Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Tuesday, May 26, 2020

Ripples in the cosmic pond

I know I've said this before, so at the risk of ringing the changes on this once too many times: I find it endlessly fascinating how much we can figure out about the universe, sitting here on this little speck of rock circling a mediocre star in the arm of an average galaxy.

Three papers came out last week in Nature Astronomy that each individually might bowl you over with the scale of things; put together, they're kind of staggering. First we have a paper by a team led by Tiantian Yuan, of Australia’s ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D).  Entitled "A Giant Galaxy in the Young Universe with a Massive Ring," this research looks at a very unusual object -- a collisional ring -- that is eleven billion light years away.

Meaning we're seeing it as it was eleven billion years ago.

"It is a very curious object that we’ve never seen before," Yuan said, in a press release.  "It looks strange and familiar at the same time.  It is making stars at a rate fifty times greater than the Milky Way.  Most of that activity is taking place on its ring – so it truly is a ring of fire."

"The collisional formation of ring galaxies requires a thin disk to be present in the ‘victim’ galaxy before the collision occurs," added Kenneth Freeman of the Australian National University, who co-authored the paper.  "The thin disk is the defining component of spiral galaxies: before it assembled, the galaxies were in a disorderly state, not yet recognizable as spiral galaxies.  In the case of this ring galaxy, we are looking back into the early universe by eleven billion years, into a time when thin disks were only just assembling.  For comparison, the thin disk of our Milky Way began to come together only about nine billion years ago.  This discovery is an indication that disk assembly in spiral galaxies occurred over a more extended period than previously thought."

Yes, you read that right.  The images of this object are pictures of something that existed two billion years before the Milky Way formed.


The second paper is about an object that is even older and father away than the ring galaxy.  Titled "A Cold, Massive, Rotating Disk Galaxy 1.5 Billion Years After the Big Bang," by a team led by Marcel Neeleman of the Max Planck Institute for Astronomy, is estimated to be 12.3 billion light years away -- so this structure is not only the oldest disk galaxy ever observed, it also gives us incredible new data on the way galaxies in general form.

The authors write:
Massive disk galaxies like the Milky Way are expected to form at late times in traditional models of galaxy formation, but recent numerical simulations suggest that such galaxies could form as early as a billion years after the Big Bang through the accretion of cold material and mergers.  Observationally, it has been difficult to identify disk galaxies in emission at high redshift in order to discern between competing models of galaxy formation...  The detection of emission from carbon monoxide in the galaxy yields a molecular mass that is consistent with the estimate [that the galaxy's mass is] about 72 billion solar masses.  The existence of such a massive, rotationally supported, cold disk galaxy when the Universe was only 1.5 billion years old favours formation through either cold-mode accretion or mergers, although its large rotational velocity and large content of cold gas remain challenging to reproduce with most numerical simulations.
So the astrophysicists are going to be sifting through that data for quite some time.


The third, "The Recurrent Impact of the Sagittarius Dwarf on the Star Formation History of the Milky Way," by a team led by Tomás Ruiz-Lara of the Instituto de Astrofísica de Canarias, describes something pretty amazing about our own galaxy; the main disc is orbited by a dwarf galaxy (the Sagittarius Dwarf in the title) which has an elliptical orbit, so it at regular intervals pierces the disc of the Milky Way -- causing eddies that trigger a huge spike in star production.

"You have the Milky Way in equilibrium, mostly calm, and then when Sagittarius passed it was like throwing a stone in a lake," said Ruiz-Lara, in an interview with New Scientist.  "It created these ripples in the galaxy’s density, so some areas became more dense and started forming stars more efficiently...  Maybe without Sagittarius the solar system wouldn’t exist.  The timing works out, but there is no way for us to know for sure."

[Image is in the Public Domain courtesy of NASA, ESA, and The Hubble Heritage Team STScI/AURA]

Gradually the dwarf galaxy is losing energy and its orbit is pulled in tighter and tighter, making these collisions and bursts of star formation more frequent.  "It’s getting closer and closer, little by little over time, and in the end it will merge with the Milky Way," Ruiz-Lara said.

Not to worry, that won't happen for another billion-odd years.  So no need to run and see if your stellar collision insurance is paid up.


It's kind of mind-boggling when you think about it, that a bunch of primates who were not so long ago loping around on the African savanna trying not to get eaten by lions have found a way to see into the farthest reaches of the universe.  Not to get cocky about it, but that's pretty spectacular.  Only a hundred years ago we didn't even know for sure how big or how old the universe is; today we're looking into the depths of space, and back in time almost as far is is physically possible.

It brings to mind the wonderful quote by Carl Sagan: "We are a way for the cosmos to know itself."

*******************************

This week's Skeptophilia book recommendation of the week is a fun one: acclaimed science writer Jennifer Ackerman's The Bird Way: A New Look at how Birds Talk, Work, Play, Parent, and Think.

