Collision of galaxies

When I was an undergraduate at the University of Louisiana, I and several of my friends were blown away by the original series Cosmos, written and narrated by Carl Sagan.

Monday mornings, we gathered in the student lounge, eagerly discussing whatever mind-blowing filigree of physics had been the subject of that week's episode.  I still recall one of the ones that made the biggest impression on me -- the tenth episode, "The Edge of Forever," which included, among many other things, wonderful simulations of the motion of stars within a galaxy, and what happens when two galaxies collide.  (You can watch a clip of it here.)  The simulations were (at the time) state-of-the-art, and certainly enough to blow the mind of a sophomore physics student like myself; what struck me most was that galaxies aren't rigid, and their constituent stars don't "hang together," but move independently around the massive black hole at the galactic core.  This can settle down into a shape that seems pretty stable -- such as the spiral pattern of the Milky Way -- or it can destabilize, flinging stars out into space, exploding the galaxy and scattering its pieces across hundreds of thousands of light years.

Sagan, of course, put it best: "A galaxy is a fluid made of a billion suns, all bound together by gravity."

When galaxies collide, it disrupts both completely; at the same time, collisions between the stars themselves are extremely uncommon.  However big the stars are, they're still minuscule with respect to the galaxies that contain them.  It's like the atoms writ large, isn't it?  The seemingly solid matter around you is made up of tiny charged particles interacting through the force of electromagnetism, but in between those particles is... nothing.  Matter is mostly empty space, and only seems solid because you're feeling the mutual repulsion of the electrons in your fingers and the electrons on the surface of whatever you're touching.  Likewise, most of interstellar space is very close to nothing, and the galaxies themselves are made up of particles (stars) interacting through a different force (gravity), and separated by vast, empty voids.

Makes you almost think that the pagans might have been on to something with their dictum of "As above, so below."

Map of the Milky Way, as it would look from above the galactic disk [Image licensed under the Creative Commons 鄭興武和馬克 裡德（Mark J. Reid）銀河系棒和旋臂結構遺產性巡天(BeSSeL)項目組/南京大學/哈佛-斯密松天體物理中心., Milky Way large, CC BY-SA 4.0]

This topic, and my reminiscences of Cosmos, come up because of a paper in Nature Astronomy last week called "Evidence for a Vast Prograde Stellar Stream in the Solar Vicinity," by a team led by astronomer Lina Necib of the California Institute of Technology.  What this paper tells us is something stunning; there is a streamer of stars in the Milky Way that started out somewhere else, and collided with our galaxy.  Rather fortunately, apparently the angle and velocity with which the streamer hit were more or less the same direction the original galaxy was turning, so these stars simply got sucked in, like some bits of debris going down a whirlpool.

The streamer has been named Nyx, after the Greek goddess of the night.  250 stars have been identified as being part of Nyx.  "The two possible explanations here are that they are the remnants of a [galactic] merger, or that they are disk stars that got shaken into their new orbits because of a collision with the disk of the Milky Way," said study lead author Lina Necib, in an interview with CNN.  The likelihood, though, is the former, something that is expected to be confirmed by chemical analysis of the constituent stars.  "Galaxies form by swallowing other galaxies," Necib said. "We've assumed that the Milky Way had a quiet merger history, and for a while it was concerning how quiet it was because our simulations show a lot of mergers.  Now, we understand it wasn't as quiet as it seemed.  We're at the beginning stages of being able to really understand the formation of the Milky Way."

I think it's stunning that we can figure out this sort of thing at all -- that 250 out of the estimated 250 billion stars in the Milky Way started out somewhere else in the universe.  I think that's pretty damn impressive.  "This particular structure is very interesting because it would have been very difficult to see without machine learning," Necib said.  "I think we reached a point in astronomy where we are not data limited anymore.  This project is an example of something that would have not been possible a few years ago, the culmination of developments in data with Gaia, high resolution simulations, and machine learning methods."

How pleased and amazed Carl Sagan would have been.  He went a long way toward bringing the wonders of the universe, from the largest scales to the smallest, to laypeople.  He certainly blew the minds of me and my friends, and that was back in 1980.  Necib's comment, that we're still at the beginning of being able to understand the formation of galaxies, tells us that we have a long way still to go -- and that many, many more eye-opening discoveries are sure to come our way in the next years.

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This week's Skeptophilia book of the week is for anyone fascinated with astronomy and the possibility of extraterrestrial life: The Sirens of Mars: Searching for Life on Another World, by Sarah Stewart Johnson.

Johnson is a planetary scientist at Georgetown University, and is also a hell of a writer.  In this book, she describes her personal path to becoming a respected scientist, and the broader search for life on Mars -- starting with simulations in the most hostile environments on Earth, such as the dry valleys of central Antarctica and the salt flats of Australia, and eventually leading to analysis of data from the Mars rovers, looking for any trace of living things past or present.

