New theory debunks consensus that math abilities are innate

This example demonstrates the relationship between size and number: usually, more items will take up more space in the shopping cart, unless you have a few larger, denser items.

A new theory regarding how the brain first learns basic math could alter approaches to identifying and teaching students with math learning disabilities. Published in the Behavioral and Brain Sciences journal, Ben-Gurion University of the Negev (BGU) researchers offer a better understanding of how, when and why people grasp every day math skills.

The most widely accepted theory today suggests people are born with a "sense of numbers," an innate ability to recognize different quantities, like the number of items in a shopping cart, and that this ability improves with age. Early math curricula and tools for diagnosing math-specific learning disabilities such as dyscalculia, a brain disorder that makes it hard to make sense of numbers and math concepts, have been based on that consensus.

Ph.D. students Naama Katzin and Maayan Harel and Prof. Avishai Henik, all from the BGU Department of Psychology and the Zlotowski Center for Neuroscience, collaborated with Dr. Tali Leibovich from the Numerical Cognition Laboratory at the Department of Psychology & Brain and Mind Institute, University of Western Ontario. Dr. Leibovich was formerly a Ph.D. researcher at BGU's Department of Brain and Cognitive Sciences and the Zlotowski Center.

"If we are able to understand how the brain learns math, and how it understands numbers and more complex math concepts that shape the world we live in, we will be able to teach math in a more intuitive and enjoyable way," says Dr. Leibovich. "This study is the first step in achieving this goal."

The study challenges the prevalent "sense of numbers" theory. Other theories suggest that a "sense of magnitude" that enables people to discriminate between different "continuous magnitudes," such as the density of two groups of apples or total surface area of two pizza trays, is even more basic and automatic than a sense of numbers.

The researchers argue that understanding the relationship between size and number is critical for the development of higher math abilities. By combining number and size (e.g., area, density and perimeter), we can make faster and more efficient decisions.

Take for example the dilemma over choosing the quickest checkout line at the grocery store. While most people intuitively get behind someone with a less filled-looking cart, a fuller-looking cart with fewer, larger items may actually be quicker. The way we make these kinds of decisions reveals that people use the natural correlation between number and continuous magnitudes to compare magnitudes.

The researchers also urge colleagues to consider the roles other factors, such as language and cognitive control, play in acquiring numerical concepts. While the theoretical models presented in this review may raise more questions than answers, the researchers hope their hypothesis will reveal new ways of identifying dyscalculia, which can currently only be diagnosed in school-aged children. By this stage, children with the disorder are already lagging behind their peers.

Read more at Science Daily

Brain's multi-track road to long-term memory

How do different brain regions interact when long-term memories are formed?

Our brain has a tough task every time we experience something new -- it must be flexible to take in new information instantly, but also stable enough to store it for a long time. And new memories may not be allowed to alter or overwrite old ones. The brain solves this problem by storing new information in two separate places -- the hippocampus, a short-term storage site with high plasticity and capacity that can absorb information quickly; and in a part of the cerebral cortex, the neocortex. This is slower to take in the information, but protects it for the long term and does not allow it to be overwritten. Researchers from the Institute of Medical Psychology and Behavioral Neurobiology at the University of Tübingen have been working with colleagues from Munich to discover how these two systems work together as we learn. Their findings have been published in the latest issue of PNAS.

The hippocampus has been the focus of intense scrutiny by memory researchers since the late 1950s, when it was surgically removed from a patient known as H.M. -- who was thereafter unable to form new memories. It was largely unknown what role the neocortex played in memory or how the two regions interacted. In their experiments, the Tübingen researchers placed test subjects at a computer screen and into a virtual maze, where they had to find hidden objects. The longer the test persons moved through the maze, the better they became at understanding how it was set out and where the hidden objects were. While the test subjects were carrying out the task, their brain activity was recorded by an MRI scanner.

In order to identify the brain region responsible for spatial memory, the researchers had a special trick. During one part of the experiment the maze did not change. This enabled the participants to slowly build up a spatial representation of it in their memories. In another part of the experiment, the maze changed constantly, so that the test subjects could not recognize it or learn a set path around it. "The comparison of the MRI images from the two mazes reveals which brain regions were specifically contributing to the formation of spatial memories," says Svenja Brodt, a doctoral candidate at the Graduate Training Center of Neuroscience and lead author of the study. "We were suprised that the activity of the precuneus, a region at the back of the neocortex, steadily increased, while the activity in the hippocampus steadily fell," Brodt explains. And communication between the two regions also fell during the learning process, according to Brodt.

