New research reveals significant changes to the circulation of the North Pacific and its impact on the initial migration of humans from Asia to North America.

The international , led by the University of St. Andrews in Scotland and published Dec. 9 in Science Advances, provides a new picture of the circulation and climate of the North Pacific at the end of the last ice age, with implications for early human migration.

The Pacific Ocean contains around half the water in Earth’s oceans and is a vast reservoir of heat and carbon dioxide. However, at present, the sluggish circulation of the North Pacific restricts the movement of this heat and carbon dioxide, limiting its impact on climate.

The international team of scientists used sediment cores from the deep sea to reconstruct the circulation and climate of the North Pacific during the peak of the last ice age, roughly 21,000 years ago. Their results reveal a dramatically different circulation in the ice age Pacific, with vigorous ocean currents creating a relatively warm region around the modern Bering Sea.

“Our data shows that the Pacific had a warm current system during the last ice age, similar to the modern Atlantic Ocean currents that help to support a mild climate in Northern Europe,” said lead author , a faculty member at the University of St. Andrews.

The warming from these ocean currents created conditions more favorable for early human habitation, helping address a long-standing mystery about the earliest inhabitants of North America.

“According to genetic studies, the first people to populate the Americas lived in an isolated population for several thousand years during the peak of the last ice age, before spreading out into the American continents,” said co-author , a professor of anthropology at the 天美影视传媒 who studies early communities in the North Pacific.

This hypothesis has been termed the “Beringian Standstill,” and a significant question is where this population lived after separation from their Asian relatives, before deglaciation of the massive ice sheet covering the northern third of North America allowed them to reach and spread throughout the Americas. The new research suggests that these early Americans may have lived in a relatively warm refugium, or habitable refuge, in southern Beringia, on the now submerged land beneath the Bering Sea. Due to the extremely cold climate that dominated other parts of this region during the ice age, it has been unclear, until now, how habitable conditions could have been maintained.

“Our work shows how dynamic Earth’s climate system is. Changes in the circulation of the ocean and atmosphere can have major impacts on how effectively humans may inhabit different environments, which is also relevant for understanding how different regions will be affected by future climate change,” said third author , a postdoctoral researcher in atmospheric sciences at the 天美影视传媒.

Wills researches the overturning circulation in the North Pacific, and did climate modeling work to help understand what the paleoclimate data 鈥� compiled by researchers at the University of St. Andrews and the University of California, Irvine 鈥� would mean for the region鈥檚 climate.

“The warm currents revealed by our data would have created a much more pleasant climate in this region than we might have previously thought,” said second author , a research scientist at the Laboratory for Sciences of Climate and Environment in France.

“This would have created milder climates in the coastal regions of the North Pacific, that would have supported more temperate terrestrial and marine ecosystems and made it possible for humans to survive the ice age in an otherwise harsh climatic period.”

The research was funded by the U.S. National Science Foundation and the U.K. Natural Environment Research Council. Other co-authors are from Scripps Institution of Oceanography; the University of California, Irvine; and the University of California, Riverside.

For more information, contact Fitzhugh at fitzhugh@uw.edu, Wills at rcwills@uw.edu and Gray at william.gray@lsce.ipsl.fr. Contact Rae via communications manager Christine Tudhope, Christine.Tudhope@st-andrews.ac.uk, 01334 467 320 or 07526 624 243 (mobile).

Adapted from a from the University of St. Andrews.

Archaeologists are a little like forensic investigators: They scour the remains of past societies, looking for clues in pottery, tools and bones about how people lived, and how they died.

And just as detectives might re-create the scene of a crime, 天美影视传媒 archaeologists have re-created the weapons used by hunter-gatherers in the post-Ice Age Arctic some 14,000 years ago. Looking for clues as to how those early people advanced their own technology, researchers also considered what that might tell us about human migration, ancient climates and the fate of some animal species.

In an published Jan. 31 in the Journal of Archaeological Science, ,聽 recent UW anthropology graduate, and , a UW professor of anthropology, show how they reconstructed prehistoric projectiles and points from ancient sites in what is now Alaska and studied the qualities that would make for a lethal hunting weapon.

