Prehistoric Art Highlights 'Supernatural' Sound Effects

Depictions of interesting sounds, such as echoes and natural amplifications, appear to have made their way into everything from cave art to Stonehenge, according to new research presented today at the Meeting of the Acoustical Society of America in Indianapolis.

Among other things, the discovery could help to explain why so much early cave art showed human hands and images of herds of running animals. Steven Waller of Rock Art Acoustics suggests that the echoes and reverberation of things like hand clapping in a cave would have been misinterpreted as being “supernatural.”

“Ancient mythology explained echoes from the mouths of caves as replies from spirits, so our ancestors may have made cave paintings in response to these echoes and their belief that echo spirits inhabited rocky places such as caves or canyons,” Waller explained in a press release.

Echoes of clapping hands can sound similar to hoof beats, he said, which could be why so many running herds of animals were featured on cave walls.

“Many ancient cultures attributed thunder in the sky to ‘hoofed thunder gods,’ so it makes sense that the reverberation within the caves was interpreted as thunder and inspired paintings of those same hoofed thunder gods on cave walls,” he said.

Waller added, “This theory is supported by acoustic measurements, which show statistically significant correspondence between the rock art sites and locations with the strongest sound reflection.”

Sounds like this are now called “auditory illusions.” Early leaders appear to have often used them. For example, prior research determined that hand clapping at the pyramid of Kukulkan in Chichen Itza, Mexico, produces an echo resembling the call of the quetzal, a sacred bird thought to hold mythical powers. Priests clapped and then interpreted what the “mystical” echo meant.

Waller even thinks that the placement of stones at Stonehenge could have been done with “supernatural” sound effects in mind. He traveled to the megalith and had two flute players play the same note at the same time in a nearby open space. Other blindfolded individuals listened to the results.

Read more at Discovery News

When Spirits 'Dictate' Books: What's to Believe?

Just in time for Halloween, there are several recent books out that are claimed to have been written by dead people through living writers. One is by musician David Young called “Channeling Harrison,” in which he claims that the spirit of ex-Beatle George Harrison is in contact with him, guiding his songwriting and teaching him life lessons.

There is nothing new about this; so-called “channeled” books were very popular in New Age circles in the 1970s and 1980s. Among the most popular was the 1970s book series “Seth Speaks,” dictated by Jane Roberts, who claimed that an energy named Seth possessed her body and dictated esoteric information through her about the soul, the nature of consciousness, spiritual truths, higher planes of reality, and so on.

Channeling remains immensely popular among New Agers; hundreds of books, audiotapes, seminars, and DVDs are devoted to the practice.

Ghost-Written Books

Earlier this year in her book “Conversations with History,” claimed psychic medium Susan Lander wrote that Betsy Ross, widely credited with sewing America’s first flag, came out to her as a lesbian about 175 years after her death. According to an interview on Out.com, “When Lander asked Ross why she contacted her, the American icon announced: ‘I am gay and I fly the flag of pride and liberty for all of us… I am gay, I am gay, I am gay… I am speaking now as a revolutionary act,” Ross explained [through Lander], saying she no longer wanted to carry this secret. ‘I want history to accurately reflect who I was.’”

It’s a surprising revelation from Ross — especially since many scholars doubt that she actually sewed the flag she’s famous for. According to “The Washington Post,” “There simply is no credible historical evidence that Ross… either made or had a hand in designing the American flag before it made its debut in 1777… it is all but certain that the story about her creating the American flag is a myth.” Given Betsy Ross’s interest in wanting history to accurately reflect who she was, it’s very strange that she would not have offered evidence defending her claim to fame.

Wendy Weir, sister of the Grateful Dead singer and guitarist Bob Weir, wrote a book titled “In the Spirit: Conversations with the Spirit of Jerry Garcia,” in which she offered 250 pages of what she says the dead singer told her about life, music, and the world, in a series of lessons from the cosmic beyond.

Unfortunately little of Jerry Garcia’s lyricism seems to have survived death, and most of his messages are indistinguishable from standard New Age platitudes; here’s a typical message: “Joy is love. Joy is peace. Joy is within each and every one of us if only we listen to it calling, follow its song, and open the doors to where we so often keep it hidden behind pressure, guilt, work, obligations, fear, and pain. Allow the light of joy to shine forth from within, allow it to penetrate the Universe, and you will be transformed, for life within you will be raised to a high vibration and the life without you will respond to this shift… This is a lesson we should incorporate into all of our lives, every day. Open up, allow your joy to shine forth, and feel the radiance, the joy, shining back to you.”