It's been known for some years that a lot of birds are a great deal more intelligent than we'd thought.  Crows and other corvids are capable of reasoning and problem-solving, and actually play, seemingly for no reason other than "it's fun."  Parrots are capable of learning language and simple categorization.  A group of birds called babblers understand reciprocity -- and females are attracted to males who share their food the most ostentatiously.

So "bird brain" should actually be a compliment.

Here, Ackerman looks at the hugely diverse world of birds and gives us fascinating information about all facets of their behavior -- not only the "positive" ones (to put an human-based judgment on it) but "negative" ones like deception, manipulating, and cheating.  The result is one of the best science books I've read in recent years, written in Ackerman's signature sparkling prose.  Birder or not, this is a must-read for anyone with more than a passing interest in biology or animal behavior.

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




Monday, May 25, 2020

Second verse, same as the first

One of many brilliant moments in the movie Jurassic Park is when the main characters realize that the cloned dinosaurs -- which were supposed to be sterile -- had reproduced, and Ian Malcolm has this slow smile cross his face, and says, "Life finds a way."

It's amazing how resilient life can be.  I got a wonderful reminder of this from my friend, writer and blogger Andrew Butters (whose awesome blog Potato Chip Math should have way more followers), who just a couple of days ago sent me a story about bird evolution I'd never heard of before.

Let's start with the "evolution" part first.  Ever heard of iterative evolution?  I hadn't.  It is the tendency -- apparently documented in a number of lineages -- where two separate closely-related lineages develop exactly the same adaptation independently.  If you're thinking, "Wait, isn't that convergent evolution?" you've got the gist, but there's a difference; convergent evolution is when two relatively unrelated species end up evolving similar features because of being under the same kinds of selective pressures.  The two then end up looking similar for one or two obvious traits, but in other respects they are still completely different species.  (If you want some examples with photographs, I dealt with this here only a month ago.)

Iterative evolution, on the other hand, occurs within a clade of already closely-related populations, and distinctive features evolve more than once, generating what may as well be the same species twice.  The suspicion is this occurs because of mutations in regulatory genes, where interfering in embryonic development results in the same change no matter where exactly the mutation occurred.

As implausible as this sounds, it's not at all unlikely if the two mutations in question are both losses of function, where the mutation causes a gene to switch off.  As a rather rough analogy, consider a car's engine.  Two completely separate mutations -- say, undoing the battery cables and removing the fuel pump -- will both result in the car not starting, even though the underlying cause is entirely different.

Which brings us to the Aldabra rail (Dryolimnas cuvieri subsp. aldabranus), a flightless bird native to Aldabra Island in the Seychelles.  It's the only extant species of flightless bird in the Indian Ocean.  Flying is an energy-wasteful activity if it's not conferring some significant benefits to the bird, so in the absence of predators, it's selected against.  That comes to a screeching halt, however, when predators are introduced to the habitat -- which on various islands across the world have included rats, cats, brown tree snakes... and humans.  The result is that flightless species have taken a huge hit worldwide.

But the Aldabra rail has survived somehow, and a recent paper has demonstrated that the flight-capable parent species, the white-throated rail, which is found on various islands including Madagascar, has on Aldabra evolved flightlessness at least twice.

[Image licensed under the Creative Commons Charles J Sharp creator QS:P170,Q54800218, White-throated rail (Dryolimnas cuvieri cuvieri), CC BY-SA 4.0]

In "Repeated Evolution of Flightlessness in Dryolimnas Rails (Aves: Rallidae) After Extinction and Recolonization on Aldabra," which appeared in the Zoological Journal of the Linnean Society, by Julian Hume (of the Natural History Museum at Tring) and David Martill (of the University of Portsmouth), we read about incontrovertible evidence that the flightless subspecies evolved again after the first population was wiped out.

The authors write:
The Aldabra rail, Dryolimnas cuvieri subsp. aldabranus, endemic to the Aldabra Atoll, Seychelles, is the last surviving flightless bird in the Indian Ocean.  Aldabra has undergone at least one major, total inundation event during an Upper Pleistocene (Tarantian age) sea-level high-stand, resulting in the loss of all terrestrial fauna.  A flightless Dryolimnas has been identified from two temporally separated Aldabran fossil localities, deposited before and after the inundation event, providing irrefutable evidence that a member of Rallidae colonized the atoll, most likely from Madagascar, and became flightless independently on each occasion.  Fossil evidence presented here is unique for Rallidae and epitomizes the ability of birds from this clade to successfully colonize isolated islands and evolve flightlessness on multiple occasions.
This inevitably brings up the question of whether the two populations -- before and after the Pleistocene inundation -- are the same species.  This is a harder question than it sounds.  First, and most superficially, since the canonical definition of species is "a group of morphologically similar individuals all of which are capable of interbreeding and producing fertile offspring," it's impossible to tell if these are the members of the same species because the pre-inundation birds are all dead.  But it's not even as simple as that, because when you look closely, you find that species is in contention for being the mushiest definition in all of science.  There are scads of nearly-identical populations that can't interbreed, very different looking-ones that can, and ones that show a continuum of types between two extremes, making the question of "where do you draw the line?" a real problem.  (I dealt with this here a long time ago, if you're curious.)

