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Should Japan default?


There are two reasons to think about what happens in the eventuality of a Japanese sovereign default. The first is that Japan's debt might be big enough, and its bond market reluctant enough, that it is forced to either default, hyperinflate, or go into severe austerity mode. In that situation, a default might be the best option. After all, after Argentina defaulted on its debt in 2001, its economy suffered for three years but then did quite well, substantially outperforming its pre-default trend:


That looks like a decently good macroeconomic scenario. And far from being an exception, this story is the norm:


So the precedent for a default is not apocalyptic. Whether this is better than hyperinflation I will leave unanswered, but it seems likely to be better than a long grinding period of austerity-induced stagnation. Also, note that austerity would redistribute wealth from Japan's young to Japan's already-comfortable older generations; a default, in contrast, represents a big transfer of wealth from the pampered old to the struggling young.

The second reason to contemplate a default is microeconomic. Observers of Japan's economy are nearly unanimous on the need for "structural reform". But Shinzo Abe's offerings on that front were extremely anemic. And given the huge edifice of special interests in Japan, and the weak political system there, we can probably expect little progress on that front. 

Structural reform is needed because Japanese productivity is stagnant. Here's a graph, from Takeo Hoshi's much-cited paper:


Hoshi attributes the stagnant TFP to "zombie" companies - companies that continue to live only through repeated infusions of below-market-rate loans. These zombies, he claims, crowd healthy, productivity-growing firms out of the market. His research with Ricardo Caballero and Anil Kashyap supports this story.

My own suspicion is that low TFP growth is also partly due to poor corporate governance in Japan. Here is a blog post I wrote about that.

A third, and related reason for low productivity growth may be the high prevalence of family businesses in Japan. There is evidence that family businesses experience slower productivity growth than non-family businesses. In this way, Japan may be similar to Portugal; I encourage everyone to read this Matt O'Brien post on family businesses and stagnation in that country.

For structural reform, Japan would need a huge blast of "creative destruction". Zombies and family businesses would need to die en masse, and healthy, independently run companies would need to emerge. The U.S. got that kind of blast in the 1980s, but Japan is unlikely to slash regulation, open up trade, and let the corporate raiders into the henhouse. The equilibrium of entrenched political interests is too strong. 

Only a big external shock is likely to be able to cause the kind of destruction needed to clear away Japan's economic ancien regime. A default would do the trick. Banks would go bamkrupt and be nationalized, and they would be forced to cut off zombies, which would then die en masse. If Japan's history is any guide, a huge burst of entrepreneurship would probably follow this die-off; witness the emergence of Sony and Honda after the shock of WW2.

So there might be some very good reasons for Japan to choose a sovereign default. But of course there would also be large costs. What would those costs be? I see three big ones: Human cost, inequality, and political risk.

The human cost could be a jump in the already sky-high suicide rate. A large number of Japanese suicides are men who lose their jobs. The close family structure of companies means that these men essentially lose access to their entire social support network. Combine this with a culture that is not very forgiving of failure, and you begin to see why a spike in unemployment might cause a large number of self-inflicted deaths.

Then again, this cost is not certain. A recovery of dynamism in Japan's economy might ultimately save more lives than it took. And human psychology is a fickle thing; it might be that in the wake of a default, unemployment might be seen as a natural disaster rather than an individual failure, and the suicide rate might even fall.

A more definite cost would be a rise in inequality. Once famed for being a middle-class society, Japan has experienced a rise in inequality over the past two decades; it is now less equal than Europe, though still more equal than the U.S. A default might change that. Family businesses might hold back productivity, but they also anchor the Japanese middle class; if large numbers of them went under, that middle class would be set adrift. 

Finally, the biggest cost of a Japanese default would be political risk. As can be seen from Argentina's example, defaults are often followed by steep drops in GDP (and rises in unemployment) that last for two or three years. That might be bad enough to destabilize Japan's already weak political institutions, and prompt the fall of the post-WW2 regime. That in turn would likely involve violence, social disruption, and increased social repression. If the winners of the coup were the "authoritarian nationalists" - basically, Shinzo Abe and his crowd - then things might not be so bad, since those guys are generally responsible and committed to a strong, stable nation. 