One of the problems with channeled books is that for the most part anyone can claim to communicate with the spirit of anyone, from Jesus to Napoleon to Michael Jackson, and write a book about it.

Verifying Ghostly Information

While the vast majority of information imparted through psychic mediums and channelers is impossible to independently verify, every now and then they do offer facts that can be examined.

For example before its demise in 2007 as a printed magazine, “Stuff” had a regular column called “Beyond the Grave: Interviews with Dead Celebrities.” It’s not clear how tongue-in-cheek the readers took it, but the psychic who wrote it, Victoria Bullis, was certainly serious about it. Bullis “interviewed” many dead celebrities including ex-model Anna Nicole Smith, and when Smith was asked about the then-hyped controversy over the paternity of Smith’s daughter Dannielynn, Smith was clear and unequivocal: “Please tell everyone it’s Howard K. Stern.”

However soon after the interview was published, DNA tests revealed that in fact Smith’s former boyfriend Larry Birkhead was the father. For Bullis and others who believe that people can talk to the dead, this presents an interesting problem, because the ghost said something that wasn’t true.

There are several possible explanations: 1) Smith did not know who the father of her child was, and therefore the dead don’t have any better information than the living (about paternity, cosmic truths, or anything else); or 2) Smith lied to Bullis and her readers (thus calling into question the truth of anything communicated by a ghost) or 3) “World-renowned psychic” Victoria Bullis cannot really talk with the dead as she claims.

The Psychology of Channeling

So are all these communications with dead people hoaxes or frauds? Not necessarily; surely some are cynically cashing in on dead celebrities, but most of them truly believe that they have been in contact with the dead or some unseen presence. This is neither pathological nor unusual: countless shamans, prophets, priests, and others claim to hear voices or receive supernatural knowledge or messages from the spirit world.

It’s an interesting phenomenon with a psychological explanation. When people meditate and relax, random thoughts, images, symbols, and messages may spontaneously arise. If we believe in ghosts or higher powers — and especially if we are actively trying to communicate with them — then in this harmless dissociative state we may interpret our own thoughts as coming from another consciousness outside the body.

David Young, author of “Channeling Harrison,” believes that George Harrison began communicating with him in his dreams, and Young soon began noticing what he considered to be significant coincidences in his life.

Read more at Discovery News

Murderers May Be Hardwired to Kill

Serial killers and other people who repeatedly commit violent crimes, such as assault and battery, may be hardwired to hurt others, suggests a new study that identifies two genetic variants tied to extreme violent behavior.

The findings, published in the latest issue of the journal Molecular Psychiatry, could help to explain why the majority of violent crimes are committed by a small group of antisocial, repeat offenders. The extensive study represents the first effort to investigate the genetic background of people exhibiting such repetitive, brutal behavior.

"I think that we have found two genes that have the largest effect in aggressive behavior, and that there are probably tens or hundreds of other genes having smaller effects," lead author Jari Tiihonen told Discovery News.

Tiihonen, a professor in the Department of Clinical Neuroscience at the Karolinska Institute in Sweden, and his colleagues screened 1004 prisoners in Finland. Of that group, 184 refused to participate in the study and 26 were excluded because of "a psychosis diagnosis." Blood samples for DNA extraction were taken from the remaining prisoners, whose crimes and backgrounds were also investigated.

The scientists determined that the prisoners who had repeatedly committed, or attempted to commit, violent crimes tended to have one or both of the following genetic variants: CDH13 and MAOA, a.k.a. the "warrior gene."

Tiihonen explained that MAOA metabolizes an important neurotransmitter called dopamine. The presence of this genetic variant and substance abuse helps to create a perfect storm.

"If this activity is decreased, it might lead to a larger dopamine burst in the brain when alcohol, cocaine or amphetamine is used," he explained. "It is known that these substances induce dopamine burst and aggression."

CDH13, on the other hand, is a gene that codes for neuronal adhesion protein, so it contributes to the development of neuronal connections in the brain. It is one of the most important genes associated with Attention Deficit Hyperactivity Disorder (ADHD).

People with both of these genetic variants have a 13-fold increase of committing a violent crime versus those who do not have the mutations, according to the study. Add substance abuse again to the mix and there is a likely recipe for disaster.

The study could also help to explain why most mass murderers are men.