So whether they're the same species or not is probably a meaningless question, a bit like drawing an arbitrary line on the ground and then arguing about why something falls on one side of the line or the other.  But the phenomenon itself is fascinating; that two virtually identical populations could evolve twice in the same place is kind of amazing.  It's almost as if when the first population was destroyed, Mother Nature said, "No, we need some flightless rails here," and the flight-capable parent species recolonized the island and evolved flightlessness a second time.

[Nota bene: no, I don't actually believe Mother Nature guides evolution in some kind of conscious fashion.  So don't yell at me, I was just being flippant.  Evolution is completely non-goal-oriented; it's the law of whatever works at the time.  So for the benefit of the serious and literal-minded readers, I should probably go back and rewrite the preceding paragraph, but I'm not gonna because I still think it's funny.]

Anyhow, this is a pretty cool example of a process that until now I had honestly never heard of.  It does reassure me that life will indeed find a way despite the idiotic and self-destructive things we're currently doing to the Earth's biodiversity.  We might be long gone by then, victims of our own short-sighted greed, but evolution will afterwards continue to do its thing -- producing a new set of endless forms most beautiful and most wonderful, to quote Darwin.

Some of which, beyond all expectation, may look a great deal like the ones that vanished.  And I find that a comforting thought.

*******************************

This week's Skeptophilia book recommendation of the week is a fun one: acclaimed science writer Jennifer Ackerman's The Bird Way: A New Look at how Birds Talk, Work, Play, Parent, and Think.

It's been known for some years that a lot of birds are a great deal more intelligent than we'd thought.  Crows and other corvids are capable of reasoning and problem-solving, and actually play, seemingly for no reason other than "it's fun."  Parrots are capable of learning language and simple categorization.  A group of birds called babblers understand reciprocity -- and females are attracted to males who share their food the most ostentatiously.

So "bird brain" should actually be a compliment.

Here, Ackerman looks at the hugely diverse world of birds and gives us fascinating information about all facets of their behavior -- not only the "positive" ones (to put an human-based judgment on it) but "negative" ones like deception, manipulating, and cheating.  The result is one of the best science books I've read in recent years, written in Ackerman's signature sparkling prose.  Birder or not, this is a must-read for anyone with more than a passing interest in biology or animal behavior.

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




Saturday, May 23, 2020

Diagnosing what ails you

When I was a kid, my parents had a set of books called The Illustrated Encyclopedia of Modern Medicine.  Now, this was circa 1972, so keep that in mind when you read the word "modern," but for the time, they were exhaustive.

Now, I was fascinated by biology even back then, at something like age twelve, so those medical encyclopedias were a source of real curiosity for me.  Not just the pages with the naughty bits -- being right on the cusp of puberty, those were really fascinating -- but all of it.  All the systems and organs and tissues and all the different ways things could go wrong.

That's where the trouble started.  Because I was an imaginative child, I lived up to the maxim of a little bit of knowledge being a dangerous thing.  I could find a good reason why I had damn near every disease mentioned in the The Illustrated Encyclopedia of Modern Medicine.  If I coughed a couple of times... well, it could be tuberculosis.  Or pleurisy.  Or lung cancer.  (Being a twelve-year-old, I didn't smoke.  My father did, although he quit cold turkey right around that time and never had another cigarette.  Still, how much exposure to smoke was... enough?)

I even remember being in the shower and convincing myself that I had a swelling in my armpit (I didn't), and forthwith deciding that I was going to die of Hodgkins' lymphoma.  "Prognosis is poor, even with prompt treatment," said The Illustrated Encyclopedia of Modern Medicine.  So that was it, then.  So young, with such a promising future... cut short by a horrific disease.

Well, of course, it turned out I didn't have any of the above.  I did start to get migraines when I was sixteen, but that didn't take any great insight to figure out given that I had weird visual disturbances, crashing headache, sound and light sensitivity, and horrid nausea, sometimes for twenty-four hours at a time.  But that set of symptoms -- which the Medical Encyclopedia correctly informed me was typical of a migraine -- is the single time I ever self-diagnosed using the books and got it right.

Turns out I'm not the only one.  According to a paper in The Medical Journal of Australia, even today's online resources -- sites like WebMD -- only give the right answer one-third of the time.

[Image is in the Public Domain]

A team of researchers from Edith Cowan University decided to test thirty-six different online "symptom checkers" using forty-eight (anonymous) case files for which the actual answer was known, and found that the top diagnosis from the websites was correct only for a third of them.  Even if you gave them the leeway of considering the top three diagnoses, they still only hit it half the time.

