On the Unreliability of Human Bodies

A recent article in the September issue of IEEE Spectrum is titled Why We Fall Apart. It analyses human aging using reliability theory, simplifying the same authors' 2001 paper in J. theor. Biol. The Reliability Theory of Aging and Longevity.

Reliability theory is pretty mundane stuff¹, although for complex systems the calculations are complicated (hence the software tools). It's used by engineers to make predictive models of failure. Among other uses, this is how designers calculate the MTBF figures you see quoted in disk drive specifications.

The essential point of the article is this: you can model the human body as being comprised of a combination of irreplaceable, redundant, non-aging parts, some of which are defective to begin with. Doing so predicts the salient characteristics of human mortality:

1. The infant mortality period, which, not ironically, is a term from both reliability theory and population dynamics.
2. The normal working period.
3. The aging period with exponentially increasing failure probability described by Gompertz 200 years ago. That is, after age 25 or-so, the probability that you'll survive another year declines very rapidly.²
4. The post-aging or late-life mortality period with linear failure probability. That is, after age 95 or-so, your probability of surviving for another year is bad, but pretty much the same as it was the year before.

The post-aging characteristic of mortality statistics is related to convergence, the fact that an 80 year-old Indian has a similar life-expectancy to an 80 year-old Dane, although the life expectancies of Indians and Danes are quite different. This reliability theory model accounts for convergence and late-life mortality nicely.

A consequence of this explanation of aging is that one way to control it might be to avoid developmental damage in vitro. Don't skimp on those anti-oxidants, mothers-to-be!

[1] See an overly simple tutorial here.

[2] Actually, mortality increase during aging is not the same in living things as in redundant machines. Failure rates in such machines follow the Weibull distribution. But that's because classical reliability theory assumes that when machines are created, all their parts are working. If you assume that there's a high probability that components are faulty, you pretty much get a Gompertz distribution.

Another anniversary

Recondite is three months old. One change I've decided on today: the tagline at the top will change fairly often.

What better way to celebrate than to talk website statistics?

1. 56% of visitors use Netscape, the other 44% IE. I would think that means recondite has readership skewed much more towards Unix (and Mac) than 'net users in general.
2. Current visitors per day average just below 50. High-water mark was August 11th, the day after I posted about Peter Deutsch's pycore, almost 1200 visitors that day.

I have no idea, really, what people like me to write about. In the absence of requests (hey, that's the ticket! radio show formats for blogs!), I guess I'll continue the random walk through topic space.

Keep those cards and letters coming in, folks.

Iraq's not like Vietnam at all...

Let's see.

• Country with no strategic value to US. Nah, Iraq's got oil. (Vietnam had fish sauce, but US had no Pho shops in '62).
• Country mostly jungle and mountainous, providing cover for enemy movement. Nope, not much jungle in Iraq. Enemy seems to be able to move pretty easily anyway, though.

Hmmm.

• US government claims general population welcomes military presence; check.
• Determined, indigenous enemy utilizing guerilla tactics; check.
• US forces rely upon heavy armor and aerial bombardment, creating resentment in local population; check.
• Enemy possesses source of supply and sanctuary in neighboring countries; check.
• US government delusionally claim signs of progress everywhere, doubters are called unpatriotic; check.
• Enemy is a coalition of nationalists and holders of a global triumphantalist ideology; check.
• US forces isolated from population by culture and language, dependent on local allies of dubious loyalty; check.
• Scenes of widespread violence and death on nightly news; check.
• Conventional wisdom is "no alternative to victory", elites are secretly pessimistic; check.
• American intervention universally deplored, even by close allies; check.
• Concern over deepening commitment causes US strategic shift to "localization"; check.
• Widespread suspicion of profiteering by companies with ties to administration; wait — did the Vietnam war have that?

Nah. The comparison's ridiculous.

Lies, Damned Lies, and Convention Speeches*

Sometimes I despair at the asymmetry between offense and defense. I'm not talking about the "war on terrorism", I'm talking about liars.

To protect commercial airliners from a couple of nuts with boxcutters we have to spend billions on baggage scanners and add an hour or more of delay for each of the million plus airline travelers each day.