It's a beautifully-told story, and the whole endeavor is tremendously exciting.  If, like me, you look up at the night sky with awe, and wonder if there's anyone up there looking back your way, then Johnson's book should be on your reading list.

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

Facing facts

"I'm sorry, but I have no idea who you are."

I can't tell you how many times I've had to utter that sentence.  Regular readers of Skeptophilia know why; I have a peculiar disability called prosopagnosia, or "face blindness."  I have a nearly complete inability to recognize faces, even of people I've known for some time.

Well, that's not exactly true.  I recognize people differently than other people do.  I remember the people I know as lists of features.  I know my wife has curly brown hair and freckles and an infectious smile, but I honestly have no mental image of her.  I can't picture my own face, although -- like with my wife -- I could list some of my features.

That system doesn't have a high success rate, however, and a lot of the time I have no idea who the people around me are, especially in a place where there are few clues from context.  I have pretty serious social anxiety, and my condition makes it worse, having put me in the following actual situations:

• introducing myself twice to the same person at a party
• getting a big, enthusiastic hug and an "it's been so long!" from someone in our local gym, and never figuring out who I was talking to
• having two of my students switch seats and not realizing it for three weeks, until finally they 'fessed up
• going to see a movie, and not knowing until the credits rolled that the main characters were played by Kenneth Branagh, Penelope Cruz, Judi Dench, Derek Jacobi, Michelle Pfeiffer, Daisy Ridley, and Johnny Depp
• countless incidents of my fishing for clues ("so, how's your, um... spouse, parents, kids, pets, job..."), sometimes fruitlessly

My anxiety has made me really good at paying attention to, and recalling, other cues like voice, manner of dress, posture, walk, hair style, and so on.  But when one or more of those change -- such as with the student I had one year who cut her hair really short during the summer, and whom I didn't recognize when she showed up in one of my classes on the first day of school the following year -- it doesn't always work.

One up side to the whole thing is that I do get asked some funny questions.  One student asked me if when I looked at people, their faces were invisible.  Another asked me if when I look in the bathroom mirror in the morning, I don't know that's me.  (It's a pretty shrewd guess that it is me, since there's generally no one else in there at the time.)

But at least it's not as bad as the dumb questions that my former students who are identical triplets sometimes get.  One of them was once asked by a friend how she kept track of which triplet she was.

No, I'm not kidding.  Neither, apparently, was the person who asked the question.

[Image licensed under the Creative Commons Randallbritten, FaceMachine screenshots collage, CC BY-SA 3.0]

In any case, all of this comes up because of some research that came out in the journal Cortex last week that tried to parse what's happening (or what's not happening) in the brains of people like me.  Some level of prosopagnosia affects about one person in fifty; some of them lose their facial recognition ability because of a stroke or other damage to the fusiform gyrus, the part of the brain that seems to be a dedicated face-memory module.  Others, like me, were born this way.  Interestingly, a lot of people who have lifelong prosopagnosia take a while to figure it out; for years, I just thought I was unobservant, forgetful, or a little daft.  (All three of those might be true as well, of course.)  It was only after I had enough embarrassing incidents occur, and -- most importantly -- saw an eye-opening piece about face blindness by Leslie Stahl on 60 Minutes, that I realized what was going on.

In any case, last week's paper looked at trying to figure out why people who are face-blind often do just fine on visual perception tests, then fail utterly when it comes to remembering photographs of faces.  The researchers specifically tried to parse whether the difference was coming from an inability to connect context cues to the face you're seeing (e.g., looking at someone and thinking, "She's the woman who was behind the counter at the library last week") versus simple familiarity (the more nebulous and context-free feeling of "I've seen that person before").  They showed each test subject (some of whom weren't face-blind) a series of 120 faces, then a second series of 60 faces where some of them were new and some of them were in the previous series.  The researchers were not only looking for whether the subjects could correctly pick out the old faces, but how confident they were in their answers -- the surmise being that low confidence on correct answers was an indicator of relying on familiarity rather than context memory.

The prosopagnosics in the test group not only were bad at identifying which faces were old and which ones they'd seen before; but their confidence was really low, even on the ones they got right.  Normally-sighted people showed a great deal more certainty in their answers.  What occurs to me, though, is that knowing they're face-blind would skew the results, in that we prosopagnosics are always doubtful we're recalling correctly.  So these data could be a result of living with the condition, not some kind of underlying mechanism at work.  I almost never greet someone first, because even if I think I might know them, I'm never certain.  A lot of people think I'm aloof because of this, but the reality is that I honestly don't know which of the people I'm seeing are friends and which are total strangers.

