an earlier and faster maritime migration. Furthermore, excavations across the Americas, the most recent of which unearthed coprolites in the Paisley Caves of Oregon’s Cascade Range, suggest the first Americans were a maritime culture (Thomas et al 2008). Beyond the earlier absence of the ice-free corridor — an absence which makes an earlier land-based migration virtually impossible — one of the primary clues is diet.
A rapidly accreting body of evidence suggests that human migration into the Americas occurred much earlier than previously thought. Two distinct waves of migration have been documented with the characteristics of each dictated by the timing of the last ice age. Coastal migration was favored at the peak of the ice age when sea levels were lower and abundant seafood was available. The ancient people of Japan were known to be excellent coastal seafarers but reluctant visitors to the open sea. Sea craft during that phase of human migration were more primitive and did not support open sea migration. Siberian migration became dominant after the receding of the ice sheet and these later migrants may have replaced or assimilated the earlier migrants.
Awareness of the broad spectrum of science advancement creates the possibility that new insights will occur when overlapping discoveries validate new theories. Overspecialization within a scientific discipline may be a handicap when it comes to the big questions of humanity. Whether as scientists, scholars, or professional field archaeologists, we are all well served by maintaining a broader view of advances in many fields. Such key advances which allow a great leap forward in our own fields of expertise might occur in an isolated and seemingly unrelated discipline, such as retrovirology.
BERINGIA AND TRAVEL TO THE AMERICA'S
Beringia was a land bridge between 12,000 and 13,000 years ago that was evident once glaciers in the area melted and sea levels decreased. Beringia linked up Siberia and what is now Alaska. What is disputed by scientists is what people came over to the America's, when and how. By land? By boat? Paleo-Indians are believed to have used Beringia. Much DNA evidence is pointing to the use of water travel by Asians. There is the study involving the Olmec "celt" inscriptions versus the Chinese Shang writing, which in many cases is very close. We must also remember the concept of independent invention--that humans do independently invent things.
CHINESE MIGRATION TO MEXICO, B.C.
Researchers studied Native Americans from the Navajo, Chamorro and Flathead tribes. They then determined that all three groups possess a unique type of retrovirus gene, JCV, found only in China and Japan (National Academy of Sciences, 1197). Would seem to suggest travel by boat.
VIRUS LINKS ANDES WITH JAPAN
There is a theory that South America was colonized from Asia thousands of years before any Spaniards set foot in South America. DNA from bone marrow of 1,500 year old mummies found in northern Chile was analyzed. The results show that a virus associated with adult T-cell leukemia was prevalent in native Andeans and in a small section of people from southwest Japan. The study also theorizes that the virus may have originated from paleo-Mongoloids who migrated to Japan and South America more than 10,000 years ago. No doubt that this was an mtDNA PCR study (Nature Medicine, 1999).
Oh come on! The Earth is only 6000 years old, dontchaknow!
"Do not judge me by my successes, judge me by how many times I fell down and got back up again." ~ Nelson Mandela