This review was originally published in September 2011.

It’s hard to name many Hollywood blockbusters that are as invested in the realities of science as . There certainly are plenty of enormously successful science-fiction films that abuse science in the name of drama, like and The Day After Tomorrow, but very few Hollywood productions realistically portray the process of science, both its successes and frustrations. That’s what makes Contagion unique. Although it is by no means flawlessly accurate – it’s not a documentary – Contagion has been well fact-checked compared to most science-y blockbusters.

Directed by Steven Soderbergh – who previously directed and the remake of – Contagion‘s all-star cast includes Marion Cotillard, Matt Damon, Laurence Fishburne, Jude Law, Gwyneth Paltrow, and Kate Winslet.

The story begins with Beth Emhoff (Paltrow) coughing in an airport in Chicago, on her way back home to Minneapolis after a business trip to Hong Kong. Before long she begins to have seizures and foams at the mouth. Meanwhile, other people around the world – in Tokyo, London and Hong Kong – succumb to exactly the same symptoms.

A series of carefully focused shots and strategically placed scenes emphasise that everything in the world is a potential vector for the fatal virus: doorknobs, credit cards, empty glasses, napkins, a bowl of peanuts at a bar, airplanes, handshakes, sex. As millions become infected worldwide, quarantines are imposed and people grow afraid to go anywhere or interact with anyone. The Centers for Disease Control and Prevention in Atlanta, Georgia and the World Health Organization in Geneva, Switzerland, work nonstop to identify the origin of the disease, create a vaccine and keep the public informed, but not panicked. But they cannot stop the riots or looting ‐ nor can they stop the avaricious freelance journalist Alan Krumwiede (Law) from spreading lies online about a false cure made from the flowering plant forsythia.

The movie’s exhilarating pace never sags, even in scenes that have the potential to bore people out of their minds: a meeting between an epidemic intelligence service officer (Winslet) and the Minnesota Department of Health, for example. But Soderbergh and screenwriter Scott Burns practice what is in effect very successful science communication: they keep the viewer’s attention as they explain statistics like the all-important R0 – the average number of people an infected person infects – and truths about the scientific process, such as the fact that before researchers can study a virus, they need to figure out how to grow it in cell cultures in the lab, without the virus destroying all the cells.

MEV-1, the film’s fictional virus, is modelled upon the bat-borne Nipah virus, which was identified in 1999 when an outbreak caused brain and lung disease in pigs and people in Malaysia. In the film, MEV-1 kills people within days, but in real life the incubation period for Nipah – and many deadly viruses – is .

Once the CDC identifies a weakened live strain of the virus that protects monkeys against the disease – and after CDC scientist Ally Hextall (Jennifer Ehle) follows a brave tradition of making herself the first human test subject – a vaccine somewhat miraculously speeds into mass-production. Outside Hollywood’s bubble, it would take many months of testing and brewing – and many more of securing authorisation from health authorities – to release a viable vaccine for global distribution. But epidemiologist of Columbia University, who consulted with Soderbergh during production, says that the pace of Contagion‘s finale is not as unrealistic as it might seem, Carl Zimmer . Lipkin says today’s scientists have the tools to create a vaccine much faster than ever before – especially if there’s impetus and funding from the government.

Throughout the film there is the suggestion that the virus might be a bioweapon, but that idea is never validated. As the CDC’s Ellis Cheever (Fishburne) tells the Department of Homeland Security, “Someone doesn’t have to weaponise the bird flu. The birds are doing that.” Contagion‘s final scenes reveal the unfortunate, but entirely plausible origin of the novel virus.

Skip the next two paragraphs if you don’t want to read any plot spoilers.

It turns out to be caused by an interaction between a bat and a pig – a pig that winds up in the kitchen of the Hong Kong casino in which Beth Emhoff spends her last night in town.