But if the victors were the "fanatic nationalists" - think of Toru Hashimoto and the guys in black vans - then Japan would be in for a very bad time indeed, and would quite probably revert to an unstable, violent, socially divided, repressive middle-income country like Thailand. That would be the worst possible outcome of a default.

So basically, a default would constitute a roll of the dice - a dramatic gamble that a collapse in the old order would be followed by a repeat of the kind of explosion of positive dynamism seen in the post-WW2 economic miracle or the Meiji Restoration. If the gamble failed, however, the consequence could be the end of the beautiful, peaceful, relatively free Japan that many of us have come to know and love.
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The Trouble with Darwin

As a biologist, I find Darwin's theory hugely disappointing. It's better than the alternative (which is to believe in magic, basically), but not by much, sadly.
Charles Darwin died before Mendel
proved the existence of genes
.

As scientific theories go, the theory of evolution is easily the weakest of all major scientific theories. It's a commendable piece of work in its ability to stir discussion, but terrible in most other ways.

To be useful, a scientific theory has to do a minimum of two things: explain what can be observed, and provide testable predictions. Darwin's theory is weak on the first count and useless on the second.

Evolutionary theory explains practically nothing, because every explanation of the theory is rooted in "survival of the fittest," which is a circular notion, utterly content-free. "Fittest" means most able to survive. Survival of the fittest means survival of those who survive.

Ironically, Darwin's landmark work was called On the Origin of Species. Yet it doesn't actually explain speciation, except in the most vacuous and speculative of terms. Of course, we can't set too high an expectation for Darwin, since he didn't live to see the publication of Mendel's work (the word "genetics" wouldn't exist until more than 20 years after Darwin's death), but still. Speciation is portrayed by Darwin as the outcome of the accumulation of small, gradual changes. That's all the explanation he offers.

But the explanation is wrong. Or at least it doesn't accord well with the facts. It doesn't explain the Cambrian Explosion, for example, or the sudden appearance of intelligence in hominids, or the rapid recovery (and net expansion!) of the biosphere in the wake of at least five super-massive extinction events in the most recent 15% of Earth's existence.

One of the most frustrating aspects of evolutionary theory (this is no fault of the theory's, though) is that it is so hard to test in the laboratory. The fact is, no one has ever seen speciation happen in the laboratory, under repeatable conditions, and until that happens we're at a distinct disadvantage for understanding speciation. (Incidentally, I don't count plant hybridization or breeding anomalies in fruit flies whose sexuality is under the control of microbial endosymbionts as examples of speciation.)

When I was in school, we were taught that mutations in DNA were the driving force behind evolution, an idea that is now thoroughly discredited. The overwhelming majority of non-neutral mutations are deleterious (they reduce, not increase, survival). Most mutations lead to loss of function (this is easily demonstrated in the lab), not gain of function. Evolutionary theory is great at explaining things like the loss of eyesight by cave-dwelling creatures (e.g., bats). It's terrible at explaining gain of function.

Even if mutations were capable of driving evolution, they simply don't happen fast enough to account for observed rates of speciation. In bacteria, the measured rate of 16S rRNA divergence due to point mutations is only 1% per 50 million years. And yet, there were no flowering plants on earth as recently as 150 million years ago! Does it take a biologist to see the disconnect?

I bring all this up because I've spent some time recently doing genomics research aimed at exploring mechanisms for new-protein creation/differentiation (mechanisms not relying wholly nor even mainly on point mutations), and I wanted to set the stage for discussing that research here. Over the next week or so, I'll be presenting some new ideas and findings. Hopefully, we can put some much-needed flesh on Darwin by exploring testable notions of how new protein motifs can arise quickly (without reliance on magic).

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A Catalase Conundrum

When I was in grad school (U.C. Davis) in the late 1970s, the bacterial world was simply the prokaryotic world, and vice versa. There hadn't yet come a distinction between eubacteria and Archaea. But now we know, or think we know, that prokaryota come in two fundamental flavors: the true bacteria (eubacteria), and the Archaea (primitive extremophiles). If you were to want to count organelles (mitochondria, chloroplasts, others) as a third fundamental grouping, I suppose you could, with some justification.

