Birds of a feather

The diversity you find among birds is really remarkable.

There are differences in bill shape, from the weird angled beaks of flamingos, to the longer-on-the-bottom fish skewers of skimmers, to the upswept needle of the avocet, to the absurd (and aptly-named) spoonbills and shoebills, to the pelicans -- about whom my dad taught me a limerick when I was little:

A wonderful bird is the pelican.
His bill can hold more than his bellican.
He can stash in his beak
All his food for the week,
But I really don't see how the hellican.

Yeah, it's kind of obvious where I got my sense of humor from.

Of course, it doesn't end there. The impossibly long toes of the South American jacanas (called "lilytrotters" because they can walk on the floating leaves of waterlilies).  The phenomenal wingspan of the albatross.  The insane plumage of the birds-of-paradise.

And the colors.  Man, the colors!  Even in my decidedly non-tropical home we have some pretty amazing birds.  The first time I saw an Indigo Bunting, I was certain that one of my sons had put a blue plastic bird on the bird feeder just to rattle my chain.  There couldn't be a real bird that was that fluorescent shade of cobalt.

Then... it moved.

But nothing prepared me for the colors I saw on my visits to Ecuador, especially amongst the birds of the tanager family.  There are hundreds of species of tanagers in that tiny little country, and because they often travel in mixed foraging flocks, you can sometimes see twenty or thirty different species in the same tree.  These include the Green-headed Tanager:

[Image licensed under the Creative Commons Lars Falkdalen Lindahl (User:Njaelkies Lea), Green-headed Tanager Ubatuba, CC BY-SA 3.0]

The Black-capped Tanager:

[Image licensed under the Creative Commons Joseph C Boone, Black-capped Tanager JCB, CC BY-SA 4.0]

And the Flame-faced Tanager:

[Image licensed under the Creative Commons Eleanor Briccetti, Flame-faced Tanager (4851596008), CC BY-SA 2.0]

Being a biologist, of course the question of how these birds evolved such extravagant colors is bound to come up, and my assumption was always that it was sexual selection -- the females choosing the most brightly-colored males as mates (in this group, as with many bird species, the males are usually vividly decked out and the females are drab-colored). If over time, the showiest males are the most likely to get lucky, then you get sexual dimorphism -- the evolution of different outward appearances between males and females.  (This isn't always so, by the way.  Most species of sparrows, for example, have little sexual dimorphism, and even experienced birders can't tell a male from a female sparrow by looking.)  More puzzling still is the general trend that tropical birds are more brilliantly-colored than bird species in higher latitudes -- a trend that is yet to be convincingly explained.

The reason this comes up today is two papers that came out last week.  The first, that appeared in Science Advances, looks at one of the most amazing things about their evolutionary history -- they were the only branch of the dinosaur clade that survived the cataclysmic mass extinction at the end of the Cretaceous Period.  What allowed birds to make it through the bottleneck that killed all of their near relatives -- and not only survive, but thrive and rediversify?

The evidence is that the extinction event selected for two things; small body size, and a shift toward young being altricial -- born relatively helpless and undeveloped, and therefore requiring more parental care.  Some lineages of birds would eventually increase in body size again, but they never again would reach the colossal proportions that their cousins did during the Jurassic and Cretaceous Periods.

"We have typically not looked at the change in DNA composition and model across the tree of life as a change that something interesting has happened at a particular point of time and place," said Stephen Smith, of the University of Michigan, who co-authored the study.  "This study illustrates that we have probably been missing something...  We found that adult body size and patterns of pre-hatching development are two important features of bird biology we can link to the genetic changes we’re detecting.  One of the most significant challenges in evolutionary biology and ornithology is teasing out the relationships between major bird groups — it’s difficult to determine the structure of the tree of life for living birds."

The study not only elucidated relationships between extant groups of birds, it allowed the researchers to pinpoint when groups diverged from each other, and therefore what innovations were likely to be connected with events occurring on the Earth at the time.

The second study, which appeared in Nature Ecology & Evolution, looked at the question I began with -- the impossibly bright colors that are characteristic of so many bird species.  Colors in birds arise two ways -- pigments (chemicals which absorb some frequencies of light and reflect others) and structural color (due to feathers creating a combination of refraction and interference; this is also known as iridescence).  Most pigmented color in birds is relatively drab -- blacks, grays, and various shades of brown -- the flashing blues, greens, and purples you see in groups like tanagers, hummingbirds, and sunbirds are almost entirely due to iridescence.

The researchers went through images of as many of the 9,409 species of birds currently in existence, along with the current best iteration of the family tree of birds, to try and figure out where along the way iridescence evolved, and how it spread so widely among this class of animals.  

And what they found was that 415 distantly-related branches of the tree have iridescent feathers, and the common ancestor of all modern birds -- something like eighty million years ago -- was very likely iridescent.

"I was very excited to learn that the ancestral state of all birds is iridescence," said Chad Eliason, of the Field Museum in Chicago, who was the paper's lead author.  "We've found fossil evidence of iridescent birds and other feathered dinosaurs before, by examining fossil feathers and the preserved pigment-producing structures in those feathers.  So we know that iridescent feathers existed back in the Cretaceous -- those fossils help support the idea from our model that the ancestor of all modern birds was iridescent too."

