The stone slabs of England's Stonehenge may have been more than just a spectacular sight to the ancient people who built the structure; they likely created an acoustic environment unlike anything they normally experienced, new research hints.

"As they walk inside they would have perceived the sound environment around them had changed in some way,"said researcher Bruno Fazenda, a professor at the University of Salford in the United Kingdom. "They would have been stricken by it, they would say, 'This is different.'"

These Neolithic people might have felt as modern people do upon entering a cathedral, Fazenda told LiveScience.

Fazenda and colleagues have been studying the roughly 5,000-year-old-structure's acoustic properties. Their work at the Stonehenge site in Wiltshire, England, and at a concrete replica built as a memorial to soldiers in World War I in Maryhill, Wash., indicates Stonehenge had the sort of acoustics desirable in a lecture hall.

Stonehenge itself is no longer complete, so Fazenda and colleagues used the replica in Maryhill as a stand-in for the original structure. At both locations, they generated sounds and recorded them from different positions to see how the structure influenced the behavior of the sound.

Scientists from Oxford University have uncovered clues as to how mammal genomes became riddled with viruses. The research, supported by the Wellcome Trust, reveals important information about the so-called 'dark matter' of the human genome.

For years scientists have been struggling with the enigma that more than 90 percent of every mammal's genome has no known function. A part of this 'dark matter' of genetic material is known to harbour pieces of DNA from ancient viruses that infected our ancestors going back as far as the age of the dinosaurs.

Researchers at Oxford University, the Aaron Diamond AIDS Research Center in New York, and the Rega Institute in Belgium wanted to know how these ancient viruses got into their hosts' genomes in such abundance.

Flipper who? The fictional dolphin may be known for rescuing trapped divers and stranded sailors. But he's got nothing on his real-life kin in Laguna, Brazil. These clever marine mammals are truly helpful, regularly aiding local fishers in trapping schools of tasty fish - a behavior not seen anywhere else in the world. Now, a new study explores the interactions between Laguna's dolphins, providing clues to how they've maintained their long-lasting collaboration with people.

Every autumn, lucky visitors to Laguna, Brazil, which is situated around a narrow lagoon on the Atlantic Ocean, catch an odd sight. Here, resident bottlenose dolphins (Tursiops truncatus) frequently turn sheepdog, herding schools of small, silver fish called mullets toward the shore - and, it turns out, toward lines of wading fishers. As soon as the dolphins get close to their human companions, they give the signal, slapping their heads or tails against the surf. In an instant, the fishers cast their nets, catching dozens of frenzied mullet.

While it's not clear whether the dolphins themselves get food out of the exchange or benefit in other ways, both people and marine mammals alike have fished side by side like this for generations, says study co-author Simon Ingram, a marine mammal biologist at Plymouth University in the United Kingdom. Still, something intrigued him and his colleagues: Only about one-third of the lagoon's more than 50 dolphins - whose genders and relatedness have yet to be determined - regularly take part in the tradition, and some of them earn nicknames from the locals such as Scooby or Caroba. The others stick to the sidelines, avoiding people. That raised the question, he says: "Why don't they all do it given the opportunity?"

Ingram and his colleagues set out in boats, taking photos of Laguna's dolphins as the creatures swam together. The goal was to explore how these animals interacted - whether some dolphins spent more time with only a few friends, isolating outsiders. For the most part, the dolphins seemed pretty egalitarian, the group discovered. A few stray animals might swim together for a time. Then they'd eventually split up, each darting off to join another group. Individuals that helped local fishers tended to also cluster more with each other, while dolphins that didn't pitch in kept more to themselves, the team reports online today in Biology Letters.

The oldest red blood cells ever identified have been found in the body of Ötzi the Iceman, a 5,300-year-old mummy found in the Alps in 1991.

The bloody find is a first for Ötzi's mummy, which has been under scientific scrutiny since a pair of hikers stumbled over the body frozen in ice on the Austrian-Italian border. And the new research, published today (May 1) in the Journal of the Royal Society Interface, helps confirm the story of Ötzi's death.

The Iceman was so well preserved that scientists could estimate his age (about 45), his health, his last meals (they included red deer meat with herb bread) and even his probable cause of death, an arrow wound to the shoulder that sliced an artery. But no one had ever found blood cells in the ancient man's corpse.

Albert Zink, a biological anthropologist at the European Academy of Bozen/Bolzano, was the leader of the study that uncovered the elusive cells. "It was very surprising, because we didn't really expect to find compete red blood cells," Zink said. "We hoped to find maybe some remnants or shrunken red blood cells, but these are looking like a modern-day sample; the dimensions are the same."

When stretched out, the genome of a single human cell can reach six feet. To package it all into a tiny nucleus, the DNA strand is tightly wrapped around a core of histone proteins in repeating units -- each unit known as a nucleosome. To allow access for the gene expression machinery the nucleosomes must open up and regroup when the process is complete.

In the May 1, 2012, issue of Genes & Development, researchers at the Stowers Institute for Medical Research demonstrate how failure to restore order has lasting consequences. During the process of gene expression, a factor known as Chd1 promotes nucleosome reassembly on the DNA strand. Without it, yeast cells are unable to attach a chemical mark called ubiquitin to one of the four types of histone proteins, which in turn hampers nucleosome re-establishment throughout the entire yeast genome. In mammalian cells, this important step could be perturbed in disease states such as cancer.

