MOSCOW: President Vladimir Putin signed a law banning smoking in public places in Russia from June, a cornerstone of the government's bid to improve public health, the Kremlin said Monday.
The law, called "On protecting the health of citizens from the danger of passive smoking and the consequences of the use of tabacco," makes smoking illegal in restaurants, cafes, hotels, trains and a host of other places.
-AFP/sb
STORY HIGHLIGHTS
(CNN) -- Park Geun-hye made history Monday by becoming South Korea's first female president, pledging to secure South Korea against the threat of an increasingly hostile North Korea at the same time as mending bridges with Pyongyang.
"North Korea's recent nuclear test is a challenge to the survival and future of the Korean people, and there should be no mistake that the biggest victim will be none other than North Korea itself," she said. "I urge North Korea to abandon its nuclear ambitions without delay and embark on the path to peace and shared development."
Reiterating her policy of 'trustpolitik' - a policy based on deterrence combined with cautious approaches to North Korea - she said she intended to "lay the groundwork for an era of harmonious unification where all Koreans can lead more prosperous and freer lives and where their dreams can come true."
"I will move forward step-by-step on the basis of credible deterrence to build trust between the South and the North."
She said South Koreans stood at a new juncture, confronting the difficulties of the global financial crisis as well as the threat from the North.
"I will usher in a new era of hope whereby the happiness of each citizen becomes the bedrock of our nation's strength which in turn is shared by and benefits all Koreans," she said.
When she was elected last December, Park broke barriers in the patriarchal East Asian nation, though she is deeply connected to its past. Her father, Park Chung-hee, was one of the founders of modern Korea who took power after a coup d'etat and ruled heavy-handedly for 18 years before being shot dead by his intelligence chief in 1979.
Read more: Park faces tough challenges
His memory still divides South Korea -- some regard him as the cornerstone of South Korea's present prosperity, others see him as a dictator who ignored human rights and crushed dissent.
Although she has apologized for human rights violations during his rule, Park has been criticized for not doing enough to distance herself from his legacy.
Still, any concerns about her family's past weren't enough to prevent 52% of voters from elevating her to the presidency.
Park, 61, and her opponent, the Democratic United Party's Moon Jae-in, offered similarly moderate plans during the campaign, addressing income inequality, reining in the power of family-owned conglomerates and improving relations with North Korea.
On North Korea, Park distinguished herself from former President Lee Myung-bak, who demanded an end to Pyongyang's nuclear arms program as a condition of economic aid, by offering a softer, carrot-and-stick approach.
I will move forward step-by-step on the basis of credible deterrence to build trust between the South and the North
Park Geun-hye
She visited the North Korean capital in 2002 and met with its late leader Kim Jong Il. Since then, his son Kim Jong Un has taken over in Pyongyang, continuing a policy of defiant work on the country's budding nuclear program, including a test earlier this month that drew widespread international condemnation.
"Precisely because trust is at a low point these days, South Korea has a chance to rebuild it," Park told Foreign Affairs magazine before she won the election. "In order to transform the Korean Peninsula from a zone of conflict into a zone of trust, South Korea has to adopt a policy of 'trustpolitik,' establishing mutually binding expectations based on global norms."
Domestically, Park campaigned as a fiscal conservative, advocating tax cuts for business to boost investment and jobs and vowing to restructure welfare programs. At the same time, she promised soon after winning election "to take care of our people one by one."
In a speech at the headquarters of her Saenuri political party Thursday morning, she invoked a phrase coined by her father, who also served as president in an era when he was encouraging people to pull South Korea out of poverty.
"I would like to re-create the miracle of 'let's live well' so people can worry less about their livelihood and young people can happily go to work," Park said.
CNN's Greg Botelho and Peter Shadbolt contributed to this report.