The UW team chose to study hunting weapons from the time of the earliest archaeological record in Alaska (around 10,000 to 14,000 years ago), a time that is less understood archaeologically, and when different kinds of projectile points were in use. Team members designed a pair of experiments to test the effectiveness of the different point types. By examining and testing different points in this way, the team has come to a new understanding about the technological choices people made in ancient times.

“The hunter-gatherers of 12,000 years ago were more sophisticated than we give them credit for,” Fitzhugh said. “We haven’t thought of hunter-gatherers in the Pleistocene as having that kind of sophistication, but they clearly did for the things that they had to manage in their daily lives, such as hunting game. They had a very comprehensive understanding of different tools, and the best tools for different prey and shot conditions.”

Prior research has focused on the flight ballistics of the hunting weapons in general, and no prior study has looked specifically at the ballistics of tools used in Siberia and the Arctic regions of North America just after the Ice Age. In addition to foraging for plants and berries (when available), nomadic groups hunted caribou, reindeer and other animals for food, typically with spears or darts (thrown from boards). Without preservation of the wood shafts, these tools are mainly differentiated in the archaeological record by their stone and bone points. But it was not known how effective different kinds of points were in causing lethal injury to prey.

Nor is it known, definitively, whether different types of points were associated with only certain groups of people, or whether with the same groups used certain point types to specialize on particular kinds of game or hunting practices. It is generally accepted that different point types were developed in Africa and Eurasia and brought to Alaska before the end of the Ice Age. These included rudimentary points made of sharpened bone, antler or ivory; more intricate, flaked stone tips popularly familiar as 鈥渁rrowheads鈥�; and a composite point made of bone or antler with razor blade-like stone microblades embedded around the edges.

The three likely were invented at separate times but remained in use during the same period because each presumably had its own advantages, Wood said. Learning how they functioned informs what we know about prehistoric hunters and the repercussions of their practices.

So Wood traveled to the area around Fairbanks, Alaska, and crafted 30 projectile points, 10 of each kind. She tried to stay as true to the original materials and manufacturing processes as possible, using poplar projectiles, and birch tar as an adhesive to affix the points to the tips of the projectiles. While ancient Alaskans used atlatls (a kind of throwing board), Wood used a maple bow to shoot the arrows for greater control and precision.

• For the bone tip, modeled on a 12,000-year-old ivory point from an Alaskan archaeological site, Wood used a multipurpose tool to grind a commercially purchased cow bone;
• For the stone tip, she used a hammerstone to strike obsidian into flakes, then shaped them into points modeled on those found at another site in Alaska from 13,000 years ago;
• And for the composite microblade tip — modeled microblade technologies seen in Alaska since at least 13,000 years ago and a rare, preserved grooved antler point from a more recent Alaskan site used more than 8,000 years ago — Wood used a saw and sandpaper to grind a caribou antler to a point. She then used the multipurpose tool to gouge out a groove around its perimeter, into which she inserted obsidian microblades.

Wood then tested how well each point could penetrate and damage two different targets: blocks of ballistic gelatin (a clear synthetic gelatin meant to mimic animal muscle tissue) and a fresh reindeer carcass, purchased from a local farm. Wood conducted her trials over seven hours 聽聽on a December day, with an average outdoor temperature of minus 17 degrees Fahrenheit.

In Wood鈥檚 field trial, the composite microblade points were more effective than simple stone or bone on smaller prey, showing the greatest versatility and ability to cause incapacitating damage no matter where they struck the animal’s body. But the stone and bone points had their own strengths: Bone points penetrated deeply but created narrower wounds, suggesting their potential for puncturing and stunning larger prey (such as bison or mammoth); the stone points could have cut wider wounds, especially on large prey (moose or bison), resulting in a quicker kill.

Wood said the findings show that hunters during this period were sophisticated enough to recognize the best point to use, and when. Hunters worked in groups; they needed to complete successful hunts, in the least amount of time, and avoid risk to themselves.

