DNA analysed from early European

Scientists have analysed DNA extracted from the remains of a 30,000-year-old European hunter-gatherer.

Studying the DNA of long-dead humans can open up a window into the evolution of our species (Homo sapiens).

But previous studies of this kind have been hampered by scientists' inability to distinguish between the ancient human DNA and modern contamination.

In Current Biology journal, a German-Russian team details how it was possible to overcome this hurdle.

Svante Paabo, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues used the latest DNA sequencing techniques to study genetic information from human remains unearthed in 1954 at Kostenki, Russia.

Excavations at Kostenki, on the banks of the river Don in southern Russia, have yielded large concentrations of archaeological finds from the Palaeolithic (roughly 40,000 years ago to 10,000 years ago). Some of the finds date back as far as 45,000 years.

The DNA analysed in this study comes from a male aged 20-25 who was deliberately buried in an oval pit some 30,000 years ago.

Known as the Markina Gora skeleton, it was found lying in a crouched position with fists reaching upwards and a face orientated down towards the dirt. The bones were covered in a pigment called red ochre, thought to have been used in prehistoric funeral rites.

The type of DNA extracted and analysed is that stored in mitochondria - the "powerhouses" of cells. This mitochondrial DNA (mtDNA) is passed down from a mother to her offspring, providing a unique record of maternal inheritance.

Using technology pioneered in the study of DNA from Neanderthal bones, they were able to distinguish between ancient genetic material from the Kostenki male and contamination from modern people who handled the bones, or whose DNA reached the remains by some other means.

The new approach, developed by Professor Paabo and his colleagues, exploits three features which tend to distinguish ancient DNA from modern contamination. One of these is size; fragments of ancient DNA are often shorter than those from modern sources.

Previous ancient DNA studies used the widespread polymerase chain reaction (PCR) technology. PCR amplifies a few pieces of genetic material, generating thousands to millions of copies of a sequence. But the researchers found many fragments of ancient DNA were too small to be amplified by PCR.

A second characteristic of ancient DNA was its tendency to show particular changes, or mutations, in the genetic sequence at the ends of DNA molecules.

A third feature was a characteristic breakage of molecules at particular positions in the DNA strand.

Trust issues

The apparent ease with which modern DNA can infiltrate ancient remains has led many researchers to doubt even those studies employing the most rigorous methods to weed out contamination by modern genetic material.

"The ironic thing is that our group has been one of those that raised this issue," Professor Paabo told BBC News.

"To take animal studies on cave bears, for example, if we use PCR primers specific for human DNA on cave bear bones, we can retrieve modern human DNA on almost every one. That has made me think: 'how can I trust anything on this'."

Using the new techniques, the researchers were able to sequence the entire mitochondrial genome of the Markina Gora individual.

Future studies like the one in Current Biology could help shed light on whether the humans living in Europe 30,000 years ago are the direct ancestors of modern populations or whether they were replaced by immigrants who introduced farming to the continent several thousand years ago.

The modern gene pool contains a wide variety of mtDNA lineages. Studying these maternal lineages provides scientists with clues to the origins and histories of human populations.

Scientists look for known genetic signatures in order to classify an individual's mtDNA into different types, or "haplogroups". These haplogroups represent major branches on the family tree of Homo sapiens.

Early arrival

The researchers were able to assign the Kostenki individual to haplogroup "U2", which is relatively uncommon among modern populations.

U2 appears to be scattered at low frequencies in populations from South and Western Asia, Europe and North Africa.

Despite its rarity, the very presence of this haplogroup in today's Europeans suggests some continuity between Palaeolithic hunters and the continent's present-day inhabitants, argue the authors of the latest study.

U2, along with closely related haplogroups such as U5, are among those which could plausibly have arrived in Europe during the Palaeolithic.

Geneticists use well-established techniques to "date" particular genetic events, such as when a haplogroup first diversified. The "U" branch (comprising haplogroups U1, U2, U3 and so on) appears to be more ancient than many other genetic lineages found in Europe.

