They lived up to 19 years longer than uncastrated men from the same social class and even outlived members of the royal family.
The researchers believe the findings show male hormones shorten life expectancy.
The study is published in the journal Current Biology.
Castration before puberty prevents the shift from boy to man. One of the scientists involved in the study, Dr Cheol-Koo Lee from Korea University, said: “The records said that eunuchs had some women-like appearances such as no moustache hair, large breasts, big hips and thin high-pitched voice.”
Eunuchs had important roles in many cultures from protecting harems to castrati superstar singing sensations. The imperial court of the Korean Chosun dynasty used eunuchs to guard the gates and manage food. They were the only men outside the royal family allowed to spend the night in the palace.
They could not have children of their own, so they adopted girls or castrated boys.
Researchers in South Korea analysed the genealogical record of these “eunuch families”.
They worked out the lifespans of 81 eunuchs born between 1556 and 1861. The average age was 70 years, including three centenarians – the oldest reached 109.
By comparison, men in other families in the noble classes lived into their early 50s. Males in the royal family lasted until they were just 45 on average.
There are no records for women at the time for comparison.
Dr Kyung-Jin Min, from Inha University, told the BBC: “We also thought that different living circumstances or lifestyles of eunuchs can be attributed to the lifespan difference.
“However, except for a few eunuchs, most lived outside the palace and spent time inside the palace only when they were on duty.”
Instead he thinks the data “provides compelling evidence that male sex hormone reduces male lifespan”.
Men v women
Women tend to outlive men across human societies. However, theories are hard to test in experiments and the exact reason for the difference is uncertain.
One thought is that male sex hormones such as testosterone, which are largely produced in the testes, could be damaging. The researchers said the hormones could weaken the immune system or damage the heart. Castration would prevent most of the hormone from being produced, protecting the body from any damaging effect and prolonging lifespan.
Dr Min said: “It is quite possible that testosterone reduction therapy extends male lifespan, however, we may need to consider the side effects of it, mainly reduction of sex drive in males.
Dr David Clancy, from the University of Lancaster, said: “The results are persuasive, but certainly not conclusive.”
He said the relatively high number of centenarians in the group suggested eliminating testosterone may have prolonged life. However, he cautioned that difference in lifestyle could have had a significant impact.
“In this case eunuchs were raised by eunuchs over generations, lifestyle differences may have been reinforced in this way.
“Castrato versus non-castrato singers are probably a better comparison, and showed no difference in lifespan. Non-castrato lived an average 65 years and both groups lived fairly cosseted lives.”
By Ken Macdonald BBC Scotland Science Correspondent
By-products, like draff, from the Tullibardine distillery are to be turned into biofuel
A deal has been signed to turn by-products from a Scottish distillery into fuel for cars.
In what is claimed to be a world first, the Tullibardine distillery in Perthshire has linked up with a spin-out company from Napier University in Edinburgh.
They plan to use bacteria to feed on the “leftovers” from the whisky making process.
This will produce butanol which can be used to fuel vehicles.
More than 90% of the stuff that comes out of a whisky distillery is not whisky. It is leftovers like draff and pot ales – both produced in the early stages of the process.
They are high in sugar and are currently used for things like fertiliser and cattle feed.
It takes a cost to us and turns it into something that has social as well as commercial value”
Douglas Ross Tullibardine distillery
Napier University’s Biofuel Research Centre (BfRC) has already shown that the right bacteria can feed on those by-products to produce butanol – a direct replacement for vehicle fuel.
Now the spin-out company, Celtic Renewables, and independent malt whisky producer Tullibardine have signed a memorandum of understanding.
Together they will apply the process to thousands of tonnes of the distillery’s leftovers.
Professor Martin Tangney, founder of Celtic Renewables, said: “Our partnership with Tullibardine is an important step in the development of a business which combines two iconic Scottish industries – whisky and renewables.
“This project demonstrates that innovative use of existing technologies can utilise resources on our doorstep to benefit both the environment and the economy.”
A powerful explosion has rocked the eastern Turkish city of Tunceli, killing seven people, media report.
The blast targeted a military vehicle carrying security personnel.
The city is near the country’s Kurdish area and suspicion will automatically fall upon Kurdish rebel group the PKK, says the BBC’s Istanbul correspondent James Reynolds.
Fighting between Turkish troops and the PKK – the Kurdistan Workers’ Party – has escalated in recent months.
Turkish TV stations showed pictures of workers trying to put out fires in two burnt-out vehicles.
Reports said a vehicle carrying explosives was remotely detonated as an armoured vehicle carrying security forces passed by, sending a huge plume of dark smoke over the city.
Several ambulances and fire engines were reported speeding to the site in the Ataturk neighbourhood.
Denmark is tightening rules on sperm donation after one donor was found to have passed on a rare genetic condition to at least five of the 43 babies he is thought to have fathered.
Neurofibromatosis type 1 (NF1) produces tumours that affect the nervous system, and the affected sperm is thought to have been used in 10 countries.
The sperm bank has been criticised for failing to screen for the condition.