At this writing, about 400 distinct Archaeal isolates, belonging to around 75 genera, have been DNA-sequenced. You can see a list of them by going to http://genomevolution.org/CoGe/OrganismView.pl?org_desc=Archaea and looking in the Organisms box. You'll see over 200 organisms listed, but bear in mind they belong to only about 75 genera. (Most genera are represented by more than one species and/or more than one isolate per species, in other words.)

Salt-loving Archaea species have been found growing in borax-saturated
desert ponds. The species growing in this small lake produce a
carotenoid pigment that gives the water a pink appearance.
The Archaea were once thought to be exclusively anaerobes, but it turns out there are a couple dozen aerobic (or facultatively anaerobic) genera in the group. In my own spare-time research, I've found that about 20% of the 75 sequenced Archaeons (all of them obligate anaerobes) have a catalase gene. (Catalase is the enzyme that breaks hydrogen peroxide down to water and oxygen.) Oddly, very few of the aerobic Archaea (except for the Halobacteriaceae group) show any evidence of having catalase. This is exactly the reverse of what's expected. In the rest of the living kingdom (from bacteria to higher plants and animals), aerobes universally have catalase; strict anaerobes don't have catalase (or at least, they aren't supposed to; but see this post for some surprising exceptions).

This is a hugely unexpected finding: Many anaerobic Archaeons have catalase, but not all aerobic ones do. Some enterprising grad student should tackle this and make a thesis project out of it.

In case you're that student, here are some additional clues.

Let's back up for a second and look at the Big Picture. No matter where on the Tree of Life you go, catalases come in only a few major types. (See the excellent 2003 review paper by Chelikani, Fita, and Loewen for details.) For example, there are heme-containing and non-heme catalases. Most of the time, what we think of as "catalase" is heme-containing catalase (and yes, that means it contains iron). In the heme-containing group, you have monofunctional catalase as well as bifunctional catalase-peroxidases or hydroperoxidases (katG). The monofunctionals come in big- and small-subunit varieties. (The biggies have subunits of 75 kDa or more and comprise just over 2100 base-pairs of DNA. The smalls have subunits under 60 kDa and typically top out at 1500 base-pairs.)

Here's what you really need to know: Within the monofunctionals, there are three clades (major subgroupings) of catalase. Clades 1 and 3 are small-subunit enzymes. Clade 1 is primarily of plant origin and is relatively rare in bacteria (the best-known examples probably being katX of Bacillus subtilis and catF of Pseudomonas syringae). Clade 3 takes in a huge number of catalases from bacteria, fungi, and various eukaryotes. (For Clade 3, think Staphylococcus catalase.)  Clade 2 is the large-subunit enzyme (think E. coli katE catalase).

The multifunctionals tend to be large (over 2100 base-pairs of DNA).

The non-heme catalases contain manganese instead of iron and are not your typical catalases. Let's leave it at that.

What do the Archaeons produce? From what little probing I've done, it seems the anaerobic Archaeons that have catalase use a modified Clade 3 type of enzyme that has little in common with other Clade 3 catalases. A few of the methane producers show good sequence agreement with Bacteroides fragilis catalase, but most anaerobic Archaeal catalases do not show good sequence concordance with any known eubacterial catalases. So it's entirely possible that a fourth clade of purely Archaeal small-subunit catalases (unlike anything else in the plant or animal worlds) awaits characterization.

The aerobic Archaeons that have catalase are all halophiles (members of the Halobacteriaceae), and all have large-subunit multifunctional peroxidases similar to those of the Cyanobacteria.

Mysteries waiting to be solved:
  • Why is it the aerobes Sulfolobus, Pyrobaculum, and Aeropyrum do not appear to have catalase? Is it that they don't have catalase, or do they have some as-yet-undiscovered new type of catalase?
  • Why is it that certain methane-generating anaerobes (e.g., Methanosarcina) have Clade 3 catalases but the rest of the methane-producing Archaea have catalases that don't match anything else in the living world? Did the former group get their catalase(s) by way of horizontal gene transfer from anaerobic eubacteria?
  • Did the multifunctional catalases of the Halobacteriaceae originally come from cyanobacteria (perhaps by way of plasmids)?
  • What overlap, if any, exists between Archaeal catalases and the catalases of algal chloroplasts?
If you find the answers to any of these, let me know!