A recent study found a very high percentage of U types in the skeletal remains of ancient hunter-gatherers from Central Europe compared with later farming immigrants and modern people from the region.

Meanwhile, an analysis last year of mtDNA from 28,000-year-old remains unearthed at Paglicci Cave in Italy showed this individual belonged to haplogroup "H" - the most common type found in modern Europeans.

Doctor Who finale watched by 10.4m as Tennant bows out

David Tennant's final outing as Doctor Who was watched by 10.4m viewers on New Year's Day, according to early overnight figures.

At the climax of the episode, a total of 10.8m tuned in to see the Time Lord regenerate into his 11th incarnation, 27-year-old actor Matt Smith.

Tennant's final words on the show were, "I don't want to go".

Smith, meanwhile, uttered the immortal line, "legs! I've got legs!" as he made his screen debut as The Doctor.

The 75-minute episode ended with the Tardis in flames, plummeting towards Earth - setting up Smith's first full episode, due later this year.

It was the highest-rated programme in its time-slot. ITV1's Coronation Street took second place, with 8.6m viewers.

However, both had lower ratings than the day's second episode of EastEnders, which attracted an audience of 11.6m at 1945GMT.

Emotions

Critics were generally appreciative of Tennant's final episode, which also marked the end of head writer Russell T Davies' tenure on the show.

The story saw The Doctor battle against his nemesis, The Master (John Simm), who took possession of the body of every human on the planet, paving the way for the return of the Time Lords - who planned to end time itself.

In The Guardian, television critic Mark Lawson likened the episode to Hamlet - a role which Tennant played with the Royal Shakespeare Company last year.

"In common with the prince of Denmark, the Time Lord from Gallifrey agonised aloud over whether it would be right to kill a man (the Master) after a painful encounter with his mother, played by Claire Bloom, whose Shakespearean roles include Hamlet's mother, Gertrude," he wrote.

Writing on Cult TV website Den Of Geek , Simon Brew felt that, by allowing Tenant to revisit the characters he met during his four-year tenure as the Doctor, Davies had given new emotional depth to the process of regeneration.

"We've never had this: 20 minutes or so for a Doctor to deal with his impending demise, with no threat to see off to get in the way.

"Usually, the emotions are dealt with afterwards, as the new Doctor gets used to his new body. Here, an outgoing Doctor got to face the ramifications of what was about to happen, and it was explored exceptionally well."

Meanwhile, in The Times, Caitlin Moran dissected Smith's debut .

"As if to remind us of how huge the Doctor Who Universe is, and how fast it gallops on, Smith wasted no time mourning his previous, dead self. Instead, feeling his delicately featured face, he started in alarm, and shouted: 'Argh! I'm a girl!'"

A preview for the new series has been made available on the official Doctor Who website.

It shows Smith facing vampire-like creatures, hitting a Dalek with a mallet, and shouting what seems set to become his catchphrase: "Geronimo!"

The trailer also hints at the return of Alex Kingston as River Song - an archaeologist who had appeared to have had an intimate relationship with The Doctor.

Her character was created by Steven Moffat, who has taken over from Davies as the head writer of the sci-fi franchise.

The new series is due on BBC One in the spring.

Late-night teens 'face greater depression risk'

Going to bed earlier protects teenagers against depression and suicidal thoughts, New York research suggests.

Of 15,500 12 to 18-year-olds studied, those who went to bed after midnight were 24% more likely to have depression than those who went before 2200.

And those who slept fewer than five hours a night had a 71% higher risk of depression than those who slept eight hours, the journal Sleep reports.

It is estimated 80,000 UK children and young people have depression.

The researchers from Columbia University Medical Center in New York looked at data from 15,500 teenagers collected in the 1990s.

One in 15 of those studied were found to have depression.

As well as the higher risk of depression, those who were set a bedtime by their parents of after midnight were 20% more likely to think about suicide than those whose bedtime was 2200 or earlier.

