Redefining the age of Clovis: implications for the peopling of the Americas

The Clovis complex is considered to be the oldest unequivocal evidence of humans in the Americas, dating between 11,500 and 10,900 radiocarbon years before the present (14C yr B.P.). Adjusted 14C dates and a reevaluation of the existing Clovis date record revise the Clovis time range to 11,050 to 10,800 14C yr B.P. In as few as 200 calendar years, Clovis technology originated and spread throughout North America. The revised age range for Clovis overlaps non-Clovis sites in North and South America. This and other evidence imply that humans already lived in the Americas before Clovis.     

Clovis age Western Stemmed projectile points and human coprolites at the Paisley Caves

The Paisley Caves in Oregon record the oldest directly dated human remains (DNA) in the Western Hemisphere. More than 100 high-precision radiocarbon dates show that deposits containing artifacts and coprolites ranging in age from 12,450 to 2295 (14)C years ago are well stratified. Western Stemmed projectile points were recovered in deposits dated to 11,070 to 11,340 (14)C years ago, a time contemporaneous with or preceding the Clovis technology. There is no evidence of diagnostic Clovis technology at the site. These two distinct technologies were parallel developments, not the product of a unilinear technological evolution. "Blind testing" analysis of coprolites by an independent laboratory confirms the presence of human DNA in specimens of pre-Clovis age. The colonization of the Americas involved multiple technologically divergent, and possibly genetically divergent, founding groups.     

The Buttermilk Creek complex and the origins of Clovis at the Debra L. Friedkin site, Texas

Compelling archaeological evidence of an occupation older than Clovis (~12.8 to 13.1 thousand years ago) in North America is present at only a few sites, and the stone tool assemblages from these sites are small and varied. The Debra L. Friedkin site, Texas, contains an assemblage of 15,528 artifacts that define the Buttermilk Creek Complex, which stratigraphically underlies a Clovis assemblage and dates between ~13.2 and 15.5 thousand years ago. The Buttermilk Creek Complex confirms the emerging view that people occupied the Americas before Clovis and provides a large artifact assemblage to explore Clovis origins.     

An El Jobo Mastodon Kill at Taima-taima, Venezuela

Excavation at Taima-taima in 1976 recovered artifacts of the El Jobo complex in direct association with the butchered remains of a juvenile mastodon. Radiocarbon dates on associated wood twigs indicate a minimum age of 13,000 years before the present for the mastodon kill, a dating significantly older than that of the Clovis complex in North America. The El Jobo complex must have evolved independently in northern South America.     

Paleoindians in beringia: evidence from arctic alaska

Excavations at the Mesa site in arctic Alaska provide evidence for a Paleoindian occupation of Beringia, the region adjacent to the Bering Strait. Eleven carbon-14 dates on hearths associated with Paleoindian projectile points place humans at the site between 9,730 and 11,660 radiocarbon years before present (years B.P.). The presence of Paleoindians in Beringia at these times challenges the notion that Paleoindian cultures arose exclusively in mid-continental North America. The age span of Paleoindians at the Mesa site overlaps with dates from two other cultural complexes in interior Alaska. A hiatus in the record of human occupation occurs between 10,300 and 11,000 years B.P. Late Glacial climatic fluctuations may have made northern Alaska temporarily unfavorable for humans and spurred their southward dispersal.     

The archaeology of Ushki Lake,Kamchatka, and the Pleistocene peopling of the Americas

The Ushki Paleolithic sites of Kamchatka, Russia, have long been thought to contain information critical to the peopling of the Americas, especially the origins of Clovis. New radiocarbon dates indicate that human occupation of Ushki began only 13,000 calendar years ago-nearly 4000 years later than previously thought. Although biface industries were widespread across Beringia contemporaneous to the time of Clovis in western North America, these data suggest that late-glacial Siberians did not spread into Beringia until the end of the Pleistocene, perhaps too recently to have been ancestral to proposed pre-Clovis populations in the Americas.     

Pre-Clovis mastodon hunting 13,800 years ago at the Manis site, Washington

The tip of a projectile point made of mastodon bone is embedded in a rib of a single disarticulated mastodon at the Manis site in the state of Washington. Radiocarbon dating and DNA analysis show that the rib is associated with the other remains and dates to 13,800 years ago. Thus, osseous projectile points, common to the Beringian Upper Paleolithic and Clovis, were made and used during pre-Clovis times in North America. The Manis site, combined with evidence of mammoth hunting at sites in Wisconsin, provides evidence that people were hunting proboscideans at least two millennia before Clovis.     

