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“We were shocked. Basically what we are looking at is a technology that was learned from one person to another, from father to son or from uncle to nephew,” explains Stanford, co-author of a recent paper on the discovery in the Journal of Archaeological Science.

Image right: Clovis stone points from the Drake Cache of Colorado. Click to enlarge. (Photo by Chip Clark, Smithsonian)

The researchers believe encounters between Clovis knappers, or stone point makers, from different groups at stone quarry sites or in settlements certainly “facilitated the sharing of technological information by allowing knappers to observe tools and techniques used by other artisans,” explains co-author Sabrina Sholts of the Human Evolution Research Center at the University of California in Berkeley. “The tools selected by the knappers, as well as how they were handled and applied, certainly were part of the Clovis technology,” that was shared between families and tribes.

This video was created by Sabrina Sholts of the Human Evolution Research Center at the University of California in Berkeley using 3D digital scans of a Clovis stone projectile point from the collections of the Department of Anthropology, National Museum of Natural History, Smithsonian Institution.

In fact, the researchers say, through a strong communication network  Clovis spear point technology spread across North America in as little as 200 years. Radiocarbon dating of the stone points backs this theory. Many Clovis points “have been recovered from kill sites, in association with the remains of animals such as mammoths and bison,” Sholts says. This “suggests that they were effective for hunting large prey.”

The scientists used high-tech 3D scanning to create detailed images of the Clovis points from the collection of the Smithsonian’s National Museum of Natural History. The researchers focused particularly on the contours of the scars on the front and back of each bi-face spear point where individual stone flakes were carefully and systematically removed centuries ago by striking with an implement made of antler, bone, ivory or even perhaps hardwood. Each 3D scan records millions of minute measurements, revealing “subtle differences in the various steps of reduction [flaking off tiny pieces of stone] and nuances that you can’t see with your eyes,” Stanford explains.

Right: Images of 3D models and overlaid front and back flake scar contours from projectile points from the Colby Cache, Wyoming (left), Drake Cache, Colorado (center left), and two modern replicas (center right and right). The Colby and Drake points have markedly different bases, but this difference is much less prominent in the flake scar contours. For the two modern replicas, their flake scar contours are generally more uneven, and also display larger differences between the overlaid contours.

“One nice thing about the study is its relative objectivity,” Sholts points out. With the 3D imaging, “it is really very automated. What we are doing is essentially data analysis, capturing the contours and curvature of the surface of each biface in a standard way. The results were surprising to me.”

This 3D study has laid to rest the theory that Clovis technology spread region by region from knappers who copied lost or discarded stone points they had found, Stanford says. In fact, the paper reveals, part of the research included projectile points made by an expert modern-day knapper who closely studied and copied Clovis points in the Smithsonian collection. Computer analysis revealed these modern creations do not share the same symmetry as do the authentic Clovis points—further proof that the real Clovis points were a learned technology.

“We are now working on a new study with Clovis points from California that we are putting into that same computer matrix,” Stanford says.–John Barrat

Article link:  “Flake scar patterns of Clovis points analyzed with a new digital morphometrics approach: evidence for direct transmission of technological knowledge across early North America,” authored by Sabrina Sholts, Dennis Stanford, Louise Flores and Sebastian Wärmländer, will appear in a forthcoming issue of the Journal of Archaeological Science.

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Across Atlantic Ice is the result of more than a decade’s research by leading archaeologists Bruce Bradley of the University of Exeter in the United Kingdom, and Dennis Stanford of the Smithsonian’s National Museum of Natural History in Washington, D.C. Through archaeological evidence, they turn the long-held theory of the origins of New World populations on its head.

For more than 400 years, it has been claimed that people first entered America from Asia, via a land bridge that spanned the Bering Sea. We now know that some people did arrive via this route nearly 15,000 years ago, probably by both land and sea.

Eighty years ago, stone tools long believed to have been left by the first New World inhabitants were discovered in New Mexico and named Clovis. These distinctive Clovis stone tools are now dated around 12,000 years ago leading to the recognition that people preceded Clovis into the Americas.

No Clovis tools have been found in Alaska or Northeast Asia, but are concentrated in the south eastern United States. Groundbreaking discoveries from the east coast of North America are demonstrating that people who are believed to be Clovis ancestors arrived in this area no later than 18,450 years ago and possibly as early as 23,000 years ago, probably in boats from Europe. These early inhabitants made stone tools that differ in significant ways from the earliest stone tools known in Alaska. It now appears that people entering the New World arrived from more than one direction.