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The Zero Upper Bound?



A funny thing happened the other day. As part of "Abenomics", the Bank of Japan has been buying long-term Japanese government bonds. This has seemed to have the expected positive effects - Inflation is up, inflation expectations are up, growth is up, consumption is up, exports are up, and the stock market, despite a recent drop, is way way up. But here's the funny thing - Japanese long-term government bond yields kept going up over most of the last month (meaning JGB prices went down).

That's weird, right? Econ 101 says that if you buy more of something, its price should go up, not down! In this long rant, Richard Koo attributes the rise in interest rates to increased inflation expectations. According to Koo, QE doesn't work, and Japanese private investors, realizing this, started to expect inflation without real growth, and ditched JGBs, causing rates to rise.

But Nick Rowe has another explanation. According to Rowe, the rate rise was due to greater expected growth (nominal growth, so both better real growth and more inflation). As the BOJ's easy monetary policy causes the economy to improve, Rowe says, interest rates will naturally rise; investors are simply anticipating that rise, and selling bonds now. Rowe also has these rather harsh words for Koo:
Is Richard Koo really a Keynesian? Or is he just a finance guy, who doesn't really get macro/money?
Ouch!

One person who would probably agree with Rowe is Paul Krugman, who is himself a big supporter of Abenomics. In this blog post, Krugman outlined three "stories" about falling bond prices. Although none of the three stories correspond to Japan's current situation (long-term bond prices are down, stock prices are up, and the yen is down), the "stronger recovery" scenario involves rising stock prices, which we have seen. Rising stock prices indicate positive expectations for real economic growth, not just inflation. (Koo explains away this by conjecturing that Japanese stock investors and Japanese bond investors have different expectations, which I guess is not totally unreasonable given that most JGB holders are Japanese, while most of the recent inflows into the Japanese stock market have been foreign money).

(I have to say, initially I was skeptical of the Rowe/Krugman story. Most models I know would say that the recovery would take a while to raise interest rates above the pre-Abenomics level; the general-equilibrium effect would take years to overcome the partial-equilibrium effect of increased BoJ purchases holding rates down. To get a Rowe/Krugman type of rapid interest rate rise, I think you'd need a "good equilibrium, bad equilibrium" sort of model, where Abenomics kicks the economy out of the bad equilibrium very abruptly, and the economy is shocked back to a sustainably higher rate of NGDP growth. But then again, I guess I do kind of believe in that sort of model. And Japan's deflationary stagnation has lasted much longer than is typically possible in the simpler models I learned in grad school. But I digress.)

So anyway...are Japanese interest rates rising because of an incipient real economic recovery? Let us hope to Amaterasu that they are not. Let us hope that the rising yields are a blip, a trick of expectations and volatile markets and jittery bond investors.

Why do I say such a crazy thing?

Nick Rowe hints at the answer at the end of his post, when he writes:
And we can only regret that Japan did not do this many years earlier, instead of wasting all those years and letting Japan's government debt/GDP ratio climb. Because that high debt/GDP ratio is the only reason why someone might want Japan's economic recovery but not want the higher interest rates that will accompany that recovery. Which is no reason to try to stop the recovery. Though it is one additional reason to regret not having done something like Abenomics a lot earlier.
Rowe is being far too blithe. At very very high levels of debt-to-GDP, a rate rise is disastrous.

Imagine, for the sake of exaggeration, that a country had a debt-to-GDP ratio of three thousand to one. Suppose this was all in 30-year bonds, so that every year the government would have to roll over about 1/30 of its total debt, or 10,000% of GDP. Suppose that interest rates are just barely above zero - low enough to allow the government to maintain this debt burden.