The authors admit there are limitations to their study, beyond the fairly small sample size.  None of the patients had comorbid conditions -- underlying diseases that contributed to the symptoms that presented (such as circulatory failure in the feet having as its ultimate cause poorly-controlled diabetes).  And there are a wide variety of other symptom-checking websites out there, some of which may work better than the relatively poor showing these ones made.

But still.  What this indicates is that if you've got symptoms that worry you, see a doctor.  Now, yes, I know, doctors make mistakes.  They're human, and while a great many are awesome, some are certainly slipshod and careless.  So don't start regaling me with horror stories about misdiagnosis.  I have a friend who damn near died of post-operative peritonitis which was misdiagnosed as, of all things, a urinary tract infection -- so I get it.  Yes, it happens, and it's awful and tragic when it does, and sometimes crosses the line into true medical malfeasance.

But as Carl Sagan points out in his wonderful book The Demon-Haunted World: Science as a Candle in the Dark, if you're going to be fair, you have to consider the hits along with the misses.  How many people are treated daily in your average city hospital -- and of those, how many suffer the effects of significant medical bungling?  By and large, modern medicine has done astonishingly well.  At the present time we have the longest average life span the human species has ever enjoyed, and diseases that were a death sentence only a hundred years ago are now completely curable.

So please, please don't rely on self-diagnosis.  Your ten minutes of online "research" is not equivalent to your family medical practitioner's ten-plus years of education and experience.

After all, I probably did myself more damage worrying over whether I had chronic myelogenous leukemia or myasthenia gravis or Creutzfeld-Jakob syndrome than any benefit I gained from finding out about them.  I'm now 59, and have been pretty healthy overall.  I don't even get migraines any more.

But if something does go wrong, I'm gonna go to the doctor, not go running to find out what WebMD might have to say about it.

**********************************

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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




Friday, May 22, 2020

Tribal tactics

Given the right context, people tend to be cooperative.

That's the gist of a study out of the University of Texas - Austin this week, called, "Prosocial Modeling: A Meta-analytic Review and Synthesis," by Haesung Jung, Eunjin Seo, Eunjoo Han, Marlone Henderson, and Erika Patall.  If behavior is characterized as helpful to others -- such as wearing a mask during a pandemic -- it triggers similar prosocial behavior in those who witness it.


"Just like the deadly virus, cooperative behavior can also be transmitted across people,” said Haesung Jung, lead author of the study, in a press release.  "These findings remind the public that their behavior can impact what others around do; and the more individuals cooperate to stop the spread of the disease, the more likely others nearby will do the same...  We found that people can readily improvise new forms of prosocial actions.  They engaged in behaviors that were different from what they witnessed and extended help to different targets in need than those helped by the prosocial model."

It's unsurprising, given that we're social primates, that we're influenced by the behavior of those around us.  Not only do we learn by imitation, there's the tendency -- often nicknamed "peer pressure" -- to pick up behaviors, good or bad, from our friends and acquaintances, usually for reasons of group acceptance and fitting in.  I vividly remember being a graduate student at the University of Washington, where my classmates were some of the most foul-mouthed, snarky, hard-drinking folks I've ever been around.  They weren't bad people, mind you; but it definitely was the intellectual version of a "rough crowd."  It took very little time for me to adopt those behaviors myself.  We tend to conform to the norm for the group we belong to.

(Yes, I know, I still swear a lot.  I swore even more then, hard though that may be to imagine.  Like I said -- rough crowd.)

So the results of the Jung et al. study make sense.  Get the ball rolling, she suggests, and the influence we have over the people we associate with can cause an increase in the overall prosocial behavior of the group.

But.

The example the paper focuses on -- the wearing of masks during the COVID-19 pandemic -- isn't as simple as that.  This isn't simply a case of enlightened people who understand risks wearing masks and waking up the uninformed, or at least encouraging them to behave in a socially responsible manner.  Simultaneously we have a group of people who are consciously and deliberately using the same tribal tendencies to stop people from wearing masks.  From the very beginning of the pandemic, we have had Fox News bombarding their listeners with the following messages:
  • COVID is a hoax.
  • Even if it's not a hoax, it's China's fault.
  • It's really just seasonal flu, so it's nothing to worry about.
  • Okay, it's worse than the flu, but the numbers being reported, especially from blue states, are wild exaggerations made to disparage the Trump administration.
  • Which, by the way, has been doing an absolutely stellar job of managing the pandemic.
  • Wearing masks is giving in to the Democrats' alarmist propaganda.
  • All this is just the "deep state" trying to get you to give up your liberties, so it's nobler and braver to defy them and not wear a mask.
Just this morning I saw a post on social media of the "Meh, why worry?" variety, to the effect that Woodstock happened right in the middle of the Hong Kong flu epidemic, and that didn't stop people from partying.

Which may well be true, but doesn't make it smart.