Image left: Dennis Stanford with Clovis stone points from the collection of the Smithsonian’s National Museum of Natural History. (Photo by Chip Clark)

In “Across Atlantic Ice,” the authors trace the origins of Clovis culture from the Solutrean people, who occupied northern Spain and France more than 20,000 years ago. They believe that these people went on to populate America’s east coast, eventually spreading at least as far as Venezuela in South America.

The link between Clovis and contemporary Native Americans is not yet clear. Bradley and Stanford do not suggest that the people from Europe were the only ancestors of modern Native Americans. They argue that it is evident that early inhabitants also arrived from Asia, into Alaska, populating America’s western coast. Their ongoing research suggests that the early history of the continent is far more intriguing than we formerly believed.

Some of the archaeological evidence analyzed in the book was recovered from deep in the ocean. When the first people arrived in America, sea levels were nearly 130 meters lower than today. The shore lines of 20,000 years ago, which hold much of the evidence left by these early people, are now under the ocean. This is also the case in Europe.

Image left: Clovis-made stone tools in the hands of Bruce Bradley, co-author of Across Atlantic Ice: The Origin of America’s Clovis Culture. (Photo by Jim Wileman)

“We now have really solid evidence that people came from Europe to the New World around 20,000 years ago,” Bradley says. “Our findings represent a paradigm shift in the way we think about America’s early history. We are challenging a very deep-seated belief in how the New World was populated. The story is more intriguing and more complicated than we ever have imagined.”

“There are more alternatives than we think in archaeology and we need to have imagination and an open mind when we examine evidence to avoid being stuck in orthodoxy,” Stanford adds. “This book is the result of more than a decade’s work, but it is just the beginning of our journey.”

Across Atlantic Ice is published by University California Press, Berkeley.–Source University of Exeter

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Across the Atlantic Ice boldly challenges this old narrative and presents overwhelming evidence for a pre-Clovis occupation of the American continents, and finds virtually no direct evidence that the progenitors of Clovis came from Siberia. Evidence put forth in this new book overwhelmingly indicates southwestern Europe, specifically the Ice Age Solutrean Culture of France and Spain, as the source of the people that developed into the Clovis.

Drawing from original archaeological analysis, paleoclimatic research, and genetic studies, noted archaeologists Dennis J. Stanford, of the Smithsonian’s National Museum of Natural History, and Bruce A. Bradley, associate professor at the University of Exeter, United Kingdom, apply rigorous scholarship to a hypothesis that places the technological antecedents of Clovis in Europe. Their research indicates that the first Americans crossed the Atlantic by boat and arrived earlier than previously thought.

Supplying archaeological and oceanographic evidence to support these assertions, the book dismantles the old paradigms while persuasively linking Clovis technology with the culture of the Solutrean people who occupied France and Spain more than 20,000 years ago.

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Image right: These ancient corn cobs date roughly from 6,500-4,000 years ago. A is Proto-Confite Morocho race; B, Confite Chavinense maize race; and C is Proto-Alazan maize race.. (Photo by Tom Dillehay)

Some of the oldest known corncobs, husks, stalks and tassels, dating from 6,700 to 3,000 years ago were found at Paredones and Huaca Prieta, two mound sites on Peru’s arid northern coast. The research group, led by Tom Dillehay from Vanderbilt University and Duccio Bonavia from Peru’s Academia Nacional de la Historia, also found corn microfossils: starch grains and phytoliths. Characteristics of the cobs—the earliest ever discovered in South America—indicate that the sites’ ancient inhabitants ate corn several ways, including popcorn and flour corn. However, corn was still not an important part of their diet.

Image left: Wild forms of Zea mays are called ‘teosinte’. Over time, selective breeding modifies teosinte’s few fruitcases (left) into modern corn’s rows of exposed kernels (right). (Photo courtesy John Doebley.).

“Corn was first domesticated in Mexico nearly 9,000 years ago from a wild grass called teosinte,” Piperno says. “Our results show that only a few thousand years later corn arrived in South America where its evolution into different varieties that are now common in the Andean region began. This evidence further indicates that in many areas corn arrived before pots did and that early experimentation with corn as a food was not dependent on the presence of pottery.”

