Yesterday the BBC reported on a study by Sonia Altizer and Andrew Davis, of the University of Georgia, purporting to demonstrate that populations of the monarch butterfly (Danaus plexippus) show differences in wing size that are correlated with whether or not the populations show migratory behavior to overwintering grounds.  Intrigued, I went to the Evolution website and read the paper, which is accepted but not yet copy-edited.  I found what seemed to be a serious problem with the interpretation—a problem that, had the BBC reporter had some expertise in evolutionary biology—could have been caught, or at least highlighted in the news report.  This underscores the recurring problem that science reporters without much formal training in science often report results without giving the proper caveats.

As you probably know (especially if you watched the NOVA program, The Incredible Journey of  the Butterflies, which aired a few days ago), some populations of monarch butterflies show bizarre and wonderful migratory abilities. Individuals from the east coast overwinter in Mexico, and those from west of the Rockies migrate to Southern California.  The migration is necessary because adult butterflies can’t tolerate cold, but also because their food plants aren’t available in winter.

But this is not a continuous movement of adults from summering grounds to wintering grounds.  The adults do fly the entire one-way journey in the fall, but it takes them several generations (each generation lasting 6-8 weeks) to get back to their summering grounds.  One of the great mysteries of monarch migration is how they’re able to return to the same summering grounds used by their great-grandparents.  What mechanism guides them in the right direction? And how did natural selection produce this directionality? We don’t know the answers to these questions.

Not all populations of monarchs are migratory.  Those in warmer areas, like southern Florida, Costa Rica, and Puerto Rica, have no impetus for migrating since the climate is tolerable and food plants continuously available. They stay put all year.

Based on this “dimorphism” among populations, Altizer and Davis  reanalyzed old data, originally collected for a study of parasitism, to test the following prediction:

We therefore predicted that monarchs from long-distance migratory populations would have larger and more elongated forewings to increase flight surface area and reduce wingtip-induced drag.

That is, individuals from migratory populations are under strong selection to fly long distances, and thus would evolve wings more suited to this task than those populations that are more sedentary.

I won’t go into all the details of this study, but here’s what they found:

1.   Wild-caught individuals from both “eastern migratory” populations (Minnesota, Georgia, and Mexican overwinterers) and “western migratory” populations (California, Utah, Nevada, Washington, and Colorado) were larger than individual from “nonmigratory” populations (Florida, Hawaii, Costa Rica, and Puerto Rico).  This verified their prediction (there were also shape differences, but I won’t discuss them here).

How do we know that these are evolved genetic differences rather than purely environmentally-induced differences in body size (correlated with wing size)? After all, we know from laboratory work that insects reared in colder temperatures grow larger than genetically identical insects reared in warmer temperatures. (I’ve done this many times, for instance, with Drosophila.) To answer this, Altizer and Davis reared three groups of butterflies under constant laboratory conditions of food and temperature.  They observed:

2.  Under these constant conditions, individuals from eastern and western migratory populations still had bigger wings than individuals from nonmigratory populations (unfortunately, they analyzed only one nonmigratory population here: that from south Florida).  From this they conclude that the differences between all populations are genetic and represent evolved adaptive differences:

Collectively, these studies suggest that the demands of long-distance flight represent an important evolutionary force operating on the physical characteristics of migratory species.

The BBC report, written by Matt Walker, echoes this conclusion in the report, titled “Supersized monarch butterflies evolved to fly far.”

These “supersized” butterflies have evolved to cope with the demands of long-distance flight.

In contrast, monarchs that live in one place all year have wings that are up to 20% smaller, report scientists in the journal Evolution. . .

Walker gives no caveats in his report. He simply blurbs the paper and gives some quotes from Altizer.  The reporter made no attempt to seek out opinions or commentary from other scientists.

Is there anything wrong with that? Well, one thing: there’s another explanation for the results, not depending on migration, that neither the paper nor Walker considers.  It is this: it has long been known that if you look at populations of insects from different areas of its range, those from colder locations tend to be larger (both developmentally and genetically) than those from warmer locations.  In other words, they conform to Bergmann’s rule, an “ecogeographic rule” that states that the body mass of an animal is positively correlated with the latitude where it lives. In other words, populations from colder areas have bigger bodies.