So we've got a "news" outlet deliberately downplaying the danger, and worse, making it look like a conspiracy to bring down Dear Leader.  The result is that wearing masks isn't seen as prosocial, at least amongst Fox viewers; it's seen as falling for the lies of the Democrats, and thus betraying Donald Trump and everything the GOP stands for.

This kind of thinking is remarkably hard to counteract, because the Fox mouthpieces -- people like Sean Hannity, Tucker Carlson, and Laura Ingraham -- started out by training their listeners to disbelieve the facts.  The administration quickly picked up on this strategy, starting with Kellyanne Conway's infamous "alternative facts" comment, and it has proven wildly successful, if you can characterize getting a significant slice of the American public to trust nothing but the party line as "success."

As I've pointed out before, once you get people to mistrust the hard evidence itself, you can convince them of anything.

So the problem with mask-wearing in the United States is that it isn't universally being seen as a compassionate protective measure, it's seen as being a dupe.  Besides the "how others are seeing our actions" factor that Jung et al. focused on, there's "how we see ourselves" -- and if we've been trained that a behavior is going to make us look like a gullible sucker, that's going to counteract the positive forces of prosocial modeling.  (Especially if the training has included a message that the risk the behavior is supposed to protect us from doesn't exist in the first place.)

Yes, we're motivated to be compassionate and protect the people around us.  But the ugly side of tribalism is equally powerful, and we now have a group of people in charge who are callously choosing their tactics to exploit those tendencies, with the end of gaining power and money.

Until we can stop the disinformation and propaganda, the kind of prosocial modeling Jung et al. describe is unlikely to have much effect.

**********************************

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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




Thursday, May 21, 2020

Talk to the hand

I used to tease my poor, long-suffering mother because of her habit of talking with her hands.

It wasn't even necessarily when the person she was talking to was physically there in the room with her.  She talked with her hands (well, with one hand) while she was on the phone.

"Mom, they can't see you," I told her.

"I know," she said in an exasperated tone.  "I can't help it."

I got my comeuppance when I started teaching, and a student -- more than one, actually -- pointed out my habit of sculpting the air while I was explaining something.  One of them challenged me to deliver a lecture with my hands clasped behind my back.

That lasted approximately two minutes, much to the class's amusement.

So Mom, if you're listening right now, you get the last laugh.  I don't know that I can explain it any better than you did, but if I sit on my hands, I become completely tongue-tied.

[Image licensed under the Creative Commons Wikimania2009 Beatrice Murch, Talking with the hands, CC BY 3.0]

Apparently it's more or less universal, and the reason may be more than just introducing expressive body language into our conversation.  A study from the University of Connecticut released this week in Proceedings of the National Academy of Sciences found that hand gestures change the quality and intonation of our voices -- therefore communicating subtle information even if the listener can't see what our hands are doing.

In "Acoustic Information About Upper Limb Movement in Voicing," by Wim Pouw, Alexandra Paxton, Steven J. Harrison, and James A. Dixon, we read about a simple experiment -- volunteers were instructed to make a continuous vowel tone ("aaaaaaa....") into a microphone, simultaneously making rhythmic motions with the arms, while listeners in another room tried to synchronize their own arm movements with those of the vocalizers.

The ability to do that was nearly universal, even though the changes in the tonal quality were very subtle.

The authors write:
Co-speech gestures, no matter what they depict, further closely coordinate with the melodic aspects of speech known as prosody.  Specifically, gesture’s salient expressions (e.g., sudden increases in acceleration or deceleration) tend to align with moments of emphasis in speech.  Recent computational models trained on associations of gesture and speech acoustics from an individual have succeeded in producing very natural-looking synthetic gestures based on novel speech acoustics from that same individual, suggesting a very tight (but person-specific) relation between prosodic–acoustic information in speech and gestural movement.  Such research dovetails with remarkable findings that speakers in conversation who cannot see and only hear each other tend to synchronize their postural sway (i.e., the slight and nearly imperceptible movement needed to keep a person upright).
Because the entire skeletomuscular system is connected, movement of the arms and hands alters the shape/position of the chest cavity and throat, creating small changes in our vocal quality.  That, apparently, is enough to convey information to our listener, even if they can't see the gestures.

"Some language researchers don't like this idea, because they want language to be all about communicating the contents of your mind, rather than the state of your body," said study co-author James Dixon. "But we think that gestures are allowing the acoustic signal to carry additional information about bodily tension and motion.  It's information of another kind."

So add this to the long list of subtleties affecting our communications.  I still remember my Intro to Linguistics professor telling us about tonal languages like Thai, in which the pitch and/or pitch changes in vocalizing a syllable change its meaning, and he asked if we thought information in English was altered by changes in tone or stress.  One person came up with the rising pitch at the end of a sentence communicating a question, and increasing stress to indicate emphasis, but that was about it.