One thing about the researchers' conclusion does ring true, however.  The subconscious "feeling of familiarity" is definitely involved.  My experience of face blindness isn't that I feel like I'm surrounded by strangers; it's more that everyone looks vaguely familiar.  The problem is, that feeling is no stronger when I see a close friend than when I see someone I've never met before, so the intensity of that sense -- what apparently most people rely on -- doesn't help me.

So that's the view of the world through the eyes of someone who more often than not doesn't know who he's looking at.  Fortunately for me, (1) at this point in my life I'm unembarrassed by my condition, and (2) most of the people in my little village know I'm face-blind and will say, "Hi, Gordon, it's Steve..." when they walk up, and spare me the awkwardness of fishing for clues.  (Nota bene: This only works if it actually is Steve.  Otherwise it would be even more awkward.)  But hopefully some good will come from this research, because face blindness is kind of a pain in the ass.

"Our results underscore that prosopagnosia is a far more complex disorder that is driven by more than deficits in visual perception," said study first author Anna Stumps, a researcher in the Boston Attention Learning Laboratory at VA Boston.  "This finding can help inform the design of new training approaches for people with face blindness."

Which would be really, really nice.

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This week's Skeptophilia book of the week is for anyone fascinated with astronomy and the possibility of extraterrestrial life: The Sirens of Mars: Searching for Life on Another World, by Sarah Stewart Johnson.

Johnson is a planetary scientist at Georgetown University, and is also a hell of a writer.  In this book, she describes her personal path to becoming a respected scientist, and the broader search for life on Mars -- starting with simulations in the most hostile environments on Earth, such as the dry valleys of central Antarctica and the salt flats of Australia, and eventually leading to analysis of data from the Mars rovers, looking for any trace of living things past or present.

It's a beautifully-told story, and the whole endeavor is tremendously exciting.  If, like me, you look up at the night sky with awe, and wonder if there's anyone up there looking back your way, then Johnson's book should be on your reading list.

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

Cat tales

Humans have been keeping pets for a very long time.

A lot of it now is companionship, and I have to admit that despite Guinness having to play fetch-the-tennis-ball for several hours a day so he runs off enough energy that he won't get fidgety and eat the sofa, he's kind of entertaining to have around.  The thought is that dogs probably began the human/canine relationship as fierce and loyal guardians of home and hearth, and from there moved into closer emotional links, ultimately giving rise to phenomena like pugs wearing knitted sweaters with matching stocking caps.

Cats, on the other hand, aren't much good at home security, and at first were most likely kept around as mousers.  It must be said, however, that all of the cats I've owned were kind of non-starters as mousers.  They mostly specialized at sitting around looking bored, only moving when the block of sunshine they were occupying had the nerve to go somewhere else.  In my experience, they were more like dubiously-useful home décor items that pooped in a box in the laundry room.

Still, the human/feline association goes back a long way as well.  Back in 2017 a study at the Jacques Monod Institute in Paris used mitochondrial DNA from both ancient cat skeletons and modern cats to show that people were bringing cats with them when they migrated as long ago as 4,500 B.C.E.  The researchers used the frequency of the "blotched tabby" allele -- a gene that causes cats to have swirls of color in their coats instead of parallel stripes -- followed human migration patterns throughout the Middle East and Europe, making cat genetics a useful tool in determining where their human owners traveled.

[Image licensed under the Creative Commons Helgi Halldórsson from Reykjavík, Iceland, Cute cat (1698598876), CC BY-SA 2.0]

This wasn't the first study to connect cat genetics with human migration.  All the way back in 1977, an article in Scientific American by Neil Todd showed that the polydactyly gene -- which gives cats six toes per foot -- jumped from colonial New England to Nova Scotia and New Brunswick after the British lost the Revolutionary War.  A lot of Loyalists went to Canada and apparently brought their six-toed cats with them, creating pockets of high frequency of that allele in areas where the Loyalists ended up.

In 2005 a study appeared in the Journal of Heredity that created a family tree for 32 different cat populations, focusing particularly on cats in Arkansas and Tennessee, and found that the genetics of domestic cats was consistent with the genetics of whoever settled the area -- that places predominantly settled by people of Scottish descent, for example, still today have cats that are more closely related to their Scottish cousins than to cats in France or Switzerland.  It's kind of fascinating to think that our kitties here in the United States have their own migration patterns, from the Middle East to Europe to America, and that the routes they took are the same ones followed by their human owners.

The reason all this comes up is a study that showed up this week in Nature Scientific Reports called "The Earliest Domestic Cat on the Silk Road," by a team led by A. F. Haruda of the University of Exeter.  In it we find that pet cats -- not just practical semi-feral barn cats -- were being kept by Kazakh pastoralists a thousand years ago.

