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The underweight brain

Okay, I give up. Dealing with the media’s breathless messes when reporting on science feels like an endless game of whack-a-mole, and I’d decided life is too short for that. But this one is so hysterical, it’s pulled me back in.

Obesity linked to stupidity, brain scans show shouts one headline. Obese People Have ‘Severe Brain Degeneration’ moans Yahoo News. Obesity Leads to Brain Degeneration says a copycat. I’m sure you’ve seen these things too.

Well, let’s plow through a small dose of the actual science because the neat thing about the truth is that it’ll set you free.

As one of my favorite bloggers, the AngryBlackBitch says, shall we?

Raji, Ho et al. Brain structure and obesity. Human Brain Mapping, 2009:


… [I]t is unknown whether these factors, specifically obesity and Type II diabetes, are associated with specific patterns of brain atrophy. We used tensor-based morphometry (TBM) to examine gray matter (GM) and white matter (WM) volume differences in 94 elderly subjects who remained cognitively normal for at least 5 years after their scan.

On a personal note, this made me feel all warm and fuzzy. I did some tensor-based morphometry as part of my Ph. D. work, so it was like meeting an old friend. It’s not a common technique, and it is a very sensitive way of measuring changes in shape.

Note, in particular, the phrase: who remained cognitively normal. This study had nothing — nothing — to do with intelligence or stupidity. They were not looking at that.

They were looking at changes in the volume of specific regions of the brain.

Changes in volume also do not relate to intelligence or stupidity. If size was that important, elephants would be rocket scientists. Size tells you about nothing except, well, size. It tells you how many cells occupy that volume, not how well-connected they are or what they’re connected about. Some birds, for instance, have large brains proportional to their weight. (For birds, that is.) That’s not because they’re thinking deep thoughts. It’s because flight requires enormously complex and rapid processing of balance and visual signals.

The abstract continues:

Bivariate analyses with corrections for multiple comparisons strongly linked body mass index (BMI), fasting plasma insulin (FPI) levels, and Type II Diabetes Mellitus (DM2) with atrophy in frontal, temporal, and subcortical brain regions. A multiple regression model, also correcting for multiple comparisons, revealed that BMI was still negatively correlated with brain atrophy (FDR <5%), while DM2 and FPI were no longer associated with any volume differences.

So, statistically, BMI had a strong correlation with certain changes in brain morphology. In two-way comparisons (bivariate analysis) other factors had some correlation, but in the multivariate case, which reflects our multifaceted reality more closely, BMI was the significant correlate.

(I know that in fat-positive writing, BMI is said to be bunk. Statistically, it is not bunk because it allows you to look at weight distribution in a population while taking height into account. This is a lot less bogus than trying to do a study that looks only at weight and ignores height, which is the other alternative given the data usually available. The main confounding factor in some populations is that highly muscular people have high BMIs, but that’s not a big issue in a study of elderly people.)

In an Analysis of Covariance (ANCOVA) model controlling for age, gender, and race, obese subjects with a high BMI (BMI > 30) showed atrophy in the frontal lobes, anterior cingulate gyrus, hippocampus, and thalamus compared with individuals with a normal BMI (18.5-25). Overweight subjects (BMI: 25-30) had atrophy in the basal ganglia and corona radiata of the WM. Overall brain volume did not differ between overweight and obese persons.

This is fascinating. Different regions were affected based on weight class. The first set are all gray matter, the second set are two regions of white matter that, between them, have a big role in connecting the first set. The fact that overall brain volume didn’t differ between the two groups means . . . what? That medium weight affects certain white matter, which then, as weight increases, affects the specific gray matter but the white matter recovers? That different physiological consequences operate at different weight levels, and affect the brain in unrelated ways?

Higher BMI was associated with lower brain volumes in overweight and obese elderly subjects. Obesity is therefore associated with detectable brain volume deficits in cognitively normal elderly subjects.

So, what does it all mean? It says nothing about intelligence. I hope I’ve made that clear. Nor does it say anything about “degeneration.” Think about the analogous case of muscles, with which we’re more familiar. A person with less muscle mass doesn’t have muscle degeneration. They just have fewer muscle cells. Depending on how they use those cells, they may be making lace.