"Since MAOA is located in the X-chromosome, men have only one copy of the gene and women have two copies," Tiihonen said, explaining that women have two X-chromosomes. "Therefore, females can have one low activity allele (alternative form of a gene that arises by mutation) and one high activity allele, but if males have a low activity allele, they cannot have another allele functioning more efficiently because they have only one copy of the gene."

Yet another recent study, conducted on a sample of about 100 inmates from a correctional institution in the Southern United States, also determined that MAOA is associated with higher rates of crime when the individual additionally experienced childhood adversity.

"These findings (published in the journal Psychiatric Genetics) indicate that gene-by-environment interactions are important for understanding variation in crime amongst populations with high base rates of criminal activity," said principal investigator Todd Armstrong of Sam Houston State University.

Read more at Discovery News

A Look Inside a Jumping Spider's Explosive Brain

The jumping spider, famed for its excellent vision and pouncing skills, has long been an enigma to neurobiologists. The arachnid's body is filled with a pressurized liquid that helps it move, and whenever curious scientists have tried to peer into its brain with surgical instruments, the spider exploded.

Now, with a new technique, scientists have recorded the electrical brain activity of these fascinating spiders, sans kaboom.

"What we've done is open up the brain basis of a very unusual animal," said researcher Ron Hoy, a professor of neurobiology and behavior at Cornell University.

The jumping spider (Phidippus audax) has a brain the size of a poppy seed, but vision almost on par with humans, making its visual system intriguing to researchers and robotic engineers who draw inspiration from nature.

Gil Menda, a postdoctoral researcher of neurobiology and behavior in Hoy’s lab, realized that if he made a tiny hole in the spider's head, the wound could self-heal around a tungsten-recording electrode as thin as a hair. He carefully inserted a microelectrode into the brains of 33 spiders, and watched how brain cells in their visual networks responded to pictures of white noise, flies and other jumping spiders.

With eight eyes, jumping spiders have an almost complete 360-degree view of their surroundings. Most spiders have poor vision and build webs to capture prey, but jumping spiders hunt nomadically much like a cat or a wolf stalks their prey, Hoy told Live Science.

He did note one small difference, however. Unlike cats, the spiders don't run after their prey. "They jump and seize their prey," Hoy said. "It's like a cat's pounce."

To keep the spiders still during the experiments, the research team created a small spider harness with a 3D printer. They covered the spiders' four back eyes, and inserted the electrode into the brain to help them look for brain cells associated with each spider's visual system. When the researchers showed the spiders an image of a fly, their natural prey, on a screen, the spiders' brain cells associated with their visual systems showed a burst of electrical activity.

In Chinese, the spider's name translates to "flying tiger." But they aren't dangerousto people. "They have venom, but it's reserved for their prey," Hoy said.

"You hear a very strong response from the brain when [the spiders] detect something that they recognize," Menda said.

To ensure the spiders weren't responding to certain parts of the fly, such as its wings or head, the researchers showed the spiders a jumbled picture of a fly. The scattered image didn't elicit a response. "They didn't respond at all to the pictures," Menda said. "It wasn't the small component of the picture, it was the image of the fly."

The jumping spiders also showed a neural response to the "white noise" static, but not to images of other spiders, according to the electrode recordings; it's possible that other neurons in their brains that weren't attached to the electrode showed a response to spider images, the researchers said.

Unlike humans, whose eyes detect both acuity and motion, the spider's large, primary eyes process acuity, and its small, secondary eyes see motion. Because researchers were unable to study the spiders' neural activity until now, they were unsure how the spiders' eyes worked together.

"You can imagine that you have four eyes that are all looking at the same thing, you get input one and input two, and you would add them together," speculated researcher Paul Shamble, a graduate student of neurobiology and behavior in Hoy's lab. "It turns out that for some of the neurons, that wasn't the case. It was much more complicated."

In the experiment, the researchers covered the spiders' front eyes and then their side eyes. The spiders showed little neural visual response to the images if either set of eyes was covered.

The spiders need both their large and small eyes to process visual information, the researchers found. "They need all of their eyes to detect the prey," Menda said.

Read more at Discovery News

Telltale Signs of Life Could Be Deepest Yet

Telltale signs of life have been discovered in rocks that were once 12 miles (20 kilometers) below Earth's surface — some of the deepest chemical evidence for life ever found.

Researchers found carbon isotopes in rocks on Washington state's South Lopez Island that suggest the minerals grew from fluids flush with microbial methane. Methane from living creatures has distinct levels of carbon isotopes that distinguish it from methane gas that arises from rocks. (Isotopes are atoms of the same element with different numbers of neutrons in their nuclei.)

