Self-correction, paradigm shifts, and Rapa Nui

It's not even 7 AM and I already broke the cardinal rule of the internet, which is, "Don't feed the trolls."

Posting as I do about controversial issues like climate change, evolution, and religion, it's only to be expected that I get pretty heated commentary sometimes.  While I'm always ready and willing to consider a well-reasoned argument against my viewpoints, I'm usually smart enough to let the "You only say that because you're a (choose one): radical leftist, godless heathen, anti-American, tree-hugger, cynic, whiny liberal, complete idiot" comments roll off me.

Usually.

The one that got me today was the person who responded to a story I retweeted about a recent discovery in evolutionary biology with the time-honored snarl, "Your sciencism is more of a faith than my religion is.  I don't get why you trust something that could be completely disproven tomorrow.  I'll stick with eternal truths."

I spent a long time (well, to quote Lieutenant Commander Data, "0.68 seconds... to an android, that is nearly an eternity") trying to talk myself out of responding.  That effort being unsuccessful, I wrote, "... and I don't get why you trust something that is completely incapable of self-correcting, and therefore wouldn't recognize if something was wrong, much less fix it."

This resulted in another time-honored snarl, namely, "fuck you, asshole," which I am always surprised to hear from someone whose holy book says lots of stuff about "turn the other cheek" and "love thy enemies" and "pray for those who persecute you" but very little about "say 'fuck you' to any assholes who challenge you."

Anyhow, I do find it puzzling that self-correction is considered some kind of fault.  Upon some consideration, I have come to the conclusion that the problem is based in a misunderstanding of what kind of self-correction science does.  The usual sort is on the level of details -- a rearrangement of an evolutionary tree for a particular group of animals (that was the link that started the whole argument), a revision of our model for stellar evolution, an adjustment to estimates for the rate of global temperature increase.  As I've pointed out more than once here at Skeptophilia, truly paradigm-changing reversals in science -- something like the discovery of plate tectonics in the 1960s -- stand out primarily because of how uncommon they are.

So "this all might be proven wrong tomorrow" should be followed up with, "yeah, but it almost certainly won't."

As an example of how self-correction in science actually works, consider the paper that appeared last week in The Journal of Archaeological Science questioning a long-held narrative of the history of Rapa Nui, more commonly known by its European-given name of Easter Island.

[Image licensed under the Creative Commons TravelingOtter, Moai at Rano Raraku - Easter Island (5956405378), CC BY 2.0]

The previous model, made famous in Jared Diamond's book Collapse, was that the inhabitants of Rapa Nui did themselves in by felling all the trees (in part to make rollers and skids for moving the massive blocks of stone that became the iconic moai, the stone heads that dot the island's terrain) and ignoring the signs of oncoming ecological catastrophe.  The story is held as a cautionary tale about our own overutilization of natural resources and blindness to the danger signals from the Earth's environmental state, and the whole thing had such resonance with the eco-minded that it wasn't questioned.

Well, a team researchers, led by Robert DiNapoli of the University of Oregon, have said, "Not so fast."

In "A Model-Based Approach to the Tempo of 'Collapse': The Case of Rapa Nui (Easter Island)," the anthropologists and archaeologists studying Rapa Nui found that it may not be so clear-cut.  The pre-European-contact ecological collapse was much more gradual than previously believed, and it looks like the building of moai went on long after Diamond and others had estimated.  The authors write:

Rapa Nui (Easter Island, Chile) presents a quintessential case where the tempo of investment in monumentality is central to debates regarding societal collapse, with the common narrative positing that statue platform (ahu) construction ceased sometime around AD 1600 following an ecological, cultural, and demographic catastrophe.  This narrative remains especially popular in fields outside archaeology that treat collapse as historical fact and use Rapa Nui as a model for collapse more generally.  Resolving the tempo of “collapse” events, however, is often fraught with ambiguity given a lack of formal modeling, uncritical use of radiocarbon estimates, and inattention to information embedded in stratigraphic features.  Here, we use a Bayesian model-based approach to examine the tempo of events associated with arguments about collapse on Rapa Nui.  We integrate radiocarbon dates, relative architectural stratigraphy, and ethnohistoric accounts to quantify the onset, rate, and end of monument construction as a means of testing the collapse hypothesis.  We demonstrate that ahu construction began soon after colonization and increased rapidly, sometime between the early-14th and mid-15th centuries AD, with a steady rate of construction events that continued beyond European contact in 1722.  Our results demonstrate a lack of evidence for a pre-contact ‘collapse’ and instead offer strong support for a new emerging model of resilient communities that continued their long-term traditions despite the impacts of European arrival.