Similarly, I could write a book exhaustively refuting just two sentences from Laura Bush's convention speech:

I could talk about the fact that my husband is the first President to provide federal funding for stem cell research. And he did it in a principled way, allowing science to explore its potential while respecting the dignity of human life.

I could talk about the fact that the $25 million in federal stem-cell research funds her husband allocated is less than 0.004% of the federal healthcare research budget. That it's less than 1/10th the funding put up by little Singapore, an economy 1/100th the size of the US. That it's about the amount of money being spent on political advertising for California's Prop 71 (which proposes $3 billion of state money for stem-cell research).

But I may as well rely on Michael Kingsley excellent LA Times Editorial:

It is true indeed that Bush's predecessors, from George Washington to Bill Clinton, failed to fund embryonic stem-cell research. Even Abraham Lincoln. Not a penny for stem-cell research from any of them. Historians believe this might have been because it didn't exist yet. But that's just a guess.

George W. Bush gave this nascent research a tiny sliver of money and piled on a smothering load of restrictions. As Laura Bush did not note, that makes Bush the only president to ever authorize federal rules against stem-cell research.

It is characteristic of Bush that he would not see, or have no patience for, the irony of justifying a policy on moral grounds and then, when it comes under attack, claiming that the policy is not having the very effect he is supposed to want. Meanwhile, it is characteristic of the Bush political machine to be utterly fearless about insisting that things are the way it would be convenient for them to be, despite the evidence that things are the way they really are.

The purpose of Bush's stem-cell policy is to discourage medical research using embryos. Bush supposedly thinks that these clumps of a few dozen cells are every bit as human as the people who will suffer and/or die from diseases that stem cells could cure. He had better believe that, because stem-cell research uses embryos being discarded by fertility clinics and doesn't actually add to the embryonic death toll at all. Only a deep conviction about the humanity of these microscopic dots (which have fewer human characteristics than a potato) could justify sacrificing real human lives to make the purely symbolic point that the dots are human too.

Scientists are in agreement that Bush's policy is succeeding. Stem-cell research has been drastically slowed. Yet Bush surrogates now pretend that the policy's real success is its failure to stop this research completely. Hey! You're supposed to think all those embryos being used in privately funded research are human victims, remember? It's a huge tragedy, remember? Stop bragging about it.

You should read the whole thing.

I could go on about this, but I'd never be able to get to Laura's next sentence, let alone her husband's speech.

[*] (Updated 10pm) Damn it, I just noticed that Fred Kaplan of Slate posted an article earlier today with the same title as this one. Well, that's just too bad, I'm not changing it.

Ich bin eine Republikaner

The Gubernator's convention speech is so easy to parody that only someone with no self-restraint would stoop to it. OK, here goes:

My fellow body-builders, my fellow Americans, how do you know if you are a Republican? Well, I tell you how. If you believe that government should be accountable to the people who make the big political contributions, not to any random idiot, then you are a Republican.

If you believe a person should only be told the things they need to know, not every detail of what their leaders do, then you are a Bush Republican.

If you believe claims of improvement in America's strategic, environmental and economic prospects more than you believe the evidence all around you, then you are a Republican.

If you believe our educational system should be accountable for our children's progress (learning abstinence and creationism), but cabinet officials needn't be accountable for the performance of their departments, then you are a Bush Republican.

If you believe that your leaders should bombastically praise our military while ignoring their advice, shortchanging them in men and material, all the while cutting soldier's benefits, then you are a Bush Republican.

If you believe that the best way to protect our way of life requires keeping American citizens jailed for years without access to courts or council, to strip-search Teddy Kennedy when he goes to the airport, and cutting the budget of the Air Marshal service, then you are a Bush Republican.

If you believe that our country is governed best when its laws and initiatives are ironically named ("Clear Skies" and "Healthy Forests" are my favorites), then you are a Bush Republican.

And, ladies and gentlemen, if you believe that we must be fierce and relentless in promoting Haliburton and other companies in the oil business, then you are a Bush Republican.

Now, there's another way you can tell you're a Bush Republican. You have faith in big business, faith in the resourcefulness of rich people and faith that losers deserve their fate. And to those critics who are always harping about the unchecked greed of our President's corporate cronies, I say: Don't be economic girlie-men.

(APPLAUSE)