"These results enable us to demonstrate that the long-term, neocortical traces of memory are formed right when the information is first gathered," says Dr. Monika Schönauer, who supervised the study. She said the pace of this process was astounding. Researchers had always assumed that the process took place very slowly, lasting weeks or months. Professor Steffen Gais explains: "The astonishing thing is that the hippocampus ceases to participate in learning after such a short time." The number of repetitions appeared to have a key influence on how quickly a long-term, stable memory was formed in the neocortex.

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9-Foot Salmon Once Spawned in California Rivers

Some 5 to 11 million years ago, the waters of the Pacific Ocean held salmon that topped out at about 9 feet long ("only" three feet for the shorter ones). What's more, they sported inch-long teeth that were wide at the base and shaped like sharpened spikes.

That's according to scientists from California State University, who spoke about the ancient fish at a meeting of the Society of Vertebrate Paleontology.

"These giant, spike-toothed salmon were amazing fish," said Julia Sankey, who led a team of researchers in a study of the extinct creatures. "You can picture them getting scooped out of the proto-Tuolumne River [near Modesto in central Calif.] by large bears 5 million years ago."

And that scooping must have been a tricky task. Even large bears would likely have had their paws full: The super-salmon could weigh up to 400 pounds.

The unusual teeth of the giant fish were the focus of the team's work. The researchers think it's likely the fish was a filter feeder, just like modern sockeye Pacific salmon, which open wide and take in plankton as they move.

If not for dining, what, then, was the purpose of the teeth?

To find out, Sankey and her colleagues compared dozens of tooth fossils from the animal that were found in freshwater and saltwater environments. The freshwater teeth were longer and more sharply curved, with clear evidence of wear, while those from saltwater sites were consistently smaller and lacked the worn-down look, indicating there was a change in the teeth before spawning.

That difference told the researchers that the large, spiky teeth were likely used for displaying and fighting among the giant salmon during spawning season. The finding dovetailed nicely with the behavior of most modern salmon species. Born in freshwater rivers and streams, they head out to salt water to live much of their lives, before moving back upstream to fresh water to spawn, after which all Pacific salmon and many other species die in a matter of weeks.

Before they migrate, though, salmon undergo physical changes, particularly to their skulls, the researchers noted. And modern males will fight with each other in defense of eggs they have fertilized. The ancient giant salmon, then, had particularly rough-house weapons at its disposal.

From Discovery News

DNA From Mystery Human Species Detected in Pacific Islanders

Melanesians — people native to Vanuatu, the Solomon Islands, Fiji, Papua New Guinea, New Caledonia, West Papua and the Maluku Islands — could carry DNA from a now-extinct human ancestor that is so far unknown in the fossil record, new genetic analysis suggests.

Melanesians retain both Neanderthal and Denisovan ancestry in their genes. Neanderthals and Denisovans were both extinct populations of humans in our genus, Homo. The new research, presented recently at the American Society of Human Genetics Annual Meeting in Vancouver, B.C., may add yet another layer to the ancestry of many Pacific Islanders.

Their mystery relative "could have been a population relative to Denisova, or something more distantly related," Ryan Bohlender, lead author of the new research, told Seeker.

Melanesians to this day have an extremely unusual trait: they often have the darkest skin in the world outside of Africa, yet about one-fourth of them have blonde afros. Their unique appearance must be due to their intricate ancestry, which involved a lot of admixture. That's when two or more previously isolated populations within a species mix. In their case, it looks like the interbreeding included modern humans (Homo sapiens), Neanderthals, Denisovans and the mystery human.

Bohlender, who is a postdoctoral researcher at the University of Texas MD Anderson Cancer Center, and his colleagues created an estimation tool to better determine how our histories interacted with those of Neanderthals and Denisovans. The scientists then looked to see how well the computer model predicted the pattern of variation seen in various existing populations.

"We find that the answer is, reasonably well in Europe and East Asia, and less well in Melanesia," Bohlender said.