First lady Michelle Obama, on a video screen, announces the winner for best picture along with actor Jack Nicholson at the 85th annual Academy Awards on Feb. 24, 2013, in Hollywood, Calif. / Getty
First lady Michelle Obama made a surprise appearance at the Oscars, opening the envelope that contained the name of the best-picture winner, "Argo."
Appearing via streaming video from the White House, Mrs. Obama said all of the nominees demonstrated that "we can overcome any obstacle."
She said that message is "especially important for our young people" and thanked Hollywood for encouraging children "to open their imaginations."
The first lady was introduced by Jack Nicholson, who noted that the best picture trophy is usually announced solo.
Mrs. Obama wore a silver, art deco-inspired gown by Indian-born American fashion designer Naeem Khan. It was the same dress she wore for the Obamas' dinner with the nation's governors at the White House on Sunday night.
"Argo" took home the top prize as best picture at the Oscars Sunday night, with first lady Michelle Obama announcing the winner from the White House.
"You directed a hell of a film," co-producer Grant Heslov told director and fellow producer Ben Affleck. "I couldn't be more proud of the film and more proud of our director."
Affleck was snubbed in the directing category but humbly accepted the best picture Oscar as one of the three producers on the film. George Clooney was the third.
Affleck thanked Stephen Spielberg and the other best picture nominees and his wife Jennifer Garner for "working on our marriage."
"It's good, it's work," he said, adding, "but there's no one I'd rather work with."
For Full List of Winners
Acknowledging his last Oscar win, as a screenwriter for "Good Will Hunting," Affleck said, "I was really just a kid. I never thought I would be back here."
In the acting categories, Daniel Day-Lewis won the Oscar for best actor, being the first actor to three-peat in that category. As he accepted the award from Hollywood's greatest actress, Meryl Streep, he joked, "I had actually been committed to play Margaret Thatcher. ... Meryl was Stephen's first choice for Lincoln."
He also thanked his wife, Rebecca Miller, for "living with some very strange men," with each new role that he takes on.
"She's the versatile one in the family and she's been the perfect companion to all of them," he said.
Kevin Winter/Getty Images
Jennifer Lewis won the award for best actress. She tripped on the stairs on her way to accepting her award but picked herself up and made her way to the stage, earning a standing ovation.
"You're just standing up because you feel bad that I fell and that's embarrassing," she said, before rattling off a list of thank-yous and leaving the stage looking slightly stunned.
Watch Jennifer Lawrence's Oscar Tumble
"Life of Pi," which had a total of 11 nominations, was another big winner of the night. Director Ang Lee took home the Oscar for best director over Stephen Spielberg and David O. Russell.
"Thank you, movie god," Lee said, accepting his award.
As expected, the film took home the first technical awards of the night for cinematography and visual effects. "Life of Pi" also won for best original score.
The first big acting awards of the night went to Christoph Waltz and Anne Hathaway in the supporting actor categories.
In one of the biggest tossups, Waltz claimed the award for supporting actor for his role in "Django Unchained." It was his second Oscar for a Quentin Tarantino film; his first was for Tarantino's "Inglourious Basterds."
PHOTOS: Stars on the Red Carpet
As expected, Hathaway took home the award for best supporting actress for her role as Fantine in "Les Miserables."
"It came true," she said, launching into a breathy speech, in which she thanked the cast and crew, her team and her husband. "The greatest moment of my life was when you walked into it," she said.
Quentin Tarantino won the Oscar for best original screenplay for his slave revenge western "Django Unchained." He thanked his cast.
"I have to cast the right people," he said. "And boy this time did I do it."
Chris Terrio won the award for best adapted screenplay for "Argo," which also won for film editing.
For only the sixth time in Academy history, there was a tie at the Oscars. "Zero Dark Thirty" and "Skyfall" tied for sound editing.