Those who had less than five hours sleep a night were thought to have a 48% higher risk of suicidal thoughts compared with those who had eight hours of sleep.

Teenagers who reported they "usually get enough sleep" were 65% less likely to be depressed.

Depression and suicidal thoughts were also more likely in girls, older teenagers and in those who had a lower self-perception of how much parents care about them.

Most of the parents of the adolescents in the study set a bedtime of 2200 or earlier.

A quarter set a bedtime of 2400 or later.

On average the teenagers were having seven hours and 53 minutes sleep a night - less than the nine hours recommended at that age.

Study leader Dr James Gangwisch said although it it was possible that youngsters with depression struggle to sleep, the fact that parental set bedtimes were linked with depression suggests that a lack of sleep is somehow underpinning the development of the condition.

He said a lack of sleep could affect emotional brain responses and lead to moodiness that hindered the ability to cope with daily stresses.

This moodiness could affect judgment, concentration and impulse control.

Regular exercise

"Adequate quality sleep could therefore be a preventative measure against depression and a treatment for depression," he added.

Sarah Brennan, chief executive at the mental health charity YoungMinds, said: "Enough sleep, good food and regular exercise are all essential to stay emotionally healthy.

"Nearly 80,000 children and young people suffer with depression, yet we are still failing to provide our young people with the help and support to cope with it and prevent it.

"Providing parents with information about how to look after your body, for example by getting enough sleep, and how to get help if they are worried about their teenager, will ensure problems are tackled early and prevent serious mental health conditions such as depression."

Singer Van Morrison denies 'unfounded' baby story

Veteran singer Van Morrison has denied reports that he had become a father again, adding they were "completely and utterly without foundation".

The Belfast-born 64-year-old said he had been the victim of an internet hacking attack that had placed "falsehoods" on his official website.

BBC News was one of several outlets to report the hoax as fact.

"The comments which appeared on my website did not come from me," he said, in a statement issued to the media.

The singer said he had asked his management team to carry out an immediate investigation, adding it was the second time his website had been hacked in the last three months.

He went on to say, "for the avoidance of all doubt and in the interests of clarity", that he was "very happily married to Michelle Morrison, with whom I have two wonderful children".

'Alarm bells'

A statement posted on the singer's website on Tuesday said he had had a son named George Ivan Morrison III with a woman named Gigi Lee.

A friend of Morrison's has since told the BBC News website that the singer had never heard of Ms Lee.

"One of the things that triggered alarm bells was the language used in the 'statement'," said John Saunders.

"It was so unlike him to make an announcement like this."

Mr Saunders, founder of Dublin-based public relations company Fleishman-Hillard, said it was he who informed Morrison of the original reports.

"I hesitated before making contact, but my wife said you had better do something," he said.

Morrison, whose hits include Brown Eyed Girl and Moondance, celebrated his 40th year in the music industry in 2008.

He first found fame in the 1960s as a member of the band Them, before embarking on a solo career.

'Sexercise' yourself into shape

The NHS has some new advice for people struggling to schedule a fitness routine into their daily lives - a workout between the sheets.

According to the NHS Direct website, "sexercise" can lower the risk of heart attacks and helps people live longer.

Endorphins released during orgasm stimulate immune system cells, which also helps target illnesses like cancer, as well as wrinkles, it states.

Sexual health experts said such claims could not be scientifically proven.

"It's good to see the NHS are promoting sexual wellbeing," Dr Melissa Sayer told the Guardian newspaper.

"Yes, there is evidence that sex has benefits for mental wellbeing, but to say there is a link with reduced risk of heart disease and cancer is taking the argument too far."

NHS Direct, however, told the paper the content was "backed by science and clinical evidence" and "isn't just a bit of fun".

'Regular romps'

The advice, published under the headline "Get more than zeds in bed", is one of several sexual health-related articles to be found on the NHS Direct website.