Those final scenes underscore Contagion‘s dedication to scientific accuracy. Throughout history, many deadly viruses have jumped from one species to another – from birds to people, or from pigs to people or from birds to pigs to people. Interspecies interactions are a major breeding ground for new terrifying viruses.

You can look again now.

“I didn’t want the virus to be divine retribution, or the result of a military conspiracy,” Burns . “I wanted it to be the result of life on Earth in its most mundane. To me there’s something more frightening about what really truly happens in the world.”

Contagion is available now

ANYONE can publish on the web, but it would be better if some people didn’t; the world does not need another site that provides advice on how to unlock an iPhone or find cheap car insurance. Now new evidence shows that search engines have upped their game to make sure their results are not dominated by such low-quality sites.

Search engines are meant to pick out high-quality sites amid the sea of knock-offs, but even they get overwhelmed. As recently as March, for example, the first 10 results from a Google search for “how to organise your desktop” contained nine links to pages churned out by “content farms” – websites that publish reams of articles, often of dubious quality, that aim simply to attract clicks and advertising dollars.

“In March, 9 of 10 top search results for ‘how to organise your desktop’ were made by content farms”

That prompted żìĂš¶ÌÊÓÆ” to ask computer scientist at the University of Glasgow, UK, to look into the issue. The results show that Google and Microsoft have won a major victory in the fight against such content farms. In the process they may have inflicted serious pain on two organisations often cited as providers of content farm material: Seed, a project from AOL, appears to have stopped commissioning content from freelance writers, though the firm declined to comment. And Santa Monica-based Demand Media has seen by over 50 per cent since it went public earlier this year for $1.5 billion.

Most of the credit for such changes has been given to Google, which this February announced that it had updated its search algorithm in a bid to prioritise sites that publish original and well-researched material. It won’t provide details, but many site owners noticed that the update detected and penalised sites that publish multiple near-identical articles, a favourite tactic of content farms. For example, the traffic flowing from search engines to eHow, a Demand Media site, . Google has also enlisted users to keep up the fight – it says that it now demotes sites that people choose to exclude from search results.

To test how successful Google and Microsoft’s Bing have been at fending off content-farmed results, McCreadie ran 50 search queries known to be a target of content farmers, such as “how to train for a marathon”, in March and August this year. Then he paid people to examine the results for links to low-quality sites, where “low quality” was defined as uninformative sites whose primary function appears to be displaying adverts.

The results are striking. In the case of the marathon query, sites that contained lists of generic tips, such as “invest in a good pair of running shoes”, were present in the top 10 in March but had disappeared by August, while high-quality sources, such as Runner’s World magazine, now appear near the top. Similar trends were found throughout the 50 queries.

The story is far from over. Search engines play such a prominent role in our lives – Google alone handles over a billion queries a day – that companies constantly vie for the top places in the results. Sites can rank highly by producing authoritative material, but this is expensive, so there will always be those looking for a cheap short cut. Content farms may be out for now, but with billions of dollars hanging in the balance, it’s just a matter of time before the next battle commences.

Pessimists, anti-capitalists, conservatives and greens, take note – we are much more peaceful now than we used to be, says the psychologist

Interactive graphic: The 20 worst things people have done to each other

What got you interested in the history of violence?
I was struck by a graph I saw of homicide rates in British towns and cities going back to the 14th century. The rates had plummeted by between 30 and 100-fold. That stuck with me, because you tend to have an image of medieval times with happy peasants coexisting in close-knit communities, whereas we think of the present as filled with school shootings and mugging and terrorist attacks.

Then in Lawrence Keeley’s 1996 book I read that modern states at their worst, such as Germany in the 20th century or France in the 19th century, had rates of death in warfare that were dwarfed by those of hunter-gatherer and hunter-horticultural societies. That too, is of profound significance in terms of our understanding of the costs and benefits of civilisation.