"Given the poor fit in Melanesia, something appears to be different there and one way for things to differ is additional admixture from some other hominin (early human) that we didn't include in the model."

The estimation tool also indicates that the early human population in Africa was about 50 percent larger than previously believed. It also suggests that Neanderthals diverged from our lineage 440,000 years ago, which is 100,000 years later than previously thought.

Why there was an archaic-modern human separation at that time is yet another mystery.

If you are Melanesian, then you are about 2 percent Neanderthal, between 3–4 percent Denisovan and also likely retain an additional small percentage of DNA from the mystery human ancestor, based on the new research.

"I think there is no such thing as a purebred modern human," Joshua Akey, who conducted some of the earlier research, told Seeker.

"All of our genomes are a mosaic of different ancestries, and admixture is a recurring theme throughout human evolutionary history," continued Akey, who is a researcher at the University of Washington's Department of Genome Science.

Interbreeding happened in Africa too, other studies indicate. A 2012 paper, for example, found DNA for yet another mystery human species in the genomes of hunter-gatherer people who live in Cameroon and Tanzania.

As for what all of this interbreeding means for us, it seems that the news is both good and bad. On the positive side, Bohlender said that "there are regions that have directly benefited from archaic DNA, like high altitude adaptation in Tibet." Today's Tibetans can therefore thank their Denisovan relatives for the ability to breathe easier than the rest of us while in the thinner air of mountainous areas.

Read more at Discovery News

Wild cat brains: An evolutionary curveball

The cheetah is social, like primates, yet unlike primates its frontal lobe is relatively small. Why? It may be a consequence of its unusual skull shape, an adaptation for high-speed pursuits.

The brains of wild cats don't necessarily respond to the same evolutionary pressures as those of their fellow mammals, humans and primates, indicates a surprising new study led by a Michigan State University neuroscientist.

Arguably, the fact that people and monkeys have particularly large frontal lobes is linked to their social nature. But cheetahs are also social creatures and their frontal lobes are relatively small. And leopards are solitary beasts, yet their frontal lobes are actually enlarged.

So what gives? Sharleen Sakai, lead investigator of the National Science Foundation-funded research, said the findings suggest that multiple factors beyond sociality may influence brain anatomy in carnivores.

"Studying feline brain evolution has been a bit like herding cats," said Sakai, MSU professor of psychology and neuroscience. "Our findings suggest the factors that drive brain evolution in wild cats are likely to differ from selection pressures identified in primate brain evolution."

Sakai and colleagues examined 75 wild feline skulls, representing 13 species, obtained from museum collections, including those at MSU. The researchers used computed tomography (CT) scans and sophisticated software to digitally "fill in" the areas where the brains would have been. From that process, they determined brain volume.

Sakai's lab is interested in uncovering the factors that influence the evolution of the carnivore brain. One explanation for large brains in humans and primates is the effect of sociality. The idea is that dealing with social relationships is more demanding than living alone and results in bigger brains, especially a bigger frontal cortex.

"We wanted to know if this idea, called the 'social brain' hypothesis, applied to other social mammals, especially carnivores and, in particular, wild cats," Sakai said.

Of the 13 wild feline species examined, 11 are solitary and two -- lions and cheetahs -- are social.

Here are some of the key findings of the research:

*Surprisingly, overall brain size did not differ, on average, between the social and solitary species of wild cats. But the part of the brain that includes the frontal cortex did differ between the two species.

*The female lion had the largest frontal cortex. Female lions are highly social, working together to protect and feed their young, hunt large prey and defend their territory. In contrast, males may live alone and may be dominant in a pride for only a few years. The larger frontal cortex in females compared to male lions and the other wild cats may reflect the lionesses' demands of processing social information necessary for life in the pride.

*The social cheetahs, in contrast, had the smallest overall brains and the smallest frontal cortex of the wild cats. Small brains weigh less and require less energy, factors that might contribute to the cheetah's remarkable running speeds. "Cheetah brain anatomy is distinctive and differs from other wild cats," Sakai said. "The size and shape of its brain may be a consequence of its unusual skull shape, an adaptation for high-speed pursuits."

Read more at Science Daily

Mystery solved behind birth of Saturn’s rings

Left: Image of Saturn's rings taken by the Cassini spacecraft. Right: Image of Uranus' rings taken by the Hubble Space Telescope.

