Conventional theories have placed life on land for the last 500 million years, but a new study from a team of American and Australian researchers might push that back to 2.2 billion years.

To support their claim, the scientists presented evidence in the form of tiny newly discovered fossils the size of a match head called Diskagma buttonii that were discovered in ancient soil samples.

"They certainly were not plants or animals, but something rather more simple," said co-author Gregory Retallack, co-director of paleontological collections at the University of Oregon's Museum of Natural and Cultural History.

The fossils are small, vase-like structures with a cup on one end and a basal tube on the other end. Retallack says these ancient organisms are comparable to a modern soil organism called Geosiphon, a fungus containing a cavity filled with symbiotic cyanobacteria.

"There is independent evidence for cyanobacteria, but not fungi, of the same geological age, and these new fossils set a new and earlier benchmark for the greening of the land," he said. "This gains added significance because fossil soils hosting the fossils have long been taken as evidence for a marked rise in the amount of oxygen in the atmosphere at about 2.4 billion to 2.2 billion years ago, widely called the Great Oxidation Event."

That event, which occurred around 2.4 billion years ago, boosted atmospheric oxygen to around 5 percent - still a far cry from today's level of 21 percent.

An analysis of data returned by the Curiosity rover, which landed on the planet a year ago, suggests there was a major upheaval which could have been caused by volcanic eruptions or a massive collision which stripped away the atmosphere.

The rover has returned its first measurements of the makeup of gases, including argon, oxygen, nitrogen, carbon monoxide and carbon dioxide, in the Martian atmosphere.

The results, published in two parallel studies in the journal Science, allow scientists to better understand how the Martian climate changed, and understand whether it ever had the right conditions for life.

Dr Chris Webster at Nasa's Jet Propulsion Laboratory in Pasadena, lead author on one of the studies, said the data enabled direct comparisons with the Earth's climate.

"As Mars became a planet and its magma solidified, catastrophic outgassing occurred while volatiles were delivered by impact of comets and other small bodies", Dr Webster said.

"Our Curiosity measurements are - for the first time - accurate enough to make direct comparisons with measurements done on Earth on meteorites using sophisticated large instrumentation that gives high accuracy results."

Behind every great man, the saying goes, there's a great woman. And behind every sperm, there may be an X chromosome gene. In humans, the Y chromosome makes men, men, or so researchers have thought: It contains genes that are responsible for sex determination, male development, and male fertility. But now a team has discovered that X - "the female chromosome" - could also play a significant role in maleness. It contains scores of genes that are active only in tissue destined to become sperm. The finding shakes up our ideas about how sex chromosomes influence gender and also suggests that at least some parts of the X chromosome are playing an unexpectedly dynamic role in evolution.

Each mammal has a pair of sex chromosomes. Females have two copies of the X chromosome, and males have one, along with a Y chromosome. The body needs only one active copy of the X chromosome, so in females, the second copy is disabled. Almost 50 years ago, a geneticist named Susumu Ohno proposed that this shutdown slowed the evolution of the X chromosome, and he predicted that its genes would be very similar across most mammals. David Page, a geneticist at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, wanted to check if that was true between mice and humans, which are separated by 80 million years of evolution.

Although the genomes of both species had already been decoded, there were gaps and mistakes in the DNA sequence of the human X chromosome that first needed to be filled in or fixed. Using a special sequencing technique that it developed, Page's research team determined the order of the DNA bases in those gaps - many contained multiple duplicated regions of DNA that were impossible to decipher with the technology available when the X chromosome was first sequenced. Then the researchers compared the genes in the mouse and human versions of the chromosome.

Warfare was uncommon among hunter-gatherers, and killings among nomadic groups were often due to competition for women or interpersonal disputes, researchers in Finland said Thursday.

Their study in the US journal Science suggests that the origins of war were not -- as some have argued -- rooted in roving hunter-gather groups but rather in cultures that held land and livestock and knew how to farm for food.

For clues on what life was like before colonial powers, missionaries and traders entered the scene, anthropologists examined a subset of records from a well-known database that contains information on 186 cultures around the world.

Douglas Fry and Patrik Soderberg of Abo Akademi University in Vasa, Finland, chose to examine only the earliest existing records on those that had no horses and no permanent settlements, leaving them with 21 mobile foraging societies for analysis.

"To be purists, we took only the oldest high-quality sources for each culture," Fry told the journal Science, adding that these studies would best showcase the people's traditional ways.

The groups included the Montagnais people of Canada, the Andamanese people of India, the Botocudos of Brazil, and the !Kung people who live in isolated areas of Botswana, Angola and Namibia.

A fossilized elephant tusk at least 100,000 years old has been discovered on the seafloor off the Sicilian coast, according to a survey of underwater archaeologists. Discovered during a series of archaeological dives in the waters off Torretta Granitola, a village on the island's southwestern coast, the tusk is more than 3 feet long.

"It was found embedded on the sea bottom in Pleistocene alluvional deposits," the Superintendency of Maritime Cultural Heritage of Sicily said in a statement.
In the same area, Giampaolo Mirabile, a local diver, found some years ago two molar teeth belonging to the dwarf elephant Palaeoloxodon mnaidriensis, or Elephas Mnaidriensis, a species that roamed Sicily between 100,000 and 200,000 years ago.

"The tusk' size confirms the previous finding and points to the same extinct species," Sebastiano Tusa, Sicily's superintendent of the Sea Office, said.

Researchers at the University of Warwick have recovered tuberculosis (TB) genomes from the lung tissue of a 215-year old mummy using a technique known as metagenomics.