There are still a lot of questions left unanswered, however.  "We still don't know why iridescence evolved in the first place," Eliason said.  "Iridescent feathers can be used by birds to attract mates, but iridescence is related to other aspects of birds' lives too.  For instance, tree swallows change color when the humidity changes, so iridescence could be related to the environment, or it might be related to another physical property of feathers, like water resistance.  But knowing more about how there came to be so many iridescent birds in the tropics might help us understand why iridescence evolved."

Which is extremely cool.  Something to think about next time you see one of those brilliant little flying jewels flit by.  The stunning colors we appreciate every day on our bird feeders and in the wild have a very long history -- going back to a trait that evolved something like eighty million years ago.

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Flocking together

One of the most mesmerizing sights in nature is the collective motion of large groups of animals.

I remember watching films by Jacques Cousteau as a kid, and being fascinated by his underwater footage of schools of fish swimming along and then turning as one, the light flickering from their silvery sides as if they were each reflective scales on a giant single organism.  Murmurations of starlings barely even look real; the flocks swirl and flow like some kind of weird, airborne fluid.  But the most astonishing example of collective motion I've ever seen was when Carol and I visited Bosque del Apache Wildlife Refuge, in central New Mexico, a few years ago, during the migration of snow geese through the region.

"Get there early," we were told.  "At least a half-hour before sunrise.  You'll be glad you did."

We arrived just as the light was growing in the eastern sky.  The wetland was full of tens of thousands of snow geese, all moving around in a relaxed sort of fashion, calling softly to each other.  The brightness in the sky grew, and then -- without any warning at all...

... BOOM.

They all exploded into the air, seemingly simultaneously.  We have wondered many times since what the signal was; there was nothing we could discern, no handful of birds that launched first, no change in the vocalizations that a human would interpret as, "Now!"  One moment everything was calm; the next, the air was a hurricane of flapping wings.  They whirled around, circling higher and higher, and within ten minutes they were all gone, coursing through the sky toward their next destination.

[Image licensed under the Creative Commons CrunchySkies, Snow goose migration at Squaw Creek National Wildlife Refuge, Feb 2013, 25, CC BY-SA 3.0]

How animals manage such feats, moving as a unit without colliding or leaving members behind -- and seemingly without any central coordination -- has long fascinated zoologists.  Way back in 1987, computer simulation expert Craig Reynolds showed (using software called "Boids") that with only a handful of simple rules -- stay within so many wing-lengths of your nearest neighbors but not close enough to touch, match the speed of your neighbors within ten percent either way, steer toward the average heading of your nearest neighbors, give other members a chance to be in any given position in the group -- he was able to create simulated flocking behavior that looked absolutely convincing.  

Last week, a paper out of the Max Planck Gesellschaft showed there's another factor that's important in modeling collective motion, and this has to do with the fact that flying or swimming animals have a rhythm.  Look, for example, at a single fish swimming in an aquarium; its motion forward isn't like a car moving at a steady speed down a highway, but an oscillating swim-glide-swim-glide, giving it a pattern a little like a Slinky moving down a staircase.

Biologist Guy Amichay, who led the research, found that this gives schools of fish a pulse; he compares it to the way we alternate moving our legs while walking.  "Fish are coordinating the timing of their movements with that of their neighbor, and vice versa," Amichay said.  "This two-way rhythmic coupling is an important, but overlooked, force that binds animals in motion.  There's more rhythm to animal movement than you might expect.  In the real world most fish don't swim at fixed speeds, they oscillate."

The key in simulating this behavior is that unlike the factors that Reynolds identified, getting the oscillating movement right depends on neighboring fish doing the opposite of what their nearest neighbors are doing.  The swim-glide pattern in one fish triggers a glide-swim pattern in its friends; put another way, each swim pulse creates a delay in the swim pulse of the school members around it.  

"It's fascinating to see that reciprocity is driving this turn-taking behavior in swimming fish, because it's not always the case in biological oscillators," said study co-author Máté Nagy.  "Fireflies, for example, will synchronize even in one-way interactions.  But for humans, reciprocity comes into play in almost anything we do in pairs, be it dance, or sport, or conversation,"

"We used to think that in a busy group, a fish could be influenced by any other member that it can see," said co-author Iain Couzin. "Now, we see that the most salient bonds could be between partners that choose to rhythmically synchronize."

So zoologists have taken another step toward comprehending one of the most fascinating phenomena in nature; the ability of animals to move together.  Something to think about next time you see a school of fish or a flock of birds in flight.  Getting it right requires rapid and sophisticated coordination we are only now beginning to understand.

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Mouse tales

Mice are kind of ubiquitous, and it's easy to think of them as all being pretty much the same, but the family they comprise -- Muridae -- contains no fewer than 870 different species.

And new ones are being discovered all the time, including the Sulawesi snouter, Hyorhinomys stuempkei.  It's a peculiar-looking little thing, with a pointy nose and incisors long even for a rodent, and is (as far as we know) only found in one location on the slopes of Mount Daro in northern Sulawesi.

Hyorhinomys stuempkei [Image licensed under the Creative Commons Kevin C Rowe and Museum Victoria, Hyorhinomys07, CC BY-SA 4.0]

But the reason the topic comes up isn't mice, nor even anything about this particular mouse's evolutionary history, behavior, or physiology.  

