Wednesday, December 29, 2010

Hindsight Is 2010

The NYTM's Year in Ideas is consistently good. My favorites for this edition were D.I.Y. Macro, Performance Enhancing Shoes, Relaxation Drinks, and The 2000's Were a Great Decade. Inspired by their ideas, my retrospective for the year will consist of twelve articles / blog posts, one for each month, that seem especially representative of the year in ideas.

January: "Lessons from a pandemic," Nature editorial, 685 words. The H1N1 virus ended up not being that lethal, but it could have been, and this article highlights the lessons. Among them is that six months is too long of a time for vaccine production, given that viruses now easily spread around the world in "a matter of weeks."

February: "The biomechanics of barefoot running," editor's summary, 283 words. Running on one's toes is healthier than running on one's heels, even though most running shoes promote the latter. This finding is largely academic for me personally, as over the years I have come to loathe jogging. Nevertheless, it is emblematic of the larger "back to nature" craze that has taken over in 2010. This includes the paleo diet, probiotics, and restroom posture designed to prevent hemorrhoids.

March: "Snake oil? The scientific evidence for health supplements," by David McCandless and Andy Perkins, infographic. Aside from being fascinating, this is a good example of an effort to harness the academic lit for the benefits of the masses. Also, it is representative of the open data movement, as the authors transparently aggregate their data set in a google doc, which anyone can view.

April: "The data-driven life," by Gary Wolf, 5808 words. Discusses the growing trend of self-experimentation. More generally, he discusses how many more people are using tech and data to inform decisions, trumping their raw intuition.

May: "The moral life of babies," by Paul Bloom, 6026 words. He discusses how our preference towards actors who "do the right thing" emerges very early. That is, it presumably emerges far earlier than the babies would be cogent enough to consciously reason about morality. This is part of a movement in psychology that is emphasizing the arbitrariness of our beliefs and decisions.

June: "Smarter than you think: IBM's supercomputer to challenge 'Jeopardy!' champions," by Clive Thompson, 6609 words. At any given point, the AI iteratively calculates the probability that an answer is correct, and then checks whether that probability passes a certain threshold. This probabilistic thinking seems to be invading fields beyond just machine learning, so it's important to understand.

July: "New developments in AI," by Steve Steinberg, 5496 words. An innocuous and perhaps unfortunate title, but a tour de force of a blog post. He discusses trends in smart cars and massive knowledge-bases, and speculates on how they will affect society. One sentence that's particularly near and dear to my heart is when he writes, "consider that 'what is the best burrito in SF' (an opinion), and 'what do most people consider the best burrito in SF' (a fact) are normally considered equivalent."

August: "A world without mosquitoes" by Janet Fang, 1929 words. She discusses whether we should try to eliminate all of these nasty, virulent insects. The downside is that it would mess with biodiversity in ways difficult to predict, while the upside is that it could save millions of lives. We will face plenty of these type of trade-offs in the coming years, specifically with respect to climate change and geoengineering, and more generally in changing aspects of our natural world that we disapprove of.

September: "Jumping to joy," by Robin Hanson, 212 words. He wonders whether we should experiment more with different lifestyles, and what our failure to do so implies about our precarious sense of self. Questioning which of our selves is the "real" one is trendy these days, boosted in part by things like the implicit association test. Experimentation is also enjoying a resurgence, championed by Dan Ariely.

October: "Lies, damned lies, and medical science", by David Freedman, 6022 words. Explains the problems with current scientific publication and data dissemination systems. Many scientists broadly agree with these critiques of their infrastructure, but lack personal incentives to change them. 

Movember: "Hangover theory and morality plays," by Steve Waldman, 1986 words. He discusses the need to frame causes of the recession in moral terms that anyone can understand, synthesizes relevant economic theories, and holds no punches. It'd be hard to describe the ideas of 2010 without including reactions to the recession.

December: "The hazards of nerd supremacy: The case of Wikileaks," by Jaron Lanier, 4704 words. Wikileaks is one of the defining stories of the year. He explains that we might support the hackers in our hearts, because we perceive them to be the underdogs, but that in our heads we should be much more skeptical.

It's been a fun year of blogging and thanks as always for reading.

Tuesday, December 21, 2010

Lehrer On Plasicity Vs Specialization

He discusses it here, a month ago:
Expertise might also come with a dark side, as all those learned patterns make it harder for us to integrate wholly new knowledge.  Consider a recent paper that investigated the mnemonic performance of London taxi drivers. In the world of neuroscience, London cabbies are best known for their demonstration of structural plasticity in the hippocampus, a brain area devoted (in part) to spatial memory....

The problem with our cognitive chunks is that they’re fully formed – an inflexible pattern we impose on the world – which means they tend to be resistant to sudden changes, such as a street detour in central London....

The larger lesson is that the brain is a deeply constrained thinking machine, full of cognitive tradeoffs and zero-sum constraints. Those chess professionals and London cabbies can perform seemingly superhuman mental feats, as they chunk their world into memorable patterns. However, those same talents make them bad at seeing beyond their chunks, at making sense of games and places they can’t easily understand.