See Other Ties in Academy History
A new market for second-hand digital downloads could let us hold virtual yard sales of our ever-growing piles of intangible possessions
WHY buy second-hand? For physical goods, the appeal is in the price – you don't mind the creases in a book or rust spots on a car if it's a bargain. Although digital objects never lose their good-as-new lustre, their very nature means there is still uncertainty about whether we actually own them in the first place, making it tricky to set up a second-hand market. Now an Amazon patent for a system to support reselling digital purchases could change that.
Amazon's move comes after last year's European Union ruling that software vendors cannot stop customers from reselling their products. But without technical support, the ruling has had no impact. In Amazon's system, customers will keep their digital purchases – such as e-books or music – in a personal data store in the cloud that only they can access, allowing them to stream or download the content.
This part is like any cloud-based digital locker except that the customer can resell previous purchases by passing the access rights to another person. Once the transaction is complete, the seller will lose access to the content. Any system for reselling an e-book, for example, would have to ensure that it is not duplicated in the transaction. That means deleting any copies the seller may have lying around on hard drives, e-book readers, and other cloud services, since that would violate copyright.
Amazon may be the biggest company to consider a second-hand market, but it is not the first. ReDigi, based in Boston, has been running a resale market for digital goods since 2011. After downloading an app, users can buy a song on ReDigi for as little as 49 cents that would costs 99 cents new on iTunes.
When users want to sell an item, they upload it to ReDigi's servers via a mechanism that ensures no copy is made during the transfer. Software checks that the seller does not retain a copy. Once transferred, the item can be bought and downloaded by another customer. ReDigi is set to launch in Europe in a few months.
Digital items on ReDigi are cheaper because they are one-offs. If your hard drive crashes and you lose your iTunes collection you can download it again. But you can only download an item from ReDigi once – there is no other copy. That is the trade-off that makes a second-hand digital market work: the risk justifies the price. The idea has ruffled a few feathers – last year EMI sued ReDigi for infringement of copyright. A judge denied the claim, but the case continues.
Used digital goods can also come with added charm. ReDigi tracks the history of the items traded so when you buy something, you can see who has owned it and when. ReDigi's second-hand marketplace has grown into a social network. According to ReDigi founder John Ossenmacher, customers like seeing who has previously listened to a song. "It's got soul like an old guitar," he says. "We've introduced this whole feeling of connectedness."
It could be good for business too if the original vendors, such as iTunes, were to support resale and take a cut of the resell price. Nevertheless, Amazon's move bucks the industry trend. Microsoft's new Xbox, for example, is expected not to work with second-hand games.
But the market could change rapidly now that Amazon's weight is behind this, says Ossenmacher. "The industry is waking up."
This article appeared in print under the headline "Old MP3, one careful owner"
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BARCELONA - Chinese handset makers will lead an onslaught on smartphone titans Samsung and Apple when the world's biggest mobile fair opens on Monday in Barcelona, Spain.
Offering big-screen, slick, slim smartphones at lower prices, Chinese manufacturers Huawei, ZTE and Lenovo will leverage the Mobile World Congress to chip away at the mighty duopoly, analysts say.
The handset battle is part of a broader revolt against a handful of companies with a stranglehold on the booming industry's handsets, operating systems and microchips, they say.
Apple, as usual, is steering clear of the February 25-28 congress that draws 1,500 exhibitors to this Mediterranean city in northeastern Spain, and Samsung is not expected to launch its next big offer, the Galaxy S4, until some time after the show.
That may leave the field clear for rivals to tout their ambitions for a slice of the smartphone market, which is set to grow to a record one billion handset shipments in 2013, according to a forecast by global consultancy Deloitte.
"I think we will see challengers trying to make noise at the Mobile World Congress this year," said Ian Fogg, London-based senior mobile analyst at research house IHS.
New players face a daunting task, though.
Samsung and Apple accounted for more than half of all smartphone sales in the final quarter of 2012 -- 29.0 percent for Samsung and 22.1 percent for Apple -- according to research firm Strategy Analytics.