It's about its name.

Both its common name of "snouter" and the species name, stuempkei, come from zoologist Harald Stümpke and his most famous work, The Snouters: Form and Life of the Rhinogrades, an exhaustive study of Order Rhinogradentia.  The members of the order lived on a small archipelago in the Pacific Ocean which had no human occupants.  However, the island chain was known to the natives of nearby islands, who gave each of the eighteen islands their names (Annoorussawubbissy, Awkoavussa, Hiddudify, Koavussa, Lowlukha, Lownunnoia, Mara, Miroovilly, Mittuddinna, Naty, Nawissy, Noorubbissy, Osovitissy, Ownavussa, Owsuddowsa, Shanelukha, Towteng-Awko, and Vinsy; the entire chain was called Hyiyiyi).  Other than occasional visits from Polynesians, the first person to go there and do a thorough mapping of the archipelago was Swedish explorer Einar Petterson-Skämtkvist in the 1940s, but it fell to Stümpke to do a biological survey.

Unfortunately, the story doesn't end well.  Stümpke's book is the only remnant of them that survives.  Stümpke and his assistants, along with all the snouters they studied, were wiped out by nuclear bomb testing on a nearby atoll.  Fortunately, before his death he'd mailed a proof copy of his manuscript to German zoologist Gerolf Steiner, or we might not know anything about these unique mammals at all.

Sad story, yes?

However, if by now you are -- pardon the expression -- smelling a rat, you're not alone.

Some questions you might be asking yourself:

1. If all the "rhinogrades" were wiped out, where did the "Sulawesi snouter" come from?
2. And how can one be from Sulawesi if they all lived on the archipelago of Hyiyiyi?
3. Those island names don't sound very Polynesian.  ("Annoorussawubbissy"?  Really?)
4. Then there's "Hyiyiyi," which is the noise an elderly family friend used to make when he was annoyed.
5. How come you never hear anything about an entire group of zoologists being killed in the bomb testing?
6. Aren't all mice in Order Rodentia?  Where the hell did Order Rhinogradentia come from?
7. I mean seriously, what the fuck?

The truth is that the entire thing -- the mysterious island chain of Hyiyiyi, both Harald Stümpke and the intrepid Einar Petterson-Skämtkvist, Order Rhinogradentia and the book detailing their biology, and the tragic bomb test that wiped all of 'em out -- were the invention of Gerolf Steiner (who was a very real biologist with a puckish sense of humor).  However, not only were some people taken in by the joke at the time, Order Rhinogradentia (and the fictitious Harald Stümpke) still occasionally find their way into real publications -- sometimes without any notes making it clear that neither one exists.

Fortunately, by now most zoologists know about Steiner's role in the story, so it's unlikely anyone these days is really taken in by it.

However, in celebration of one of the most elaborate pranks in the history of biology, a recently-discovered (real) mouse species on Sulawesi was named by its discoverer, zoologist Jacob Esselstyn, not after Steiner, but after the fictitious Stümpke!  And even its common name -- the Sulawesi snouter -- is an hommage to Steiner and his masterful monograph.

Keep this story in mind if you ever are inclined to think of scientists as humorless, dry-as-dust pedants.

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Living crystals

Starfish are odd creatures in just about every respect.

They belong to a phylum called Echinodermata, which is Greek for "spiny skin" and also includes such weird animals as sea urchins, sand dollars, brittle stars, sea cucumbers, and crinoids (also called "sea lilies" or "stone lilies" because they look more like some kind of weird undersea plant than they do animals).  One of the big surprises for my AP Biology students, during the unit on zoology, was that echinoderms are our closest non-vertebrate relatives.  The old distinction of vertebrate versus invertebrate turns out to reflect less of a real genetic and evolutionary split than the distinction between protostome and deuterostome; the former includes insects, crustaceans, arachnids, mollusks, annelids (e.g. earthworms), and nematodes (roundworms), while the latter is just the echinoderms and vertebrates such as ourselves.

The names protostome and deuterostome, if you're curious, are also Greek; they mean (respectively) "first mouth" and "second mouth," referring to the order in which the openings of the digestive tract form.  In protostomes, when the beachball-shaped early embryo forms an inpocket that will lead to the formation of the gut, that first opening will eventually become the mouth; the anus forms when the inpocket tunnels its way through and comes out of the other side.  In deuterostome, it happens the other way around, but early embryologists evidently thought that "mouth second" sounded more genteel than "ass first," and that's how we ended up called "deuterostomes."  (I remember the shocked look on one of my students' faces when I told the class about this fun feature of embryonic development.  She said, wide-eyed, "So, at some point, all humans are just... a butthole?"  I deadpanned back, "Yup.  Unfortunately, some people never get past that stage.")

You might wonder how echinoderms can look so different from vertebrates if we're actually on the same branch of the animal family tree.  In fact, echinoderm larva are clearly bilaterally symmetric, just like vertebrates are; they largely lose that symmetry as they mature, although the apparent pentaradial symmetry of a starfish is kind of an illusion, because they do have organs (like the water intake organ, or sieve plate) that are offset to one side.  But they lose more than their symmetry; the adults have no true circulatory system (all they end up with is a set of what are essentially water pipes), no central nervous system (just a nerve ring and branched peripheral nerves), and the simplest of digestive tracts.  This despecialization seems to underlie their wild ability to regenerate lost or damaged limbs -- a capacity that has been under intensive study because of the possible applications to medical science.