Understanding the subtle transformations in the characteristics of cobs and kernels that led to the hundreds of maize races known today, as well as where and when each of them developed, is a challenge. Corncobs and kernels were not well preserved in the humid tropical forests between Central and South America, including Panama—the primary dispersal routes for the crop after it first left Mexico about 8,000 years ago.

“These new and unique races of corn may have developed quickly in South America, where there was no chance that they would continue to be pollinated by wild teosinte,” Piperno says. “Because there is so little data available from other places for this time period, the wealth of morphological information about the cobs and other corn remains at this early date is very important for understanding how corn became the crop we know today.”

“Preceramic corn from Pardones and Huaca Prieta, Peru,” Grobman, A., Bonavia, D., Dillehay, T.D., Piperno, D.R., Iriarte, J., Holst, I. 2012. . PNAS early online edition, week of Jan. 16, 2012.

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As a coastal archaeologist and expert in prehistoric and historic settlement sites in the Chesapeake Bay region, Darrin Lowery of the Smithsonian’s National Museum of Natural History and University of Delaware, is carefully watching the effects of coastal erosion and rising sea levels on coastal archaeological sites. As sea levels creep slowly upward, scores of these sites are slipping under water and becoming more difficult, if not impossible, to excavate and study.

Image right: Darrin Lowery examines soils and peat marsh for evidence of ancient landscapes and sea level rise on the Mockhorn Island in Virginia. (Photo by Mike Hardesty, Washington College)

Of equal concern, says Lowery, are the chemical processes that accompany rising seas, which can modify and deteriorate the stone tools that early Americans used to hunt and prepare food and clothing hundreds of years ago. Lowery is co-author of a recent paper in the Journal of Archaeological Science on the geochemical impacts to prehistoric artifacts in coastal zones. He recently answered a few questions about his work.

Q. How do the chemical processes of sea level rise affect primitive stone tools?

A. Slowly rising sea levels result in the regular input of sediment and organic matter into low-lying areas, essentially creating areas covered in tidal marsh. Sulfidization in a tidal marsh is a process that reduces iron to its ferrous state and produces pyrite, turning stone artifacts black. A prehistoric projectile point made of jasper that has been exposed to sulfidization looks like it is made of a different type of stone called chert. This is a challenge to archaeologists because it is generally assumed that broad lithic categories can be distinguished between stone tools that are made of either chert or jasper. Over time this process can change the look of a stone artifact both inside and out.

Image left: Jasper (A) and chert (B) projectile points found at eroding shoreline sites in the Middle Atlantic. (Images courtesy Darrin Lowery)

A second process common in salt marshes is sulfuricization, which creates sulfuric acid. Highly corrosive, this acid attacks the silicate structure of a stone tool, first staining the rock with a reddish brown color and eventually causing the artifact to decompose. Having these artifacts disappear from the historic record is also of great concern to archaeologists. For a museum curator, safely storing iron-rich stone tools or artifacts that have been exposed to acid sulfate is problematic.

Q. Is sea level rise the only culprit in these changes?

A. No. The widespread practice of dredging sediment from the bottom of estuaries or along the coast and using it to build up shorelines and create living coastlines and areas for housing developments can create a situation that results in a sulfuric-acid producing machine. Marine sediments that have been oxygen-starved for several millenia are dredged up, brought to the surface and exposed to oxygen. Aerobic bacteria working on the sulfates in the sediments create sulfuric acid, as well as a series of iron oxides. If the acid is dissolving silica in iron-rich prehistoric stone tools from archaeological sites on the coast, as I have witnessed, I can only imagine how it is impacting marine life in the area adjacent to the dredge spoils.

Image right: This freshly broken projectile point made of jasper reveals the gradual precipitation of pyrite into its core, a process that has dramatically changing its color.

Q. Can you determine how much sea levels have risen since prehistoric times in North America 1,000 years ago?

A. Humans don’t like to get their feet wet so we know that prehistoric coastal sites now underwater or buried in a tidal marsh were once terrestrial, and that people were once eating, sleeping and living on these spots. Because we know that some prehistoric settlement sites in the Chesapeake Bay area are situated beneath a meter of tidal marsh peat, we can use certain “known-age” iron-rich artifacts from these submerged coastal sites to assess rates of sea level rise, as well as the rates of acid sulfate chemical change. From this we can also gauge the accuracy of the reported sea level rise rates over the past few centuries.

Surveying a large number of drowned prehistoric sites gives us the opportunity to understand those rates and the reported magnitudes.