The classic explanation of this “rule” involves mammals: if you’re living in a colder climate, it’s adaptive to have a larger mass, for the ratio of heat produced (proportional to the cube of a linear dimension, in other words body mass) to heat lost through radiation (proportional to the square of a linear dimension, in other words body surface area) is lower for larger animals.  That is, it’s easier to stay warm if you’re bigger.  Now this explanation holds only for warm-blooded animals (homeotherms), but we now know that the “rule” is also obeyed by many cold-blooded animals (poikilotherms).  I’ve spent a lot of my career documenting this in Drosophila, and it’s clear that, regardless of the species, populations from colder areas evolve larger size.  Why this is so in poikilotherms, who don’t produce body heat to keep warm, is an intriguing but unanswered question. But the phenomenon is real.

The apparent problem with Altizer and Davis’s result is this: all the “nonmigratory” populations live in warmer areas than do the “migratory” populations.  Therefore, we expect nonmigratory individuals to be smaller than migratory individuals (i.e., have smaller wings), even if there were no difference in migration behavior. (This is aside from the fact that the authors draw sweeping conclusions about genetic differences from comparing only two migratory populations with only a single nonmigratory population.)

Now the authors don’t discuss this potential problem, which I think is serious.  The reviewers of the Evolution paper should have caught it.  Nor does the BBC highlight it.   My verdict on the paper: it’s intriguing but nowhere near conclusive, and should have been reviewed more thoroughly.

I may be wrong in this conclusion, and perhaps the authors will point out my error. And of course further work may show that they’re correct about a correlation between migration and wing size.  But in the meantime, it highlights an apparent breakdown in not only reviewing papers (which has grown more cursory with the exponentially increasing submissions reflecting both the existence of more scientists and the greater pressure on scientists to publish more), but also in the tendency of science reports to avoid looking too hard at research that produces interesting conclusions.

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Altizer, S., and A. K. Davis. 2010. Populations of monarch butterflies with different migratory behaviors show difference in wing morphology. Evolution, in press.

I was going to post on this, but Matthew Cobb beat me to it.  (If you’re not looking in at his online Z-letter, you’re missing some good biology.)  In today’s Nature is a nice article by a group of scientists from China, Ireland, and the UK, showing that color-bearing organelles (“melanosomes”) can be preserved in some fossils, giving us a clue to the color of ancient animals in life.  In this way they found out that the “feathered dinosaur” Sinosauropteryx had reddish-brown stripes on the tail!

They also found similar melanosomes in fossils of early birds.  Because melanosomes were previously known from living birds but not from dinosaurs or ancient birds, this gives additional evidence (as if we needed any!) that birds evolved from theropod dinosaurs. See Matthew’s post (and the Nature article, if you have access) for more.

Fig. 1.  Sinosauropteryx, replete with colored feathers. Illustration by James Robins (from report on National Geographic website).

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F. Zhang, S. L. Kearns, P. J. Orr, M. J. Benton, Z. Zhou, D. Johnson,  X. Xu and X. Wang.  2010.  Fossilized melanosomes and the colour of Creteaceous dinosaurs and birds.  Nature online, 27 January.

Over at today’s New York Times, conservative author Ross Douthat is upset at Richard Dawkins’s piece on Pat Robertson, Haiti, and theodicy.

But Dawkins’ “defense” of Robertson, against the “milquetoast” Christians who rushed to disavow the televangelist’s suggestion that the Haitian earthquake victims were being singled out for divine punishment, offers an interesting illustration of militant atheism’s symbiotic relationship with religious fundamentalism.

How does Douthat (the name begs for puns!) harmonize the disaster in Haiti with the notion of a powerful and loving God? By quoting the words of Jesus:

I say unto you, love your enemies, bless them that curse you, do good to them that hate you, and pray for them that despitefully use you and persecute you, that ye may be the children of your Father who is in Heaven. For He maketh His sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust. (Matthew 5:44-45) . .