Carbon-14 dates at grande pile: correlation of land and sea chronologies

Sixteen radiocarbon dates extending back to 70,000 years provide a chronology for the continuous continental pollen record of Grande Pile. This record reflects climatic changes over the last 140,000 years in northeastern France. The cold period initiating the Middle Weichselian, dated previously at 55,000 years, is dated at 70,000 years before the present (B.P.) at Grande Pile. This event is marked by the disappearance of deciduous forests at this site. The Early Weichselian is placed before 70,000 years B.P. A correlation with the oxygen isotope stages from oceanic records is demonstrated until 70,000 years B.P. and attempted beyond.     

Chronology for the Aegean Late Bronze Age 1700-1400 B.C

Radiocarbon (carbon-14) data from the Aegean Bronze Age 1700-1400 B.C. show that the Santorini (Thera) eruption must have occurred in the late 17th century B.C. By using carbon-14 dates from the surrounding region, cultural phases, and Bayesian statistical analysis, we established a chronology for the initial Aegean Late Bronze Age cultural phases (Late Minoan IA, IB, and II). This chronology contrasts with conventional archaeological dates and cultural synthesis: stretching out the Late Minoan IA, IB, and II phases by approximately 100 years and requiring reassessment of standard interpretations of associations between the Egyptian and Near Eastern historical dates and phases and those in the Aegean and Cyprus in the mid-second millennium B.C.     

Human occupations and climate change in the Puna de Atacama,Chile

Widespread evidence for human occupation of the Atacama Desert, 20 degrees to 25 degrees S in northern Chile, has been found from 13,000 calibrated 14C years before the present (cal yr B.P.) to 9500 cal yr B.P., and again after 4500 cal yr B.P. Initial human occupation coincided with a change from very dry environments to humid environments. More than 39 open early Archaic campsites at elevations above 3600 meters show that hunters lived around late glacial/early Holocene paleolakes on the Altiplano. Cessation of the use of the sites between 9500 and 4500 cal yr B.P. is associated with drying of the lakes. The mid-Holocene collapse of human occupation is also recorded in cave deposits. One cave contained Pleistocene fauna associated with human artifacts. Faunal diversity was highest during the humid early Holocene.     

Interhemispheric correlation of late pleistocene glacial events

A radiocarbon chronology shows that piedmont glacier lobes in the Chilean Andes achieved maxima during the last glaciation at 13,900 to 14,890, 21,000, 23,060, 26,940, 29,600, and >/=33,500 carbon-14 years before present ((14)C yr B.P.) in a cold and wet Subantarctic Parkland environment. The last glaciation ended with massive collapse of ice lobes close to 14,000(14)C yr B.P., accompanied by an influx of North Patagonian Rain Forest species. In the Southern Alps of New Zealand, additional glacial maxima are registered at 17,720(14)C yr B.P., and at the beginning of the Younger Dryas at 11,050 (14)C yr B. P. These glacial maxima in mid-latitude mountains rimming the South Pacific were coeval with ice-rafting pulses in the North Atlantic Ocean. Furthermore, the last termination began suddenly and simultaneously in both polar hemispheres before the resumption of the modern mode of deep-water production in the Nordic Seas. Such interhemispheric coupling implies a global atmospheric signal rather than regional climatic changes caused by North Atlantic thermohaline switches or Laurentide ice surges.     

7500 years of prehistoric footwear from arnold research cave, missouri

Accelerator mass spectrometer dating of an assemblage of fibrous and leather footwear from Arnold Research Cave in central Missouri documents a long sequence of shoe construction by prehistoric Midwestern peoples, beginning perhaps as early as 8300 calendar years before the present (cal years B.P.). An earlier fibrous sandal form dates from 8325 to 7675 cal years B.P., and later fibrous or leather slip-ons span the period from 5575 to 1070 cal years B.P. The assemblage adds to a growing picture of the highly varied nature of prehistoric footwear production in the United States throughout the Holocene.     

Dating Caral, a preceramic site in the Supe Valley on the central coast of Peru

Radiocarbon dates from the site of Caral in the Supe Valley of Peru indicate that monumental corporate architecture, urban settlement, and irrigation agriculture began in the Americas by 4090 years before the present (2627 calibrated years B.C.) to 3640 years before the present (1977 calibrated years B.C.). Caral is located 23 kilometers inland from the Pacific coast and contains a central zone of monumental, residential, and nonresidential architecture covering an area of 65 hectares. Caral is one of 18 large preceramic sites in the Supe Valley.     

