Wipeout

252 million years ago, the Earth was hit by a confluence of Very Unfortunate Events.

First, most of the large continental land masses locked up into a single supercontinent, Pangaea.  This had multiple effects, including alterations of oceanic currents, massive desertification, and the collapse of the convection cells powering seafloor spreading at mid-ocean ridges.  The latter caused a drastic lowering of sea level and exposure of continental shelves, reducing habitat for marine species that live in shallow water (which is most of them).

Second, the tinder box that had formed in the Carboniferous Period -- enormous deposits of coal, oil, and limestone produced when the Earth was basically one giant greenhouse -- found its lit match when the Siberian Traps erupted.  This is one of the largest volcanic events known, and produced an almost unimaginable four million cubic kilometers of basaltic lava.  This ripped through all that coal and carbonate rock, releasing catastrophic amounts of carbon dioxide and sulfur dioxide into the atmosphere.  The portion of the excess absorbed into the ocean caused acidification, killing any marine animal with carbonate shells or skeletons.  The resulting temperature rise caused worldwide oceanic anoxia.  It very likely also triggered the unraveling of unstable methane clathrate deposits on the seafloor, releasing gaseous methane and further boosting the temperature.

If that weren't enough, right around this time the Araguainha Impactor hit what is now Brazil.  The spot where it struck was at the time mostly composed of another gift from the Carboniferous -- oil shale.  This was flash-incinerated, releasing yet more carbon dioxide.

The result: the extinction of between 80% and 95% of the species on Earth, depending on how you count them and who you ask.  

What there's no doubt of, though, is that it was devastating.  It's the closest the Earth has come to undergoing a complete wipeout.  Entire taxa went extinct, including eurypterids (sea scorpions), trilobites, blastoids, tabulate and rugose corals, and acanthoid fish; 99% of radiolarian species vanished, as well as 98% of gastropods and 97% of ammonites and foraminiferans.  The entire food web collapsed.

Afterward, the Earth was an overheated, sulfur-smelling, hypoxic, largely lifeless wasteland.

And yet, somehow, it recovered.  How exactly the Earth's living things made it through the largest bottleneck ever is the subject of a paper last week in the Geological Society of America Bulletin, authored by a team from University College Cork, the University of Connecticut, and the Natural History Museum of Vienna.  And what it found was that the bounce-back didn't happen all at once.  It was far from a linear progression toward rebuilding the biosphere -- there were further shifts and setbacks over several million years as life "found a way."

The team focused mainly on the plants, given that they're the base of the food web.  Some of the first recolonizers were conifers, but they suffered a reversal not even a million years after the main pulse of extinctions with the Smithian-Spathian Boundary Event, a further spike in global temperature that ultimately saw sea surface temperatures of 40 C (104 F), but which was then followed by an unexplained and equally rapid drop.  The wild pendulum swings in temperature caused the collapse of the resurgent coniferous forests; ultimately they were replaced by seed ferns and club mosses (the latter were larger than the ones we have today, but not as big as the enormous Lepidodendrons that were around during the Carboniferous).  

An early Triassic seed fern, Lepidopteris [Image licensed under the Creative Commons Vivi Vajd, Stephen McLoughlin, Sam M. Slater, Ola Gustafsson, Allan G. Rasmusson, Lepidopteris life restoration, CC BY 4.0]

Eventually the climate stabilized, but any way you spin it, the Early Triassic Period was a horrible time to be alive.  It was largely hot and dry, but then -- with startling rapidity -- terrestrial biomes were swamped during the weird Carnian Pluvial Episode, a two-million-year-long thunderstorm which I wrote about not long ago.  Then, at the end of the Triassic, there was yet another massive extinction, this one probably caused by the volcanism from the Central Atlantic Magmatic Province (which would ultimately open the Atlantic Ocean).  Things had largely settled down by the beginning of the Jurassic Period, at which point we were heading into a period of lush forests and (mostly) stable climate -- the long, glorious Age of Dinosaurs.

But as you know, even their salad days weren't destined to last forever.

It always strikes me, when I read papers like this one -- the colossal hubris and ignorance of people who think we can mess around with Earth's ecosystems with complete impunity.  They often shrug off any Cassandras with breezy lines like, "The Earth's climate has had swings in the past, and has always recovered."  And in one sense, sure, that's true.  Faced even with a catastrophic extinction like the Permian-Triassic, enough species made it through the bottleneck -- and the whipsawing that happened afterward, as the climate gradually restabilized -- to repopulate the Earth.