What it does mean is that there are fewer cells “in the bank,” so to speak. The brain is a very adaptable organ, even in old age it turns out. After damage, such as from a small stroke, it’s capable of routing around the problem and eventually learning to use other cells to do the same task. But to do that, those other cells have to be available. The fewer there are, the higher the likelihood the brain can’t recover from increasingly minor damage.

The younger the person, the less this matters, because the natural loss of cells with age hasn’t yet had much of an effect. The older the person, the more it means greater susceptibility to anything that does cause problems for the brain. It still does not mean there necessarily will be problems. It just increases susceptibility because there’s less in reserve.

That’s not great news for fat people, but neither does it have anything to do with instant cretinism. However, that boring reality doesn’t sell any ad space.

brain, obesity, Thompson

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Biology, Caster Semenya, Athletics, and Ignorance

With the continuing flap over Caster Semenya, it may be interesting to get some background on the biology involved. A recent article I saw mentions testosterone levels, and that made me think that perhaps (yet another) post on the biology might be useful. So this isn’t about social gender, athletics, Caster Semenya herself, or anything but biology. Modal concepts of gender see it as a binary, either-or matter, but in reality it’s way fuzzier than that.

The good old X and Y chromosomes themselves don’t always come in pairs, to start with. You can have XXX, XXY, XXXXY, XYY, and the like. This is possible for two reasons. One is that even in a typical XX situation, one of the X chromosomes is silenced early in development. With more than one X, the extras are also silenced, so it doesn’t wreak the havoc of having, say, an extra chromosome 13 or 21. The second X is needed early on to develop functional ovaries, which is why XO (Turner’s Syndrome) people are infertile. The Y chromosome has very little information on it, and an extra copy or so therefore doesn’t do much damage.

So the X has its “ovary determining factor,” and there’s a sex-determining region on the Y (SRY). This is where things get even more interesting. All our chromosomes come in pairs, and despite their vast difference in size, the X and the Y are a pair. That means they can exchange bits of material in crossovers. It’s a bit like an elephant dancing with a hamster, but they manage. So you have a couple of unexpected possibilities, both of which would look quite ordinary on a regular count, i.e. 46 chromosomes, of which two are sex chromosomes.

1) XY, but the Y is missing the SRY. In this case, the person is anatomically female, but sterile. Since there’s a lack of testis determining factor (TDF), there’s also female levels of testosterone. That has particular relevance in the case of an athlete.

2) XX, but the SRY has translocated onto one of the Xs. In this case the person is anatomically male, and probably infertile unless the Y regions that code for sperm production also translocated. Testosterone is produced at male levels.

3) There are also genetic factors that alter the sensitivity of cells to circulating testosterone. Ordinary amounts of the hormone might be produced, but the rest of the body’s cells can over- or under-react (e.g. androgen-insensitivity syndrome, AIS).

The real point here is that the only valid concern is testosterone. That will give you an advantage in sports like sprinting, and that’s why doping yourself up with it is considered cheating. (When they talk about “steroids” in sports, they don’t mean any old steroids. Corticosteroids, for instance, wouldn’t do any good.) That’s also why there’s a concern about the femaleness of athletes, but not the maleness, in those sports where testosterone helps. (Just for the record, it’s not a huge advantage in all sports. Look at the early history of English Channel swimmers, for instance. Even against a tide of social disbelief, a number of early record holders were female.)

What the committee is really worrying about is that Semenya might have a testosterone advantage and be unfairly matched against other women who produce less and/or react less to it. They don’t need to know whether she’s a “girl.” They need to be measuring long term circulating testosterone and androgen sensitivity. To do it right, that could take years.

But there are implications far beyond that. The point that an athlete like Semenya brings home is that there are variations in testosterone among people. This has always been true. So, if the Committee really wants to be fair, they should be doing long term testosterone tests for everyone, male and female. Then, to continue being fair, they have to accommodate our non-binary reality properly and have different testosterone-based classes, like boxers do for weight. We could have quintiles 1 through 5, for instance, from the barely-measurable class up to the watch-for-eventual-heart-problems class.