Q. Are your projects in the Chesapeake region only focused on prehistoric settlement sites?

A. With one of my research projects, I am trying to assess the reported historic rates of sea level rise using, in part, farm fields next to tidal marshes that were first plowed long ago. We have numerous detailed historic maps showing the topographically low tidal marsh areas around the Chesapeake Bay. These maps, which encompass the last 165 years, show many tilled upland hummocks surrounded by tidal marsh. Agriculturally mixed soils are a distinctive archaeological feature formed when the thin organic soil has been turned and thickened by the plow. Back in the 17th, 18th, and 19th centuries, farmers in these low tidal marsh areas around the Chesapeake Bay didn’t have much land and they cleared every upland area right up to the edge of the marsh for cultivation. The 1840s and 1850s coastal survey maps clearly show the tilled field boundaries and historic structures on these upland hummocks.

Image left:  The chemical processes that accompany rising seas is evident on the two halves of this jasper biface projectile point. The top of this artifact was found along the eroded forested upland (B). The bottom part (C) was altered by geochemical processes in the eroded upland area surrounded by tidal marsh (D) where it was found.

I’m geo-referencing these historic maps and overlaying them with recent satellite images to form a single comparative map. By doing this I can see the historic distribution of plowed fields and farms in these low coastal areas and compare them with today. Fieldwork in these areas has allowed me to relocate the historic plowed or tilled field boundaries. Many of the shorelines have been eroded by the effects of wind and waves. However, the historic plowed fields have not been inundated or covered by tidal marsh peat over the past 150 years.

What I’ve observed is that sea levels in the Chesapeake Bay may have come up a little bit in the last 150 years but I don’t believe they have risen as much as one foot, as some groups are reporting. In all my years of shoreline surveys I have never seen a 17th, 18th, or 19th century domestic site beneath a covering of tidal marsh peat. I think people are mistaking shoreline erosion and land loss, caused by wind and water chewing away at unconsolidated terrestrial sediments, with sea level rise.

For example, currently at Kent Narrows in the Chesapeake, a series of hummocks above sea level appear as upland landscapes with the same dimensions on the earlier 1840s coastal maps. Also on the Chesapeake’s Hoopers Island are a series of hummocks that were being tilled in the 1840s, the plowed landscape features are still there adjacent to the marsh and above sea level. I have observed the same conditions on Messongo Creek on Virginia’s eastern shore.

If sea levels had risen as much as one foot over the past century, the aerial extent of these isolated upland landforms should have shrunk in size and the historic plow zones associated with the hummocks should have been covered or partially covered by expanding tidal marsh.

It is important to remember that sediment erosion along shorelines does not equate to sea level rise and sediment accretion along shorelines does not equate to a sea level fall. As an example, Sharp’s Island at the mouth of the Choptank River consisted of more than 700 acres of land in 1847, but by the mid-1950’s the island had completely eroded away. Meanwhile, in 1849, Fisherman’s Island at the mouth of the Chesapeake Bay on Virginia’s eastern shore did not exist. Fisherman’s Island today consists of more than 1,800 acres of land and the island also has an extensive forested upland.

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Small monkey groups may win territorial disputes against larger groups because some members of the larger, invading groups avoid aggressive encounters. In a new report published in Proceedings of the National Academy of Sciences, Margaret Crofoot and Ian Gilby of the Smithsonian Tropical Research Institute in Panama and the Max Planck Institute of Ornithology show that individual monkeys that don’t participate in conflicts prevent large groups from achieving their competitive potential.

Image above: Is this monkey a wimp? A new study by Margaret Crofoot and Ian Gilby carried out at a research station run by the Smithsonian on an island in the Panama Canal shows that the answer may depend on the size of the group it belongs to. (Photo by Marcos Guerra)

The authors used recorded vocalizations to simulate territorial invasions into the ranges of wild white-faced capuchin monkey groups at the Smithsonian reasearch station on Barro Colorado Island in Panama. Monkeys responded more vigorously to territorial challenges near the center of their territories and were more likely to flee in encounters near the borders.

Defection by members of larger groups was more common than defection by members of smaller groups. Groups that outnumbered their opponents could convert their numerical superiority to a competitive advantage when defending the center of their own range against neighboring intruders, but failed to do so when they attempted to invade the ranges of their neighbors, because more individuals in large groups chose not to participate. According to the authors, these behavior patterns even the balance of power among groups and create a ‘home-field advantage’ which may explain how large and small groups are able to coexist.

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