But keep in mind that a great many species didn't make it.  Most of them, in fact.  Then, at the end of the Cretaceous, the non-avian dinosaurs -- that had been the dominant group worldwide for two hundred times longer than humans have existed -- were completely eliminated.  Okay, life recovered once again, but even for the survivors, living through the event itself was no fun.

Oh, and allow me to put this whole grim story into perspective by mentioning the second paper that came out this week; a huge study out of James Cook University and the University of Adelaide showing unequivocally that tropical forests are dying off because of human-induced climate change -- that they're not adapting fast enough to cope with how quickly we're altering the climate.

We are the first species that has sufficient brainpower to understand how our actions affect the biosphere, and (perhaps) enough power to work toward mitigating them.  And instead, we're largely doing nothing, selling out the future in exchange for short-term expediency, a use-it-once-then-throw-it-away lifestyle, and enriching the coffers of corporate billionaires.  The current so-called administration's mottos with regards to the environment are "Deregulate everything," "Cut down more trees," and "Drill, baby, drill."

They, and all of us, should remember: sure, it's likely that whatever we do, in a million years there still will be plenty of life on Earth.  No matter the mistakes we make, the biosphere will survive.

But there is no guarantee that the survivors will include us.

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

Top of the heap

I don't understand why, amongst prehistoric animals, dinosaurs get all the attention.

Don't get me wrong, I like dinosaurs just fine, but there are so many others that are insanely cool.  

Many of which would be no fun to meet close-up.

Take, for example, the gorgonopsians, that had their heyday in the mid to late Permian Period.  These creatures were serious badasses -- apex predators that predated most of the dinosaurs, and which actually are a sister clade to the one containing mammals (Cynodontia), making them far more closely related to us than they are to a velociraptor.  The name means "looks like a Gorgon" -- referring, of course, to the terrifying monster from Greek mythology.

[Image licensed under the Creative Commons Mario Lanzas, Inostrancevia reconstruction, CC BY-SA 4.0]

The above shows a size comparison between Inostrancevia, one of the largest gorgonopsians, and a human.  You have to wonder why this guy is willing to walk right behind it like that, hands in his jacket pockets, whistling a tune.  Of course, I'm reminded of observing human behavior around bison, elk, and even once a juvenile grizzly bear, when I was in Yellowstone National Park, where many people seemed to think the place was an enormous petting zoo.  We talked to an exasperated ranger, who told us that his main job in the park was "keeping stupid tourists from committing suicide by wild animal."

But I digress.

Anyhow, the selective pressures on carnivores triggered something like convergent evolution between the gorgonopsians and (much more recent) animals like saber-toothed cats.  Gorgonopsians had elongated canine teeth and serrated molars, perfect for killing and slicing up prey.  The jaw morphology indicated that they had something like a ninety-degree gape, allowing for an enormous bite force when they closed.

Inostrancevia latifrons, attacking what is about to be an ex-Scutosaurus [Image licensed under the Creative Commons Creator: Dmitry Bogdanov, Inostranc lati2DB, CC BY 3.0]

Gorgonopsian fossils have been found primarily in two places -- Russia and South Africa.  While they're pretty distant from each other now, keep in mind that in the Permian, they (and every other land mass on Earth) were a lot closer:

[Image licensed under the Creative Commons Massimo Bernardi, MUSE, Trento, Italy. Published by Michael J. Benton., Permian–Triassic paleoclimate, CC BY 4.0]

The gorgonopsians were the top-tier carnivores for over twenty million years -- which, to put it in perspective, is around a hundred times longer than anatomically-modern humans have been in existence.  And who knows how long that hegemony would have lasted, and what direction history (well, prehistory) would have taken, but catastrophe was on the horizon.  The powder keg had been filled to overflowing during the preceding period, the Carboniferous, when high temperatures and precipitation had fostered the formation of enormous swaths of rain forest and swamp, leading to the accumulation of vast coal beds.  The climate had been drying out through the entire Permian, but the fuse was lit with the eruption of the Siberian Traps, the biggest volcanic eruption ever recorded.  The outpouring of lava ripped through the coal seams, depleting oxygen and dumping gigantic amounts of carbon dioxide into the atmosphere, and spiking the global average temperature by an estimated fourteen degrees Celsius.