Isn’t this topic a departure for you? Your earlier books focus on how the mind and brain work

Two of my earlier books, How The Mind Works and The Blank Slate, were not about language or even cognition, narrowly, but about human nature. In them I talked about violence, for example, the abolition of barbaric customs such as torturing people to death for religious heresy, to reinforce the point that human nature comprises many components, some of which incline us toward violence, some of which pull us away from it. The fact that violence has declined and what this implied for human nature were spelled out in both books, but I decided that those paragraphs deserved to be expanded into a book of their own.

Where did you find evidence for how violence has changed over time?
For prehistoric times, the main evidence is from forensic archaeology: the proportion of skeletons that had bashed-in skulls, or arrowheads embedded in bones, together with archaeological evidence such as fortifications. For homicide over the last millennia or so, there are records in many parts of Europe that go back to the Middle Ages. And we know from documents of the era that crucifixions and all manner of gory executions took place in the ancient world.

For data about wars, there are many , and in recent eras, governments and social scientists have tracked just about every aspect of life, so we really can get a clear view of things like child abuse, spousal abuse, rape and so on.

How do you explain the decline in violence?
I don’t think there is a single answer. One cause is government, that is, third-party dispute resolution: courts and police with a monopoly on the legitimate use of force. Everywhere you look for comparisons of life under anarchy and life under government, life under government is less violent. The evidence includes transitions such as the European homicide decline since the Middle Ages, which coincided with the expansion and consolidation of kingdoms; the transition from tribal anarchy to the first states. Watching the movie in reverse, in today’s failed states violence goes through the roof.

Do you think commerce helps too?
Commerce, trade and exchange make other people more valuable alive than dead, and mean that people try to anticipate what the other guy needs and wants. It engages the mechanisms of reciprocal altruism, as the evolutionary biologists call it, as opposed to raw dominance.

“Trade and exchange make other people more valuable alive than dead”

What else has contributed to the decline?
The expansion of literacy, journalism, history, science – all of the ways in which we see the world from the other guy’s point of view. Feminisation is another reason for the decline. As women are empowered, violence can come down, for a number of reasons. By all measures men are the more violent gender.

Has human nature, specifically our inclination toward violence, changed? Or is it more a change in how this inclination manifests itself?
I argue for the latter, although it’s not inconceivable that the former has taken place, that we have literally evolved so that the more pacific parts of human nature have been strengthened, at least over a span of centuries or millennia. I have a lengthy discussion in the book for how that could happen: it’s certainly biologically possible.

But some of the declines are far too recent to be explicable by natural selection, which has a speed limit measured in generations. So the most parsimonious explanation is that all the changes are environmental rather than genetic, while not ruling out the possibility of genetic changes.

Why do so many people think we live in incredibly violent times?
I think there are a number of systematic biases, what I call “historical myopia” being one of them. The closer you get to the present, the better the records are, and I think this is a major distorter of our impressions of violence. We know about every massacre that has taken place close to the present, but the ones in the distant past are like trees falling in the forest with no one to hear them.

So you think that we care more about violence than we used to?
Yes. Forms of violence that would once have been off people’s radar are now characterised as violence. Capital punishment was just a part of life. Pickpockets would be hanged. Now the most vicious serial murderer is executed painlessly after an appeal process that lasts decades and you’ve got nuns holding candles.

Also the human mind loves to learn about violence. Blood sells. The media don’t report that yesterday in Buenos Aires several hundred people died peacefully in their sleep, but if five of them were blown up, that would be news. More generally, when conflicts peter out it never makes the headlines. Unless you systematically tabulate violent deaths as a proportion of all deaths or as a proportion of population size, you will be misled.

What would you say to someone who doesn’t understand how a society capable of fighting the second world war could be less violent than ancient societies?
I would say look at the numbers. In the book I present a table where the second world war only comes in ninth place in the world’s atrocities. And one point is not a trend – the second world war, in terms of history, was very much an outlier.