The authors write:

We present the earliest evidence for domestic cat (Felis catus L., 1758) from Kazakhstan, found as a well preserved skeleton with extensive osteological pathologies dating to 775–940 cal CE from the early medieval city of Dzhankent, Kazakhstan.  This urban settlement was located on the intersection of the northern Silk Road route which linked the cities of Khorezm in the south to the trading settlements in the Volga region to the north and was known in the tenth century CE as the capital of the nomad Oghuz.  The presence of this domestic cat, presented here as an osteobiography using a combination of zooarchaeological, genetic, and isotopic data, provides proxy evidence for a fundamental shift in the nature of human-animal relationships within a previously pastoral region.  This illustrates the broader social, cultural, and economic changes occurring within the context of rapid urbanisation during the early medieval period along the Silk Road.

The study looked at an amazingly complete cat skeleton that was buried beside a trade route.  What was remarkable was that the cat had apparently had a rough life -- it had several broken bones -- but those bones had healed, meaning it had been cared for post-injury.  Isotopic analysis of its bones showed that it had a very high protein diet, suggesting it was fed by humans rather than foraging on its own.  Toward the end of its life, it lost most of its teeth, so the fact that its diet remained good throughout is a pretty good indicator that someone was caring for it as a prized pet.

We often associate reverence for cats with the ancient Egyptians, but it's clear they weren't the only ones who held our feline friends in high regard.  We've been fond of our companion animals for a very long time, and wherever we go, they do.

Which I think is pretty sweet.  Even if they're only useful as décor.

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

This week's Skeptophilia book of the week is for anyone fascinated with astronomy and the possibility of extraterrestrial life: The Sirens of Mars: Searching for Life on Another World, by Sarah Stewart Johnson.

Johnson is a planetary scientist at Georgetown University, and is also a hell of a writer.  In this book, she describes her personal path to becoming a respected scientist, and the broader search for life on Mars -- starting with simulations in the most hostile environments on Earth, such as the dry valleys of central Antarctica and the salt flats of Australia, and eventually leading to analysis of data from the Mars rovers, looking for any trace of living things past or present.

It's a beautifully-told story, and the whole endeavor is tremendously exciting.  If, like me, you look up at the night sky with awe, and wonder if there's anyone up there looking back your way, then Johnson's book should be on your reading list.

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

Genes on loan

I wonder what the early pioneers of genetics -- people like Gregor Mendel, Thomas Hunt Morgan, Reginald Punnett, and William Bateson -- would think if they could peruse a modern genetics textbook.

My hope is that they'd be delighted beyond words at where the science has gone since their time.  The simple foundation laid down by the first geneticists has been elaborated and modified into a complex, far-reaching science that has explanatory power from the molecular level to the characteristics of the organisms themselves (the phenotypes, or physical expressions, of the genes).  And now, just over 150 years after the publication of Mendel's book on statistical genetics that showed that inheritance of traits followed natural laws and generated predictable statistics, we're still adding to what we know.

Take the paper that came out in Nature this week, that describes a fascinating exception to Mendel's Law of Independent Assortment (one of his four laws of statistical genetics).  The Law of Independent Assortment says that every gene inherits by its own separate statistics.  Put another way, genes don't inherit in chunks; each one is its own flip of the coin.  Here's an example:

Let's say your mom inherited a type A blood type gene and an Rh negative gene from her father, and a type B blood type gene and an Rh positive gene from her mother.  (This, by the way, would make her AB+.)  Now, she passed on to you her father's type A gene.  Which Rh gene did you get?

Answer: by the Law of Independent Assortment, there's no way to be sure. Knowing she passed on her father's type A gene doesn't make it any more likely you got her father's Rh negative gene; each gene operates by its own statistics, and the inheritance of one gene does not influence the inheritance of any other.

Well, we've known about some exceptions to that law for years; in fact, the aforementioned Bateson and Punnett were the ones who figured out what was going on with the discovery of linked genes, genes that lie near each other on the same chromosome.  In my earlier example, if the ABO blood type gene and the Rh+/- gene were close together on the same chromosome (they're not), then inheriting the A gene from her dad would make you more likely to also get the negative gene from her dad.  (You may be wondering why, if they're on the same chromosome, it doesn't make the likelihood of their inheriting together 100%; that's a whole 'nother topic, called crossing over, which I won't explain in this post because otherwise we'll never get to the recent research.)

The paper in Nature, called "Massive Haplotypes Underlie Ecotypic Differentiation in Sunflowers," by a huge team led by the trio of Marco Todesco, Gregory Owens, and Natalia Bercovich of the University of British Columbia, describes how the inheritance of huge chunks of DNA -- hundreds of millions of base pairs long, inherited as a single block -- has allowed related species of sunflowers to grab beneficial traits from each other and triggered differentiation and, ultimately, the formation of new species.