[Image licensed under the Creative Commons Copyright (c) 2004 Richard Ling, Blue Linckia Starfish, CC BY-SA 3.0]

The reason all this comes up is because of yet another bizarre and beautiful feature of starfish, just discovered at MIT.  When they're still very early in embryonic development, and resemble spherical glass beads, they exhibit a peculiar behavior -- they spin, creating tiny vortices in the water and drawing other nearby embryos in.  Eventually they self-assemble into a living crystal -- a regular, tightly-packed lattice of embryos all spinning in the same direction.  They undergo peculiar ripples that the researchers call "odd elasticity" -- odd because the oscillations aren't damped down by the water's drag, but continue to propagate through the entire crystal, like some sort of biological standing wave pattern.

"The spontaneous, long-lasting ripples may be the result of interactions between the individual embryos, which spin against each other like interlocking gears," said Alexander Mietke, who co-authored the paper on the phenomenon that appeared last week in Nature.  "With thousands of gears spinning in crystal formation, the many individual spins could set off a larger, collective motion across the entire structure."

The benefit to this behavior isn't known.  One possibility is that the formation of these crystals makes it less likely that the embryos will be eaten by predators, but that's just speculation.  At the moment, though, it's enough to wonder at the intricacy and beauty of these odd creatures, our distant cousins on the evolutionary family tree.

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Death, with big nasty pointy teeth

Australia has a reputation for being the home of wildlife that pretty much all wants to kill you.

It has some of the world's most venomous (and aggressive) snakes and some of the world's most venomous (and aggressive) spiders.  There are enormous saltwater crocodiles lying in the shallows, waiting for the next stupid tourist to happen along.  In the northern part of the country, they have cassowaries, which will eliminate any doubt that birds are descended from dinosaurs.  They have "paralysis ticks" that are pretty much exactly what they sound like.  There's the most venomous creature known, the innocent-looking box jellyfish, whose toxin is one of the most poisonous naturally-occurring substances -- 0.04 milligrams per kilogram of body weight is the LD50 (dose that would kill fifty percent of the individuals exposed to it).  Most of the mammals are relatively benign, although it's worth mentioning that the iconic kangaroo has kicked people to death, mostly the stupid tourists who didn't get eaten by crocodiles earlier in this paragraph.

There's even a plant called the gympie-gympie that is basically the nettle from hell; the hairs on the leaves embed themselves in your skin, leading to excruciating pain that can last over a year.  And they have a species of grass, spinifex grass (Triodia spp.) that pulls up silica from the soil and deposits it in the needle-sharp leaf tips.  Silica, of course, is the chemical name for glass.  So walking naked through a field of spinifex grass is highly discouraged.

Australia: where even the plants want to cut a bitch.

So I suppose it shouldn't have been surprising that a recent discovery of a previously-unknown species of pterodactyloid in Australia yielded a picture of this critter that is like something out of a nightmare.  Christened Thapunngaka shawi -- the genus name comes from the indigenous Wanamara language, and means "spear mouth;" the species name is after the fossil's discoverer, Len Shaw -- the creature was described by paleontologist Tim Richard of the University of Queensland as "the closest thing we have to a real-life dragon."

This thing had a wingspan of seven meters, making it neck-and-neck with the largest pterodactyloid yet known, Quetzalcoatlus, which at least didn't have big nasty pointy teeth.  Thapunngaka, though?  C'mon.  It's from Australia.

Here's an artist's recreation of Thapunngaka:

"It was essentially just a skull with a long neck, bolted on a pair of long wings," Richard said.  "This thing would have been quite savage.  It would have cast a great shadow over some quivering little dinosaur that wouldn't have heard it until it was too late."

So that's cheerful.  The good news is that when it was alive, most of central Australia was a huge inland sea, and the last of them died out something on the order of 92 million years ago.

It's an open question why Australia is the home of so many dangerous life forms.  I have to wonder if it's not some kind of evolutionary arms race; when one species evolves a toxin (or other dangerous feature), the other species in the area are highly selected for any genetic variations that allow them to become (1) resistant, and (2) more dangerous themselves.  Each improvement (so to speak) in one species leads to pressure to improve in the other species, until you finally have a faunal and floral assemblage that makes Audrey II from Little Shop of Horrors seem positively friendly by comparison.

In any case, it's interesting that this has been going on since prehistoric times.  I guess it's not surprising, really; such a scary bunch of wildlife doesn't just evolve overnight.  I have friends in Australia who have assured me that the danger is over-hyped and that they haven't had any bad encounters, so i suppose it shouldn't discourage me from visiting.  At least I have the comfort of knowing that all I have to avoid are the spiders and snakes and ticks and jellyfish and crocodiles and cassowaries and various native plants; at least I don't have to worry about getting speared by a seven-meter-wingspan aerial death machine.

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This week's Skeptophilia book-of-the-week is by an author we've seen here before: the incomparable Jenny Lawson, whose Twitter @TheBloggess is an absolute must-follow.  She blogs and writes on a variety of topics, and a lot of it is screamingly funny, but some of her best writing is her heartfelt discussion of her various physical and mental issues, the latter of which include depression and crippling anxiety.