Now suppose that interest rates suddenly "normalize" to 1%. Next year, the government will abruptly owe 1% of 10,000% of GDP in interest on the portion of its debt that it had to roll over. 1% of 10,000% is equal to 100%, so the government would owe all of the country's GDP in interest costs, in the first year alone. In the second year of the recovery, it would roll over another 10,000% of GDP, and thus owe 200% of GDP in interest costs!

How could it pay up? You can't tax 100% of GDP. So the government would have to borrow the rest. It seems clear that the higher the debt/GDP ratio, the less likely it would be that the private sector would be to lend to the government at an interest rate less than the economy's growth rate (the necessary condition for "stable Ponzi finance"; see discussion in comments with Nick Rowe for why this would be the case).

The only entity that would then lend the government the necessary sum is the central bank. In other words, seigniorage would be the only option to avoid default. This would either push interest rates back down to about 0%, or cause hyperinflation. Alternatively, the government could have the central bank buy outstanding bonds to push rates back down to 0%.

Now, Japan is not close to a 300,000% debt-to-GDP ratio. Its gross debt is about 240% of GDP. But a rise in interest rates would still exact a heavy burden on Japan's public finances; according to this guy, an increase in JGB yields to 2.2% would mean that 80% of Japan's current tax revenue would be eaten up by interest costs. Whether that number is correct, it's clear that with debt at 240% of GDP, Japan's growth would have to go up by a lot more than its interest rates in order to avoid a big rise in interest costs.

Also, realize that higher interest costs could easily start to hurt an economy long before they reach 100% of GDP, or even 100% of tax revenue. Why? Because of fiscal Keynesian effects. If fiscal policy affects demand (as most Keynesians and neo-Keynesians believe it does), then raising taxes to pay higher interest costs would stall the economy, as would drastic cuts in transfers or government purchases. (Of course you could borrow to pay the increased interest costs, as mentioned earlier.) So if an incipient recovery quickly causes higher rates, higher interest costs could kill the recovery.

(Now of course, all this time, increased nominal growth would erode the debt-to-GDP ratio. But that takes a long time to work. And Japan, which runs big primary deficits, is probably going to see its debt-to-GDP ratio continue to climb even if a recovery comes.)

So if monetary expansion can only cause the kind of recovery where interest rates rise, Japan is in deep shiitake. Japan's only hope is to cause the kind of recovery where interest rates stay very low for a very long time. If Japan is living in a Nick Rowe type world, that will prove impossible, and Japan's only options will be stagnation, default or hyperinflation. We should pray with all our might that we are living in a Richard Koo world instead, and that there is an economic policy that will allow Japan to boost growth and inflation while keeping interest rates low.

Anyway, this whole exercise raises the possibility that very high debt-to-GDP ratios could act as a long-term growth trap. We often talk about the "zero lower bound" on nominal rates, but very high debt-to-GDP ratios mean that there is also a zero upper bound. If recoveries always cause rates to rise (as Rowe contends), then high-debt-to-GDP ratios force governments to allow their economies to stagnate forever (or default/hyperinflate). In that case, the much-maligned Reinhart and Rogoff would be right.

If you get into a high government debt situation, a long periods of very low interest rates and robust real growth is really your only hope for a clean escape.


Update: Paul Krugman weighs in, saying my concerns are unwarranted. I've been thinking in terms of nominal rates this whole time, but Paul says that what really matters are real quantities; if the real interest rate stays low, it's all good.

Update 2: The more I think about it, the more certain I am that this post (of mine) confused and obfuscated more than it clarified. I think there was a good point somewhere in here, but I failed to make it. Oh well. That happens. For a simpler and (in my opinion) better take on the matter, see this brief post by Brad DeLong.