[Image is in the Public Domain]

The authors write:

Species often include multiple ecotypes that are adapted to different environments.  However, it is unclear how ecotypes arise and how their distinctive combinations of adaptive alleles are maintained despite hybridization with non-adapted populations.  Here, by resequencing 1,506 wild sunflowers from 3 species (Helianthus annuus, Helianthus petiolaris and Helianthus argophyllus), we identify 37 large (1–100 Mbp in size), non-recombining haplotype blocks that are associated with numerous ecologically relevant traits, as well as soil and climate characteristics.  Limited recombination in these haplotype blocks keeps adaptive alleles together, and these regions differentiate sunflower ecotypes.  For example, haplotype blocks control a 77-day difference in flowering between ecotypes of the silverleaf sunflower H. argophyllus (probably through deletion of a homologue of FLOWERING LOCUS T (FT)), and are associated with seed size, flowering time and soil fertility in dune-adapted sunflowers.  These haplotypes are highly divergent, frequently associated with structural variants and often appear to represent introgressions from other—possibly now-extinct—congeners. These results highlight a pervasive role of structural variation in ecotypic adaptation.

Catch that last bit?  Some of these "supergenes," as they're called, could have come from now-extinct species, whose DNA still exists and is still influencing the evolution of a different species.  How cool is that?

"What we think could have happened is that a species arrives in a new habitat, 'steals' adaptive supergenes from a local related species, and then replaces that species," said study co-lead author Marco Todesco, in an interview with Science Daily.  "We could call this a 'ghost supergene', the lingering contribution of a species that no longer exist."

How Gregor Mendel and the pioneers that followed would have been fascinated by all this!  We've come a tremendously long way from Mendel's mysterious "factors" (what we now call alleles) and the simplistic probabilities that generate the inheritance of flower color in pea plants.  Even the linked genes of Bateson and Punnett now seem like only the prologue to the story.

And what's more mindblowing still is that to geneticists in a hundred years hence, even what we know now will still probably only be chapter one.

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This week's Skeptophilia book recommendation of the week is for anyone who likes quick, incisive takes on scientific topics: When Einstein Walked with Gödel: Excursions to the Edge of Thought by the talented science writer Jim Holt.

When Einstein Walked with Gödel is a series of essays that explores some of the deepest and most perplexing topics humanity has ever investigated -- the nature of time, the implications of relativity, string theory, and quantum mechanics, the perception of beauty in mathematics, and the ultimate fate of the universe.  Holt's lucid style brings these difficult ideas to the layperson without blunting their scientific rigor, and you'll come away with a perspective on the bizarre and mind-boggling farthest reaches of science.  Along the way you'll meet some of the key players in this ongoing effort -- the brilliant, eccentric, and fascinating scientists themselves.

It's a wonderful read, and anyone who is an aficionado of the sciences shouldn't miss it.

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

Big voices

One of the funniest scenes in the Monty Python movie Life of Brian is when a man is condemned to be stoned for saying "Jehovah," and the High Priest (played by John Cleese) is facing a crowd which is already armed with stones, ready to carry out the sentence.  The crowd, unbeknownst to the High Priest, is made up of women (who by law are forbidden from being there), and it's even funnier because that means the crowd was men playing women who were pretending they were men.

Well, at one point in the proceedings, the High Priest says the word "Jehovah" and gets clunked in the head by a rock.  He then demands to know who threw the rock.

A chorus of high-pitched, pseudo-feminine voices shouts, "She did!  She did!  She did!... um...."  (continuing in deeper, masculine voices)  "He did!  He did!  He did!"

This was the first thing my rather loopy brain thought of when I read a paper yesterday in Biology Letters.  In "Acoustic Allometry and Vocal Learning in Mammals," by Maxime Garcia (of the University of Zurich) and Andrea Ravignani (of the Max Planck Institute for Psycholinguistics), we find out that "dishonest signaling" -- using a voice that makes you sound bigger or more threatening than you actually are -- has been found in dozens of mammalian species.

The authors write:

Vocal production learning (VPL) can be defined as the experience-driven ability, rare among mammals, to modify existing vocalizations, to produce novel sounds or to imitate sounds that do not belong to an individual's vocal repertoire...  VPL inherently involves modulation of acoustic features related to the source, filter or both.  Yet, different species have varying degrees of control over the anatomical components involved in phonation.  For instance, despite a generally assumed lack of vocal control some non-human primates might have limited sound production plasticity, including for non-voiced sounds.  While the presence of VPL in non-human primates is debated, strong evidence for VPL has been found to date in humans and four other mammalian clades: non-otariid Pinnipedia, Elephantidae, Chiroptera and Cetacea.