The result: 95% of life on Earth became extinct, including the gorgonopsians.  The biggest, meanest, most badass predators of the Permian were one of the many groups that didn't survive the cataclysmic bottleneck between the Permian and Triassic Periods.

What did survive was the group that was to dominate everything for the next 180 million years -- the dinosaurs.  And, obviously, our own ancestors, the cynodonts, who at that point were pretty much small, scurrying, shrew-like beasts that a visitor to Earth wouldn't think could ever amount to much.  But as you know, the dinosaurs had their heyday come to a sudden, unexpected, and violent end as well, 66 million years ago.

Just shows that nothing stays on top forever -- something our policymakers might do well to heed, because we're the only animals on Earth that have the intelligence to recognize that what we're doing might endanger our own survival, and potentially do something about it.

We're not immune to the fates of other groups that, in their time, seemed like they'd be permanently on the top of the heap.  

Let's hope we can learn from our planet's past history.

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

Life finds a way

I've written here before about the Permian-Triassic Extinction, sometimes nicknamed "the Great Dying."  It occurred 251.9 million years ago, and like the Cretaceous Extinction 186 million years later -- the one that knocked out the non-avian dinosaurs -- it happened suddenly, destroying ecosystems worldwide that had been thriving prior to the event.

The cause of this cataclysm is still a matter of some debate.  Hypotheses include:

• The formation of the Siberian Traps, an unimaginably huge lava flow covering most of eastern Siberia. (Its volume is estimated at four million cubic kilometers.)  The eruption would have burned everything in its wake, ripping through the vast Carboniferous coal and limestone beds, pumping tons of carbon dioxide into the atmosphere.  It would also have released huge amounts of sulfur dioxide -- not only a poison, but one of the most powerful greenhouse gases.  The result; massive global warming, oceanic acidifiction, and a catastrophic change in ecosystems worldwide.
• The lockup of Pangaea.  The collision of smaller continents to form a supercontinent has a number of effects -- the eradication of coastline along the colliding margin, ecological changes from shifting ocean currents, and collapse of mid-ocean ridges (resulting in a huge drop in sea level) among them.
• A "methane burp."  This sounds innocuous, but really, really isn't.  There's a tremendous amount of methane locked up in the form of clathrates -- a network of water ice with methane trapped inside.  These "frozen methane hydrates" coat the entire deep ocean floor.  The stuff is stable under cold temperatures and high pressures, but if something disturbs them, they begin to come apart, releasing bubbles of methane gas.  The bubbles expand as they rise, displacing more and more water, and when they hit the surface it causes a tsunami, not to mention releasing tons of methane into the atmosphere, which is not only toxic, it's also a greenhouse gas.
• Bombardment by swarms of comets and/or meteorites.  The problem with confirming this hypothesis is that any geological evidence of meteorite collisions would be long since eroded away.  If the object(s) that impacted the Earth were metallic meteorites, it's possible that you could use the same technique Luis Alvarez pioneered to explain the Cretaceous Extinction, which wiped out most of the dinosaurs -- enrichment of a layer of sediment by dust that's high in metallic elements not found in large quantities elsewhere.  But if it was a comet (mostly ice) or a rocky meteorite, we might not see much in the way of evidence of the event.

Current expert opinion is that the first one is strongly implicated as the prime cause, but the others may have played a role as well.

In any case, the end result was the extinction of an estimated 95% of marine life and 85% of terrestrial life.  Several groups that had been dominant for millions of years -- trilobites, eurypterids, blastoids, and the orthid and productid brachiopods, for example -- were wiped out completely.

It's hard to fathom what this would be like (although we'd damn well better try; there are estimates of the current, largely anthropogenic, extinction rate that place it in the same range as the Permian-Triassic).  Overall, it seems like ninety percent of the world's species died.  At the same rates today, we'd be left with a grand total of two hundred species of birds in all of North America -- and only forty different kinds of mammals.  

The reason this rather dismal topic comes up is some new research that actually provides a glimmer of hope; a find by paleontologists in China suggesting that after this cataclysm, life rebounded amazingly fast -- resulting in thriving and diverse ecosystems in as little as a million years.