The team, led by Professor Mark Pallen, Professor of Microbial Genomics at Warwick Medical School, working with Helen Donoghue at University College London and collaborators in Birmingham and Budapest, sought to use the technique to identify TB DNA in a historical specimen.

The term 'metagenomics' is used to describe the open-ended sequencing of DNA from samples without the need for culture or target-specific amplification or enrichment. This approach avoids the complex and unreliable workflows associated with culture of bacteria or amplification of DNA and draws on the remarkable throughput and ease of use of modern sequencing approaches.

The sample came from a Hungarian woman, Terézia Hausmann, who died aged 28 on 25 December 1797. Her mummified remains were recovered from a crypt in the town of Vác, Hungary. When the crypt was opened in 1994, it was found to contain the naturally mummified bodies of 242 people. Molecular analyses of the chest sample in a previous study confirmed the diagnosis of tuberculosis and hinted that TB DNA was extremely well preserved in her body.

Scientists have found a new virus thought to be the biggest ever seen on Earth.The virus, dubbed Pandoravirus, is one micrometre big - up to ten times the size of other viruses - and only six per cent of its genes resemble anything seen on Earth before. This has led French researchers to believe the virus may have come from an ancient time or even another planet, such as Mars.

The giant virus is only found underwater and is not thought to pose a serious risk to humans. However, the researchers, who published their findings in the journal Science, believe that the virus opens up a range of questions about the history of life on Earth.

Dr Jean-Michel Claverie of Aix-Marseille University in France, who found the virus, told NPR: 'We believe that these new Pandoraviruses have emerged from a new ancestral cellular type that no longer exists.'Many traditional viruses range in size from around 10 nanometres (nm) to around 500nm.The Pandoravirus is around one micrometre big and there are 1,000nm in a micrometre.This means the Pandoravirus is big enough to be seen under the most basic microscopes.

Scientists at the U.S. Naval Research Laboratory (NRL) have determined that there has been an increase in bright polar mesospheric clouds (PMCs) in the last two years, an unexpected result since these clouds are generally thought to be less prevalent during conditions of high solar activity which acts to destroy the tiny ice particles. Their research suggests that the man-made effect of water released by exhaust from space traffic during recent years has overwhelmed the effect of higher solar activity. This research was published in the June 6, 2013, issue of Geophysical Research Letters.

This new understanding of weather at the edge of space serves to test high altitude weather and climate models of the upper atmosphere, including the co-located D&E-regions of the ionosphere which is critical for improving models of over-the-horizon-radar (OTHR) propagation, explains NRL's Dr. David Siskind, a scientist in NRL Space Science Division and principal investigator for the research.

Each summer, the Arctic and Antarctic atmospheres at very high altitudes (the upper mesosphere, 80 to 100 km) become extremely cold with temperatures well below -100°C, despite the presence of 24 hours of sunlight. These very low temperatures allow the atmosphere to become supersaturated, and enable thin, wispy ice clouds to condense on nuclei of meteoric dust and smoke particles. Because of the possibility that this region of the atmosphere may be changing due to man-made effects, NASA launched a dedicated satellite, the Aeronomy of Ice in the Mesosphere (AIM) mission six years ago. Scientists used the AIM data to test atmospheric analyses provided by special high altitude prototype versions of the then-operational Navy Global Forecast System (NOGAPS). Previous studies by NRL scientists had shown this high altitude version of NOGAPS could demonstrate how variations in lower atmospheric weather conditions thousands of miles away might "teleconnect" to the Arctic and cause PMCs to vary.

Tuscaloosa, Alabama - University of Alabama researchers have discovered the fossilized remains of a large marine reptile that once ruled the open seas 80 million years ago.

The initial discovery, made June 20 by middle-school student Noah Traylor during a UA-hosted expedition, was later identified as part of a large neck vertebra of an elasmosaur, which is a subgroup of the late Cretaceous plesiosaurs.

Elasmosaurid plesiosaurs are easily recognized by their large body size - some species reach up to 45 feet in length.

"Think Loch Ness monster," said Dr. Dana Ehret, UA Museum paleontologist. "They have very large flippers for swimming and extremely long necks, consisting of up to about 70 neck vertebrae."

Plesiosaurs became extinct by the end of Cretaceous, or about 65.5 million years ago, and they are generally rare in the fossil record for Alabama. This is only the second elasmosaurid specimen containing more than one or two bones found in the state, Ehret said. The first, which consists of 22 vertebrae, was found in the late 1960s and is now part of UA Collections.

This discovery appears to be on par with the first one. To date, about 15 large vertebrae, a few paddle bones and many bone fragments have been collected, but an extensive excavation is still in progress, so Ehret is uncertain how complete this skeleton is.

ISNS -- The discovery of two new jumbo-sized viruses is blurring the lines between viral and cellular life and could point to the existence of a new type of life, scientists suggest.

The two large viruses, detailed in this week's issue of the journal Science, have been dubbed "Pandoraviruses" because of the surprises they may hold for biologists, in reference to the mythical Greek figure who opened a box and released evil into the world.

The discovery of Pandoraviruses is an indication that our knowledge of Earth's microbial biodiversity is still incomplete, explained study coauthor Jean-Michel Claverie, a virologist at the French National Research Agency at Aix-Marseille University.

"Huge discoveries remain to be made at the most fundamental level that may change our present conception about the origin of life and its evolution," Claverie said.

Eugene Koonin, a computational evolutionary biologist at the National Center for Biotechnology Information in Bethesda, Md., who was not involved in the study, called the Pandoraviruses a "wonderful discovery," but not a complete surprise.

"In a certain sense, it's something that we saw coming, and it's wonderful that it has come," Koonin said.