Saturday, November 19, 2011

Weekend Post - What do modern medicine, flu, ice cream and pirates have in common?

Here are some dangerous but factual observations.

Since the introduction of modern healthcare in Botswana more people than ever before have died of cancer. People suffer from more infectious diseases in colder seasons. The more ice cream that is consumed, the higher the number of drownings that occur. The reduction in the number of pirates (yes, I said pirates) in the world has coincided with gradually increasing global temperatures.

All of these are facts, there is overwhelming evidence to support them. But the big question is what they actually mean. Is it true that modern healthcare causes cancer? Does cold weather cause colds and flu? Does ice cream cause people to drown? Has the loss of pirates actually caused global warming? Should any of us actually do anything, should we take any lifestyle decisions based on these undeniable facts?

Of course not, but that’s where the danger lies. You only have to hear of these facts for a chill to go through you. It’s only one step further before you begin to suspect the benefits of modern medicine and science.

The real facts are simple. More people are dying of cancer since the introduction of modern, scientifically based medicine because we’re living longer. Cancer is largely a disease of older people. As we’ve done away with so many of the causes of death from the past that killed younger people like infectious disease and starvation other causes of death have stepped in to fill the void. Like cancer.

People suffer more colds and flu in the winter, not because our immune systems are weaker in the cold months or because viruses are stronger but simply because when we’re cold we stay inside much more. When we’re stuck inside our homes with our families we’re much more likely to spread infections by close-proximity coughs and sneezes.

The really good news is that ice cream doesn’t make you more likely to drown. However, both rates of drowning and consumption of ice cream are both associated with hot weather. Both are caused by something else.

One of the easiest mistakes to make when looking at the world is to assume that correlation implies causation. Because two observations are somehow related then one must have caused the other. It’s a fundamental mistake and one of many logical fallacies that people often make.

A recent example. A couple of weeks ago the BBC reported that scientists had announced in the British Medical Journal “a link” between use of the oral contraceptive pill and prostate cancer. The interesting thing is that only women take the pill and only men get prostate cancer so how can one possibly cause the other? The suggestion is that the hormone oestrogen in the contraceptive pill may be released in the urine of pill-taking women into the water supply. Men then drink the water and experience one of the side-effects of oestrogen: higher rates of cancer. The team of researchers from Canada had carefully examined various countries that used of different forms of contraception and found higher levels of prostate cancer in those countries where the pill was widely used. In countries where other forms of contraception were widespread the higher levels of cancer couldn’t be found.

However they were very careful to say that their study “has significant limitations with respect to causal inference”. In other words they are most certainly NOT saying that the pill increases the risk of prostate cancer. This was just what they call “an ecological study”. They observed a correlation between two things and said that “it must be considered hypothesis generating, and thought provoking”. This wasn’t an experiment, it was just some careful observations that make scientists want to ponder a bit and then design more detailed studies.

One problem is that it’s very difficult to design an experiment to test this. If we suspect there’s a link between oestrogen and prostate cancer we can’t just expose a group of men to oestrogen and see if they develop cancer, that would be inhumane. However it would be worth conducting animal tests and further ecological studies. For instance, does the rate of prostate cancer go down in countries where the use of the pill declines or where lower oestrogen pills are used?

Finally, in case you were worried, nobody really believes there’s a relationship between the number of pirates and global warming. However if you’re willing to suspend your skeptical faculties you can join the Church of the Flying Spaghetti Monster for whom this is a core belief. Perhaps not entirely seriously!


For various sources on "Correlation Does Not Imply Causation" see the Skeptics Dictionary chapter here (180kb pdf download) or the Wikipedia page here. There's also a comprehensive list of the many logical fallacies courtesy of the Skeptic's Guide to the Universe here.

The story from the BBC about the pill and prostate cancer can be seen here and the original article in the British Medical Journal here.

For the Church of the Flying Spaghetti Monster just say "Arrrgh".

Monday, November 14, 2011

Weekend Post - We're still alive!

The world narrowly avoided destruction yet again last week.

Asteroid 2005 YU55 sped past the earth at nearly 50,000 km/h coming so close that it was within the orbit of the Moon. Although this wasn’t the biggest of objects flying through space it was big enough. Astronomers estimate it was about 400m wide, roughly spherical and something that size hitting the Earth would have caused devastation. I’m no expert but a little maths suggests that it might easily have a mass of many millions of tonnes and people have estimated that impact may have exceeded the effect of any atomic bomb ever constructed.

You might think that given that 70% of the Earth’s surface is covered in water it probably would have landed there and just made a bit of a splash but that might have actually been as bad or worse than hitting land. The tsunami that followed would have been devastating.

However this was never going to happen anyway. NASA and other agencies had been tracking it for long enough to know that it would sail right passed the Earth and would hardly been noticed. If the boffins at the various space agencies hadn’t spotted it we never would have known it was there.