In a calcium carbonate mineral called aragonite, the standard mix of carbon isotopes was radically shifted toward lighter carbon isotopes (by about 50 per mil, or parts per thousand). This ratio is characteristic of methane gas made by microorganisms, said Philippa Stoddard, an undergraduate student at Yale University who presented the research Tuesday (Oct. 21) at the Geological Society of America's annual meeting in Vancouver, British Columbia. "These really light signals are only observed when you have biological processes," she told Live Science.

The pale aragonite veins cut through basalt rocks that sat offshore North America millions of years ago. The veins formed after the basalt was sucked into an ancient subduction zone, one that predated today's Cascadia subduction zone. Two tectonic plates smash together at subduction zones, and one plate descends under the other, creating deep trenches.

Methane gas supplied the carbon as aragonite crystallized in cracks in the basalt, and replaced pre-existing limestone. The researchers think that microbes produced the methane gas as a waste product.

"We reason that you could have life deeper in subduction zones, because you have a lot of water embedded in those rocks, and the rocks stay cold longer as the (plate) comes down," Stoddard said.

But the South Lopez Island aragonite suggests the minerals formed under extreme conditions that push the limits of life on Earth. For example, temperatures reached more than 250 degrees Fahrenheit (122 degrees Celsius), above the stability limit for DNA, Stoddard said. However, the researchers think the higher pressures at these depths may have counterbalanced the effects of the heat. The rocks are now visible thanks to faulting, which pushed them back up to the surface.

Read more at Discovery News

Supervolcano Cleared in Neanderthals' Demise

Neanderthals disappeared from Europe 40,000 years ago, about the same time as the region's biggest volcanic blast in the last 200,000 years. But don't blame the volcano, a new study suggests.

Most of the eruption's climate-cooling pollution spread east, away from Neanderthal territory, according to research presented Monday (Oct. 20) here at the Geological Society of America's annual meeting.

"The pattern where the cooling was most intense doesn't overlap with where most of the Neanderthal sites are located," said study author Benjamin Black, a postdoctoral scholar at the University of California, Berkeley.

The Neanderthals' demise is an ongoing mystery. Their steep population decline followed the arrival of modern humans in Europe, studies show. Did our ancestors play a role in the Neanderthal extinction? Was it the onset of a cold, dry climate? Or did Italy's Campi Flegrei volcano deliver the final blow?

Campi Flegrei is an active volcano west of Naples that erupted in a tremendous explosion between 39,000 and 40,000 years ago. Superheated pyroclastic flows of volcanic gas and ash raced up nearby ridges more than 3,200 feet (1,000 meters) high and crossed miles of open water in the Bay of Naples, scorching the Sorrento Peninsula. The ash layers left behind are known as the Campanian Ignimbrite. The volcano also shot sulfur dioxide into the stratosphere, the layer of the atmosphere above the one we live and breathe in. In the stratosphere, sulfur dioxide is transformed into particles that reflect sunlight and cool the planet.

Black created a computer model of Campi Flegrei's global environmental effects, and then compared the extent of cooling and acid rain with locations of known Neanderthal and human archaeological sites of the same age. (Sulfur dioxide gas can also lead to acid rain.) The results suggest the volcano's fallout was brief and limited in Western Europe, where most Neanderthals met their end by 40,000 years ago, according to the latest studies. "The unusual climatic conditions may have impacted daily life, but the effects did not last long enough to trigger a catastrophic collapse of the Neanderthal population," Black told Live Science.

In Eastern Europe, temperatures fell by about 5.4 degrees Fahrenheit (3 degrees Celsius). This amount of cooling is similar to Europe's so-called "year without a summer" in 1816, which followed Mount Tambora's 1815 eruption. On the Volcano Explosivity Index, a scale that ranks eruptions, both Campi Flegrei and Mount Tambora rank a 7 out of 8.

The most intense cooling, of up to 11 degrees F (6 degrees C), was centered over Asia and North America rather than Europe, according to Black's model. And even then, the worst of the chill lasted about a year. Within five years, sulfur levels and temperatures in the Northern Hemisphere were nearly back to normal.

Scientists aren't sure how much ash and volcanic gas spewed from Campi Flegrei, so Black modeled both high- and low-emission scenarios and checked the results against 40,000-year-old sulfate levels preserved in the Greenland Ice Sheet. The best match comes from the low-emission scenario, with an estimated 55.1 million tons (50 teragrams) of volcanic sulfur dioxide used in the model.