Regular readers know I've struggled with these two awful conditions my entire life, and right now they're manageable (instead of completely controlling me 24/7 like they used to do).  Still, they wax and wane, for no particularly obvious reason, and I've come to realize that I can try to minimize their effect but I'll never be totally free of them.

Lawson's new book, Broken (In the Best Possible Way) is very much in the spirit of her first two, Let's Pretend This Never Happened and Furiously Happy.  Poignant and hysterically funny, she can have you laughing and crying on the same page.  Sometimes in the same damn paragraph.  It's wonderful stuff, and if you or someone you love suffers from anxiety or depression or both, read this book.  Seeing someone approaching these debilitating conditions with such intelligence and wit is heartening, not least because it says loud and clear: we are not alone.

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

Creatures from the permafrost

In the episode of The X Files called "Ice," some geophysicists working in northern Alaska bring up a 250,000 year old ice core from what is thought to be a buried meteor crater.  Of course, being The X Files, the ice core contains frozen (but not dead) organisms that are pathogenic to humans.  Like the rabies virus, these pathogens make you violent, so that you'll injure and then infect other hosts; unlike the rabies virus, these are macroscopic, and in fact can be seen moving under the skin of infected individuals.

Mulder and Scully barely escape with their lives, but not before death and destruction is wrought amongst the hapless geophysicists, only one of whom survives.  

To say that show didn't specialize in cheerful endings is a vast understatement.

The reason this rather horrifying episode came to mind is a discovery announced last week by some Russian scientists of organisms brought up from 24,000 year old Siberian permafrost.  To put this into perspective, when these organisms were buried, there were still woolly rhinos, mammoths, and cave bears stalking around the place.  And when the unearthed animals were warmed back up, they cheerfully came back to life and began to reproduce.

Well, maybe not "cheerfully."  It's hard to tell, because these animals are bdelloid rotifers, which are known for having a fairly poor repertoire of facial expressions.  Plus, they reproduce parthenogenetically, meaning that the species is all female, and they produce offspring without having sex.

So there goes another reason they'd be cheerful about the whole thing.

A bdelloid rotifer [Image is in the Public Domain courtesy of photographer Damián Zanetta]

As amazing as it may seem, rotifers are actually true animals, despite their small size.  They have eyespots, a nervous system, a brain (albeit a tiny one), and a complete digestive tract.  Plus, they're right up there with tardigrades for indestructibility.  There are modern bdelloids, and one of the things the scientists want to do is to compare the genomes of the current ones with the ones that were resurrected from the permafrost.  Because they're parthenogenetic, their genomes should only vary because of mutations -- the advantage of sex is that it scrambles the genes every generation, producing greater variation in the population.

Also, it's kind of fun, but that probably is not as significant evolutionarily.

As far as Life Following Art, and the scientists digging around in Siberia releasing some horrific pathogen, I probably should cool my jets.  "The most spectacular implication of the research was that there may be all sorts of animals frozen in the permafrost that could awake as global warming melts the permafrost," said Matthew Cobb, professor of zoology at the University of Manchester, who was not involved in the research.  "[This] doesn’t mean that terrifying things are going to come out and eat us, but it gives scientists the possibility of studying how the rotifer has adapted to resist the bad effects of freezing, and… [the] opportunity to explore the difference between existing species and their predecessors."

But of course, that's what he would say.  Right before we all end up with worms squiggling around under our skin and making us violently insane.

So that's our fascinating but kind of scary scientific discovery for today.  A critter who can go into stasis for 24,000 years, frozen solid, without food, and come back to life as if nothing had happened.  It brings to mind cryogenic stasis of humans -- a staple of space-travel science fiction -- I wonder what we might learn about how bdelloid rotifers can accomplish such an amazing feat of survival.  And it does make me wonder what else is down there, waiting to be brought back to life.  Given the rate the world is warming, and how fast the permafrost is melting, we may find that out all too soon.

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I'm in awe of people who are true masters of their craft.  My son is a professional glassblower, making precision scientific equipment, and watching him do what he does has always seemed to me to be a little like watching a magic show.  On a (much) lower level of skill, I'm an amateur potter, and have a great time exploring different kinds of clays, pigments, stains, and glazes used in making functional pottery.

What amazes me, though, is that crafts like these aren't new.  Glassblowing, pottery-making, blacksmithing, and other such endeavors date back to long before we knew anything about the underlying chemistry and physics; the techniques were developed by a long history of trial and error.

This is the subject of Anna Ploszajski's new book Handmade: A Scientist's Search for Meaning Through Making, in which she visits some of the finest craftspeople in the world -- and looks at what each is doing through the lenses of history and science.  It's a fascinating inquiry into the drive to create, and how we've learned to manipulate the materials around us into tools, technology, and fine art.

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

Sighting a survivor

I think if I had to choose one extinct species to bring back, it would be the thylacine (Thylacinus cynocephalus).  Second place would be a harder choice; I've always wished we could resurrect some of the dozens of extinct endemic Hawaiian birds, including the three species of 'o'o and the various Hawaiian honeycreepers -- all of which were wiped out in the past 150 years from a combination of habitat destruction, hunting for decorative feathers, and the introduction of mosquitoes and avian malaria.

