Occasional reflections on Life, the World, and Mathematics

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Obesity and cancer

The Guardian has prominently posted a report by Cancer Research UK with a frightening headline:

Obesity to eclipse smoking as biggest cause of cancer in UK women by 2043

That’s pretty sensational. I was intrigued, because the mortality effects of obesity have long intrigued me. It seems like I’ve been hearing claims for decades, loudly trumpeted in the press, that obesity is turning into a health crisis, with the mortality crisis just around the corner. It seems plausible, and yet every time I try to dig into one of these reports, to find out what the estimates are based on, I come up empty. Looking at the data naively, it seems that the shift from BMI 20 to BMI 25 — the threshold of official “overweight” designation — has been associated in the past with a reduction in all-cause mortality. Passing through overweight to “obesity” at BMI 30 raises mortality rates only very slightly. Major increases in mortality seem to be associated with BMI over 35 or 40, but even under current projections those levels remain rare in nearly all populations.

There is a chain of reasoning that goes from obesity to morbid symptoms like high blood pressure and diabetes, to mortality, but this is fairly indirect, and ignores the rapid improvement in treatments for these secondary symptoms, as well as the clear historical association between increasing childhood nutrition and improved longevity. Concerned experts often attribute the reduction in mortality at low levels of “overweight” to errors in study design — such as confusing weight loss due to illness with healthy low weight — which has indeed been a problem and negative health consequences attributable to weight-loss diets tend to be ignored. All in all, it has always seemed to be a murky question, leaving me genuinely puzzled by the quantitative certainty with which catastrophe is predicted. Clearly increasing obesity isn’t helping people’s health — the associated morbidity is a real thing, even if it isn’t shortening people’s lives much — but I’m perplexed by the quantitative claims about mortality.

So, I thought, if obesity is causing cancer, as much as tobacco is, that’s a pretty convincing piece of the mortality story. And then I followed up the citations, and the sand ran through my fingers. Here are some problems:

  1. Just to begin with, the convergence of cancers attributable to smoking with cancers attributable to obesity is almost entirely attributable to the reduction in smoking. “By 2043 smoking may have been reduced to the point that it is no longer the leading cause of cancer in women” seems like a less alarming possible headline. Here’s the plot from the CRUK report:
    Screenshot 2018-09-24 11.48.43
  2. The report entirely conflates the categories “overweight” and “obese”. The formula they cite refers to different levels of exposure, so it is likely they have separated them out in their calculations, but it is not made clear.
  3. The relative risk numbers seem to derive primarily from this paper. There we see a lot of other causes of cancer, such as occupation, alcohol consumption, and exposure to UV radiation, all of which are of similar magnitude to weight. Occupational exposure is about as significant for men as obesity, and more amenable to political control, but is ignored in this report. Again, the real story is that the number of cancers attributable to smoking may be expected to decline over the next quarter century, to something more like the number caused by multiple existing moderate causes.
  4.  Breast cancer makes up a huge part of women’s cancer risk, hence a huge part of the additional risk attributed to overweight, hence presumably makes up the main explanation for why women’s additional risk due to overweight is so much higher than men’s. The study seems to estimate the additional breast cancer risk due to smoking at 0. This seems implausible. No papers are cited on breast cancer risk and smoking, possibly because of the focus on British statistics, but here is a very recent study finding a very substantial increase. And here is a meta-analysis.
  5. The two most common cancers attributable to obesity in women — cancer of the breast and uterus — are among the most survivable, with ten-year survival above 75%. (Survival rates here.) The next two on the list would be bowel and bladder cancer, with ten-year survival above 50%. The cancer caused by smoking, on the other hand, is primarily lung cancer, with ten-year survival around 7%, followed by oesophageal (13%), pancreatic (1%), bowel and bladder. Combining all of these different neoplasms into a risk of “cancer”, and then comparing the risk due to obesity with that due to smoking, is deeply misleading.

UPDATE: My letter to the editor appeared in The Guardian.