Behind Samsung and Apple, however, Chinese firms held the third, fourth and fifth spots -- with 5.3 percent for Huawei, 4.7 percent for ZTE and 4.4 percent for Lenovo.
Demand for smartphones in developing countries could give Chinese firms a bigger opening, said Magnus Rehle, senior partner at telecommunications management consultancy group Greenwich Consulting.
"Hundreds of millions of Africans and Indians and Asians want to have a smartphone and so far the blocking point has been the price," said Rehle, speaking from Ghana.
Now the Chinese firms were offering attractive smartphones at lower prices, he said.
"I think they will be quite successful in grabbing the new market outside of Europe and the US, and that is where the growth is," Rehle said.
An even mightier duopoly holds sway over the operating system software that makes the smartphones work.
Google's Android ran 69 percent of all handsets sold last year and Apple's iOS 22 percent, said a study by independent analytical house Canalys.
Yet they face challengers, too, including Mozilla's new open-sourced Firefox OS, backed by an array of mobile phone operators.
Microsoft's new Windows Mobile operating system is struggling, however.
"The number of apps that is available is one thing that is blocking Windows from being successful," Rehle said.
"They have had problems and everybody is hoping this will change because the duopoly is maybe not good for the market."
Firefox could face similar difficulties, he predicted.
A battle has broken out, too, over the processor chips that run the smartphones.
Santa Clara, California-based Intel is offering new high-performance chips to break its way into smartphones, of which almost all now use chip technology licensed by ARM, based in Cambridge, England.
Chinese group Lenovo, for example, is launching a new handset, the IdeaPhone K900, just 6.9mm thick with a 5.5-inch high definition screen, which contains an Intel Clover Trail processor.
The potential rewards for Intel could be rich: the market in processor chips for smartphone applications was worth nearly seven billion euros (US$9 billion) last year, said Francis Sideco, communications technology analyst at IHS.
Despite robust growth in smartphones and tablet sales, however, the mobile industry still faces a major challenge moving customers over to new ultrafast fourth generation, or 4G, networks, which can offer speeds similar to a fixed fibre-optic connection.
"There are 3G networks in many parts of the world like in Sweden that have been overcrowded and then you have parallel 4G networks that are almost empty," said Greenwich Consulting's Rehle.
Network operators need to convince their customers to pay a little more for the faster speeds, he said, pointing to videos as the "killer application" to lure people to the system over the longer term.
If the operators succeed, they can make more money and invest in greater capacity, the analyst said.
"Otherwise, they will have problems."
- AFP/ir
By Greg Botelho, CNN
updated 10:29 PM EST, Sat February 23, 2013
Ammar Asim Faruq Harris, 26, suspected in a shooting on the Las Vegas Strip on Thursday, is still at large, police said.
STORY HIGHLIGHTS
Follow the story here and at CNN affiliates KVVU, KLAS, KTNV and KSNV.
Las Vegas (CNN) -- Police have identified a suspect in a fatal shooting and crash on the Las Vegas Strip that left three people dead.
The suspect is 26-year-old Ammar Asim Faruq Harris, the Las Vegas Metropolitan Police Department said Saturday in a press release. He is at large, though a black Range Rover police said he was driving early Thursday morning has been impounded.
Kenneth Cherry, an aspiring rapper known as Kenny Clutch, was driving his Maserati around 4:20 a.m. Thursday when someone in a Range Rover shot at his car as it headed north on Las Vegas Boulevard.
The Maserati continued into the intersection of the boulevard and Flamingo Road and collided with a taxi, which caught fire, killing cab driver Michael Boldon, CNN affiliate KVVU said.
A passenger in that taxi -- identified by the Clark County coroner's office as Sandra Sutton-Wasmund, 48, of Maple Valley, Washington -- also died. Her death and the deaths of Boldon and Cherry have been ruled homicides, according to the coroner's office.
See an iReporter's video of the fire
The fire closed a block and a half of the Strip near some of its biggest draws: Caesars Palace, the Bellagio, Bally's and the Flamingo. Police collected surveillance video from the casinos.