Donors will now only be allowed to donate enough for 12 inseminations.
Denmark has liberal sperm donation policies that appeal to women who want to conceive using artificial insemination.
The Copenhagen sperm bank Nordisk Cryobank said it was aware of five babies that had been born with NF1.
The clinic’s director, Peter Bower, told Agence France-Presse that confidentiality rules meant he was unable to give detail on how old the children were, or where they lived.
But he said the donor was known to have provided sperm to women prior to October 2008, in countries inside and outside Europe.
He said Nordisk Cryobank did not stop using the sperm immediately because it could not be sure the donor was responsible for passing on the condition.
The donated sperm was used by 14 different fertility clinics, Danish broadcaster DR reports.
‘Shaken and shocked’
NF1 is caused by a genetic mutation. In half of all cases it is passed from a parent to their child. In other cases, the mutation develops on its own.
It can produce a wide range of symptoms – from unusual skin pigmentation, to serious and disfiguring non-cancerous tumours which can sometimes turn cancerous.
It can also cause learning difficulties, problems with vision, and an abnormally curved spine.
There is no treatment for the condition, but the symptoms can be managed.
A mother of one of the affected children, Mia Levring, condemned the clinic’s actions, saying she was “shaken and shocked”.
Another, Sonja Pedersen, said: “We are dealing with a lot of children, but there is also the economical aspect. They earn a lot of money doing this. And one has a responsibility to make sure that the product, so to speak, is all right.”
The head of the Danish Health and Medicines Authority, Anne-Marie Vangsted, criticised the sperm bank, saying it had failed to withdraw the sperm when it first became aware of the problem.
It is unclear how the donor who passed on NF1 was able to father 43 children, despite Denmark’s current limit of 25.
The new limit of 12 will be introduced from 1 October
Kenya’s director of public prosecutions has ordered the arrest of a deputy minister, for alleged incitement and hate speech against ethnic Maasai.
The order comes after parts of a speech made by MP Ferdinand Waititu were posted on YouTube.
He was reacting to the killing of a street child, allegedly by a Maasai security guard, for stealing a chicken in Nairobi’s Kayole suburb.
There are fears politicians may whip up ethnic tensions ahead of March’s polls.
In order to prevent a repeat of the deadly violence which followed the 2007 election, the constitution passed two years ago says that any minister charged with an offence must stand down and cannot seek re-election unless acquitted.
Earlier this month, another Kenyan politician was charged with inciting violence that recently claimed more than 100 lives in the south-eastern Tana River area.
Two Russian police officers have been jailed after a suspect was tortured in custody and later died of his wounds.
Ramil Nigmatzyanov and Ilshat Garifullin were jailed for two and two-and-a-half years respectively for exceeding their authority in Kazan.
The pair did not directly take part in torture. Several other officers are accused of beating Sergei Nazarov and sexually abusing him with a bottle.
His death in March led to protests in Kazan that drew nationwide attention.
Nigmatzyanov and Garifullin were sentenced on Tuesday by the court in the capital of Russia’s Tatarstan republic.
The courtroom was full of journalists, who by far outnumbered relatives of both the accused and the victim.
Speaking very quietly, Garifullin asked Mr Nazarov’s family to pardon him. He pleaded not to be put in jail, promising to pay 500,000 roubles (£9,930; $16,140) in compensation demanded from each police officer by Mr Nazarov’s brother. Nigmatzyanov chose not to speak in the courtroom.
The policemen’s relatives started crying after the verdict was announced. Garifullin’s lawyer later said he would appeal against the verdict.
They were the first to be convicted in a case that has sent shockwaves across Russia.
The pair were found guilty of illegally detaining Mr Nazarov, 52, on suspicion of theft and then falsifying his statement, which led to his arrest.
Nine other police officers, including those who are suspected of torturing Mr Nazarov, are yet to go on trial.
The victim died in hospital of his injuries, after telling investigators about his ordeal.
This case opened a floodgate of complaints about police violence in Kazan.
The street protests in the city also forced the resignation of Tatarstan’s interior minister.
The incident happened after a much-vaunted nationwide reform of the police force, which the authorities had hailed as a triumph.
However, Russian human rights activists say that nothing has radically changed since Mr Nazarov’s death, the BBC’s Olga Ivshina in Kazan reports.
The activists say they continue to systematically receive complaints about violence in police stations, including beatings and torture, our correspondent adds.
The US Supreme Court is to consider if police need a warrant before ordering a blood test on a drink-driving suspect.
Justices will hear the case of a Missouri man who was taken to hospital for a blood sample after refusing to provide a breath test.
The Missouri Supreme Court upheld the exclusion of the blood sample at trial, finding that the arresting officer should have sought a warrant.
The Supreme Court is expected to hear Missouri v McNeely in January.
The legal saga began when Tyler McNeely was pulled over on suspicion of speeding on 3 October 2010.
After refusing a breath test, he was taken to a nearby hospital where his blood-alcohol content was measured at 0.154%, almost twice the state’s legal limit.