A team of researchers has presented a new model for the origin of Saturn's rings based on results of computer simulations. The results of the simulations are also applicable to rings of other giant planets and explain the compositional differences between the rings of Saturn and Uranus. The findings were published on October 6 in the online version of Icarus.

The lead author of the paper is HYODO Ryuki (Kobe University, Graduate School of Science), and co-authors are Professor Sébastien Charnoz (Institute de Physique du Globe/Université Paris Diderot), Professor OHTSUKI Keiji (Kobe University, Graduate School of Science), and Project Associate Professor GENDA Hidenori (Earth-Life Science Institute, Tokyo Institute of Technology).

The giant planets in our solar system have very diverse rings. Observations show that Saturn's rings are made of more than 95% icy particles, while the rings of Uranus and Neptune are darker and may have higher rock content. Since the rings of Saturn were first observed in the 17th century, investigation of the rings has expanded from earth-based telescopes to spacecraft such as Voyagers and Cassini. However, the origin of the rings was still unclear and the mechanisms that lead to the diverse ring systems were unknown.

The present study focused on the period called the Late Heavy Bombardment that is believed to have occurred 4 billion years ago in our solar system, when the giant planets underwent orbital migration. It is thought that several thousand Pluto-sized (one fifth of Earth's size) objects from the Kuiper belt existed in the outer solar system beyond Neptune. First the researchers calculated the probability that these large objects passed close enough to the giant planets to be destroyed by their tidal force during the Late Heavy Bombardment. Results showed that Saturn, Uranus and Neptune experienced close encounters with these large celestial objects multiple times.

Next the group used computer simulations to investigate disruption of these Kuiper belt objects by tidal force when they passed the vicinity of the giant planets. The results of the simulations varied depending on the initial conditions, such as the rotation of the passing objects and their minimum approach distance to the planet. However they discovered that in many cases fragments comprising 0.1-10% of the initial mass of the passing objects were captured into orbits around the planet. The combined mass of these captured fragments was found to be sufficient to explain the mass of the current rings around Saturn and Uranus. In other words, these planetary rings were formed when sufficiently large objects passed very close to giants and were destroyed.

The researchers also simulated the long-term evolution of the captured fragments using supercomputers at the National Astronomical Observatory of Japan. From these simulations they found that captured fragments with an initial size of several kilometers are expected to undergo high-speed collisions repeatedly and are gradually shattered into small pieces. Such collisions between fragments are also expected to circularize their orbits and lead to the formation of the rings observed today.

This model can also explain the compositional difference between the rings of Saturn and Uranus. Compared to Saturn, Uranus (and also Neptune) has higher density (the mean density of Uranus is 1.27g cm-3, and 1.64g cm-3 for Neptune, while that of Saturn is 0.69g cm-3). This means that in the cases of Uranus (and Neptune), objects can pass within close vicinity of the planet, where they experience extremely strong tidal forces. (Saturn has a lower density and a large diameter-to-mass ratio, so if objects pass very close they will collide with the planet itself). As a result, if Kuiper belt objects have layered structures such as a rocky core with an icy mantle and pass within close vicinity of Uranus or Neptune, in addition to the icy mantle, even the rocky core will be destroyed and captured, forming rings that include rocky composition. However if they pass by Saturn, only the icy mantle will be destroyed, forming icy rings. This explains the different ring compositions.

Read more at Science Daily

Research into extreme weather effects may explain recent butterfly decline

While it is well known that changes to the mean climate can affect ecosystems, little is known about the impact of short-term extreme climatic events (ECEs) such as heatwaves, heavy rainfall or droughts.

Increasingly frequent extreme weather events could threaten butterfly populations in the UK and could be the cause of recently reported butterfly population crashes, according to research from the University of East Anglia (UEA).

Researchers investigated the impact of Extreme Climatic Events (ECEs) on butterfly populations. The study shows that the impact can be significantly positive and negative, but questions remain as to whether the benefits outweigh the negative effects.

While it is well known that changes to the mean climate can affect ecosystems, little is known about the impact of short-term extreme climatic events (ECEs) such as heatwaves, heavy rainfall or droughts.