Read more at Discovery News

Baby Stars' Twisted Magnetism More Chaotic Than Thought

As we zoom-in to stars light-years distant, we’re not only trying to understand the vast stellar menagerie that awaits our telescopic inquisitiveness, we’re also trying to decipher where we — and our bountiful solar system — came from.

Interestingly, the answer to how our unique planetary system came into being may be hiding in the magnetic configuration of a young sun that sparked to life over 4 billion years ago. Now, astronomers appear to have added another interesting finding to the magnetism surrounding a young star and how that may influence its ability at building a system of planets — thereby providing an insight to how our primordial solar system came to be.

Stars form as large clouds of cold molecular gas collapse under mutual gravity, eventually creating an environment so dense that nuclear fusion can spark inside stellar cores. Surrounding these embryonic stars, disks of gas and dust collect, creating accretion disks. It’s from these accretion disks that planetary systems will eventually evolve.

However, a baby star’s emerging magnetic field is thought to have a huge impact on planetary formation and the magnetic field’s configuration can make a huge difference for the final outcome of that star system.

Until now observations of young stars’ magnetic fields have been hard to come by, but an international team of astronomers have now measured the magnetic field surrounding a T Tauri star only 1 million years old. Their research was published in the journal Nature last week.

T Tauris are stars that are currently undergoing gravitational contraction and it is thought that the magnetic field these T Tauri stars possess strongly influence the configuration of the stars’ accretion disks. Using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) of radio telescopes in California, the researchers were able to capture the magnetic morphology of the T Tauri star HL Tau, which is located 450 light-years from Earth

Theoretical studies of baby star magnetic fields suggest they should either be “poloidal” (magnetic field lines that loop from the north to south poles of the protostar) or “toroidal” (wrapped around the circular accretion disk). What the observations of HL Tau appear to show, however, is a more complex picture — neither theoretical model fits the observation.

Read more at Discovery News

Stellar Fireball Captured in Action

The expanding fireball of a nova explosion has been observed in unprecedented detail for the first time.

The new observations, reported in the journal Nature, show these eruptions are far more complicated than previously thought.

"Bright novae go off every few years, but this is the first to have occurred in good weather since the development of reliable optical telescope interferometers," said one of the study's authors, Dr Michael Ireland of the Australian National University. "Everything has come together to give us a really good look at one."

A nova is the thermonuclear explosion of hydrogen on the surface of a dead star called a white dwarf. When a white dwarf comes into a very close orbit with a companion star, it can suck hydrogen off the other star onto its own surface.

Once this hydrogen ocean reaches a depth of around 200 meters, gravity produces enough pressure to trigger thermonuclear fusion -- essentially a stellar atomic bomb -- that is visible many light years away.

On Aug. 14, 2013 a nova exploded about 14,800 light-years away in the constellation Delphinus. The 'new' star was subsequently named Nova Delphinus 2013.

"This nova was bright enough to be seen with the unaided eye," said Ireland.

Within hours of its discovery, Ireland and colleagues pointed the telescopes of the CHARA array in California toward the expanding nova fireball.

The CHARA Array combines the light from six optical telescopes in a process called interferometery, to create very high resolution images. The first measurements, which were the earliest ever obtained for a nova, showed the fireball was already as big as Earth's orbit around the sun.

This dramatically expanded to the size of Neptune's orbit by the time of the final observations 43 days after the initial blast.

One of the big questions about novae is how the explosion happens. Astronomers suspect the blast must happen all over the star at once, but the process is very complex and not well understood.

"We found the initial nova explosion wasn't spherical, giving the fireball a slightly elliptical shape," said Ireland.

"This happens because the white dwarf's atmosphere is spinning, and there's a disk of accreted material falling onto it from the companion star, so there's a lot happening to prevent the system from being spherical when it goes bang."

This provides clues to understanding how material is ejected from the surface of the white dwarf during the explosion.

"The interesting thing for me, were the multiple shells seen as the nova explodes," said Ireland.

"There's a main shell expanding at about 600 kilometres per second, but then there were also semi-transparent shells further out going even faster. So we could see both the optically thick inner shell, and the transparent outer shells expanding at the same time."

Ireland and colleagues still don't know what these shells are.

"I think there's a very tenuous outer shell, and as you look deeper and closer into the star, things get denser until eventually you can't see through things," said Ireland. "It looks like there are multiple shells, but it could be a continuance of thicker stuff near the white dwarf and thinner stuff further out."