All of which points out that -- like yesterday's post about the Greenland Vikings' demise -- complex events seldom result from single causes.  Note that the researchers are not saying that the inhabitants of Rapa Nui's felling of the native trees was inconsequential, nor that the contact with Europeans was without negative repercussions for the natives, just as the paper cited yesterday didn't overturn completely the prior understanding that the Greenland Vikings had been done in by the onset of the Little Ice Age.  What it demonstrates is that we home in on the truth in science by questioning prior models and looking at the actual evidence, not by simply continuing to hang on to the previous explanation because it fits our version of how we think the world works.

So the self-correction about the history of Rapa Nui isn't a paradigm shift, unless you count the fact that its use as a caution about our own perilous ecological situation won't be quite so neat and tidy any more.  And what it definitely doesn't do is to call into question the methods of science themselves.  The proponents of "it could all be proven wrong tomorrow" seem to feel that all scientists are doing is making wild guesses, then finding out the guesses are wrong and replacing them with other wild guesses.  The reality is closer to an electrician trying to figure out what's wrong with the wiring in your house, first testing one thing and then another, gradually ruling out hypotheses about what the problem might be and homing in on where the fault lies so it can be repaired.  (And ultimately, ending up with functional circuitry that works every time you use it.)

But the truth is, I probably shouldn't have engaged with the person who posted the original comment.  There seems little to be gained by online snark-fests other than raising the blood pressure on both sides.  So I'm recommitting myself to not feeding the trolls, and hoping that my resolution will last longer than 0.68 seconds this time.

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This week's Skeptophilia book of the week is a dark one, but absolutely gripping: the brilliant novelist Haruki Murakami's Underground: The Tokyo Gas Attack and the Japanese Psyche.

Most of you probably know about the sarin attack in the subways of Tokyo in 1995, perpetrated by members of the Aum Shinrikyo cult under the leadership of Shoko Asahara.  Asahara, acting through five Aum members, set off nerve gas containers during rush hour, killing fifty people outright and injuring over a thousand others.  All six of them were hanged in 2018 for the crimes, along with a seventh who acted as a getaway driver.

Murakami does an amazing job in recounting the events leading up to the attack, and getting into the psyches of the perpetrators.  Amazingly, most of them were from completely ordinary backgrounds and had no criminal records at all, nor any other signs of the horrors they had planned.  Murakami interviewed commuters who were injured by the poison and also a number of first responders, and draws a grim but fascinating picture of one of the darkest days in Japanese history.

You won't be able to put it down.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

The case of the crystalline eyes

One comment from students that consistently drove me crazy, as a science teacher, was, "Why do we have to learn this?  It could all be proven wrong tomorrow."

The implication is that since science alters its models based on new evidence, we could wake up one morning and find that we have to throw out the chemistry texts because the alchemists were right after all.  As I've mentioned before here at Skeptophilia, such complete recasting of our understanding is awfully uncommon; the majority of scientific discoveries refine the models we already have rather than completely overthrowing what we thought we understood.

The most frustrating thing about that attitude, though, is the suggestion that science's capacity for self-correction is some kind of flaw.  Is it really better to persist in error despite new information, damn the opposition, rather than saying, "Okay, I guess we were wrong, then," and fixing the mistakes?

I saw a great example of how science handles that sort of thing last week, when a fantastically well-preserved fossil of a crane fly 54 million years ago called into question a long-held theory about the eyes of trilobites.  You've probably seen crane flies; they're the insects that look like large, bumbling mosquitoes, entirely harmless (although two European species, now introduced and invasive in the United States, feed on plant roots and will muck up your lawn).