That would involve acknowledging differences. Real differences as opposed to “vive la difference” differences. What do you think? Conceptually feasible? I mean, I realize I’m suggesting that a committee consider more than two categories at the same time.

athletics, gender verification, Semenya

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We all have one-track minds

As a person who can only do one thing at a time (if that), all I have to say is: HA!

BBC | Multitaskers bad at multitasking

The people who engage in media “multitasking” are those least able to do so well, according to researchers.

A survey defined two groups: those who routinely consumed [Ed. note: “consumed”?] multiple media such as internet, television and mobile phones, and those who did not.

In a series of three classic psychology tests for attention and memory, the “low multitaskers” consistently outdid their highly multitasking counterparts.

The results are reported in Proceedings of the National Academy of Sciences. …

“If you look at classical psychology textbooks, people cannot multitask – but if you walk around on the street, you see lots of people multitasking,” [Cliff Nass] told BBC News.

“So we asked ourselves the question, ‘what is it that these multitaskers are good at that enables them to do this?'” …

[In tests of the ability to ignore irrelevant information, organize working memory, and ability to switch tasks,] “the shocking discovery of this research is that [high multitaskers] are lousy at everything that’s necessary for multitasking,” Professor Nass said.

“The irony here is that when you ask the low multitaskers, they all think they’re much worse at multitasking and the high multitaskers think they’re gifted at it.”

The pressing question that remains, Professor Nass said, is one of cause and effect: are those people with a dearth of multitasking skills drawn to multitasking lifestyles, or do the lifestyles dull the skills?

Academics always make everything so difficult. The answer is obvious: it’s the well-known, pathetically consistent, Dunning-Kruger Effect.

multitasking, Dunning-Kruger, Nass, psychology

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This is how the world ends

Not with a financial collapse. Not with death by insurance company. Those are all just human disasters. We hear them loud and clear, but they drown out the faint thrumming which is the hoofbeats of all four horsemen of the Apocalypse. They’re coming up way too fast for us. This is the worst news out there:

BBC | Methane seeps from Arctic sea bed

Scientists … have evidence that the powerful greenhouse gas methane is escaping from the Arctic sea bed. …

As temperatures rise, the sea bed grows warmer and frozen water crystals in the sediment break down, allowing methane trapped inside them to escape.

The research team found that more than 250 plumes of methane bubbles are rising from the sea bed off Norway. …

Writing in Geophysical Research Letters, the team says the methane was rising from an area of sea bed off West Spitsbergen, from depths between 150 and 400m.

The gas is normally trapped as “methane hydrate” in sediment under the ocean floor.

“Methane hydrate” is an ice-like substance composed of water and methane which is stable under conditions of high pressure and low temperature.

As temperatures rise, the hydrate breaks down. So this new evidence shows that methane is stable at water depths greater than 400m off Spitsbergen.

However data collected over 30 years shows it was then stable at water depths as shallow as 360m.

Ocean has warmed

Temperature records show that this area of the ocean has warmed by 1C during the same period. …

Their most significant finding is that climate change means the gas is being released from more and deeper areas of the Arctic ocean. …

The team found that most of the methane is being dissolved into the seawater and did not detect evidence of the gas breaking the surface of the ocean and getting into the atmosphere.

They stress that this does not mean that the gas does not enter the atmosphere. They point out that the methane seeps are unpredictable and erratic in quantity, size and duration. …

Most of the methane reacts with the oxygen in the water to form carbon dioxide, another greenhouse gas. In sea water, this forms carbonic acid which adds to ocean acidification, with consequent problems for biodiversity.

Graham Westbrook, lead author and professor of geophysics at the University of Birmingham said: “If this process becomes widespread along Arctic continental margins, tens of megatonnes of methane a year – equivalent to 5-10% of the total amount released globally by natural sources, could be released into the ocean.”