A beautiful exposition. However, I think the trade-off can be found more generally than in just the human brain. Indeed, most evolving biological systems impose limits on plasticity because of the costs. This suggests new minds or systems we might design will probably deal with this trade-off too. But this is all still hotly debated.

Sunday, December 19, 2010

Douglas Adams On Robustness Vs Fragility

From The Hitchhiker's Guide:
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair."

Aging And Happiness

How does subjective well-being vary with age? To find out, Stone et al (here, HT: The Brits (HT: BC)) conducted a large random-digit dial survey of 300,000+ US citizens. They asked about well-being and a few other variables, like age. We can only hope they had a good wireless plan. Here's the big result:

The covariates are unemployment, marital status, whether one has children living at home, and gender. Younger people increase in well-being ratings once you adjust for these because they're more likely to be unemployed. Of course be careful of the axes, as their real rating scale varies from 0 to 10. But the large sample size and continuous trend across age groups lends credence: I buy it.

What about anxiety and age? Here's the proportion of respondents who reported feeling "a lot" of stress the previous day, in different age groups:

I wonder what explains this trend. Perspective? Fiscal and emotional stability? Norepinephrine levels in the amygdala?

Finally, for those readers who do not trust their eyes, here's their table showing the percent of variances explained:

So anger and stress show a pretty consistent decline across age groups, while the curves are more U-shaped for measures of subjective well-being. Note sadness follows an inverted U-shaped curve.

Many top 250 movies explore this curious relationship between happiness and age, like Up, Ikiru, Cinema Paradiso, and The Wrestler. Much of it seems counter-intuitive. Here's a post of mine from '07 wondering whether we become happier with age, but I apparently didn't see the U-shaped curve coming.

Sunday, December 5, 2010

Why Nature Didn't Choose Arsenic

Phosphate is of course a part of the structures of DNA and RNA, but it is also in many metabolic intermediates like ATP and glucose-6-phosphate. The idea that a bacterium could survive without it (see here) would require updating some concepts about the flexibility of reaction rates in physiological systems.

A 1986 paper by Frank Westheimer, cited 400+ times, abstract here and pdf here, explains why phosphates are preferred. In particular, he notes how the negative charge of the phosphate ester makes it relatively more resistant to hydrolysis, while it still can act as a leaving group if enzymatically activated. Then, in an intriguing section, he discusses why various other alternatives would not make sense, including arsenic:
Another compound that must be considered as a basis for a possible genetic material is arsenic acid, which is also tribasic. The poisonous effects, however, of compounds of arsenic probably cannot be avoided, since these effects are centered in the lower valence states of arsenic, and the reduction of pentavalent arsenic is much easier than that of pentavalent phosphorus. In any case, arsenic esters are totally unsuitable; the hydrolysis of esters of arsenic acid is remarkably fast. The triisopropyl ester in neutral water at room temperature is completely hydrolyzed in a couple of minutes. Apparently the hydrolysis of the diesters is even faster than that of the triesters.
The idea is that esters of arsenic are too liable to be cut by water, thus making them poor linkers for bases of DNA and RNA. But this is assuming that the reaction will occur under relatively stable conditions (i.e., pH and temp), and perhaps those conditions are somehow altered in this particular bacterium, sufficiently lowering the hydrolysis rate of arsenic. We will have to wait and see, but in the meantime where are the prediction markets when we need them?

Saturday, December 4, 2010

Trade Off #16: Impulse vs Incentives

At one of the stoplights on my drive to the gym, there is often someone walking through the cars asking for change. Let's assume, reasonably, that she needs the money more than I do. Let's also assume, somewhat less reasonably, that she'll spend the money in a productive manner. We can now break the decision down into the benefits she'd gain from leveraging my money versus the perverse incentives I'd reinforce by rewarding people for begging in traffic.

Generally, this trade-off is between the benefits from an impulse meant to rapidly improve and stabilize a condition, versus the costs of long-term instabilities that could result. Some examples:
  • Keynesian econ emphasizes the multiplier of a gov intervention, which they consider to be an impulse, whereas Austrian econ emphasizes the moral hazard (i.e., bad future incentives) of such impulses. ("in the long run we're all dead", also see here)
  • Radiotherapy has a good chance of killing tumors, and thus can be thought of as an impulse. But it also makes mutations in other genes more likely, which could develop into secondary tumors in the future, and thus can be thought of as bad "incentives." (see here)
  • WikiLeaks might incite people to speak out against or question their government, thus acting as an impulse to increase freedom, but it also incentives governments to be even more secretive and centralized, thus decreasing freedom. (see here)
The previous trade off we're most worried about conflicting with here is some now vs more later. And indeed, it is true that there is a time component to both of these trade offs. But the difference between them is that in this trade off the two possible outcomes are not quantitatively but instead qualitatively different.

Now, the previous paragraph is somewhat of a technicality, and is probably boring. But if I didn't mention it now, just imagine the kind of incentives that would introduce for sloppiness in the future.

(Kudos to Alan Grinberg for the photo)