Read more at Discovery News

Some like it loud: Warning coloration paved the way for louder, more complex calls in poisonous frogs

Frogs are well-known for being among the loudest amphibians, but new research indicates that the development of this trait followed another: bright coloration. Scientists have found that the telltale colors of some poisonous frog species established them as an unappetizing option for would-be predators before the frogs evolved their elaborate songs. As a result, these initial warning signals allowed different species to diversify their calls over time.

Zoologists at the National Evolutionary Synthesis Center (NESCent), the University of British Columbia, and other research universities assembled an acoustic database to analyze more than 16,000 calls from 172 species within the poison frog family, Dendrobatidae. The paper, which will appear in the December issue of the Proceedings of the Royal Society B, is now available online.

The study included both frogs that display bright colors and others that rely on camouflage for protection. Each call was examined in terms of pitch and duration, and researchers also factored in the size of the frogs and their visibility to predators. They found that because warning coloration protected them from predators, they were better able to attract a mate with low-pitch, pulsing vocalizations in plain sight than their quieter, darker-hued relatives.

"This allows the frog to have a unique type of call -- a noisy call," said lead author Juan C. Santos, formerly of NESCent and now at the University of British Columbia. "These noisy kinds of calls, in general, are what the females really like."

Scientists already understood that predators shied away from brightly colored frogs because of visual cues, but Santos and his colleagues hypothesized that some species evolved to include audio signals, as well. Such a warning system is not unprecedented: Tiger moths emit ultrasonic chirps to communicate their unsavory taste to bats. Without a similar ability, frogs navigate a precarious dilemma in which they must either risk detection by predators or forgo possible courtship.

Initially the researchers expected that audio warnings predated coloration, but the results indicate the opposite. Using molecular data and statistical analyses, they were able to infer a phylogenetic tree and pinpoint which trait came first. Their findings indicate that visual traits established the frogs as poisonous and cleared the way for louder, more elaborate calls.

Species relying on camouflage for defense will not invite attention with boisterous calls, while their protected relatives -- including nonpoisonous frogs that mimic the appearance of their toxic counterparts -- can be loud and more nuanced.

"The type of color they have is in the range of the noisy ones," Santos said. "When you're mimicking somebody that's already protected, you have some freedom to be found by potential mates."

Read more at Science Daily

Climate change caused by ocean, not just atmosphere

Most of the concerns about climate change have focused on the amount of greenhouse gases that have been released into the atmosphere.

But in a new study published in Science, a group of Rutgers researchers have found that circulation of the ocean plays an equally important role in regulating Earth's climate.

In their study, the researchers say the major cooling of Earth and continental ice build-up in the Northern Hemisphere 2.7 million years ago coincided with a shift in the circulation of the ocean -- which pulls in heat and carbon dioxide in the Atlantic and moves them through the deep ocean from north to south until it's released in the Pacific.

The ocean conveyor system, Rutgers scientists believe, changed at the same time as a major expansion in the volume of the glaciers in the northern hemisphere as well as a substantial fall in sea levels. It was the Antarctic ice, they argue, that cut off heat exchange at the ocean's surface and forced it into deep water. They believe this caused global climate change at that time, not carbon dioxide in the atmosphere.

"We argue that it was the establishment of the modern deep ocean circulation -- the ocean conveyor -- about 2.7 million years ago, and not a major change in carbon dioxide concentration in the atmosphere that triggered an expansion of the ice sheets in the northern hemisphere," says Stella Woodard, lead author and a post-doctoral researcher in the Department of Marine and Coastal Sciences. Their findings, based on ocean sediment core samples between 2.5 million to 3.3 million years old, provide scientists with a deeper understanding of the mechanisms of climate change today.

The study shows that changes in heat distribution between the ocean basins is important for understanding future climate change. However, scientists can't predict precisely what effect the carbon dioxide currently being pulled into the ocean from the atmosphere will have on climate. Still, they argue that since more carbon dioxide has been released in the past 200 years than any recent period in geological history, interactions between carbon dioxide, temperature changes and precipitation, and ocean circulation will result in profound changes.

Scientists believe that the different pattern of deep ocean circulation was responsible for the elevated temperatures 3 million years ago when the carbon dioxide level in the atmosphere was arguably what it is now and the temperature was 4 degree Fahrenheit higher. They say the formation of the ocean conveyor cooled Earth and created the climate we live in now.

Read more at Science Daily