But there's something about the thylacine that has always fascinated me.  Also called the "Tasmanian wolf" -- a complete misnomer, as its range was not restricted to Tasmania, and it's not a wolf but a marsupial -- the last wild thylacine was shot by a farmer in 1931, and the last captive individual of the species died in a zoo in Hobart in 1936.  They certainly look canine, but it's a case of convergent evolution.  Adults were on the size of a large German shepherd, something on the order of a meter and a half tip-to-tail and sixty centimeters at the shoulder, with a distinctive pattern of stripes on the back (giving them their other misnomer of "Tasmanian tiger").  Their jaws were odd -- long and narrow and capable of almost a ninety-degree gape, giving it a powerful "scissor bite" that allowed them to take down prey far larger than themselves.

This, in fact, was largely their undoing.  They often went after domestic animals, especially sheep, earning them the enmity of farmers and other residents.  They were hunted as nuisances, and in the early twentieth century the Tasmanian government offered a £1 a head bounty on thylacines, something that was taken advantage of over two thousand times.  The scheme worked.  Within two decades the thylacine was functionally extinct, and a few years after that, extinct in reality.

Captive thylacines, ca. 1903 [Image is in the Public Domain]

Since its official extinction in the 1930s, however, there have been regular sightings of thylacines.  At least alleged sightings, because none of them have resulted in anything a scientist would accept as hard evidence -- a photograph, a clump of hair, a bone, even a footprint.  But the claims that the thylacine still exists refuse to die down as they have with other animals.  (No one, for example, claims to have seen a dodo recently on Mauritius Island.)

The problem, besides the lack of evidence, is that there are a lot of ways to misidentify this animal, similar to how an untrained observer might mistake the probably-extinct Ivory-billed Woodpecker for the relatively common Pileated Woodpecker.  A quick glance could well make someone identify an Australian wild dog (or dingo) for a thylacine -- or even a large feral domestic dog.  Plus, most of the sightings have been in poor light or from a distance.  (To be fair, even if some of these have been actual sightings, that wouldn't be unusual; thylacines were notoriously shy of contact with humans.)

The reason this comes up is because just a few days ago, there was an alleged thylacine sighting, not in Tasmania but in the Adelaide Hills of South Australia.  Once again, there was no photograph or other hard evidence, but this sighting does have some features that make me hopeful it could be the real deal.

According to the Thylacine Awareness Group of Australia, a gentleman who lives in the Adelaide Hills -- a relatively wild forested area, where you can easily picture an animal living and going unnoticed -- was up at six AM and saw what he unequivocally thinks was a mother thylacine with several pups.  What sets his account apart is that he claims he heard the animal vocalizing, and what he describes is very similar to how the howling of thylacines was described in accounts from the nineteenth century.

TAGOA explains the sighting as follows:

Last night, however, when we spoke and I interviewed them both, it was clear he now has 100% belief in what his wife had witnessed as he too has now seen the unbelievable.  A podcast of our discussion will be released soon on our YouTube channel, as well as Mark Taylor's report when he heads out there in the next day or so to set up trail cameras and get a handle on the area….more to come soon...

The witnesses both claim that they have heard weird noises of a screaming nature several times and just fobbed it off.  The beauty of this sighting is that the husband saw the mother (animal) make the weird screechy noise…that part is rare as rocking horse shit.

Which is a wonderful simile that I will be sure to incorporate in my conversations from now on.

Okay, I know, claims like this are a dime a dozen, and I've been unhesitating in dismissing that sort of thing vis-à-vis bigfoot and the Loch Ness Monster.  But at least this claim has going for it that we know thylacines did exist at some point in the past, which is more than I can say for most other cryptids.

And wouldn't it be wonderful if the claim was borne out?  It would mean there was a breeding population of thylacines not just in Tasmania but in mainland Australia that has persisted since the last wild sighting occurred in 1931.  And hell, the coelacanth was supposedly extinct for sixty-odd-million years until someone caught one off the coast of Madagascar, so stranger things have happened.

Anyhow, keep your eye on Australia.  It'll be interesting to see how the ongoing search progresses.  How encouraging would it be to find out that at least one of us humans' attempts to wipe out an entire species actually failed?

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Just last week, I wrote about the internal voice most of us live with, babbling at us constantly -- sometimes with novel or creative ideas, but most of the time (at least in my experience) with inane nonsense.  The fact that this internal voice is nearly ubiquitous, and what purpose it may serve, is the subject of psychologist Ethan Kross's wonderful book Chatter: The Voice in our Head, Why it Matters, and How to Harness It, released this month and already winning accolades from all over.

Chatter not only analyzes the inner voice in general terms, but looks at specific case studies where the internal chatter brought spectacular insight -- or short-circuited the individual's ability to function entirely.  It's a brilliant analysis of something we all experience, and gives some guidance not only into how to quiet it when it gets out of hand, but to harness it for boosting our creativity and mental agility.

If you're a student of your own inner mental workings, Chatter is a must-read!

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

Elephant shrews, babblers, and stilt mice

Because I'm tired of doomscrolling on Twitter and getting more and more discouraged about what's going on in the United States right now, today we're going to focus on: cool zoological discoveries.