Can you say “feedback loop”? Or, to be more precise, “vicious circle”? This is what everyone who understands the situation has been dreading.

At some point — you never know when until it happens — it won’t just be us belching out greenhouse gases. So far, if we’d only stopped belching, that would have been the end of it. The greenhouse gases would have gradually been recycled out of the atmosphere and the climate could have returned to normal.

But the next phase is that the whole planet starts emitting extra CO2 and extra methane because it’s warmer. That makes it even warmer. That makes the planet emit even more greenhouse gases.

At that point we can stop our own idiocy cold … and it won’t make much difference. When the permafrost in the Arctic tundras melts, it releases greenhouse gases. When the ocean warms, it releases greenhouse gases. Molecule per molecule, methane is about eight times stronger as a greenhouse gas than carbon dioxide. The best we can hope at that point is most of it will turn into CO2 in the ocean, and acidify that instead.

The grim news is that we’ve reached that point. The permafrost is melting (pdf). The shallower methane hydrates are bubbling up. Ocean circulation rates are changing. (There is variation.)

I’m beginning to think the saddest words a human being can say are, “I do not envy the young.”

global warming, methane, methane hydrates

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It’s About Who Decides (One More Time)

Being forced to die against my will would be terrifying. And I, personally, wouldn’t care whether the death panels making that decision were staffed by private bean counters from an insurance company — our current situation — or government bean counters from the Liberal Nazi Socialist Death Squad Agency — as imagined by the more crass or hallucinatory right wingers.

Being forced to live against my will is terrifying. Strapped into a chair so I can sit in front of a TV set. Or with a tube down my throat while my brain screams somewhere. Or . . . anyway, I can’t even stand to think about it. And I, personally, don’t care whether the people condemning me are on a private hospital “ethics” panel or represent the power of the State.

I’m not sure why any of this is hard for anyone to grasp. It’s not about death. It’s about who decides.

My right to control my life and death: essential. Somebody else controlling my life and death: hell on earth.

Unfortunately, I can only say that in bald and boring words. Terry Pratchett recently weighed in on this. Nothing further remains to be said.

Let me make this very clear: I do not believe there is any such thing as a ‘duty to die’; we should treasure great age as the tangible presence of the past, and honour it as such. …

But neither do I believe in a duty to suffer the worst ravages of terminal illness. …

Life is easy and cheap to make. But the things we add to it, such as pride, self-respect and human dignity, are worthy of preservation, too, and these can be lost in a fetish for life at any cost.

I believe that if the burden gets too great, those who wish to should be allowed to be shown the door. …

[M]y father’s problem was pain, and pain can be controlled right until the end.

But I do not know how you control a sense of loss and the slow slipping of the mind away from the living body – the kind that old-timer’s disease causes.

I know my father was the sort of man who didn’t make a fuss, and perhaps I would not, either, if pain were the only issue for me. But it isn’t.

I am enjoying my life to the full, and hope to continue for quite some time. But I also intend, before the endgame looms, to die sitting in a chair in my own garden with a glass of brandy in my hand and Thomas Tallis on the iPod – the latter because Thomas’s music could lift even an atheist a little bit closer to Heaven – and perhaps a second brandy if there is time.

Oh, and since this is England I had better add: ‘If wet, in the library.’

euthanasia, death panels, right-to-die, Terry Pratchett

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Celebrating geezerdom

I saw what follows on the BBC, written by a young teenager and good sport named Scott Campbell. I laughed practically non-stop through the whole thing, coming at it from the geezer side myself. I have to share snippets with you.

BBC | Giving up my iPod for a Walkman

My dad had told me it was the iPod of its day.

He had told me it was big, but I hadn’t realised he meant THAT big. It was the size of a small book. …

From a practical point of view, the Walkman is rather cumbersome, and it is certainly not pocket-sized, unless you have large pockets. It comes with a handy belt clip screwed on to the back, yet the weight of the unit is enough to haul down a low-slung pair of combats.

And you probably thought we didn’t wear those diaper pants because we weren’t cool, huh?