Osgur McDermott-Long, PhD student and lead author from the School of Environmental Sciences at UEA, said: "This is the first study to examine the effects of extreme climate events across all life stages of the UK butterflies from egg to adult butterfly. We wanted to identify sensitive life stages and unravel the role that life history traits play in species sensitivity to ECEs."

The researchers used data from the UK Butterfly Monitoring Scheme (UKBMS), a high-quality long-term dataset of UK butterfly abundances collected from over 1,800 sites across the UK, spanning 37 years, to examine the effects of weather data and extreme events (drought, extremes of rain, heat and cold) on population change.

The team looked at resident species of butterflies, those which only breed once in a year, and those having more than one brood annually. Multi-brood species were found to be more vulnerable than single brood species and in general extremes of temperature rather than precipitation were found to influence changes in butterfly populations.

Dr Aldina Franco, co-author said: "A novel finding of this study was that precipitation during the pupal (cocoon) life-stage was detrimental to over one quarter of the species. This study also found that extreme heat during the 'overwintering' life stage was the most detrimental extreme weather event affecting over half of UK species. This may be due to increased incidents of disease or potentially extreme hot temperatures acting as a cue for butterflies or their larvae to come out from overwintering too early and subsequently killed off by temperatures returning to colder conditions."

In addition to the negative impacts, the authors found that some life stages may benefit from climatic extreme weather, with extreme heat in the adult stage causing a positive population change in over one third of the UK species.

Dr Franco, added: "This is not an unexpected finding given that butterflies are warm loving creatures. Years with extreme warm summers and winters may have mixed effects. For example, this year was terrible for butterflies, although the summer was warm the number of butterflies counted during the Big Butterfly Count was particularly low. Our study indicates that this could have resulted from the detrimental effects of the warm winter, for example the recent low counts1 of Gatekeeper, Common Blue, Comma, Peacock and Small Tortoiseshell butterflies could be explained by our results due to their negative response to warm winters which was just experienced2."

Mr McDermott Long said: "The study has demonstrated previously unknown sensitivities of our UK butterflies to extreme climatic events, which are becoming more frequent with climate change. Some of these effects are undoubtedly putting future populations at risk, such as extremely warm winters, however we've seen that warm and even climatically extreme hot summers may actually benefit butterflies.

Further research is needed regarding the balance of the importance that these variables could have, to see if the benefits of warmer summers will be outweighed by the detrimental winter effects."

Dr Tom Brereton from Butterfly Conservation and a co-author of the study, said: "If we are to mitigate against extreme events as part of conservation efforts, in particular, we need a better understanding of the habitat conditions which can lead to successful survival of adult, pupal and overwintering life stages of UK butterflies in these situations."

Read more at Science Daily

Monster Chinese Telescope to Join Tabby's Star Alien Hunt

The world's largest single-dish radio telescope will join the hunt for intelligent aliens that could be building a "megastructure" around the star KIC 8462852 — otherwise known as "Tabby's Star."

The recently completed Five-hundred-meter Aperture Spherical radio Telescope, or "FAST," occupies a valley in the southwestern Guizhou province of China. With a diameter of 500 meters, this monstrous telescope is almost 200 meters wider than the famous Arecibo Observatory in Puerto Rico. And now FAST will join the Breakthrough Listen SETI project to "listen in" on the strange star.

Though the likelihood of actually finding any chatty aliens around the star is slim, great mystery still surrounds the cause of some dramatic dimming events. NASA's Kepler space telescope recorded these events as transits that caused the star to dip in brightness of up to 22%. Kepler looks for exoplanets by detecting their transits (i.e. as a planet orbiting another star passes in front, blocking a tiny fraction of starlight). Typically, these transit events block a fraction of one percent of starlight.

Add to these unprecedented transit events the fact the star has apparently been dimming for over a century, and astronomers have been presented with a quandary: what is blocking the light from Tabby's Star?

One hypothesis put forward is that the dramatic transits were caused by a cloud of comets, but that explanation has fallen short of proving the source of the anomaly. Most likely is that Tabby's Star's weirdness is being caused by some overlooked phenomenon, or a completely new natural phenomenon that has yet to be understood.