Artists' reconstruction of the Guiyang biota [Image courtesy of artists Dinghua Yang and Haijun Song]

The most amazing thing about this is that at that point, the situation was still, in a word, lousy.  The average sea surface temperature at the equator is estimated at around 35 C (95 F).  The pH was still way down -- how far down isn't known, but certainly enough to inhibit calcium carbonate production by mollusks and corals.  The carbon dioxide levels were still sky-high.  But astonishingly, the organisms that made it through the bottleneck managed to adapt even to these hostile conditions.  Even in the (very) early Triassic Period, life found a way to adapt.

I hesitate to draw too much cheer from all this, however.  The fact that the species who survived the Great Dying eventually did okay is little consolation to the tens of thousands of species that went extinct.  Even if what we're now doing -- rampant fossil fuel use, pollution, and deforestation -- won't wipe out every last living thing on Earth, the results could still be beyond catastrophic.  And while it's "geologically rapid," "recovery in a million or so years" won't help our children and grandchildren.

It's time we extend "learn from the past rather than ignoring it" to prehistoric events, not just historical ones.

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

Creepy crawlies

Whenever we have a wet summer -- not an uncommon occurrence in our rainy climate -- we have a plague of little pests trying to get into our house.

They're called millipedes, slinky guys maybe a couple of centimeters long, with lots of legs (not a thousand, though).  They're completely harmless; they don't bite like their cousins the centipedes do, and if you poke at them, they coil up into a ball.  So I guess they're really more of a nuisance than an actual problem.  They don't even damage anything, the way mice can.  Mostly what they seem to do is get in through every crack and crevice (there are lots of these in a big old house like ours), look around for a while, then curl up and die.

[Image licensed under the Creative Commons Totodu74, Anadenobolus monilicornis 03, CC BY-SA 3.0]

So I don't like them, and I wish they stayed outside, but in the grand scheme of things they're no big deal.  Imagine, though, if they were bigger.

A lot bigger.

Just last week, paleontologists announced the discovery on a beach in Northumberland, England, of a millipede fossil from the Carboniferous Period.  It's been dated to the middle of the period, about 326 million years ago.  It looks a bit like the millipedes I see trundling across my basement floor in summer.

Only this one was 2.6 meters long (approximately the length of a Mini Cooper), a half a meter across, and weighed something on the order of fifty kilograms.

It's been named Arthropleura, and holds the record as the largest-known arthropod in Earth's history.  Nothing is known for sure about its behavior; if it's like the rest of millipedes, it was a scavenger on leaf detritus, but there's no way to know for certain.  Given its size, it could well have been a lot more dangerous than the ones we have around now.  To paraphrase the old joke about five-hundred-pound gorillas:

Q:  What does a fifty-kilogram millipede eat?

A:  Anything it wants.

Those of you who are (like me) biology nerds may be frowning in puzzlement at this point.  How on earth could an arthropod get so big?  Their size is limited by the inefficiency of their respiratory system (not to mention the weight of their exoskeletons).  Most arthropods (millipedes included) breathe through pairs of holes called spiracles along the sides of the body.  These holes open into a network of channels called tracheae, which bring oxygen directly to the tissues.  Contrast that with our system; we have a central oxygen-collecting device (lungs), and the hemoglobin in our blood acts as a carrier to bring that oxygen to the tissues.  It's a lot more efficient, which is why the largest mammals are a great deal bigger than the largest arthropods.  (So, no worries that the bad sci-fi movies from the 50s and 60s, with giant cockroaches attacking Detroit, could actually happen.  A ten-meter-long cockroach not only wouldn't be able to oxygenate its own tissues fast enough to survive, it couldn't support its own weight.  It wouldn't eat Detroit, it would just lie there and quietly suffocate.)

So how could there be such ridiculously enormous millipedes?

The answer is as fascinating as the beast itself is.  As the temperature warmed and rainfall increased after the previous period (the Devonian), it facilitated the growth of huge swaths of rain forest across the globe.  In fact, it's the plant material from these rain forests that produced the coal seams that give the Carboniferous its name.  But the photosynthesis of all these plants drove the oxygen levels up -- by some estimates, to around 35% (contrast that to the atmosphere's current 21% oxygen).  This higher oxygen level facilitated the growth of animals who are limited by their ability to uptake it -- i.e., arthropods.  (At the same time, there was a dragonfly species called Meganeura with a seventy-centimeter wingspan.  And unlike millipedes, these things were carnivores, just as modern dragonflies are.)