The dead end of 70s childrearing

People often raise their children with ideals that they don’t really hold themselves, either because they on some level think they would be better people if they shared these ideals and hope their children will be better (tolerance, patience), or because they think these ideals are particularly appropriate to this stage of life (sharing, studiousness, Santa Claus). But I’ve been realising that some of what I learned as I child — at home, at school, and from the general culture

I genuinely found it weird that Barack Obama was attacked for harboring a secret “anti-colonialist” agenda (inherited from his father’s experience fighting the British for Kenyan independence. If I’d had to say what the core historical experience was that Americans harked back to, that defined our national identity, that we could agree upon, it was the history as colonials fighting for independence. The people opposing Obama dressed up in colonial-era costumes, harked back to the Boston Tea Party, striking a blow against the imperial power. (more…)

Those foreign provinces all look the same…

From the Guardian,

Screenshot 2018-03-09 18.33.49

Copy-editing is dead.

The eat-your-marshmallows party

When did the Conservatives become the party of immediate gratification? This follows a development across the Atlantic that I first noticed thirty years ago when Democratic presidential candidate Michael Dukakis was described as the “eat your peas” candidate.

I was shocked to hear from my daughter that her high school class had been given a talk encouraging them to consider leaving school and switching to an apprenticeship programme, because they could immediately be earning £3 an hour, or whatever it was. I thought this was just some weird individual thing, but then I saw an official government advertisement on a bus shelter making exactly this argument. I’m all in favour of apprenticeship programmes, but I think the choice of who should continue on to further education should not be best on the goal of getting paid £3 an hour right now. It is so obviously targeted at getting underprivileged children into menial jobs, to prevent them from rising above their station, that it astonishes me that the government was not too embarrassed to create this campaign.

Similar thinking seems to underly the recent proposal by the education secretary to reduce university fees for courses of study that tend to lead to lower salaries, which has been taken to be suggesting lower fees for arts and social science degrees, while maintaining current fees for science and technology degrees. This is a proposal to incentivise poorer students to prioritise short-term costs over long-term benefits. The most charitable interpretation one can have is that they read chapter 1 of the economics textbook, about prices being set by an equilibrium of supply and demand, and never made it to chapter 2, on the effect of incentives.

It’s purely coincidental that this would tend to brighten the career prospects of dimmer children of affluent familes. It’s almost like the Tories read about Mischel’s marshmallow test, and their response was that it’s unfair that poor children can get ahead just because they might happen to be constitutionally better inclined to delay gratification. I remember John Kerry being mocked in 2004 for having limited his children’s television viewing when they were young, showing them as out of touch with the habits of ordinary Americans, and thinking, self-indulgent habits work out different for aristocrats like the Bushes than for children of middle-class and working-class families. Which is perhaps exactly the point.

Hoisted from the Archives: Institutions of higher perspiration

It seems like a good time to repost this from the time of the ineffectual strike of 2014:

“They don’t want to turn the universities into sweatshops. They’ll be institutions of higher perspiration.”

That was my conclusion about the trajectory to which our managerial overlords aspire, as I was trying to convince a colleague that he should support the UCU, the British academics union, and its escalating strike action. I walked the picket lines for the first time on Thursday, during our two-hour strike. There were about 20 of us there, and only a few were senior academics, which is somewhat disheartening. There were almost as many reporters as strikers, so I got to talk to all of them. Their questions were interesting:
(more…)

Kettle logic on Fox News

Most Republican leaders, in their concern to defend the president from accusations of racist over his terming African nations and Haiti “shithole countries” and saying “get them out”, have resorted to one of two strategies:

  1. Fake news. He didn’t say it, and it’s outrageous to suggest that he did.
  2. Harsh but true. He did say it, and it shows how forthright and unconcerned he is with liberal pieties.

Neither is entirely satisfactory. It is natural, then, that a Fox News correspondent, in the spirit of Freud’s “kettle logic“, combines the two:

I think it’s either fake news or if it’s true, this is how the forgotten men and women in America talk at the bar.