There’s a heavy stress on sin and the possibility of ultimate punishment here, obviously. (Plenty for Richard Dawkins to find obnoxious, in other words.) But Jesus also lays a heavy emphasis on the idea that we shouldn’t interpret the vicissitudes of this life as God’s way of picking winners and losers, or of punishing particularly egregious sinners. Until the harvest, the wheat and tares all grow together, the rain falls on the just and unjust alike, and those who survive natural disasters are as liable to judgment as those who perish in them. . .

In other words, everything will be equalized in the afterlife.  That’s bogus, of course.  What could happen in the afterlife to discount the suffering of children who die of leukemia, before they’ve even had a chance to sin?  Or those innocent victims of Haiti?  Do you stand a better chance of going to heaven if you’re a good person who has experienced undeserved illness, evil, or disaster, than if you’re a good person who hasn’t?  Douthat’s remedy here is the same as those who take the Bible literally:  in the end, everything is judged appropriately, although we can’t understand exactly how God is going to do it.

So is it reasonable to believe that the Gospel passages quoted above “speak more clearly” than, say, the story of Sodom and Gomorrah to the question of whether Christians should interpret the events in Haiti as God’s punishment for some (spurious) 18th-century sin? I think it is. So do many theologians, ancient as well as modern, Protestant as well as Catholic, And the fact that Richard Dawkins and Pat Robertson both disagree tells us something, important, I think, about the symbiosis between the new atheism and fundamentalism — how deeply the new atheists are invested in the idea that a mad literalism is the truest form of any faith, and how completely they depend on outbursts from fools and fanatics to confirm their view that religion must, of necessity, be cruel, literal-minded, and intellectually embarrassing.

I’m not sure exactly which “new atheist” has claimed that “mad literalism is the truest form of faith.”  I think people like Dawkins assert that it is a very common form of faith, and those who don’t adhere to it—who pick and choose what they want from Scripture (as Douthat does above, conveniently leaving out the Old Testament)—don’t have good reasons for their particular interpretations.

Douthat neglects the theodicy of Jews, who of course don’t accept the New Testament and so can’t invoke the conciliatory words of Jesus. But even considering Christianity alone, Doubthat still fails to address the most important question of all:  how do you harmonize an ominipotent and beneficent God with the idea of natural disasters and the horrible suffering of some innocent people?  True, some “modern” Christians don’t see the events in Haiti as God’s punishment of sinners, or of anyone else.  But these Christians still haven’t explained, at least to the satisfaction of any rational and inquisitive person, why God allows things like that to happen if He could prevent them. In that sense, Pat Robertson has a better answer than those oh-so-sophisticated modern theologians.

If Douthat was right, there would be no need for theodicy. But of course there is: it’s one of the busiest areas of modern, non-literalistic theology.

The same muscles (arectores pilorum) that enable a cat to do this:

also enable us to do this:

And in both cats and ourselves, the same stimuli cause goosebumps/hair erection: cold and fear.

But of course goosebumps aren’t of any use to us. They don’t keep us warm, nor do they make us look bigger and fearsome, like the kitteh above. They’re evolutionary leftovers, evidence of our common ancestry with other mammals.

Three days ago, The New York Times published an op-ed by Harvard professor James Wood, noting that the tragedy in Haiti makes hash of theodicy and of the notion of a powerful and beneficent God.  Well, Times readers couldn’t let that one go by, and so  several of them wrote back. Of course they can’t reconcile the notion of a good God with natural disasters, but they try anyway:

We do not know the answer to this conundrum except to say that is the nature of freedom in an imperfect world and that is the mystery of the providence of God. God will work all things for our good even if we don’t understand. That is what faith is: the moment we say we understand, there is no longer any faith.

I love that last sentence.  The guy says that we don’t understand anything about God, but he’s absolutely certain that “God will work all things for our good”!  How does he know that?

This from a professor at Harvard Divinity School:

The bishop’s theology is neither mystifying nor contradictory, and in fact represents one version of a view held by many Christians and other religious people: namely, that God is deeply present in and through the events of the world — often inscrutably, but always powerfully and lovingly — and though we cannot for the life of us see how, even catastrophes include divine presence and power.