Here's the fossil in question, specifically a close-up of its multi-faceted eyes:

What was interesting about this fossil was that the lenses of the crane fly's compound eyes were composed of crystals of calcite, and that put the researchers -- a team led by Johan Lindgren, a paleontologist at Lund University in Sweden -- in mind of a claim about the eyes of trilobites, a distantly-related group of much older arthropods that went extinct in the massive Permian-Triassic Extinction, 252 million years ago.

In a paper in Nature, Lindgren et al. point out that crystals of calcite in fossilized trilobites were interpreted as being the lenses of the animals when they were alive -- i.e., the crystals were present in trilobites' eyes while living, and were left behind in the fossils.  But the discovery of similar crystals in fossil crane flies calls that into question; after all, there are still living crane flies, and none of them have crystalline eyes (nor do any extant groups of insects).

So it appears that the calcite crystals formed during the fossilization process -- that they're "artefacts," which is paleontology-speak for a feature that was generated by inorganic processes after the organism's death.  Lindgren's point is that since the crystals are artefacts in the crane flies' eyes, it's pretty likely they are in the trilobites' eyes, as well.

This discovery overturns something we thought we understood -- and while I imagine that the paleontologists who framed the crystal-eyes-in-trilobites model are saying, "Well, hell," they're not staunchly refusing to budge.  In science, our models stand or fall based upon evidence and logic; if the evidence changes, the models have to, as well.

And that, really, is the main strength of science as a way of knowing.  We continue to refine it as we know more, homing in on a model that works to explain all the available data.

Even knowing that "it could all be proven wrong tomorrow" -- but very likely won't be -- we keep moving forward, whether or not it lines up with our preconceived notions of how the world works.

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This week's Skeptophilia book recommendation is a classic: James Loewen's Lies My Teacher Told Me.  Loewen's work is an indictment not specifically of the educational system, but of our culture's determination to sanitize our own history and present our historical figures as if they were pristine pillars of virtue.

The reality is -- as reality always is -- more complex and more interesting.  The leaders of the past were human, and ran the gamut of praiseworthiness.  Some had their sordid sides.  Some were a strange mix of admirable and reprehensible.  But what is certain is that we're not doing our children, nor ourselves, any favors by rewriting history to make America and Americans look faultless.  We owe our citizens the duty of being honest, even about the parts of history that we'd rather not admit to.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Science vs. common sense

A regular reader of my blog commented to me, rather offhand, "To read your posts, you sound awfully sure of yourself.  A little arrogant, even."

I'll leave the last part to wiser heads than mine to answer; I may well have an arrogant streak, and in fact I've remarked more than once that to have a blog at all implies a bit of arrogance -- you have to believe, on some level, that what you think and write will be interesting to enough people to make it worth doing.  But I'd like to leave my own personality flaws aside for a moment, and take a look at the first part of the statement, which is saying something quite different, I think.

In saying that I sound "sure of myself," the fellow who made the comment was saying, so far as I can tell, that I sound like I've got all the answers; that my pronouncements on ghosts and faces on grilled cheese sandwiches and Florida Skunk Apes, and -- on a more serious level -- ethics, politics, philosophy, and religion, are somehow final pronouncements of fact. I come across, apparently, as if I'm the last word on the subject, that I've said fiat lux in a booming voice, and now all is light.

Nothing could be further from the truth, both in fact and in my own estimation.

It's because I have so little certainty in my own senses and my brain's interpretation of them that I have a great deal of trust in science.  I am actually uncertain about most everything, because I'm constantly aware about how easily tricked the human brain is.  Here are five examples of just how counter-intuitive nature is -- how easily we'd be misled if it weren't for the tools of science.  I'll present you with some explanations of commonly-observed events -- see if you can tell me which are true and which are false based upon your own observations.