"If you saw a Chihuahua barking as deep as a Rottweiler, you would definitely be surprised," said study co-author Andrea Ravignani, in an interview with Science Daily.  "Nature is full of animals like squeaky-Rottweilers and tenor-Chihuahuas...  Some animals fake their size by developing larger vocal organs that lower their sound, which makes them sound larger than you would expect.  Other animals are good at controlling the sounds they produce.  Such strategies -- 'dishonest signaling' -- could be driven by sexual selection, as males with larger body size or superior singing skills (hitting very high or low notes) attract more females (or vice versa)."

I know one good example of little animal/big voice from my own back yard -- the Carolina Wren (Thryothorus ludovicianus).  It's a tiny thing, what birders call an "LBJ" (Little Brown Job), but its outsized shriek of "TEAKETTLE TEAKETTLE TEAKETTLE" frequently wakes me up at four in the morning during the spring and early summer, especially given that there's one of 'em who likes to sing from the branches of the box elder tree right outside my bedroom window.  But this is volume, not pitch.  For misleading pitch, there's none that can compete -- at least in the bird world -- with the Great Potoo (Nyctibius grandis) of the rainforests of South America.  Take a listen to this:

Since this bird is nocturnal, and (as you can see) is very cryptically colored, a lot of the natives didn't realize that sound was a bird for a long time.  Their explanation -- that there was a horrible monster out there in the forest roaming around at night -- is completely understandable, given what its vocalizations sound like.

So the capacity to create misleading sounds isn't the sole provenance of the Monty Python crew's fake falsettos.  There are lots of animal species that do the same thing, either to frighten off potential predators or to sound sexier for potential mates.

Or, perhaps, to give a misleading answer to questions like, "Are there any women here today?... good, very well then."

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

This week's Skeptophilia book recommendation of the week is for anyone who likes quick, incisive takes on scientific topics: When Einstein Walked with Gödel: Excursions to the Edge of Thought by the talented science writer Jim Holt.

When Einstein Walked with Gödel is a series of essays that explores some of the deepest and most perplexing topics humanity has ever investigated -- the nature of time, the implications of relativity, string theory, and quantum mechanics, the perception of beauty in mathematics, and the ultimate fate of the universe.  Holt's lucid style brings these difficult ideas to the layperson without blunting their scientific rigor, and you'll come away with a perspective on the bizarre and mind-boggling farthest reaches of science.  Along the way you'll meet some of the key players in this ongoing effort -- the brilliant, eccentric, and fascinating scientists themselves.

It's a wonderful read, and anyone who is an aficionado of the sciences shouldn't miss it.

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

Reptilian splits

One of my favorite lectures in my AP Biology class was about how there's no such thing as a reptile.

If you took your last biology class before about 1995, you probably learned about Class Reptilia, containing turtles, lizards, snakes, crocodiles, alligators, and a few other assorted groups.  The class was defined by having dry, scaly skin, internal fertilization, "amniote" eggs with shells, and hearts that had incomplete septa (the wall down the center that separates the oxygenated left side from the deoxygenated right side).

Well, the last one wasn't 100% true, and that should have been a clue to what was going on.  Crocodiles and alligators have four-chambered hearts, and are also partial endotherms -- they show some capacity for internally regulating their own body temperatures, just as birds and mammals do.

It was genetic testing that finally settled who was related to whom, and that was when a lot of us got a shock (not so much the evolutionary biologists, who kind of expected this was how it was gonna work out).  The word "reptile" has no real taxonomic significance, because it lumps together groups that really aren't very closely related, and excludes others that are closer.  Here's how this branch of Kingdom Animalia evolved:

As you can see from the diagram, the problem was birds.  Crocodiles are more closely related to birds than they are to lizards (despite superficial appearance); and if you throw dinosaurs into the mix, it becomes even clearer, because birds are dinosaurs.

Think about that the next time you feed the chickadees.

So if you throw all the reptiles together, by the rules of cladistic taxonomy, you'd have to include birds, and nobody much wanted to call birds reptiles.  So the entire Class Reptilia was broken up, now as three different classes: Lepidosauria (lizards, snakes, and the oddball tuatara of New Zealand), Testudines (turtles), and Crocodilia (obviously crocodiles et al.).  Birds have their own class (Aves).

But what this brings up is how such different-looking animals as turtles and snakes evolved from a common ancestor.  The differences between the different groups of reptiles is pretty dramatic.  The explanation has usually been that it was adaptive radiation, a phenomenon that deserves some explanation.