In the last few weeks, there have been three papers that look at some amazing research on various animal species.  Let's start with the one in the Zoological Journal of the Linnean Society that described two new species of the rodent group with the amusing name "stilt mice" -- African mice with extra-long feet they stand upright on (a little like kangaroos).  If this isn't weird enough, they are also aquatic.

It's been a difficult group to study.  One of the stilt mice was known from a single specimen collected in Ethiopia 93 years ago, and had not been seen since.  This new study didn't find any more of that species -- scientists surmise that it was already on the brink of extinction when the specimen was collected -- but found what are probably its closest cousins.

"It's underappreciated how little is known about the biodiversity of small mammals, especially in tropical parts of the world," said Tom Giarla, professor of biology at Siena College in New York and lead author of the study.  "We're not discovering a whole lot of new lions, tigers, and bears, but there's an incredible potential for discovery of new species of small mammals because they're tough to find.  And they're sort of underappreciated animals -- they're really cool when you start to learn about their ecology.  These are semi-aquatic mice, so they're not just your average, everyday rodents."

[Image courtesy of Velizar Simeonovski, Field Museum]

Study co-author Julian Kerbis Peterhans, researcher at the Field Museum, agrees.  "These mice are long-footed, kind of like a kangaroo.  They sit up on their haunches, and they wade through shallow streams with their whiskers on the water's surface detecting movements, like sonar.  They have unusually large brains in order to process this sensory information from their whiskers when they hunt. They're cute, too.  When I caught my first one some thirty years ago, it was the most beautiful African mouse I'd ever seen, it had water repellent fur that's very thick and lush and warm and cozy.  They're incredibly soft, and they have this remarkable snow-white belly."

The second paper appeared in the journal Biotropica, and is a study of a bird called the Sulawesi babbler (Pellorneum celebense) that lives on a number of islands in eastern Indonesia.  What the researchers found was that the babblers were undergoing rapid evolution on the smaller islands in its range -- the birds on smaller islands had a greater amount of sexual dimorphism (physical difference between the sexes) than birds on larger islands.  In particular, the size difference was measurably greater on the small islands of Kabaena, Muna, and Buton.

[Image licensed under the Creative Commons A.S.Kono, Pelanduk sulawesi 1, CC BY-SA 3.0]

What the zoologists think is going on is that on smaller islands, with limited resources, having high sexual dimorphism helps to decrease competition if the resources are partitioned.  Partitioning is seen in a lot of groups of related species -- the wood warblers of my home state of New York are a good example, where you might have six or seven species of small, forest-dwelling, insect-eating birds in the same quarter of an acre of woods.  The way they've "solved" the problem of high competition -- and I put "solved" in quotation marks, because of course the birds didn't figure it out -- is that they each occupy different bits of the habitat.  Blackburnian warblers are usually high up in the treetops, yellow-rumped warblers in the low understory, black-throated-blue warblers in the middle parts of trees, and so on.

It's a remarkably efficient way of decreasing interspecific competition.

But this is one of only a handful of cases I know of where the resources are partitioned between different sexes of the same species.  (The others I'm aware of are some tropical hummingbirds, where the bill shapes of males and females are adapted to fit different species of flowers, and the extinct huia, a bird from New Zealand for whom the male and female bill shape were so different you might well think they're different species.)

The third paper is about the rediscovery of an animal that hasn't been seen for fifty years -- a species of elephant shrew from Somalia.  Elephant shrews are neither shrews nor (obviously) elephants.  They have a superficial similarity to shrews, but genetic analysis has shown that they are actually more closely related to elephants than they are to shrews.  (Another indicator that appearance has little relevance to genetic closeness.)  They're in their own order, Macroscelidia.

[Image licensed under the Creative Commons Galen B. Rathbun, Petrosaltator rozeti-Zootaxa, CC BY 3.0]

In any case, the Somali sengi (Elephantulus revoilii) was known from thirty-nine different specimens in museums, but hadn't been seen in the wild in fifty years -- until now.  A colony of them was discovered in the country of Djibouti, the exact location of which is being kept secret.

The rediscovery, and the genetic information scientists are gleaning from these animals, looks like it's going to force a re-analysis of the taxonomy of the group, with the Somali sengi ended up in its own, new genus (Galegeeska).  The research is ongoing, and we'll undoubtedly be finding out more about these strange little animals of the east African desert.

So that's our news from the zoological world for today.  All in all, a much happier topic than a lot of others I could have chosen.  Better to focus, at least for a while, on the wonderful and multifarious critters out there in the world -- many of which we have just begun to understand.

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One of my favorite TED talks is by the neurophysiologist David Eagleman, who combines two things that don't always show up together; intelligence and scientific insight, and the ability to explain complex ideas in a way that a layperson can understand and appreciate.

His first book, Incognito, was a wonderful introduction to the workings of the human brain, and in my opinion is one of the best books out there on the subject.  So I was thrilled to see he had a new book out -- and this one is the Skeptophilia book recommendation of the week.

In Livewired: The Inside Story of the Ever-Changing Brain, Eagleman looks at the brain in a new way; not as a static bunch of parts that work together to power your mind and your body, but as a dynamic network that is constantly shifting to maximize its efficiency.  What you probably learned in high school biology -- that your brain never regenerates lost neurons -- is misleading.  It may be true that you don't grow any new neural cells, but you're always adding new connections and new pathways.