Of course that didn’t stop the usual suspects claiming that this was the end of the world, many of them probably the same people who predicted the end of the world on October 21st. A variety of conspiracy theorists with too much time on their hands also started spreading rumours that there was a government cover-up of the impending doom. They’ve all been proved wrong by events as well as the science.

However we have to face the fact that sooner or later an asteroid like this IS going to hit us. It’s certainly happened before. Although it’s widely thought that an asteroid impact 65 million years ago killed off the dinosaurs there’s no conclusive proof that this was the case, it’s just one of various theories. However it’s a persuasive one. Such an impact would certainly have had a devastating effect on the planet, throwing up a global dust cloud that would have prevented sunlight getting through to the plants that feed the entire food chain. Geologists have found a layer in sedimentary rock all over the world that they call the K-T boundary. This layer contains massive amounts of iridium, and element found often in asteroids. Below the K-T boundary fossils of dinosaurs are found, above the layer they’re mostly absent which suggests whatever caused the increase in iridium in the atmosphere might be connected with dinosaur extinction. Another theory observes that iridium can also be found in the Earth’s core and a massive upsurge in volcanic activity might have been the cause. At the very least the impact of that and other asteroids certainly had a dramatic effect on the Earth and it’s not something anyone wants to happen again. But it will.

Incidentally, our recent fly-by visitor, Asteroid 2005 YU55, probably wasn’t actually big enough to cause an extinction event. We’d need to have a cosmic punch-up with something a lot bigger for that to happen.

The good news is that scientists at NASA reckon they’ve now detected almost all of the asteroids that pose a threat to the Earth and there is no evidence that any of them are coming close enough for us to worry. However, they’ve adopted the “hope for the best, plan for the worst” approach. A variety of techniques have been discussed for nudging any potentially threatening asteroid off course so that it gives the Earth a miss. They’ve considered atomic weapons, ion beams and even just throwing large rocks at it. Anything just to give it enough of a nudge to bypass us.

While the threat is real and the possible effect is devastating, the chance of it actually happening in our lifetime, or that of anyone we can imagine, is so vanishingly small that it’s not worth losing any sleep. Better still to spent our time and resources fighting the things that DO threaten us, like global warming, population growth or our species’ innate ability to kill itself with the slightest provocation. Those are things worth worrying about and worth paying scientists to find solutions for.


Start with a BBC story on the asteroid passing by. Also the Washington Post covered it here.

As always with astronomical news stories you should always consult Phil Plait, the Bad Astronomer. His comments on Asteroid 2005 YU55 are here. He also has a good animation from NASA JPL that shows the passage of the asteroid.

For some of the doom and conspiracy lunacy surrounding the asteroid see here and here.

The Washington Post discusses the efforts to detect all potentially risky asteroids here. For ideas on how to deflect asteroids heading our way the Wikipedia page summarises them well.

Wikipedia also has pages on asteroid impact events and the K-T boundary including some fantastic pictures of the boundary itself.

Sunday, November 06, 2011

Weekend Post - Was Einstein right all along?

In September there was a big fuss, reported all over the world, about an experiment conducted in Italy that suggested that Albert Einstein, his Special Theory of Relativity and his notion that nothing can travel faster than light might be wrong.

Almost every newspaper in the world asked “Was Einstein wrong?” The Italian scientists claimed that they had managed to force a beam of neutrinos to travel faster than the speed of light. Admittedly only very slightly faster than light, but even a little bit would have been enough. Their beam of neutrinos had travelled all the way from the CERN laboratory in Geneva, a trip of 730km, across the border into Italy and they arrived 60 billionths of a second earlier than light would have covered the same distance. Clearly something is wrong. Either one of the cornerstones of our understanding of the universe is wrong or there’s been a mistake by the scientists. My money was on the latter.

Obviously the results are interesting. Was Einstein right or wrong? It’s a big question. But I think it’s just as interesting for the public to see how science works. The researchers in Italy went public with their results and said to the entire world (in an Italian accent) “Hey, look at this, can this be right or have we made a mistake?”

The physics community around the world went into overdrive. They thought about repeating the experiment, tried to think of new rules of physics and, most critically, tried to help the Italians discover any mistakes.

It didn’t take long for things to happen. As we speak they’re trying to repeat the experiment in a slightly different way to rule out any systematic errors in their measurements. Just as importantly experts at the University of Groningen in the Netherlands might have come up with an explanation.

This is where it gets complicated. Einstein’s Special Theory of Relativity is simultaneously simple and complex. At it’s simplest he just suggested two things: firstly that it doesn’t matter where you are or what you’re doing, the law of physics remain the same. That’s the easy one. The second is more complicated. It says that wherever you are and whatever you’re doing, the speed of light is always the same. That isn’t as simple as it sounds. Imagine you are the passenger in a car travelling at 50km/h and you lean out of the window and throw a ball ahead of the car at 10 km/h. The speed of the ball will be 60km/h.