Adaptive radiation is when a group undergoes rapid diversification to fill many available niches.  The classic example is Darwin's finches, a group of birds on the Galapagos Islands, which descend from a common ancestral group that split up to occupy different niches because of bill size and strength (which determines what they can eat).  That's a pretty drastic oversimplification, but it captures the essence: many available niches, and a population with sufficient genetic diversity to split up and specialize into those niches.

Because of the "many available niches" part, adaptive radiation is most common under two scenarios: a population colonizing a previously-uninhabited territory (as with Darwin's finches), and remnant populations left after a major extinction.  This was what was thought to have powered the split-up of the reptiles -- the "Great Dying," the Permian-Triassic extinction of 252 million years ago that by some estimates wiped out 95% of life on Earth.

Nota bene: there is fairly good evidence that the trigger for the Permian-Triassic extinction was hypercapnia -- a sudden increase in atmospheric carbon dioxide.  This led to drastic warming of the atmosphere and ocean acidification.  The cause -- according to a paper that just came out two weeks ago in the journal Geology -- was massive burning of coal.  Sound familiar?  In this case the cause was natural; it's thought to have been triggered by massive volcanism.  But the end result was the same as what we're doing now by runaway use of fossil fuels.  I'd like to think this would be a cautionary note, but the world's leaders seem to specialize in ignoring science unless it can directly make them money and/or keep them in power, so I'm not holding my breath.

But back to the reptiles.  The study that triggered this post, which came out this week in Nature Communications, points out the flaw in the argument that the adaptive radiation of reptiles was due to the Permian-Triassic extinction.  According to recent analysis, the split up was already well underway before the extinction started.  And the extinction itself was sudden, at least in geological terms; from start to catastrophic finish, the whole event took about a hundred thousand years.  In geological strata, this length of time is a very, very narrow band.

Plus, the different groups of reptiles individually show drastically different rates of specialization. "Our findings suggest that the origin of the major reptile groups, both living and extinct, was marked by very fast rates of anatomical change, but that high rates of evolution do not necessarily align with taxonomic diversification," said study lead author Tiago Simões of Harvard University, in an interview in Phys.Org.  "Our results also show that the origin of snakes is characterized by the fastest rates of anatomical change in the history of reptile evolution -- but that this does not coincide with increases in taxonomic diversity [as predicted by adaptive radiations] or high rates of molecular evolution."

The end result of the study is that the cause of the adaptive radiation is unknown.  It probably was pushed along by the mass extinction -- the species that survived the hypercapnia and the resulting environmental devastation were set up to have a whole empty world to colonize.  But what was driving the split-up of the group prior to the extinction itself?

Unknown, but the current study shows that clearly the adaptive radiation had already started.

I love puzzles like this.  In science, there are almost always more questions than answers, and every answer brings up new questions.  But another feature of science is the conviction that there is an answer even if we don't currently know what it is.  And chances are, further study will elucidate what exactly was going on -- and what led to the fragmentation of a group that now, over 250 million years later, comprises some of the best-known and most familiar critters who have ever walked (or flown across) the Earth.

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This week's Skeptophilia book recommendation of the week is for anyone who likes quick, incisive takes on scientific topics: When Einstein Walked with Gödel: Excursions to the Edge of Thought by the talented science writer Jim Holt.

When Einstein Walked with Gödel is a series of essays that explores some of the deepest and most perplexing topics humanity has ever investigated -- the nature of time, the implications of relativity, string theory, and quantum mechanics, the perception of beauty in mathematics, and the ultimate fate of the universe.  Holt's lucid style brings these difficult ideas to the layperson without blunting their scientific rigor, and you'll come away with a perspective on the bizarre and mind-boggling farthest reaches of science.  Along the way you'll meet some of the key players in this ongoing effort -- the brilliant, eccentric, and fascinating scientists themselves.

It's a wonderful read, and anyone who is an aficionado of the sciences shouldn't miss it.

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

Cause and effect

In 1960, Carl Jung coined the term synchronicity in his book of the same name, and defined it as follows:

How are we to recognize acausal combinations of events, since it is obviously impossible to examine all chance happenings for their causality?  The answer to this is that acausal events may be expected most readily where, on closer reflection, a causal connection appears to be inconceivable...  It is impossible, with our present resources, to explain ESP [extrasensory perception], or the fact of meaningful coincidence, as a phenomenon of energy.  This makes an end of the causal explanation as well, for "effect" cannot be understood as anything except a phenomenon of energy.  Therefore it cannot be a question of cause and effect, but of a falling together in time, a kind of simultaneity.  Because of this quality of simultaneity, I have picked on the term "synchronicity" to designate a hypothetical factor equal in rank to causality as a principle of explanation.