The shooting took place two blocks from where rapper Tupac Shakur was killed in 1996.
The 27-year-old Cherry leaves behind three children, the oldest being 2 years old and the youngest just 2 months, his father said. He died after being shot in the chest and arm.
Kenneth Cherry Sr. blasted news reports and social media messages about his son, claiming some had falsely characterized him as a person "involved in the rap life." He also disputed accounts that his son exchanged gunfire with the Range Rover's driver, saying he wasn't even armed at the time.
"I don't like the way that some of the media stations are portraying my son, because he was black, (like) he's a criminal," the elder Cherry told reporters. "My son was a good boy."
While the police department statement named Harris as the suspect, it did not indicate any charges have been filed so far.
CNN's Elwyn Lopez, Traci Tamura and Miguel Marquez contributed to this report.
Updated at 9:35 p.m. ET
DAYTONA BEACH, Fla. At least 33 fans were injured Saturday during a NASCAR race when a car flew into the fence at Daytona International Speedway, hurling a tire and large pieces of debris into the stands.
The accident happened on the last lap of the second-tier Nationwide Series race on the eve of Sunday's Daytona 500, which officials said would go on as scheduled.
The crash began as the field approached the checkered flag and leader Regan Smith attempted to block Brad Keselowski to preserve the win. That triggered a chain reaction, and rookie Kyle Larson hit the cars in front of him and went airborne into the fence.
The entire front end was sheared off Larson's car, and his burning engine wedged through a gaping hole in the fence. Chunks of debris from the car were thrown into the stands, including a tire that cleared the top of the fence and landed midway up the spectator section closest to the track.
The 20-year-old Larson stood in shock several yards away from his car as fans in the stands waived frantically for help. Smoke from the burning engine briefly clouded the area, and emergency vehicles descended on the scene.
Ambulance sirens could be heard wailing behind the grandstands at a time the race winner would typically be doing celebratory burnouts.
"It was freaky. When I looked to my right, the accident happened," said Rick Harpster of Orange Park, Fla., who had a bird's-eye view of the wreck. "I looked over and I saw a tire fly straight over the fence into the stands, but after that I didn't see anything else That was the worst thing I have seen, seeing that tire fly into the stands. I knew it was going to be severe."
Daytona International Speedway released a statement from speedway President Joie Chitwood Saturday evening saying 28 people were injured in the accident in the race held the day before the season-opening Daytona 500.
According to the statement, emergency medical personnel transported 14 people off the property and 14 others were treated at the on-track care center.
"We are in the process of repairing the facility, and we will be ready to go racing tomorrow," Chitwood said.
Nathan Kimpel, 24, who works at a concession stand near where the crash happened, told CBS News correspondent Adriana Diaz that he saw 10 to 15 fans being carried out on stretchers.
"As soon as I saw the accident I just turned my head because I didn't want to get injured or anything," Kimpel told Diaz. "I saw the fence separate and more pieces of car parts flying up."
Meghan Willams, 20, who also works at a concession stand, told Diaz the crash sounded like an "earthquake." She saw people running and crying and a girl completely covered in engine oil.
Byron Cogdell, a spokesman for Halifax Health Medical Center, told CBS News that one of the 11 patents taken to the hospital was in critical condition and five more were listed as "trauma" patients.
Lindsay Rew, a spokeswoman for Florida Hospital Memorial Medical Center, said its Daytona Beach hospital had one fan there who was in good condition. She said they were expecting three more people who were coming by ambulance, but she didn't yet know their conditions.
"There obviously was some intrusion into the fence and fortunately with the way the event's equipped up, there were plenty of emergency workers ready to go and they all jumped in on it pretty quickly," NASCAR President Mike Helton said. "Right now, it's just a function of determining what all damage is done. They're moving folks, as we've seen, to care centers and take some folks over to Halifax Medical."