Update 3: Nick Rowe has a follow-up post in this series that is also much better than mine. This is basically the point I was trying to make, but stated much more cleanly. Excerpt:
Let's assume the worst-case scenario. Let's assume that I am right and Paul [Krugman] is wrong, so r increases [when the economy recovers]. And let's also assume that r increases more than g, so (r-g) increases. (Or (i-n) increases, if you prefer.) So economic recovery, by assumption, makes it harder for Japan to service the debt. [<-- at="" blockquote="" get="" i="" in="" my="" nbsp="" post.="" scenario="" the="" this="" to="" trying="" was="">
Let us also assume that Japan is like an OverLapping Genererations model, where Ricardian Equivalence is false, and where the equilibrium level of (r-g) is an increasing function of the debt/NGDP ratio. 
These worst case assumptions mean that there must exist some maximum Debt/NGDP ratio, call it Rmax, such that if the actual debt/NGDP ratio exceeds Rmax, then it would be impossible for Japan to service its debt if economic recovery causes interest rates to rise. Japan would either have to default, or create a big enough unanticipated rise in the price level to inflate away the old debt and bring the debt/NGDP ratio back down below Rmax. 
Let us further assume that Japan's current debt/NGDP ratio exceeds Rmax. 
In other words, I have deliberately set up a case in which Richard Koo would be right (maybe for the wrong reasons, but let that pass). I have deliberately made worst-case assumptions so that the higher interest rates caused by loosening monetary policy creating economic recovery would cause Japan to default on its debt, either literally or via very high inflation. 
Does this mean that "Japan cannot afford recovery"?
No. It means that Japan is already dead. It just doesn't know it yet... 
If Japan is already past the point of no return, then recovery will mean default. But delaying recovery will simply mean an even bigger default.
Now I feel even more ashamed for writing a sucky post. But at least I can link to similar posts that do not suck.
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Strict Anaerobes that Produce Catalase

One thing every new bacteriology student learns on Day One is that some microbes are strict anaerobes (completely unable to use oxygen), and a universal characteristic of strict anaerobes is that they lack an important enzyme called catalase that breaks down hydrogen peroxide to oxygen and water. The idea is that anaerobes don't need to have catalase, because they don't live in the kind of highly oxidized environments where hydrogen peroxide forms. Lack of catalase is supposedly why many anaerobes are killed upon exposure to air. According to legend, once oxygen gets into the cells, hydrogen peroxide starts to build up, and with no catalase to break it down, anaerobes choke on toxic peroxides.

I'll let you in on a little secret, though. This nice-sounding story (about peroxide buildup killing anaerobes upon exposure to air) turns out to be mostly conjecture, not well supported by science. Even the bit about anaerobes lacking catalase isn't completely true. Many anaerobes do make catalase.

For today's post, I did a protein-sequence BLAST search against several families of obligate anaerobes using the katA gene of Proteus mirabilis as a reference, and I was quickly able to identify two dozen strict anaerobes that do, in fact, have a catalase gene (see table below).

Table 1: Strict Anaerobes that Produce Catalase
(tblastn query: Proteus mirabilis katA gene)

Organism
Length (AA)
E-value
Percent identities
Alkaliphilus metalliredigens strain QYMF
475
4.0E-97
40.0
Anaerococcus prevotii strain DSM 20548
473
2.0E-162
59.6
Anaerococcus vaginalis strain ATCC 51170
482
3.0E-171
61.4
Bacteroides coprocola strain DSM 17136
479
0
68.6
Bacteroides coprophilus strain DSM 18228
477
0
68.3
Bacteroides eggerthii strain 1_2_48FAA
478
0
69.6
Bacteroides intestinalis strain DSM 17393
478
0
70.0
Bacteroides ovatus strain 3_8_47FAA
478
0
69.0
Bacteroides plebeius strain DSM 17135
479
0
68.2
Bacteroides thetaiotaomicron strain VPI-5482
480
0
68.7
Clostridium botulinum A3 strain Loch Maree
341
4.0E-67
38.1
Clostridium botulinum B1 strain Okra
463
1.0E-67
33.9
Clostridium hathewayi strain WAL-18680
474
7.0E-167
58.6
Clostridium lentocellum strain DSM 5427
476
2.0E-168
59.4
Clostridium phytofermentans strain ISDg
472
3.0E-107
43.6
Desulfitobacterium dichloroeliminans strain LMG P-21439
477
0
72.3
Desulfitobacterium hafniense DCB-2
493
1.0E-100
39.9
Desulfosporosinus youngiae strain DSM 17734
491
7.0E-103
41.1
Desulfotomaculum ruminis strain DSM 2154
477
2.0E-142
52.2
Dethiobacter alkaliphilus strain AHT 1
468
5.0E-102
40.3
Lachnospiraceae bacterium strain 3_1_57FAA_CT1
470
1.0E-165
59.5
Propionibacterium acnes strain 266
444
3.0E-114
47.2
Syntrophobotulus glycolicus strain DSM 8271
484
2.0E-102
40.7
Veillonella sp. strain 3_1_44
474
0
66.0