1. Homing pigeons, which can find their way home from amazing distances, are navigating using visual cues such as the positions of the sun and stars.
2. A marksman shoots a gun horizontally over a level field, and simultaneously drops a bullet from the same height as the gun barrel.  The dropped bullet will hit the ground before the shot bullet because it has far less distance to cover.
3. Flowering plants are temperature-sensitive, and spring-flowering plants like daffodils and tulips recognize the coming of spring (and therefore time to make flowers) when the earth warms up as the days lengthen.
4. Time passes at the same rate for everyone; time is the one universal constant.  No matter where you are in the universe, no matter what you're doing, everyone's clock ticks at exactly the same rate.
5. Herding behavior in collies and other sheepdogs is learned very young; herding-breed puppies reared by non-herding breed mothers (e.g. a collie puppy raised by a black lab mother) never learn to herd.

Ready for the answers?

All of them are false.

1. Homing pigeons are remarkably insensitive to visual cues.  A paper by R. Wiltschko and W. Wiltschko of J.W.Goethe-Universität Frankfurt describes research showing showed that pigeons' tiny little brains allow them to navigate by picking up the magnetic field of the earth -- i.e., they have internal magnetic compasses.  These compasses take the form of magnetite crystals near the trigeminal nerve in the face, and the crystals' movements tells the birds not only what direction is north, but their inclination tell them how far north (i.e., the latitutde).  This ability, called magnetotaxis, is shared with only a few other species, including at least one species of motile bacteria.
2. In this classic thought experiment, the two bullets hit the ground at precisely the same moment.   Vertical velocity and horizontal velocity are entirely independent of each other; the fact that the one bullet is moving very quickly in a horizontal direction, and the other isn't, is completely irrelevant.
3. Temperature has very little to do with the timing of flowering, although a prolonged period of cold can slow down early-flowering plants some.  What actually is cueing plants to flower is the relative lengths of day and night; this response is called photoperiodism.  It used to be thought that flowering plants were timing their flowering cycles using a chemical called phytochrome that oscillates between two different forms in the light and in the dark; this clearly has something to do with it, but the mechanism controlling it is still poorly understood.
4. The General Theory of Relativity, which has been experimentally confirmed countless ways, actually says exactly the opposite of this.  What it does say is that the speed of light is constant in all frames of reference, and this has, as one of its bizarre outcomes, that time is completely relative.  Not only might your clock be ticking at a different rate than mine, depending on our relative motion, but events that look simultaneous to you might look sequential to me.  No wonder Einstein won the Nobel, eh?
5. Herding behavior in collies is entirely genetic, not learned (although they refine the skill with training).  Most amazingly, it seems to be caused by very small number of genes (possibly only a single gene, but that point isn't settled).  A dog with a specific genetic makeup can be trained to herd; a dog without it can't.  Scientists are still trying to figure out how such a small chunk of DNA can control a complex behavior like herding ability.  This sheds some interesting light on the nature-vs.-nurture question, though, doesn't it?

[image courtesy of the Wikimedia Commons]

All of this is just to indicate that our intuition, our "common sense," and even our sensory information, can sometimes be very misleading.  Science is our only way out of this mess; it has proven itself, time and again, to be the very best tool we have for not falling into error because of the natural mistakes made by our brains, the fallacies of wishful thinking and confirmation bias, and being suckered by charlatans and frauds.

A charge levied against science by some people is that it changes; the "truths" of one generation may be different from those of the next.  (I call this the "They Used to Believe the Sun Went Around the Earth" argument.)  Myself, I find this a virtue, not a flaw.  Science, by its nature, self-corrects.  Isn't it better to put your trust in a world view that has the capacity to fix its own errors, rather than one which promises eternal truths, and therefore doesn't change regardless of the discovery of contrary evidence?

I realize that this line of reasoning approaches some very controversial thin ice for many people, and I've no intent to skate any nearer to the edge.  My own views on the subject are undoubtedly abundantly clear.  I firmly believe that everyone buys into the world view that makes the best sense of his/her world, and it would be arrogant for me to tell another person to change -- the most I can do is to present my own understanding, and hope that it will sell itself on its own merits.  And for me, the scientific model may not be perfect, but given the other options, it's the best thing the market has to offer.