Understanding how this happens is the key to figuring out how we learn.

In his usual fascinating fashion, Eagleman lays out the frontiers of neuroscience, giving you a glimpse of what's going on inside your skull as you read his book -- which is not only amusingly self-referential, but is kind of mind-blowing.  I can't recommend his book highly enough.

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

Black as the night

You wouldn't think that fish living three miles deep in the ocean, far beneath the level that sunlight can penetrate, would worry much about being seen.

Well, I'm not sure they're worried, exactly.  But they still have the problem that if they do somehow get seen, they're likely to get eaten.

This lies at the heart of the reason that bioluminescence exists in the deep ocean.  You probably know that bioluminescence is the ability of some organisms to use chemical reactions in their bodies to emit light.  (Fireflies are a common example.)  In the deep ocean, it was thought the main reason animals might do this is to create a lure; the illuminated "fishing pole" of the grotesque angler fish brings in curious smaller fish, which then get turned into lunch.

[Image licensed under the Creative Commons Masaki Miya et al., Bufoceratias, CC BY 2.0]

There are other functions for light-emitting structures besides lures.  Squid that live in shallow water have ink they squirt into the water then they're attacked, creating a dark cloud to confuse the predator, thus allowing the squid to escape.  But if you live at a depth where its perpetually dark, black ink is fairly useless; so there are deep-sea squid that emit luminescent ink, creating a burst of light to startle the predator and give the would-be dinner a chance to live for another day.

Last week in Current Biology, though, there was a paper wherein I learned about another reason for bioluminescence in the deep ocean.  In "Ultra-black Camouflage in Deep-Sea Fishes," by Alexander L. Davis, Sönke Johnsen, and Karen J. Osborn (Duke University), Kate N. Thomas (The London Museum of Natural History), Freya E. Goetz (Smithsonian National Museum of Natural History), and Bruce H. Robison (Monterey Bay Aquarium Research Institute), we read about fish like the evocatively-named fangtooth, Pacific blackdragon, and black swallower, whose skin is amongst the blackest naturally-occurring substances, reflecting less than 0.5% of the light the falls on it.

But as with the squid ink, why bother to evolve such dark skin if there's no light there to reflect?  The answer turns out to be that there is light there to reflect; the bioluminescence emitted by other predatory fish.  If you're in the complete darkness, even the reflection of a tiny amount of light from your body might give away your position.  So this is a third reason for deep-sea bioluminescence; not as a lure, nor a distraction, but as a searchlight.

These fish, however, are so dark that even in bright sunlight they look like black silhouettes, as study co-author Karen Osborn found out when she tried to photograph them.  This confers a significant advantage over other fish, even if there's only a marginal difference in the skin blackness.  The authors write:

At low light levels, as is the case with a fish reflecting <2% of an already dim source (i.e., a bioluminescent flash, lure, glow, or searchlight), against the black deep-sea background, the model predicts that the sighting distance is proportional to the square root of the number of photons being reflected back to the viewer.  Using this relationship, we find that reducing skin reflectance from 2% to 1% reduces sighting distance by 29% and that decreasing further to 0.5% or 0.05% reflectance reduces sighting distance by 50% and 84%, respectively.  Because visual predators typically search a volume of space, and this reduction in sighting distance is linear, the camouflage benefits of ultra-black skin may be even greater than the reduction in sighting distance calculated here.  Given the small size of the fishes studied here, it is likely that predator-prey interactions occur over short distances, where even small differences in sighting distance can have meaningful effects on interaction outcomes.

I've read that we know less about the abyssal regions of the ocean than we do about the surface of the Moon.  I don't know if that's true -- it's a little hard to quantify what we don't know about something -- but what's certain is that the deep ocean harbors some astonishingly weird creatures.  I'll end with a quote from H. P. Lovecraft, in whose writings the ocean represents everything that is dark and mysterious about the universe: "But more wonderful than the lore of old men and the lore of books is the secret lore of ocean...  The process of delving into the black abyss is to me the keenest form of fascination."

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This week's Skeptophilia book recommendation of the week is about as cutting-edge as you can get, and is as scary as it is fascinating.  A Crack in Creation: Gene Editing and the Unthinkable Power to Control Evolution, by Jennifer Doudna and Samuel Sternberg, is a crash course in the new genetic technology called CRISPR-Cas9 -- the gene-editing protocol that Doudna herself discovered.  This technique allows increasingly precise cut-and-paste of DNA, offering promise in not just treating, but curing, deadly genetic diseases like cystic fibrosis and Huntington's disease.

But as with most new discoveries, it is not without its ethical impact.  The cautious are already warning us about "playing God," manipulating our genes not to eliminate disease, but to enhance intelligence or strength, to change personal appearance -- or personality.

A Crack in Creation is an unflinching look at the new science of gene editing, and tries to tease out the how much of what we're hearing is unwarranted fear-talk, and how much represents a genuine ethical minefield.  Doudna and Sternberg give the reader a clear understanding of what CRISPR-Cas9 is likely to be able to do, and what it won't, and maps out a direction for the discussion to take based on actual science -- neither panic and alarmism, nor a Panglossian optimism that everything will sort itself out.  It's a wonderful introduction to a topic that is sure to be much in the news over the next few years.

[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."

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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!]