Each entry in this table represents a protein-sequence (not DNA sequence) match between a gene in the organism listed and the catalase gene of Proteus mirabilis. (Proteus is a facultative anaerobe related to E. coli and Salmonella.) The length of each organism's catalase enzyme, in amino acids, is shown under Length. (By way of reference, the Proteus catalase is 484 amino acids long.) E-value is the so-called expectation value, a measure of how likely the sequence match would be by chance. All of the values shown are extraordinarily low. "Percent identities" is the percentage of amino-acid matches between the Proteus enzyme and the target organism's enzyme. Values in the 30% to 40% range are not unusual for functionally related enzymes in otherwise distantly related organisms. Values above 60% tend to suggest a phylogenetic relationship, whereas in two organisms that are known to be unrelated, a value above 70% would (in many cases) be considered evidence of possible horizontal gene transfer. 

Here's the protein-blast query sequence I used, in case you want to verify these results (or go looking for more catalase-producing anaerobes):

>Proteus mirabilis strain HI4320(v1, unmasked), Name: PMI1740, YP_002151471.1, katA, Type: CDS, Feature Location: (Chr: 1, 1861974..1863428) Genomic Location: 1861974-1863428
MEKKKLTTAAGAPVVDNNNVITAGPRGPMLLQDVWFLEKLAHFDREVIPERRMHAKGSGAFGTFTVTHDITKYTRAKIFSEVGKKTEMFARFSTVAGER
GAADAERDIRGFALKFYTEEGNWDMVGNNTPVFYLRDPLKFPDLNHIVKRDPRTNMRNMAYKWDFFSHLPESLHQLTIDMSDRGLPLSYRFVHGFGSHT
YSFINKDNERFWVKFHFRCQQGIKNLMDDEAEALVGKDRESSQRDLFEAIERGDYPRWKLQIQIMPEKEASTVPYNPFDLTKVWPHADYPLMDVGYFEL
NRNPDNYFSDVEQAAFSPANIVPGISFSPDKMLQGRLFSYGDAHRYRLGVNHHQIPVNAPKCPFHNYHRDGAMRVDGNSGNGITYEPNSGGVFQEQPDF
KEPPLSIEGAADHWNHREDEDYFSQPRALYELLSDDEHQRMFARIAGELSQASKETQQRQIDLFTKVHPEYGAGVEKAIKVLEGKDAK


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What is "derp"? The answer is technical.



There has been much discussion lately concerning the word "derp" and its appropriate usage. For example, Josh Barro used the word to describe conservative bigmouth Erick Erickson, and Paul Krugman used it as well. This prompted a primer on the history of the term, followed elsewhere by the usual hand-wringing by self-appointed cultural policemen annoyed by the word.

Now, I myself have used the word "derp" quite a lot. Possibly more than any other pundit I know, with the exception of Dave Weigel. But in any case, not only do I consider myself an expert in the use of "derp", I also have a very precise idea of what "derp" means, and how it should be used. I think "derp" is incredibly useful as a term for an important concept for which the English language has no other word.

It has to do with Bayesian probability.

Bayesian probability basically says that "probability" is, to some degree, subjective. It's your best guess for how likely something is. But to be Bayesian, your "best guess" must take the observable evidence into account. Updating your beliefs by looking at the outside world is called "Bayesian inference". Your initial guess about the probability is called your "prior belief", or just your "prior" for short. Your final guess, after you look at the evidence, is called your "posterior." The observable evidence is what changes your prior into your posterior.

How much does the evidence change your belief? That depends on three things. It depends on A) how different the evidence is from your prior, B) how strong the evidence is, and C) how strong your prior is.