As emergency workers tended to injured fans and ambulance sirens wailed in the background, a somber Tony Stewart skipped the traditional post-race victory celebration.
Stewart, who won for the 19th time at Daytona and seventh time in the last nine season-opening Nationwide races, was in no mood to celebrate.
"The important thing is what going on on the frontstretch right now," said Stewart, the three-time NASCAR champion. "We've always known, and since racing started, this is a dangerous sport. But it's hard. We assume that risk, but it's hard when the fans get caught up in it.
"So as much as we want to celebrate right now and as much as this is a big deal to us, I'm more worried about the drivers and the fans that are in the stands right now because that was ... I could see it all in my mirror, and it didn't look good from where I was at."
The accident spread into the upper deck and emergency crews treated fans on both levels. There were five stretchers that appeared to be carrying fans out, and a helicopter flew overhead. A forklift was used to pluck Larson's engine out of the fence.
"It's a violent wreck. Just seeing the carnage on the racetrack, it's truly unbelievable," driver Justin Allgaier said.
It was a chaotic finish to a race that was stopped for nearly 20 minutes five laps from the finish by a 13-car accident that sent driver Michael Annett to a hospital, where his Richard Petty Motorsports team said he would be held overnight with bruising to his chest.
The race resumed with three laps to go, and the final accident occurred with Smith trying to hold off Keselowski through the final turn.
"I tried to throw a block. It's Daytona, you want to go for the win here," Smith said. "I don't know how you can play it any different other than concede second place, and I wasn't willing to do that today. Our job is to put them in position to win, and it was, and it didn't work out."
As the cars began wrecking all around Smith and Keselowski, Stewart slid through for the win, but Larson plowed into Keselowski and his car was sent airborne into the stands. When Larson's car came to a stop, it was missing its entire front end. The 20-year-old, who made his Daytona debut this week, stood apparently stunned, hands on his hips, several feet away from his car, before finally making the mandatory trip to the care center.
He said his first thought was with the fans.
"I hope all the fans are OK and all the drivers are all right," Larson said. "I took a couple big hits there and saw my engine was gone. Just hope everybody's all right."
"Honestly, the race itself pales in comparison to the injuries sustained by the fans," said Chip Ganassi, the team owner who has Larson in his driver development program. "Our thoughts and prayers go out to all the fans that were injured as a result of the crash. As for Kyle, I am very happy that he is OK."
Keselowski watched a replay of the final accident, and said his first thoughts were with the fans. As for the accident, he agreed he tried to make a winning move and Smith tried to block.
"He felt like that's what he had to do, and that's his right. The chaos comes with it," Keselowski said. "I made the move and he blocked it, and the two of us got together and started the chain events that caused that wreck. First and foremost, just want to make sure everyone in the stands is OK and we're thinking about them."
Keselowski said the incident could cast a pall on the Daytona 500.
"I think until we know exactly the statuses of everyone involved, it's hard to lock yourself into the 500," Keselowski said. "Hopefully, we'll know soon and hopefully everyone's OK. And if that's the case, we'll staring focusing on Sunday."
Las Vegas police identified a suspect today in a shooting on the strip that caused a Maserati to hit a taxi and burst into flames, killing three people.
Ammar Harris, 26, has been named a suspect in the Thursday skirmish that killed three people, including rapper Kenny Clutch.
The altercation between Harris and Clutch, 27, whose legal name was Kenneth Cherry Jr., is believed to have originated in the valet area of a Las Vegas hotel, police said.
Police said Harris fired several rounds into a Maserati that was being driven by Cherry as both vehicles continued northbound on glitzy Las Vegas Boulevard.
The rapper's expensive sports car careened out of control after he was shot, slamming into several cars, including a taxi. The impact caused the cab to burst into flames, killing the driver, Michael Boldon and a female passenger. Witnesses said it looked like the car exploded.