"Really?" he said.  "Then tell me why the following all mean something different."  And he read us this list of sentences:
  • She gave the money to him today?
  • She gave the money to him today?
  • She gave the money to him today?
  • She gave the money to him today?
  • She gave the money to him today?
Minor alterations in the way a sentence is uttered can entirely change the meaning of the words.

I guess I shouldn't have picked on my mom for talking with her hands.  Human communication is complex, and what we end up saying to our listeners can depend on a great many things beyond the exact words used.  So be careful how your hand moves when you're talking to a friend on the telephone.

You may be telling them more than you realize.

**********************************

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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




Wednesday, May 20, 2020

Mind the gap

In 1869, explorer John Wesley Powell did the first systematic study of the geology of the Grand Canyon.  As impressive as it is, the Grand Canyon's not that complicated geologically; it's made of layers of sedimentary rock, most of them relatively undeformed, one on top of the other from the oldest at the bottom to the newest at the top.  A layer cake of billions of years of Earth history, and a wonderful example of the principle of superposition -- that strata form from the bottom up.

However, Powell also noted something rather peculiar.  It's called the Great Unconformity.  In geologic parlance, an unconformity is a break in the rock record, where the layer below is separated from the layer above by a gap in time when either no rocks were deposited (in that location, at least), or the rocks that were laid down were later removed by some natural process.  At that stage in the science, Powell didn't know when exactly the Great Unconformity occurred, but it was obvious that it was huge.  Something had taken away almost a billion years' worth of rocks -- and, it was later found out, that same chunk of rock was missing not only at the future site of the Grand Canyon, but across most of North America.

It was an open question as to why this happened, but one leading hypothesis was that it was massive glaciation.  Glaciers are extraordinarily good at breaking up rocks and moving them around, as I find out every time I dig in my garden and my shovel runs into the remnants of the late Pleistocene continental glaciation.  At that point, where my house is would have been under about thirty meters of ice; the southern extent is the Elmira moraine, a line of low hills thirty miles south of here, left behind when the glaciers, pushing piles of crushed rock and soil ahead of them like a backhoe, began to melt back and left all that debris for us gardeners to contend with ten thousand years later.

There was a time in which the Earth was -- as far as we can tell -- completely covered by ice.  The Cryogenian Period, during the late Precambrian, is sometimes nicknamed the "Snowball Earth" -- and the thawing might have been one contributing factor to the development of complex animal life, an event called the "Cambrian explosion," about which I've written before.

The problem was, the better the data got, the more implausible this sounded as the cause of the Great Unconformity.  The rocks missing in the Great Unconformity seem to have preceded the beginning of the Cryogenian Period by a good three hundred million years.  And while there were probably earlier periods of worldwide glaciation -- perhaps several of them -- the fact that the Cryogenian came and went and didn't leave a second unconformity above the first led scientists away from this as an explanation.

Now, a new paper in Proceedings of the National Academy of Sciences, written by a team led by Francis Macdonald of the University of Colorado - Boulder, has come up with evidence supporting a different explanation.  Using samples of rock from Pike's Peak in Colorado, Macdonald's team used a clever technique called thermochronology to estimate how much rock had been removed.  Thermochronology uses the fact that some radioactive elements release helium-4 as a breakdown product, and helium (being a gas) diffuses out of the rock -- and the warmer it is, the faster it leaves.  So the amount of helium retained in the rock gives you a good idea of the temperature it experienced -- and thus, how deeply buried it was, as the temperature goes up the deeper down you dig.

What this told Macdonald's team is that the Pike's Peak granite, from right below the Great Unconformity, had once been buried under several kilometers of rock that then had been eroded away.  And from the timing of the removal -- on the order of a billion years ago -- it seems like what was responsible wasn't glaciation, but the formation of a supercontinent.

But not Pangaea, which is what most people think of when they hear "supercontinent."  Pangaea formed much later, something like 330 million years ago, and is probably one of the factors that contributed to the massive Permian-Triassic extinction.  This was two supercontinents earlier, specifically one called Rodinia.  What Macdonald's team proposes is that when Rodinia formed from prior separate plates colliding, this caused a huge amount of uplift, not only of the rocks of the continental chunks, but of the seafloor between them.  A similar process is what formed the Himalayas, as the Indian Plate collided with the Eurasian Plate -- and is why you can find marine fossils at the top of Mount Everest.

[Image is in the Public Domain]

When uplift occurs, erosion increases, as water and wind take those uplifted bits, grind them down, and attempt to return them to sea level.  And massive scale uplift results in a lot of rock being eroded.

Thus the missing layers in the Great Unconformity.

"These rocks have been buried and eroded multiple times through their history," study lead author Macdonald said, in an interview with Science Daily.  "These unconformities are forming again and again through tectonic processes.  What's really new is we can now access this much older history...  The basic hypothesis is that this large-scale erosion was driven by the formation and separation of supercontinents.  There are differences, and now we have the ability to perhaps resolve those differences and pull that record out."