Isn’t it simplistic to just compare the numbers of deaths in ancient wars and modern wars? How do you account for the difference in the nature of warfare and the technologies used?
That is part and parcel of the question that I am asking: namely, assuming that being killed is equally bad in all societies and at all times, was the tribal way of warfare more quantitatively destructive of human life than modern forms of warfare? They are qualitatively different, but in a way that is my point: knowing these differences, which was a worse time to be a human being?

What do you want readers to take away from your new book?
To be grateful for some of the institutions we take for granted, such as government and the court system. That, as much as we are irritated by lawyers, cops and government, the alternative is worse. The forces of reason, enlightenment, cosmopolitanism, women’s empowerment – we should be grateful for all this and not nostalgic for a time in which everyone’s world was far more constricted.

This goes for trade and commerce too. Capitalism is a dirty word for many intellectuals but there are a number of studies showing that open economies and free trade are negatively correlated with genocide and war. I would lump all of these things together under “modernity”.

So modernity tends to result in less violence?
Yes. There is an enormous current of romantic nostalgia among many sectors of intellectual life – the religious right, the green left. What I hope to remind people is that modernity, for all its problems, has brought us many gifts. Foremost is one that few people appreciate, namely a reduction in overall violence.

If certain areas of the brain that process visual information are activated – by a blow to the head, for example – tiny stars of light appear in vision. People experience such “phosphenes” even if their eyes are closed or they are blind. of the Massachusetts Institute of Technology in Cambridge and his colleagues stimulated these brain areas in monkeys to determine what the phosphenes look like to them and where they appear in line of sight.

First, they trained rhesus macaques to stare at two dots on a computer screen and direct their gaze towards the larger dot or the dot of higher contrast to the background. Schiller then implanted electrodes in each monkey’s primary visual cortex (V1), the main region responsible for processing visual information.

Schiller then removed one of the two dots on the computer screen and replaced it with a phosphene by stimulating an area of the V1. If the monkey’s gaze moved towards the phosphene, Schiller knew the star must be larger or of higher contrast than his programmed dot.

By varying the size of the dot on the screen, as well as the darkness and colour of the background, Schiller worked out that the stars were between 9 to 26 arc minutes (1 arc minute is 1/60th of a degree) in diameter and appeared in a variety of colours, including pink, blue, green and yellow.

“We want to understand the brain to help the blind,” Schiller says. His goal is to pair electrical stimulation of the visual cortex with a small camera – this would allow researchers to stimulate the visual cortex with a pattern of activity that translates the information captured by the camera, giving a kind of sight to blind people.

“There is growing interest in developing and applying brain-machine interfaces and neural prostheses, but there is not a whole lot of foundation in terms of understanding the coupling of physical signals you put into the brain and perceptual experiences you get out of the brain,” says of Harvard Medical School. “Studies like this allow you to move forward. Imagine if you could give vision back to people who have lost function of their eyes but have a perfectly intact brain.”

Journal reference:

Video: Monkey brainwaves control avatar

Monkeys have feelings too. In a mind-meld between monkey and computer, rhesus macaques have learned to “feel” the texture of virtual objects without physically touching a thing. In the future, prosthetic limbs modelled on similar technology could return a sense of touch to people with amputations.

Using two-way communication between brain and machine, the monkeys manoeuvred a cursor with their minds and identified virtual objects by texture, based on electrical feedback from the computer.

of Duke University Medical Center in Durham, North Carolina, and his colleagues implanted electrodes into the brains of two monkeys. The electrodes recorded activity in the motor cortex and somatosensory cortex (SSC) – brain areas that orchestrate voluntary movement and sense of touch. Electrical activity from the motor cortex was sent to a computer, which translated the neural chatter into instructions that moved a cursor on screen. The monkeys learned what patterns of thought reliably changed the cursor’s position.

The team then assigned a unique texture to each of three identical circles on the screen. When the cursor hovered over each circle, the computer zapped the monkeys’ SSCs with the same electrical impulses that occurred when they touched each texture in real life. Finally, the team taught the monkeys to associate a particular texture with a reward.