What does it mean for a prior to be "strong"? It means you really, really believe something to be true. If your start off with a very strong prior, even solid evidence to the contrary won't change your mind. In other words, your posterior will come directly from your prior. (And where do priors come from? On this, Bayesian theory is silent. Let's assume they come directly from your...um...posterior.)

There are many people who have very strong priors about things. For example, there are people who believe, very strongly, that solar power will never be cost-efficient. If you confront them with evidence of solar's rapid price declines, they will continue to insist that, despite this evidence, solar will simply never be cost-competitive with fossil fuels. That they continue to insist this does not necessarily make them irrational in the Bayesian sense; they simply have very strong priors. Someday they may be convinced - for example, if and when unsubsidized solar power starts being adopted on a mass scale. It'll just take a LOT to convince them. (A more entertaining example can be seen in this classic comedy video.)

But here's the thing: When those people keep broadcasting their priors to the world again and again after every new piece of evidence comes out, it gets very annoying. After every article comes out about a new solar technology breakthrough, or a new cost drop, they'll just repeat "Solar will never be cost-competitive." That is unhelpful and uninformative, since they're just restating their priors over and over. Thus, it is annoying. Guys, we know what you think already.

English has no word for "the constant, repetitive reiteration of strong priors". Yet it is a well-known phenomenon in the world of punditry, debate, and public affairs. On Twitter, we call it "derp".

So "derp" is a unique and useful English word. Let's keep using it.

(Also, the verb associated with "derp" is "herp". It describes the action of coughing a large sticky mass of derp onto the internet in front of you. For example, to use it in a sentence: "That twerp just herped a flerp of derp!" A "flerp" is a unit I made up. It is the amount of derp that can be herped by one twerp. See?)
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Atlantic column: "Should we trust economists?"



Excerpts from my latest Atlantic column:
Imagine you are the Royal Physician in England some time during the 14th century. The prince is sick, and you've been summoned to help. You call in two experts for advice. The first says: "Use leeches to suck out the evil humors." The second says "No, you must bleed him to get the evil humors out." Just to make sure, you summon a third expert all the way from Austria, who says “No, the disease is God’s punishment for the prince’s sins, you should let it run its course.” After the Austrian expert is duly led off to the dungeons and beheaded, you’re still left with the question of whether to treat the prince with leeches or bleeding. They start to argue, insulting each other in nasty epistles. "Leech guy is secretly working for the French!" alleges Bleeding Guy. "Bleeding Guy just wants the prince to die because the prince wanted higher taxes on the nobles!" Leech Guy fires back. 
What's the right move? Well, in an ideal world, you would go and get 999 patients who have illnesses similar to the prince's and give them all a variety of household substances, such as bread mold. Then you would take careful note of who died and use statistical analysis to figure out which household substances cured disease. Thus, you would discover penicillin and invent modern medicine. 
Sadly, this is not what you do, because a) if you proposed it, you would be led off to the dungeons and beheaded right next to the Austrian guy, b) it's the 14th century and you have no concept of the scientific method, and c) you don't really have the right tools for that experiment, anyway. Instead, it's bleeding or leeches. So you take your best guess and you pray you're right. 
The economic situation we find ourselves in today is a little bit like the example above...
If economists ever do succeed in developing formal models that work better, then we'll be able to go to them with questions (like "Should the Fed print more money?") and simply trust their expert advice. But until that day, all economists can really give us is intuition, suggestions, and ideas... 
No matter how much we might wish they were, economists are not go-to experts who know just how the world works or how to fine tune it...But they do have a lot of interesting things to say. They might help you clarify or re-evaluate your own beliefs about how the economy functions. They can also help you spot the flaws in each other's arguments. 
And in the end, you're the Royal Physician. You may not know everything, but the prince is dying, and you pick from among the "experts" you've got.
You can read the whole thing here. Unfortunately, the part about the Austrian guy was edited for length. :(

Regular blog readers will recognize material from some of my past blog posts, such as:

"What can you do with a DSGE model?"

"The swamps of DSGE despair"

"A world without macroeconomists?"

"A satisfactory philosophy of ignorance"
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