"He was a number one guy," Carolyn Jean Trimble, Boldon's sister, told ABC News.
"I looked out my window and I could see one vehicle down here on the corner of the intersection totally engulfed in flames," witness John Lamb told ABC News.
Boldon, 62, and his passenger, who has not yet been identified, were both killed, as was Clutch.
Timble said her brother loved driving his taxi around Vegas.
"He came to live with me in Las Vegas last year to help take care of our mother, and the first day he got here he said, 'I have to get a job.' The second day, I came home from work, and he said he got a job," she recalled.
"He says, 'You'll never guess what it is,' and I said, 'what,' and he said, 'taxi cab driver,' and we both fell out laughing," Trimble said. "He loved that job. He never complained. He'd come home and tell me stories about what happened, who he picked up."
Boldon was a single father who raised a 36-year-old son and was a new grandfather. His grandson was named after him, Trimble said.
"Of all the people to take from this earth," she said. "But I guess the Lord needed him."
A passenger in the Maserati was hit and sustained only a minor injury to his arm. Clutch died at University Medical Center.
His father, Kenneth Cherry Sr., expressed his grief for the loss of his son while speaking with ABC News.
"This is something you never really, really ever want to experience as a parent, to lose a child before you go," he said.
Harris is described as 5-foot-11 and 180 pounds. Anyone with information is asked to contact the Las Vegas Metro Police Department's homicide division.
SUN-WORSHIP began even earlier than we thought. The world's oldest sedimentary rocks suggest an early form of photosynthesis may have evolved almost 3.8 billion years ago, not long after life appeared on Earth.
A hallmark of photosynthesis in plants is that the process splits water and produces oxygen gas. But some groups of bacteria oxidise substances like iron instead – a form of photosynthesis that doesn't generate oxygen. Evolutionary biologists think these non-oxygen-generating forms of photosynthesis evolved first, giving rise to oxygen-generating photosynthesis sometime before the Earth's atmosphere gained oxygen 2.4 billion years ago (New Scientist, 8 December 2012, p 12).
But when did non-oxygen-generating photosynthesis evolve? Fossilised microbial mats that formed in shallow water 3.4 billion years ago in what is now South Africa show the chemical fingerprints of the process. However, geologists have long wondered whether even earlier evidence exists.
The world's oldest sedimentary rocks – a class of rock that can preserve evidence of life – are a logical place to look, says Andrew Czaja of the University of Cincinnati in Ohio. These rocks, which are found in Greenland and date back almost 3.8 billion years, contain vast deposits of iron oxide that are a puzzle. "What could have formed these giant masses of oxidised iron?" asks Czaja.
To investigate, he analysed the isotopic composition of samples taken from the oxidised iron. He found that some isotopes of iron were more common than they would be if oxygen gas was indiscriminately oxidising the metal. Moreover, the exact isotopic balance varied subtly from point to point in the rock.
Both findings make sense if photosynthetic bacteria were responsible for the iron oxide, says Czaja. That's because these microbes preferentially oxidise only a small fraction of the dissolved iron, and the iron isotopes they prefer vary slightly as environmental conditions change (Earth and Planetary Science Letters, doi.org/kh5). His findings suggest that this form of photosynthesis appeared about 370 million years earlier than we thought.
It is "the best current working hypothesis for the origin of these deposits", says Mike Tice of Texas A&M University in College Station – one of the team who analysed the 3.4-billion-year-old microbial mats from South Africa.
William Martin at the University of Düsseldorf, Germany, agrees. "Anoxygenic photosynthesis is a good candidate for the isotope evidence they see," he says. "Had these fascinating results been collected on Mars, the verdict of the jury would surely remain open," says Martin Brasier at the University of Oxford. "But [on Earth] opinion seems to be swinging in the direction of non-oxygen-generating photosynthesis during the interval from 3.8 to 2.9 billion years ago."
This article appeared in print under the headline "Photosynthesis has truly ancient origins"
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