Synchronicity is a peculiar thing, and when it happens to us it can be extremely startling.  I recall going to a doctor's appointment one day, and in the car I was listening to a station that plays classical music.  When I arrived I was in the middle of the first movement of Beethoven's Moonlight Sonata, a piece I love -- but I was right on time for the appointment and couldn't sit and listen to the rest of it.

So I shut the engine off, got out of my car, and went into the doctors' office.  I checked in, went to the waiting room...

... and over the speakers came the ethereal notes of the piano playing the first movement of the Moonlight Sonata, picking up almost exactly where I had left off five minutes earlier.

This would have been surprising but not really all that peculiar if they had simply been tuned to the same station on Sirius-XM satellite radio as I was; but they weren't.  As I found out from sitting there for the next half hour (just because I was on time for my appointment doesn't mean the doctor was), the music being piped in was just a collection of "atmospheric piano music" for waiting rooms and the like.  The fact that it seemed to pick up exactly where I'd turned the radio in my car off was pure coincidence.

Or, if you like Jung's term, synchronicity.  I'm wary of it for two reasons.  First, it immediately turns on our conviction that occurrences like this Mean Something, that it was more than simple random chance at work.  Second, this kind of magical thinking is at the heart of dart-thrower's bias -- our tendency to notice (or overemphasize) the hits and ignore the misses.  In this case, all of the millions of times I've walked into a waiting room or elevator or grocery store and the speakers weren't playing a tune I was just listening to or thinking about.  All of that randomness gets subsumed into the background white noise of life.  I only noticed it this time, and remembered it afterward, because the music I heard was unexpected in some way.

The reason this comes up is because of an article at Insider about a phone app called "Randonautica," which takes the concept of synchronicity to new levels.  What the app does is to give you a random set of coordinates within a ten minute drive of your home, and then acts as a GPS to get you there.  Before you leave, you're supposed to "set an intention" -- something you want to find or learn when you arrive -- with the expectation that at the site, you'll discover something relevant to that intention.

Various "Randonauts" have reported all sorts of things -- creepy abandoned buildings, unexpected beautiful spots hidden away from view, cryptic graffiti on walls that seemed in some way to connect to the seekers' intention, and so on.  One group had a horrifying experience; Randonauts in Seattle stumbled upon a suitcase that contained human remains in a plastic garbage bag.

Now, I'm not trying to rain on anyone's parade (although finding a dead body certainly would quell my enthusiasm for the whole enterprise).  I can see how Randonautica could be a great deal of fun, and in fact, it's related in spirit to a hobby my wife and I both participate in, geocaching.  But it's an interesting question to consider whether what the Randonauts are finding is meaningful.

My take on it is that sure, it's meaningful, but the meaning is something the Randonauts are imposing upon what they find.  Put another way, there's nothing mystical to this; if you go to a strange place and look for something, with the only criterion being that it has to be relevant to a broad intention to "find something strange," then you're almost certain to succeed.  I can pretty much guarantee that no matter where you go, if you look for weird and unexpected stuff, you'll find something.

But that's just me being a hyperrational type, and there are people who absolutely swear by synchronicities that even I would find a little hard to explain as dart-thrower's bias.  Jung, for example, told the story of a patient who had a vivid dream of a golden scarab beetle, and asked him what relevance it had to her life.  While she was telling him this, he heard a noise, and saw there was an insect trying to get out of the window -- and reached out his hand and caught it.  Guess what it was?  He handed the shining green-gold beetle to the patient, and said, "Here is your scarab."

"This experience punctured the desired hole in her rationalism and broke the ice of her intellectual resistance," Jung wrote.  "The treatment could now be continued with satisfactory results."

[Image is in the Public Domain]

So who knows?  Maybe there's more to this than I'm seeing.  I'd encourage you to try Randonautica if you're so inclined, and let me know if anything untoward happens.  I may well do the same -- although I wonder what would happen if your intention contains the subclause, "... but there's probably nothing mystical going on here."

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This week's Skeptophilia book recommendation of the week is for anyone who likes quick, incisive takes on scientific topics: When Einstein Walked with Gödel: Excursions to the Edge of Thought by the talented science writer Jim Holt.

When Einstein Walked with Gödel is a series of essays that explores some of the deepest and most perplexing topics humanity has ever investigated -- the nature of time, the implications of relativity, string theory, and quantum mechanics, the perception of beauty in mathematics, and the ultimate fate of the universe.  Holt's lucid style brings these difficult ideas to the layperson without blunting their scientific rigor, and you'll come away with a perspective on the bizarre and mind-boggling farthest reaches of science.  Along the way you'll meet some of the key players in this ongoing effort -- the brilliant, eccentric, and fascinating scientists themselves.

It's a wonderful read, and anyone who is an aficionado of the sciences shouldn't miss it.

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