Random circles

When the circles were randomly moved on the screen, the monkeys were able to identify the circle associated with the reward with around 90 per cent accuracy.

“Amazing stuff – you can take information from the brain, analyse it outside, bring it back to the brain and affect computation,” says psychobiologist of Tel Aviv University in Israel. “That’s the model vision of brain-computer interfaces.”

“It really is novel,” says , who works on neuroprosthetic limbs at the Advanced Platform Technology Center of the US Department of Veterans Affairs. Marasco says he does not know of a prosthetic limb that not only can be controlled by a patient, but also allows them to pick up and respond to sensory information from the limb itself – an ability he calls “user-inclusive sensory feedback”.

Whereas typical brain-machine interfaces return some motor control to people who are paralysed or who have had amputations, brain-machine-brain interfaces could return lost sensory experience to them as well.

Journal reference:

Update 27 March 2015 Italy’s high court has annulled the convictions of Amanda Knox and Raffaele Sollecito in the 2007 murder of Meredith Kercher. Convictions for the pair had been reinstated in 2014. The story below details our previous assessment of the quality of the DNA evidence used in the 2009 trial.

An Italian appeals court has cleared American Amanda Knox and her Italian former boyfriend of the 2007 murder of British student Meredith Kercher, overturning murder convictions made in 2009.

The judge who delivered the verdict from the eight-person jury said the evidence linking the two to the crime was “” – echoing concerns raised previously by forensic scientists in both the US and Italy. Following the verdict, Knox is expected to return to the US.

In November 2007, 21-year-old Meredith Kercher – a British university student on an exchange programme in Perugia, Italy – was found half-naked and dead in the flat she shared with two Italian women and Knox, a college student who was also studying abroad. A year later, Perugia resident Rudy Guede was convicted of sexually assaulting and murdering Kercher. Guede is currently serving a 16-year sentence.

In December 2009, in a separate trial, Knox and her boyfriend at the time, Raffaele Sollecito, were also convicted of murdering Kercher and sentenced to 26 and 25 years in prison, respectively.

The forensic evidence tying Guede to the crime scene was strong: DNA matching Guede’s was on and inside Kercher’s body, as well as on her shirt, bra and handbag. Guede’s bloody handprint was also found on a pillow in Kercher’s room.

Little DNA recovered

But questions about the reliability of DNA evidence implicating Knox and Raffaele were raised even before their 2009 convictions.

One half of the DNA evidence came from a knife found in a kitchen drawer at Sollecito’s apartment: the lab that tested the knife said that DNA on the handle matched that of Knox, whereas DNA on the blade matched that of Kercher. The lab also found Sollecito’s DNA on a clasp that was severed from the bra Kercher was wearing.

In 2009, US forensic experts wrote an open letter voicing concerns about the DNA evidence. They pointed out that a chemical test for blood on the knife came back negative and that the little DNA recovered was only enough for a partial DNA profile.

In June 2011, court-appointed forensic experts Stefano Conti and Carla Vecchiotti from Rome’s Sapienza University reviewed the DNA evidence and similarly concluded that very little DNA was obtained from the knife and that the lab did not follow the proper technical procedures for testing small amounts of DNA, a procedure known as “low copy number DNA analysis”.

Possible contamination

Conti and Vecchiotti further said that they could not rule out the possibility that the knife and bra had been contaminated by other sources of DNA because the items were collected and handled improperly, without following international procedures.

One possibility is that investigators contaminated the bra clasp at the crime scene, as it was until more than a month after Kercher’s death. It is also possible that when the lab performed multiple DNA tests simultaneously, DNA from one sample contaminated another.

The defence had argued that Knox’s DNA would have been transferred to knives in Sollecito’s apartment when she used them for cooking. During the appeals trial, Carlo Torre, a professor of criminal science based in Turin hired by Knox, also testified that the knife wounds on Kercher’s neck were made by a than that from Sollecito’s kitchen.