Sex with a little energy and imagination provides a workout worthy of an athlete, the article says.

"Forget about jogging round the block or struggling with sit-ups.

"Sex uses every muscle group, gets the heart and lungs working hard, and burns about 300 calories an hour."

The advice suggests "regular romps this winter" could lead to a better body and a younger look.

Increased production of endorphins "will make your hair shine and your skin smooth," it adds.

"If you're worried about wrinkles - orgasms even help prevent frown lines from deepening."

The article goes on to say that orgasms release "painkillers" into the bloodstream, which helping keep mild illnesses like colds and aches and pains at bay.

The production of extra oestrogen and testosterone hormones "will keep your bones and muscles healthy, leaving you feeling fabulous inside and out".

Jet bomb suspect's journey 'began in Ghana'

The Nigerian man accused of trying to blow up a transatlantic airline on Christmas Day began his journey in Ghana, the Nigerian authorities say.

Umar Farouk Abdulmutallab spent just half an hour at the airport in Lagos before transferring to an Amsterdam flight, the information minister said.

It had been assumed the 23-year-old began his journey in Nigeria.

But Ghana has disputed Nigeria's timings, saying Mr Abdulmutallab's stop-over was at least three hours.

A senior Ghanaian government official told the BBC that the suspect bought a one-way ticket to Lagos from Accra that would have given him more than three hours at the airport.

He accused the Nigerians of attempting to "pass the buck" as the search for security lapses continues, the BBC's West Africa Correspondent Caspar Leighton reports from Accra.

Nigeria's Information Minister Dora Akunyili earlier told the BBC that it was now known Mr Abdulmutallab had boarded a Virgin Nigeria plane from Accra to Nigeria, arriving at Lagos' Murtala Muhammed airport on 24 December.

His passport was scanned on entry into Nigeria at 2008 (1908GMT), and again, as he boarded the flight to Amsterdam, at 2035, she said.

"He was able to connect that fast because he was not checking in any luggage," she said.

From Amsterdam, the Northwest Airlines Flight 253 - with 278 passengers and 11 crew aboard - went on to the US city of Detroit.

Some 20 minutes before landing at the city's Metropolitan Airport, on the afternoon of Christmas Day, Mr Abdulmutallab was spotted by flight crew and passengers trying to ignite explosives strapped to his leg, investigators say.

The explosives failed to detonate, although it is thought they may have caused a small fire which burned the suspect's leg.

He is now in US custody.

Body scanners

The incident has led to a worldwide re-think about security procedures.

US President Barack Obama is reading reports received about the security lapses that led to the near-disaster in Detroit, and intends to meet security chiefs on Tuesday to discuss new measures.

British Prime Minister Gordon Brown announced on Friday he had ordered a review of existing security measures, and would "move quickly" to enhance airport security.

Full-body scanners would be among the new technologies considered, he said.

The Dutch authorities announced earlier this week that body scanners would be used on all passengers flying from Amsterdam's Schiphol airport to the US.

Shebab 'help'

The incident has also thrown the spotlight on Yemen, where Mr Abdulmutallab was living in the months leading up to the attack.

It is feared the troubled country is becoming a major training centre for militants, with several hundred al-Qaeda members believed to be operating there.

In recent weeks, Yemen has launched major operations against al-Qaeda with US backing, but has warned that it needs more Western support to tackle the threat.

Britain's prime minister has called a summit in London to discuss radicalisation in Yemen.

Mr Brown's office said the 28 January event had support from Washington and the European Union, and Mr Brown aimed to attract Saudi Arabia and Gulf states.

Somalia's hardline Shabab group - which controls large swathes of Somalia, including much of the capital Mogadishu - said on Friday it would send fighters to help fellow militants in Yemen.

"We tell our Muslim brothers in Yemen that we will cross the water between us and reach your place to assist you fight the enemy of Allah," said Shebab's Sheikh Mukhtar Robow Abu Mansour.

Jet bomb suspect's journey 'began in Ghana'