But say if the cause isn't natural? What if there's an advanced alien civilization building some kind of "Dyson Sphere"-like structure — basically a star-enshrouding solar array that is designed to harness all the star's energy? Unlikely as it may sound and, as Occam's Razor dictates, aliens are the least likely explanation, Breakthrough Listen will study the star and it now has a powerful new tool to add to its growing arsenal of radio antennae.

It was announced that FAST would be joining Breakthrough Listen earlier this month, and now it looks like hopes are high that it will be committed specifically to the monitoring of Tabby's Star despite a busy observing schedule.

"The FAST telescope will be absolutely incredible for conducting extremely sensitive searches of Tabby's star for evidence of technologically produced radio emissions," Andrew Siemion, director of the Berkeley SETI Research Center and co-director of Breakthrough Listen, told the South China Morning Post. "We are very excited to work with our colleagues in China on conducting SETI observations with FAST, including of Tabby's star. Within its frequency range, FAST is the most sensitive telescope in the world capable of conducting SETI observations of Tabby's star, and will be able to detect the weakest signals."

Read more at Discovery News

Enormous dome in central Andes driven by huge magma body beneath it

The Altiplano-Puna plateau in the central Andes features vast plains punctuated by spectacular volcanoes, such as the Lazufre volcanic complex in Chile seen here.

A new analysis of the topography of the central Andes shows the uplifting of Earth's second highest continental plateau was driven in part by a huge zone of melted rock in the crust, known as a magma body.

The Altiplano-Puna plateau is a high, dry region in the central Andes that includes parts of Argentina, Bolivia, and Chile, with vast plains punctuated by spectacular volcanoes. In a study published October 25 in Nature Communications, researchers used remote sensing data and topographic modeling techniques to reveal an enormous dome in the plateau.

About 1 kilometer (3,300 feet) high and hundreds of miles across, the dome sits right above the largest active magma body on Earth. The uplifting of the dome is the result of the thickening of the crust due to the injection of magma from below, according to Noah Finnegan, associate professor of Earth and planetary sciences at UC Santa Cruz and senior author of the paper.

"The dome is Earth's response to having this huge low-density magma chamber pumped into the crust," Finnegan said.

The uplifting of the dome accounts for about one-fifth of the height of the central Andes, said first author Jonathan Perkins, who led the study as a graduate student at UC Santa Cruz and is now at the U.S. Geological Survey in Menlo Park, Calif.

"It's a large part of the evolution of the Andes that hadn't been quantified before," Perkins said.

The other forces uplifting the Andes are tectonic, resulting from the South American continental plate overriding the Nazca oceanic plate. The subduction zone where the Nazca plate dives beneath the western edge of South America is the source of the magma entering the crust and feeding volcanic activity in the region. Water released from the subducting slab of oceanic crust changes the melting temperature of the overlying wedge of mantle rock, causing it to melt and rise into the overriding plate.

Perkins and Finnegan worked with researchers at the University of Arizona who had used seismic imaging to reveal the remarkable size and extent of the Altiplano-Puna magma body in a paper published in 2014. That study detected a huge zone of melted material about 11 kilometers thick and 200 kilometers in diameter, much larger than previous estimates.

"People had known about the magma body, but it had not been quantified that well," Perkins said. "In the new study, we were able to show a tight spatial coupling between that magma body and this big, kilometer-high dome."

Based on their topographic analysis and modeling studies, the researchers calculated the amount of melted material in the magma body, yielding an estimate close to the previous calculation based seismic imaging. "This provides a direct and independent verification of the size and extent of the magma body," Finnegan said. "It shows that you can use topography to learn about deep crustal processes that are hard to quantify, such as the rate of melt production and how much magma was pumped into the crust from below."

The Altiplano-Puna Volcanic Complex was one of the most volcanically active places on Earth starting about 10 million years ago, with several super-volcanoes producing massive eruptions and creating a large complex of collapsed calderas in the region. Although no major eruptions have occurred in several thousand years, there are still active volcanoes and geothermal activity in the region. In addition, satellite surveys of surface deformation since the 1990s have shown that uplifting of the surface is continuing to occur at a relatively rapid rate in a few places. At Uturuncu volcano located right in the center of the dome, the uplift is about 1 centimeter (less than half an inch) per year.

"We think the ongoing uplift is from the magma body," Perkins said. "The jury is still out on exactly what's causing it, but we don't think it's related to a supervolcano."