… It took me three days to figure out that there was another side to the tape. That was not the only naive mistake that I made; I mistook the metal/normal switch on the Walkman for a genre-specific equaliser ….

I love it.

You can almost imagine the excitement about the Walkman coming out 30 years ago, as it was the newest piece of technology at the time.

Perhaps that kind of anticipation and excitement has been somewhat lost in the flood of new products which now hit our shelves on a regular basis.

Personally, I’m relieved I live in the digital age, with bigger choice, more functions and smaller devices. I’m relieved that the majority of technological advancement happened before I was born . . .

Bwahahaha.  Sort of reminds me of whoever it was before Niels Bohr and Einstein burst upon the scene, saying there was nothing new to be discovered in physics.  The boy’s in good company.

. . . as I can’t imagine having to use such basic equipment every day. …

Did my dad, Alan, really ever think this was a credible piece of technology?

Walkman, Mp3, tech, music

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I told you so: negawatts work

Not only have I told you so, repeatedly, but so did everybody else who’s capable of coming up with four when adding two plus two, going right back to Amory Lovins and the DFHs.

US’ best source of carbon-free energy is efficiency. Not just the US of course. The laws of physics are the same all over the planet.

The McKinsey report [pdf] arrived at [its] figures by performing a fairly simple economic analysis: what measures, if rolled out on a large scale starting in the near future, would have a positive return on investment by 2020. Those are fairly conservative conditions, since many efficiency projects require a substantial up-front investment that’s only paid back gradually; time horizons longer than a decade aren’t uncommon when it comes to payback. Nevertheless, the numbers were staggering. $520 billion worth of investments would produce a total of $1.2 trillion in savings by 2020. Presumably, the numbers would look even better later into the century.

At 2020, we’d be avoiding using that 9.1 quadrillion BTUs. That would be enough to knock 23 percent off the expected demand, dropping it below the current national usage. It’s worth pointing out that there’s a bit of a multiplier effect of efficiency efforts, as well—by not producing the energy in the first place, all the losses that occur during generation and transport never come into play. The net result would be over a gigaton of greenhouse gas emissions avoided as well.

As far as the National Academies is concerned, the McKinsey report might just as well have been a chapter in its own publication. “The deployment of existing energy-efficiency technologies,” it has concluded, “is the nearest-term and lowest-cost option for moderating our nation’s demand for energy, especially over the next decade.” [emphasis added]

So could we now get with the program and stop chasing more pollution with less power? Crap like “clean coal” and nukes. And, environmentally less appalling but socially more so: food-sourced biofuels. Here’s yet one more repeat of what’s wrong with them.

“Clean” coal produces all the same destruction and pollution — and energy costs! — during mining as dirty coal. And another not-so-minor data point: the industrial-scale process to do it has not been invented yet (pdf, eg p. 31).

Nuclear energy: Produces pollution, environmental destruction, and uses energy during mining. Uranium is a finite resource. A finite resource. It will . . . wait for it . . . run out. (Am I frustrated that some people don’t get this yet? Yes, I’m frustrated.) It will run out in about a century if used to produce most of our energy. It takes time to build plants. One plant would have to be built every six weeks, starting yesterday, going on until the uranium runs out, to produce most of our energy. Nuclear energy creates radioactive waste. We have no viable method of dealing with current waste, forget the amount of waste that would be generated by a bigger nuclear program. Decommissioning costs are huge and underfunded. Companies are mothballing old plants to delay the day of reckoning when people are presented with the price tag. All that money spent on nuclear energy to get a fraction of the power needed cannot be spent on real solutions.

Biofuel produced from corn and other food sources: Destruction of habitat to grow monocultures of energy crops (a problem with any biofuel not generated from waste). Increased food prices in a world where around one billion people are living on around one dollar a day. That leads to even worse mass starvation than we already have. That leads to even more mass migration, social dislocation, riots, and wars. Just in case I’m not being clear, this is Not Good.

Now that we have yet more studies all saying the same thing, how about we all get on the same page and DO THE OBVIOUS!

energy, efficiency, NAS, McKinsey

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