Mr. Wood may not share this view, but he has no right to scorn it, especially from a safe harbor.

Of course he has a right to scorn it!  In fact, he has a duty to scorn it.

What Haiti tells us is exactly nothing about God but everything about ourselves: we are mortal and vulnerable, every one. For some, this is the beginning, not the end, of religious devotion. Is it not imperiously condescending to those Haitian Christians gathered to worship in the rubble to say that “no invocation of God beyond a desperate appeal for help makes much theological sense”? Such a worshiper might counter: suffering and death come to all, even to a God who in his love took on our mortal, vulnerable condition as his own.

And another:

James Wood neglects the two fundamental themes of the Judeo-Christian Scriptures: the Exodus and the Resurrection. Both suggest that catastrophe is never the final word and that human beings should never be without hope. A fair reading of history suggests that such hope is not misguided.

What these letters prove, as if we need more proof, is that being smart doesn’t mean that you’re rational.  There is no evil, no disaster, so great that the faithful can’t rationalize it as the plan of a loving God.  Could some of them please tell us what circumstance would convince them that either there is no God, or that the one who exists isn’t so benevolent after all?

My nephew Steven is sometimes a pain in the tuchus, and he’s always squeezing his old uncle for a few bucks, but he has undeniably good taste in movies and writes about them well.  He runs a website, Truth at 24 (“Cinema is truth at 24 frames per second.”—Jean-Luc Goddard), where the posts are sporadic. However, he’s just posted his choice for the best films of the decade, and it’s worth a look.  Every film on the list is worth seeing, although I think he vastly overrates Lost in Translation, and Y Tu Mama Tambien, a true classic, should be ranked higher.

The “On Faith” column at The Washington Post is on a godless roll.  First they publish Dan Dennett’s critique of theodicy, calling it a “fraudulent contract,”   and then today Richard Dawkins on the hypocrisy of reactions to the Haiti disaster. Here’s the peroration, strong even for Dawkins:

. . .To quote the President of one theological seminary [R. A. Mohler, Jr.], writing in these very pages:

“The earthquake in Haiti, like every other earthly disaster, reminds us that creation groans under the weight of sin and the judgment of God. This is true for every cell in our bodies, even as it is for the crust of the earth at every point on the globe.”

You nice, middle-of-the-road theologians and clergymen, be-frocked and bleating in your pulpits, you disclaim Pat Robertson’s suggestion that the Haitians are paying for a pact with the devil. But you worship a god-man who—as you tell your congregations even if you don’t believe it yourself—’cast out devils’. You even believe (or you don’t disabuse your flock when they believe) that Jesus cured a madman by causing the ‘devils’ in him to fly into a herd of pigs and stampede them over a cliff. Charming story, well calculated to uplift and inspire the Sunday School and the Infant Bible Class. Pat Robertson may spout evil nonsense, but he is a mere amateur at that game. Just read your own Bible. Pat Robertson is true to it. But you?

Educated apologist, how dare you weep Christian tears, when your entire theology is one long celebration of suffering: suffering as payback for ‘sin’—or suffering as ‘atonement’ for it? You may weep for Haiti where Pat Robertson does not, but at least, in his hick, sub-Palinesque ignorance, he holds up an honest mirror to the ugliness of Christian theology. You are nothing but a whited sepulchre.

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UPDATE:  As Richard notes in his comment below the fold, the Post actually published a number of responses to the question, “Does God allow Haiti to suffer,” which you can find here.

Appearing on ABC news, Greg Epstein, Harvard’s humanist “chaplain” (is that an oxymoron?),  calls for the formation of atheist congregations.

Now Epstein has a lot of good things to say in this interview, and kudos to Harvard for hiring a nonreligious minister-equivalent, but really, do we atheists want to gather together once a week to celebrate our nonbelief? Once a year at an atheist convention, fine, but is common nonbelief a good basis for forming a community? It seems to me that that’s more like what Kurt Vonnegut calls a granfalloon.

(p.s. Epstein has been ordained as a “humanist rabbi.” Nice title!)

h/t: RichardDarwkins.net