Age determination of burned flint by a thermoluminescent method

Interference by tribothermoluminescence and by regeneration thermoluminescence can be eliminated for burned flint if thin polished slices are used instead of the powders conventionally used in thermoluminescent measurements. Measurement of the internal and external radiation dose rates then makes possible the absolute determination of the date of pyrolization of small fragments of chert or chalcedony to an accuracy of about 10 to 15 percent. The method may be usable to ages in the range from 200,000 to 300,000 years before the present (B.P.). For samples from the archeological site at Carigüela in southern Spain dates from 12,000 to 50,000 years B.P. have been determined, covering deposits ranging from Late Paleolithic-Epipaleolithic to Mousterian. One Bronze Age specimen gave an age of 4,300 years B.P., in excellent agreement with the age determined by other methods.     

Origin and environmental setting of ancient agriculture in the lowlands of Mesoamerica

Archaeological research in the Gulf Coast of Tabasco reveals the earliest record of maize cultivation in Mexico. The first farmers settled along beach ridges and lagoons of the Grijalva River delta. Pollen from cultivated Zea appears with evidence of forest clearing about 5100 calendar years B.C. (yr B.C.) [6200 (14)C years before the present (yr B.P.)]. Large Zea sp. pollen, typical of domesticated maize (Zea mays), appears about 5000 calendar yr B.C. (6000 yr B.P.). A Manihot sp. pollen grain dated to 4600 calendar yr B.C. (5800 yr B.P.) may be from domesticated manioc. About 2500 calendar yr B.C. (4000 yr B.P.), domesticated sunflower seeds and cotton pollen appear as farming expanded.     

High-resolution holocene environmental changes in the thar desert, northwestern india

Sediments from Lunkaransar dry lake in northwestern India reveal regional water table and lake level fluctuations over decades to centuries during the Holocene that are attributed to changes in the southwestern Indian monsoon rains. The lake levels were very shallow and fluctuated often in the early Holocene and then rose abruptly around 6300 carbon-14 years before the present (14C yr B.P.). The lake completely desiccated around 4800 (14)C yr B.P. The end of this 1500-year wet period coincided with a period of intense dune destabilization. The major Harrapan-Indus civilization began and flourished in this region 1000 years after desiccation of the lake during arid climate and was not synchronous with the lacustral phase.     

African populations and the evolution of human mitochondrial DNA.

The proposal that all mitochondrial DNA (mtDNA) types in contemporary humans stem from a common ancestor present in an African population some 200,000 years ago has attracted much attention. To study this proposal further, two hypervariable segments of mtDNA were sequenced from 189 people of diverse geographic origin, including 121 native Africans. Geographic specificity was observed in that identical mtDNA types are shared within but not between populations. A tree relating these mtDNA sequences to one another and to a chimpanzee sequence has many deep branches leading exclusively to African mtDNAs. An African origin for human mtDNA is supported by two statistical tests. With the use of the chimpanzee and human sequences to calibrate the rate of mtDNA evolution, the age of the common human mtDNA ancestor is placed between 166,000 and 249,000 years. These results thus support and extend the African origin hypothesis of human mtDNA evolution.     

Mammoth-bone shaft wrench from murray springs, Arizona

Archeological excavations at Murray Springs, Cochise County, Arizona, in July 1967 uncovered a unique bone tool in the Clovis occupation level and in association with bones of a mammoth. The tool may be a wrench for straightening shafts of spears; if so, shaft diameters ranging from 14 to 17 millimeters were most likely used in hafting Clovis projectile points.     

Transitional pre-desert phase in san diego county, california

Excavations at site U.C.L.J.-M-15 at Agua Hedionda Lagoon in southern California have provided a radiocarbon date of 7070 B.C. for a transitional phase between the San Dieguito and the La Jolla complex. The many radiocarbon dates taken from sites in San Diego County demonstrate a somewhat greater age than was hitherto generally expected for the three cultures in the area. The age of the most recent culture, the Yuman-Diegueno, has been extended to about 1000 B.C. The La Jolla shows an extremely long period of occupation spanning roughly 1000 B.C. to 7070 B.C. The third group, the San Dieguito, a pre-Desert culture, is still undated. Samples are now in process and should, judged from the new La Jolla dates, give a date earlier than 7000 B.C. for the earliest phases of the San Dieguito.     

Chilean glacial chronology 20,000 to 11,000 carbon-14 years ago: some global comparisons

Chilean glaciers at a latitude of 41 degrees S reached a maximum extent about 19,400 carbon-14 years before the present (B. P.), shrank 50 percent by 16,000 years B. P., and readvanced to a smaller maximum after 14,800 years B. P. These fluctuations were closely in step with those of the Laurentide ice sheet east of the Mississippi River but differ somewhat from the accepted sequence in New Zealand. A corresponding pattern is not apparent in the Antarctic paleotemperature curve deduced from changes in oxygen isotope ratios.