Read more at Science Daily

Early Pacific seafarers likely latched onto El Nino, other climate patterns

The colonization of far-flung Remote Oceania some 3,400 years ago was one of the most ambitious and expansive population dispersals in human history.

Seafarers traveled thousands of miles of ocean, navigating by stars and overcoming currents and difficult weather to arrive in a region that includes present-day Tonga, Samoa, Hawaii, Micronesia and Fiji.

Now research by a three-member team provides new insights into how these early travelers came to travel the Pacific Ocean and populate one of the most remote regions on Earth.

"Where did these people come from? How did they get to these really remote places, and what were the factors, culturally, technologically and politically that led to these population dispersals?" said co-author Scott Fitzpatrick, an anthropologist at the University of Oregon. "These are really big questions for Pacific archaeology and other related disciplines."

Fitzpatrick and his team, which includes Ohio State University geographer Alvaro Montenegro, the paper's corresponding author, and University of Calgary archaeologist Richard Callaghan, offer some potential answers in a paper published Oct. 24 in the online Early Edition of the Proceedings of the National Academy of Sciences.

The paper, "Using Seafaring Simulations and 'Shortest Hop' Trajectories to Model the Prehistoric Colonization of Remote Oceania," details the team's use of computer simulations and climatic data to analyze ocean routes across the Pacific. The simulations take into account high-resolution data for winds, ocean currents, land distribution and precipitation.

"We synthesized a lot of new climatic data and ran a lot of new simulations that are exciting in terms of highlighting and pinpointing where some of these prehistoric populations might have come from," Fitzpatrick said. "The simulation can assess, at any point in time, if somebody left point A, where would they end up if they drifted? We can also model directed voyages. If somebody knew where they were going, how long would it take them to get there?"

Fitzpatrick and his colleagues used their simulations to identify most likely ports of departure for the settlers of five major regions in Remote Oceania. To account for course variations due to wind and currents, the team created "shortest hop" trajectories to assess the likely paths of least resistance. This technique factors in the role that distance and remoteness may have played in facilitating voyaging from one island to another, and can include changes in sea level at different points in time that may have made these trips easier or harder.

Seafaring models have been developed and used by other researchers in the past, Fitzpatrick said, but they weren't able to fully harness the high-resolution satellite data sets that have only recently been made available to scientists.

The research team's simulations include El Nino Southern Oscillation patterns, which settlers most likely knew about and used to their advantage, Fitzpatrick said. Archaeological records reflect El Nino occurrences, which typically happen every three to seven years, and can be seen in evidence marking droughts and fires. Because winds and associated precipitation shift from westerly to easterly during El Nino years, settlers would have found travel toward Remote Oceania more favorable when the pattern was occurring and may have timed their departures accordingly.

"What Pacific scholars have long surmised but never really been able to establish very well is that, through time, Pacific Islanders should have developed a great deal of knowledge of different climactic variations, different oscillations of wind and changes in environments that would have influenced their survivability and their abilities to go to certain places," Fitzpatrick said.

The analysis provides insights about the origins of the early seafarers. The settlers of western Micronesia probably came from near the Maluku (Spice) Islands. Some of the team's findings challenge current archaeological theories, while other data support existing lines of evidence. The research suggests Samoa was the most likely staging area for colonizing East Polynesia. It also indicates that Hawaii and New Zealand may have been settled from the Marquesas or Society Islands. Easter Island may have been settled from the Marquesas or Mangareva.

The new paper also highlights areas worthy of further research. It suggests that Samoa may have been an epicenter for colonization and challenges data that links the Philippines as a potential point of departure for the settlement of Micronesia.

Each team member brought complementary expertise to the study. Fitzpatrick contributed his knowledge of the archaeology of island and coastal regions in the Pacific and the Caribbean. Montenegro, the paper's lead author, is a geographer and climatologist. Callaghan is an archaeologist specializing in seafaring simulations.

A question that may never be resolved is why seafaring settlers traveled such immense distances. Although there's evidence that some settlers were motivated by a desire to obtain new resources such as basalt or obsidian for making stone tools, Fitzpatrick said, there's no easy way to explain the leap of faith it would take to set off on a colonizing mission of 400 to 2,500 miles.

Read more at Science Daily