What I find most amazing about this is how the subtle chemistry of rock layers can give us a lens into the conditions on the Earth a billion years ago.  Our capacity for discovery has expanded our view of the universe in ways that would have been unimaginable only thirty years ago.

And now, we have a theory that accounts for one of the great geological mysteries -- what happened to kilometer-thick layers of rock missing from sedimentary strata all over North America.

John Wesley Powell, I think, would have been thrilled.

**********************************

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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




Tuesday, May 19, 2020

Danger down under

Following hard on the heels of Saturday's post, which started with a description of the cassowary -- Australia's killer bird -- today we follow up with a paper in Nature Communications just yesterday that falls under the "You think things are bad now?" department.

It's not like modern Australian wildlife is anything to trifle with.  The country is where you can find some of the world's most dangerous snakes, including the taipan, the brown snake, and the tiger snake.  The north coast is home to the enormous and aggressive saltwater crocodile, while the south coast has a sizable population of great white sharks.  The eastern coast, not to be outdone, is where you can run into the harmless-looking box jellyfish, which is in contention for winner of the most-potent venom contest; it injects its victim with a substance that has an LD-50 of 0.04 milligrams per kilogram of body weight, and can kill in under five minutes if an antidote isn't administered.  Even the plants bear watching.  The north coast has the beach spinifex grass, which reinforces the pointed tips of its leaves with silica drawn from the soil, essentially turning the plant into a cluster of tiny glass shards.  Worst of all is the gympie-gympie, which is like the humongous nettle from hell, inflicting an excruciating sting that can last for years.

(The Wikipedia article I linked says that the fruit of the gympie-gympie is "edible if the stinging hairs are removed first."  To which I respond, "Do I look like a fucking lunatic to you?"  I'll stick with fruit that's not attempting to murder me, thanks.)

But the paper "Extinction of Eastern Sahul Megafauna Coincides with Sustained Environmental Deterioration," by a team led by Scott Hocknull of the University of Melbourne, gives you a good feeling for how much worse it could be.  It describes a treasure-trove of fossils from Walker Creek in northeastern Australia that had the remains of hitherto-unknown species of fauna, including:
  • a thus-far unclassified kangaroo that was four meters tall and weighed just shy of three hundred kilograms
  • a new species of the genus Diprotodon, which was basically a wombat on steroids -- it's estimated to have been two meters tall at the shoulder and had a mass of 2,500 kilograms
  • a new species of the horrific carnivorous marsupial Thylacoleo, which was slightly smaller than your average African lion, but is estimated to have had the most powerful bite of any known mammal, living or extinct
  • a six-meter-long goanna and two never-before-seen species of monitor lizards
  • a land-dwelling crocodile, because apparently the water-dwelling ones weren't bad enough
Artist's reconstruction of Thylacoleo carnifex [Image licensed under the Creative Commons Nobu Tamura (http://spinops.blogspot.com), Thylacoleo BW, CC BY 3.0]

The kicker is that these things were around after the colonization of Australia by humans, and in fact, by some estimates there was a fifteen thousand year overlap where the ancestors of today's Native Australians had to contend with a nightmarish megafauna.  Me, I wonder why they stuck around, you know?  If I was one of them, and landed in my boat on the shores of Australia, and saw land crocodiles and six-meter-long lizards and a lion-sized Tasmanian devil, I would have used the words of the inimitable Eric Cartman: "Screw you guys, I'm goin' home."

Of course, home was Papua-New Guinea, which honestly wasn't all that much better.

It's an interesting question as to what finally did in these formidable critters.  Hocknull et al. write the following, in an article in The Conversation:
Why did these megafauna become extinct?  It has been argued that the extinctions were due to over-hunting by humans, and occurred shortly after people arrived in Australia. 
However, this theory is not supported by our finding that a diverse collection of these ancient giants still survived 40,000 years ago, after humans had spread around the continent. 
The extinctions of these tropical megafauna occurred sometime after our youngest fossil site formed, around 40,000 years ago.  The timeframe of their disappearance coincided with sustained regional changes in available water and vegetation, as well as increased fire frequency.  This combination of factors may have proven fatal to the giant land and aquatic species.
As magnificent as these creatures undoubtedly were, it's probably better that they're gone.  I've heard Australia is a pretty cool place, even considering its dangerous flora and fauna, but if the animals of Walker Creek were still around, it'd be hard to understand how anyone could manage to live there.  Just taking a short walk to the grocery store would be risking getting dismembered by enormous carnivorous marsupials.

Makes today's snakes and crocodiles and whatnot seem tame by comparison, doesn't it?

**********************************

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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




Monday, May 18, 2020

Quick takes

Today I'd like to look at three topics that came up for one reason or another in the last few days.