But instead imagine now that you lean out of the car window and shine a beam of light from a torch ahead of you. Light travels at roughly a billion km/h. So the light will now be going at a billion plus 50 km/h? No. It still travels at a billion km/h. The speed of light in a specific medium doesn’t change. Not ever. If you travel in a spaceship at half the speed of light and shine that torch forwards the light will still just travel at a billion km/h.

The effect of this is profound. I don’t have the skill or space to explain the steps (I’ll put links on the web site) but it follows from this that as you go faster and faster some pretty strange things happen. The faster you go the greater your mass and the more energy is needed to accelerate further so that actually to get to light speed you would need infinite energy. Most importantly, the closer you get to the speed of light, the slower time itself progresses as seen by an outside observer.

That last element is the critical one for the Italian experimenters. The critics at Groningen noticed that the Italians had used GPS satellites to measure the time the neutrinos were travelling. But GPS satellites are themselves moving, nowhere near light speed but fast enough that their ability to measure time as accurately as the Italians needed was affected. The Groningen scientists did the maths and worked out that this would affect the calculations by, yes, you’ve guessed it, 60 billionths of a second.

The new experiments aren't done yet but we now have a very plausible possible explanation for the effect the Italians saw. Will they be proved right? Only time will tell.


The original news story can be seen here courtesy of the BBC. The original notice in Nature is here.

For an overview of Special Relativity see How Stuff Works or the Wikipedia page here.

For news on the repeat of the experiment see the BBC story here. For a summary of the Groningen suggestions about GPS satellites and their time dilation see here.

Saturday, November 05, 2011

Weekend Post - We’re all dying

More people are dying these days than ever before. And that’s a good thing.

There was a news story from the BBC last week entitled “Cancer cases projected to rise 45% in next two decades”. The research by Cancer Research UK projected 23 different types of cancer and concluded that the “numbers of cancers in men and women are projected to increase by 55% and 35%, respectively”. The impact on the health sector in the UK is going to be profound. The UK has rapidly increasing health care costs, just like we do, and the costs of care for cancer are amongst the highest. Such a dramatic increase in the number of cancer cases is going to have an enormous impact on everyone. While the story was specific to the United Kingdom, I don’t think there’s any reason to suspect we’re very different.

I’m prepared to stick my head above the parapet and make a dangerous prediction. More people reading this will die of cancer than did in their parent’s generation. In fact I’ll go further. I predict that a larger number of people will die in the next century than died in the last one. Many more.

The first reason for this prediction of doom is simple. More people will die because more people will be alive. Whether we like it or not, everyone who is alive will, one day, be dead and a greater number of living people means that eventually there will be a greater number of deaths. That’s just a sign of progress.

The fact that there are more living people is a direct result of many influences including better health care, lower infant mortality and better education. Despite what certain “alternative” health product manufacturers with a vested interest in selling their bogus products will tell you, our diet these days is much better than it was in our grandparent’s time. Our food is more hygienically produced, more nutritious and even tastes better than it did in the past. Our health care systems, while still imperfect, are an immense improvement over what existed in the past. While “traditional” knowledge systems had something to offer us, the truth is that they are nothing compared with what a pharmacy can give you today. Better transportation means that doctors and nurses are more available to us than ever before, even in a country as large as ours and with a population as small and as widely distributed.

In Botswana even with the extra burden of HIV/AIDS our life expectancy is improving. Our nation’s life expectancy at birth, even including our brothers and sisters with HIV, is now double what it was a few years ago thanks to anti-retroviral drugs and PMTCT. Our population now apparently exceeds 2 million, up by almost a quarter in a decade.

So because of all these dramatic improvement more people are alive and as a result more will die.

The second reason for growing levels of cancer is due to that longer lifespan. As a result of living longer and of all this progress we’re now dying of different diseases and conditions that afflicted us in the past. We’ve completely eradicated diseases like smallpox and can prevent many other diseases like polio and influenza and consequently most of us are living through our youth and middle age into our elderly years when we’re susceptible to an entirely different set of diseases. Most of us are now dying of diseases of the elderly, not of the young.

Cancer is a good example. The vast majority of cancer victims develop cancer in their 50s or later. If people don’t survive until their 50s they’re not going to get cancer at all. All you have to do is increase life expectancy from 50 to 60 and you’ll see a massive increase in cancer rates. It’s the downside of living longer but you have to ask yourself something. Knowing that you’re certainly going to die one day, would you rather do it tomorrow or in 10 years? Or in 20 or 30 years time? The effect of scientific and medical progress is that you and I will hopefully live long enough to die of something our great grandparents had never even heard of. What better example can there be of progress?


The original BBC story can be seen here and the Cancer Research UK paper in the British Journal of Cancer it's based on is here. Cancer Research UK also provide historical data on levels of cancer over time and by age here.

Loads of fascinating data on life expectancy in Botswana can be seen here.