You'll have to pee at least once during an 8-hour workday. So how can most of us sleep through the night without visiting the porcelain throne? New research fingers the circadian clock, a molecular timer responsible for keeping us on daily sleep-wake cycles.

Scientists compared urination patterns, both volume and frequency, in normal mice and in mice genetically engineered without two circadian genes, Cryptochrome-1 and Cryptochrome-2, resulting in dysfunctional circadian rhythms. They found that a circadian gene called Rev-erbα controlled the production of Cx43, a protein that determines how much urine bladders hold.

Normal mice urinated more frequently when awake, compared with when they slept, while genetically altered mice urinated without regard to daily cycles, scientists report online today in Nature Communications. (Normal and engineered mice produced the same volume of urine.) The researchers also found that increases in Rev-erbα caused increases in Cx43 concentrations when normal mice were awake.

Since more Cx43 means less room in the bladder, the team speculates that although normal mice didn't stop producing urine when asleep, their bladders were able to hold more due to decreased Cx43 concentrations. This allowed the mice to urinate less frequently. The authors note that scientists investigating why children wet the bed or why older people get up to urinate during the night should consider circadian clock effects.

A once-in-a-lifetime event is on its way - an event that hasn't occurred since 1882 and will not occur again until 2117 - and will be a spectacular event for millions of people all around the world.

The Transit of Venus, as it is called, occurs when the planet passes across the face of the Sun. It is viewable from Earth as a small black dot on the solar surface and takes about six hours to complete its transit. The event will occur on June 5 and 6 and will be visible across much of the world.

Transits of Venus only occur when the Earth and Venus are in line with the Sun, according to Jay M Pasachoff, an astronomer at Williams College, Massachusetts. Normally Venus passes below or above the Sun because our orbits are slightly angled to one another, he said, reporting in the journal Physics World.

Transits occur in pairs separated by eight years, with the gap between pairs of transits alternating between 105.5 and 121.5 years - Venus's last transit was in 2004.

Transits were first theorized by Renaissance astronomer Nicolaus Copernicus in 1543, and scientists later were able to predict and record the transits of both Mercury and Venus based on Copernicus's theories. Johannes Kepler successfully predicted both planets would transit the Sun in 1631. However, the first transit of Venus to be viewed didn't occur until 8 years later, in 1639.

The 1639 event was only seen, however, by two people: Jeremiah Horrocks, an English astronomer from Much Hoole, Lancashire, and his correspondent, William Crabtree, from Manchester.

Research by NASA and international scientists concludes giant asteroids, similar or larger than the one believed to have killed the dinosaurs, hit Earth billions of years ago with more

According to NASA, to cause the dinosaur extinction, the killer asteroid that impacted Earth 65 million years ago would have been almost 6 miles (10 kilometers) in diameter. By studying ancient rocks in Australia and using computer models, researchers estimate that approximately 70 asteroids the same size or larger impacted Earth 1.8 to 3.8 billion years ago. During the same period, approximately four similarly-sized objects hit the moon.

"This work demonstrates the power of combining sophisticated computer models with physical evidence from the past, further opening an important window to Earth's history," said Yvonne Pendleton, director of NASA's Lunar Science Institute (NLSI) at NASA's Ames Research Center at Moffett Field, Calif.

Evidence for these impacts on Earth comes from thin rock layers that contain debris of nearly spherical, sand-sized droplets called spherules. These millimeter-scale clues were formerly molten droplets ejected into space within the huge plumes created by mega-impacts on Earth. The hardened droplets then fell back to Earth, creating thin but widespread sedimentary layers known as spherule beds.

The new findings are published today in the journal Nature.

Skywatchers take note: The biggest full moon of the year is due to arrive this weekend.

The moon will officially become full Saturday (May 5) at 11:35 p.m. EDT. And because this month's full moon coincides with the moon's perigee - its closest approach to Earth - it will also be the year's biggest.

The moon will swing in 221,802 miles (356,955 kilometers) from our planet, offering skywatchers a spectacular view of an extra-big, extra-bright moon, nicknamed a supermoon.

And not only does the moon's perigee coincide with full moon this month, but this perigee will be the nearest to Earth of any this year, as the distance of the moon's close approach varies by about 3 percent, according to meteorologist Joe Rao, SPACE.com's skywatching columnist. This happens because the moon's orbit is not perfectly circular.

While on duty observing the Sun from its position in solar orbit, NASA's STEREO-B spacecraft captured the sudden appearance of a distant bright object. This flare-up turned out to be a nova - designated Sagittarii 2012 - the violent expulsion of material and radiation from a re-igniting white dwarf star.

Unlike a supernova, which is the cataclysmic collapse and explosion of a massive star whose core has finally fused its last, a nova is the result of material falling onto the surface of a white dwarf that's part of a binary pair. The material, typically hydrogen and helium gas, is drawn off the white dwarf's partner which has expanded into a red giant.

Eventually the white dwarf cannot contain all of the material that it has sucked in from its neighbor... material which has been heated to tremendous temperatures on its surface as it got compressed further and further by the white dwarf's incredibly strong gravity. Fusion occurs on the dwarf's outermost layers, blasting its surface out into space in an explosion of light and energy.

This is a nova - so called because, when witnessed in the night sky, one could suddenly appear as a "new star" in the heavens - sometimes even outshining all other visible stars!

An individual nova will soon fade, but a white dwarf can produce many such flares over time. It all depends on how rapidly it's accreting material (and how much there is available.)