“We have shown how each point has its own performance strengths,” she said. Bone points punctured effectively, flaked stone created a greater incision, and the microblade was best for lacerated wounds. “It has to do with the animal itself; animals react differently to different wounds. And it would have been important to these nomadic hunters to bring the animal down efficiently. They were hunting for food.”

Weapon use can shed light on the movement of people and animals as humans spread across the globe and how ecosystems changed before, during and after the ice ages.

It could also inform debates on whether human hunting practices directly led to the extinction of some species. The team鈥檚 findings and other research show that our ancestors were thinking about effectiveness and efficiency, Wood said, which may have influenced which animals they targeted. An animal that was easier to kill may have been targeted more often, which could, along with changing climates, explain why animals such as the horse disappeared from the Arctic. A shot to the lung was lethal for early equines, Wood said, but a caribou could keep going.

“I see this line of research as looking at the capacity of the human brain to come up with 聽innovations that ultimately changed the course of human history,” she said. “This reveals the human capacity to invent in extreme circumstances, to figure out a need and a way to meet that need that made it easier to eat and minimized the risk.”

Upon completion of the experiment, the bones were sterilized for future study of projectile impact marks.

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For more information, contact Wood at 206-618-3142 or jbwood3@alaska.edu, or Fitzhugh at fitzhugh@uw.edu.

The 天美影视传媒’s new “” initiative seeks to build on that research in a region now undergoing rapid changes. The initiative includes several new hires, a new minor in Arctic studies and a winter lecture series.

“This is partly recognizing how much is going on in polar research at the UW,” said initiative director , a UW professor of Earth and space sciences who studies ice cores. “This initiative is designed to bring more visibility, integration and investment in an area that is experiencing dramatic changes.”

The UW College of the Environment will hire in polar research, while the UW Applied Physics Laboratory will hire two or three . The two units, along with the Quaternary Research Center, will hire up to three joint for interdisciplinary work relating to polar science.

“This initiative is about building the pipeline, attracting new talent and promoting collaboration so the UW can continue to be a strong player in high-latitude research,” said , chair of the Applied Physics Laboratory’s Polar Science Center.

A winter quarter , organized with support from the UW Graduate School and the Alumni Association, will feature UW faculty and off-campus experts.

Among those attending the talks will be UW undergraduates doing a winter quarter based around the series. Roughly 30 students will meet with the speakers and do coursework around each topic, ranging from Arctic governance to the marine organisms that live in sea ice.

Students in that course will be earning the first credits toward the new, interdisciplinary , pending UW faculty council approval. The minor, which is open to students in all departments, is being led by of the UW Canadian Studies Center, of aquatic and fishery sciences,聽 from the UW Applied Physics Laboratory and from oceanography.

The initiative and minor also include faculty from international studies, Earth sciences, anthropology, law, policy and the Burke Museum.

Over time, the initiative seeks to connect researchers from across campus and create a central hub for polar education and scholarship.

“Our goal is to bring together people working on different pieces that help us to understand the connections, to provide better insight into policy decisions and give communities a better understanding of their options,” said initiative co-director , a UW associate professor of anthropology. Fitzhugh’s archaeological studies in Northern communities reveal how early people developed the adaptations that made it possible for humans to live in very cold and highly seasonal environments.

The Future of Ice initiative’s first large research event will be a spring workshop, supported by the UW College of the Environment, that brings together UW faculty, colleagues, industry experts, non-governmental organizations, Arctic leaders and others to discuss research priorities.

“The reason for creating a College of the Environment was to achieve new levels of integration,” said , dean of the college. “The UW has tremendous depth in Arctic research, and it’s shared among a number of units. Pulling these threads together will allow researchers to take their scholarship to the next level, and more closely connect it to policy 鈥� a key component of the vision for our college.”

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For more information, contact Steig at 206-685-3715 or steig@uw.edu or Graumlich at 206-221-0908 or graumlic@uw.edu.