Siding with the defendant, Missouri’s Supreme Court ruled that police need a warrant to take a suspect’s blood, except in cases where a delay could threaten life or destroy evidence.
Mr McNeely’s lawyers said the reason the arresting officer made no effort to obtain a warrant was because he was unaware one was needed, not because he was concerned alcohol would dissipate in the accused’s bloodstream.
In its appeal to the US high court, Missouri argued that the decision by its supreme court “requires police officers to stand by and allow the best, most probative evidence to be destroyed during a drunk-driving investigation”.
Other US courts have ruled that the lowering of blood alcohol levels over time justifies police ordering a blood test without a warrant.
More than 1.4 million people are arrested each year in the US for drink and drug-driving charges, according to the FBI.
US doctors say children should be discouraged from using trampolines because they are a health hazard.
The American Academy of Pediatrics (AAP) estimates that almost 98,000 people are injured each year in the US on trampolines and many of these are children.
UK safety experts say the sport is growing in popularity here and related injuries are on the rise.
But they say trampolining can be a healthy way to exercise and good fun.
A safety net is not a substitute for adult supervision”
The renewed advice from the AAP says paediatricians need to “actively discourage” recreational trampoline use.
Dr Michele LaBotz, who co-authored the AAP report said: “Families need to know that many injuries occur on the mat itself, and current data do not appear to demonstrate that netting or padding significantly decrease the risk of injury.”
The researchers found that most injuries occur when more than one person is on a trampoline.
Children under five are more likely to suffer serious injury, with 48% of injuries in this group resulting in fractures and dislocations.
Some injuries may even be fatal – failed attempts at somersaults and flips frequently cause cervical spine injuries, resulting in permanent and devastating consequences, says the AAP.
But the UK’s Royal Society for the Prevention of Accidents (Rospa) says trampolining can be enjoyed safely if a few simple rules are followed.
For example, put the trampoline on a softer surface like the lawn rather than concrete and consider using safety netting.
“But a safety net is not a substitute for adult supervision,” a spokesman added.
More than half of all trampoline accidents occur while children are being watched by an adult, but using trained supervisors can greatly reduce this risk, says Rospa.
Latest UK figures show that, in 2002, 11,500 people in the UK ended up in hospital after a trampoline accident – an increase of more than 50% in five years.
German doctors have voiced concern about EU plans to speed up clinical drug trials and streamline testing procedures across the 27-nation bloc.
The German Medical Association (Bundesaerztekammer) said the proposal would undermine the safety mechanism provided by ethics committees, which do prior assessment of clinical trials.
The EU Commission wants a new EU draft regulation to take effect in 2016.
Bureaucracy is hampering human drug tests in Europe, the Commission argues.
After World War II Germany tightened up ethical standards in medicine, shocked by the abuses committed by Nazi doctors.
The new EU regulation would replace the 2001 Clinical Trials Directive.
Health Commissioner John Dalli, who presented the proposal on 17 July, said “800 million euros [£637m; $1.03bn] per year could be saved in regulatory costs and boost research and development in the EU, thus contributing to economic growth”.
He insisted that patient safety would not be compromised.
The Commission says the current directive has been applied in diverse ways in the EU, leading to a big regulatory burden. That contributed to a 25% fall in the number of clinical trials conducted in Europe in 2007-2011, it says.
The new proposal cannot become law until EU health ministers – grouped in the EU Council – and European Parliament have approved it.
The Commission aims to make it easier to conduct multi-national clinical trials in Europe, by introducing one authorisation procedure, simplified reporting procedures and more transparency.
The proposal also calls for checks by Commission specialists on the conduct of clinical trials in the EU and other countries, to make sure the rules are properly supervised and enforced.
The news website Nature says the current directive has been criticised by many medical experts as excessively bureaucratic. They have also blamed the directive for the transfer of medical research to some non-EU countries where oversight of clinical trials is less strict.
German MPs are set to examine the new EU proposal this week.
The German Medical Association – the main ethical watchdog for doctors in Germany – says it wants the role of ethics committees in clinical trials to be made explicit in the EU proposal. It also says that rejection of a clinical trial by an ethics committee must mean that the trial is ruled out.
The proposal must also allow for member states to conduct their own checks in cases where a clinical trial is pioneered by one member state, the German doctors say.
The proposal also undermines German clinical trial safeguards for minors and for people incapable of giving consent, the association says.
Nasa’s Curiosity rover has completed its first close-contact science.
The robot pushed its arm instruments up against a pyramidal rock to assess the atomic elements that were present.
The rock – dubbed “Jake Matijevic” after a late rover engineer – was not expected to have high research value. Rather, it was regarded as an early opportunity to demonstrate the performance of the arm’s “hand lens” and X-ray spectrometer.
Curiosity has now continued driving.
On Monday, it moved some 42m (138ft), the single biggest roll for the robot since landing seven weeks ago in Mars’ equatorial Gale Crater.
The vehicle is endeavouring to get to location that scientists have nicknamed Glenelg, which satellite images have indicated is a junction between three types of geological terrain.
It is at Glenelg that Curiosity will likely use one of its key arm tools – its drill – for the first time.