First, have you ever thought about catnip?  It's peculiar stuff.  A member of the mint family, Nepeta cataria (no, I didn't make up the species name) is a rather un-showy plant with gray-green stems and off-white flowers.  Its strangest characteristic, as I'm sure you know, is that it produces what amounts to kitty drugs.  The chemical nepetalactone is produced in significant quantities by the plant, and is responsible not only for its musky smell but for its apparent psychedelic effects on cats.  Cats who are susceptible to it -- and some, I understand, are not, although every cat I owned was a total catnip junkie -- purr, roll around in it, become playful and frisky, and their eyes dilate.

[Image licensed under the Creative Commons AlishaLH, Bee on Catnip Flowers, CC BY 4.0]

Clearly this is an accident; it's hard to imagine a plausible scenario in which the trait of producing this chemical evolved for the express reason of making cats flail around.  There's a presumption that it has a repellent effect on insects, which is certainly true about a lot of the aromatic substances produced by plants, but that's unsubstantiated.

The reason this comes up is that scientists at the Max Planck Institute of Chemical Ecology have decoded the genome of catnip, and they found that the nepetalactone gene apparently evolved more than once.  There are inactive "pseudogenes," stretches of DNA whose function has been lost over time to mutations, nearly identical to the current (functional) nepetalactone gene.  So evidently the gene evolved a second time, probably from another gene for producing chemicals of the class nepetalactone belongs to (the iridioids, which sounds like an alien species on Doctor Who but isn't), and then was advantageous enough that it kind of went into overdrive in catnip.

Apparently whatever its function is, it's important for more than getting kitties high.

So we're not the only species that has a strange psychological reaction to various naturally-produced chemicals in plants.  It's a good thing, though, that there's no such thing as (for example) moosenip, because the idea of a bunch of moose frolicking about and rolling around in your front yard is a little terrifying.


The next story comes from some research released last week by NASA's Transiting Exoplanet Survey Satellite (TESS), which made an interesting discovery about a rather odd kind of star.  Called Delta Scuti stars (after the first star identified in this class), they are a pulsating variable that are more common than astronomers thought at first -- there's good evidence that the bright stars Altair and Denebola, in the constellations Aquila and Leo respectively, are also in this class.

What makes these stars so odd is not their fluctuations -- periodic variable stars are actually rather common -- but that some parts of the star move outward and dim, and other parts pull inward and brighten, at the same time.  The whole star, therefore, seems to ripple.  The astrophysicists believe this is because as parts of the star heat up, more of the helium in the outer shell becomes ionized; ionized helium is more opaque to light, so it blocks light trying to escape from the core and balloons outward.  Once it cools, it falls back inward, and since this happens at different times in different places on the surface of the star, there are pulsations in not only the overall brightness of the star, but which parts of the star are bright and which are dim.

A paper in Nature last week showed that their behavior may not be as chaotic as it seemed at first.  Data from TESS has shown that these surface fluctuations have their own kind of periodicity -- some, for example, seem to contract and expand one hemisphere at a time, not at random places on the star.

"Delta Scuti stars have been frustrating targets because of their complicated oscillations, so this is a very exciting discovery," said Sarbani Basu, a professor of astronomy at Yale, who studies asteroseismology but was not involved in the study, in an interview in Science Daily.  "Being able to find simple patterns and identify the modes of oscillation is game changing.  Since this subset of stars allows normal seismic analyses, we will finally be able to characterize them properly."


Last, I was contacted by a reader regarding last week's post about the presence of iridescence in the fossilized feathers of ancient birds, with a question as to whether this discovery might shed any light on the presence of tetrachromacy in birds.  You probably know that (most) humans are trichromats -- we have three different kinds of color-detecting cones in the retina of the eye, sensitive to blue, green, and red wavelengths.  The combination of these three gives us our perception of color.

Mammals, apparently, descend from animals that were tetrachromats -- they had four different cones, and presumably, a more highly refined sense of color detection than humans have.  But in most mammals, such as dogs, there were mutations that knocked out two of the genes responsible -- similar to the loss of the catnip gene described earlier -- leaving behind two functioning cone types, and poorer color discrimination.

Some humans -- almost all are female -- have a fourth working cone, and are true tetrachromats.  This is undoubtedly why when my wife and I are going out, a common comment from her is, "Seriously?  You think that shirt matches those pants?"  Saying my aesthetic sense, especially when it has to do with sartorial matters, is poorly developed is kind of a massive understatement.

Birds -- at least the species that have been tested -- seem to all be tetrachromats, which may be why so much of their display behavior has to do with flashing bright colors around.  The presence of feather iridescence in birds from 52 million years ago may be an indication that they've been able to do this for a very long time.

It must be said, however, that the record holder for number of different kinds of color-sensitive photoreceptor is the mantis shrimp, which (depending on species) has between twelve and sixteen independent kinds of cones.  You have to wonder what the world looks like to them, don't you?


So that's three quick takes from the world of science.  And thanks to the reader who suggested a post on tetrachromacy -- it's a fascinating subject, well worth a look.  So keep those cards and letters comin'.

**********************************

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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