The bar is the new locker room. It’s kind of weird, though, when the best defense for the president’s behaviour is, he’s talking in the formal setting of a negotiation with senators the way even average uneducated Americans would only talk in a private setting when somewhat inebriated.

The anarchist Trump

I just read Chris Hedges’s book The Wages of Rebellion, about the small sprouts of revolt against the omnipotent corporate state that are still popping up. I was struck by this quote from Jeremy Hammond, who was sentenced to 10 years in federal prison for hacking into government computers to steal and release evidence of government crimes:

He said he did not support what he called a “dogmatic nonviolence doctrine” held by many in the Occupy movement, describing it as “needlessly limited and divisive.” He rejected the idea of protesters carrying out acts of civil disobedience that they know will lead to arrest. “The point,” he said, “is to carry out acts of resistance and not get caught.”

In this he has a soul-brother in the White House, famous for having mocked John McCain for his years in Vietnamese captivity:

He’s not a war hero. He was a war hero because he was captured. I like people who weren’t captured.

True friends and False friends

This week’s Spiegel has a headline quote from Emmanuel Macron:

Ich bin nicht arrogant… Ich sage und tue was ich mag.

I don’t know whether everyone does this, but whenever I read a line translated from a language that I know well, I subliminally translate it back. Often you find, particularly in news reports, that lazy translators have used false — or at least dubious -cognates. For example, I vaguely remember a quote from an English source referring to a leader being irritated by protests getting translated into irritiert, which actually means confused.

In this case, my own subliminal process stumbled over the cognate tue, meaning “I do” in German — so Macron said “I say and do what I want”, but “I kill” in French. Which immediately mapped onto another language giving me a momentary flash of Oscar Wilde’s famous line from The Ballad of Reading Gaol:

Yet each man kills the things he loves

It would have been pretty interesting if Macron had actually quoted Wilde to say “Je tue ce que j’aime”.

As for the other part, it’s probably a pretty good bet that if you find yourself insisting “I’m not arrogant”, you’re probably pretty arrogant. Speaking of which, I recently came across these videos of Donald Trump actually (and apparently unironically) acting out the classic punchline of the guy who boasts about his exceptional humility:

In the second one he manages to innovate beyond the obvious comedy of boasting about humility, by going one step farther and ridiculing the interviewer for being too stupid to be able to appreciate his humility.

A boot stamping on the face of Mars — forever

I’m reasonably positive about space exploration, and see it generally as humane and progressive, rather than as an extension of colonialist male impulses to rape virgin nature. But along comes US Vice President Mike Pence, expressing support for human space exploration in these terms:

Our nation will return to the moon and we will put American boots on the face of Mars.

I understand that books are for liberal weenies, but surely everyone hearing this must immediately think of one of the most famous lines in 20th century literature, from Nineteen Eighty-Four:

If you want a picture of the future, imagine a boot stamping on a human face — forever.

The secret of my success

A persistent obstacle to social reform is the common tendency to ignore the merely fortuitous in ones good fortune, and to attribute success to some self-flattering decision or essential virtue. I dropped out of school, taught myself computer programming, and became a wealthy entrepreneur. Or I became a world-famous surgeon despite growing as an impoverished black orphan. So don’t complain about being held back by poor schools and racial discrimination. It’s just hard work and faith that you need to get ahead.

This fallacy was already recognised, I have just noticed, by the Amoraim, the authors of the Babylonian Talmud. The tractate Yoma mentions Kimhith, a woman whose seven sons served, at some point*, as high priests:

The Sages said unto her: What hast thou done to merit such [glory]? She said: Throughout the days of my life the beams of my house have not seen the plaits of my hair. They said to her: There were many who did likewise and yet did not succeed.

In other words, she attributes her sons’ success to her exceptional modesty in always keeping her hair covered. The rabbis answer, many women have covered their hair without having such success.

* The story is pretty weird. If I understand correctly, two of the sons were called in to do the High Priest duties because on two different occasions their elder brother Ishmael ben Kimhith was defiled by having spat on himself during a heated discussion.

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