Eventually, though, the system was unsustainable, and a lot of the rain forests began to die off in the Late Carboniferous, leading to a drier, cooler climate.  However, remember the coal seams -- by that time a huge percentage of the carbon dioxide that had fed the photosynthesis of those rain forests was now locked underground.  The fuse was lit for a catastrophe.

Fast forward to the end of the next period, the Permian, 255 million years ago.  What seems to have happened is a series of colossal volcanic eruptions that created the Siberian Traps, a basalt deposit covering most of what is now Siberia.  The lava ripped through the coal seams, blasting all that stored carbon into the atmosphere as carbon dioxide.  The temperature in the late Permian had been cool and dry, and the spike of carbon dioxide created a commensurate spike in the temperature -- as well as a huge drop in oxygen, used up by the burning coal.  The oxygen concentration seems to have bottomed out at around twelve percent, just over half of what it is now.  The extra carbon dioxide dissolved into ocean water, dropping the pH, and the increasing acidity dissolved away the shells of animals who build them out of calcium carbonate -- e.g. corals and mollusks.

Wide swaths of ocean became anoxic, acidic dead zones.  The anaerobic organisms began to eat through all the dead organic matter, churning out more carbon dioxide and another nasty waste product, sulfur dioxide (which gives the horrible smell to rotten eggs, and is also an acidifier).  The result: an extinction that wiped out an estimated ninety percent of life on Earth.  In short order, a thriving planet had been turned into a hot, dead, foul-smelling wasteland, and it would take millions of years to recover even a fraction of the previous biodiversity.

Of course, at highest risk would be the big guys like our friends Arthropleura and Meganeura, and the Earth hasn't seen giant arthropods like this since then.  Today, the largest arthropod known is the Japanese spider crab (Macrocheira), topping out at around twenty kilograms -- but crabs and other crustaceans have gills and an oxygen carrier called hemocyanin, so they can boost the efficiency of their respiratory system somewhat over their terrestrial cousins.  The largest insect today is the African Goliath beetle (Goliathus), at about a tenth of a kilogram.  And in today's atmosphere, it's at a pretty significant disadvantage.  They may look big and scary, but in reality, they're slow-moving, harmless creatures.  Kind of a beer can with six legs, is how I think of them.

So that's today's look at creepy-crawlies of the past.  In my opinion it's just as well the big ones became extinct.  The last thing I need is having to shoo a fifty-kilogram millipede out of my basement.

 **********************************

Neil deGrasse Tyson has become deservedly famous for his efforts to bring the latest findings of astronomers and astrophysicists to laypeople.  Not only has he given hundreds of public talks on everything from the Big Bang to UFOs, a couple of years ago he launched (and hosted) an updated reboot of Carl Sagan's wildly successful 1980 series Cosmos.

He has also communicated his vision through his writing, and this week's Skeptophilia book-of-the-week is his 2019 Letters From an Astrophysicist.  A public figure like Tyson gets inundated with correspondence, and Tyson's drive to teach and inspire has impelled him to answer many of them personally (however arduous it may seem to those of us who struggle to keep up with a dozen emails!).  In Letters, he has selected 101 of his most intriguing pieces of correspondence, along with his answers to each -- in the process creating a book that is a testimony to his intelligence, his sense of humor, his passion as a scientist, and his commitment to inquiry.

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

A bolt from the blue

Two weeks ago, I wrote about a surprising fossil find in China showing that insects had rebounded after the horrific Permian-Triassic Extinction, 252 million years ago, with amazing speed considering the scale of the extinction and how slowly evolution generally goes.  An extinction opens up hundreds or thousands of ecological niches, which increases the selective pressure on the survivors to occupy them and avoid competition with the others -- which insects did, par excellence, and have been doing ever since.

The cause of the "Great Dying" has been a subject of conjecture for as long as we've known about it.  Candidates include:

• The formation of the Siberian Traps, an unimaginably huge lava flow covering most of eastern Siberia.  (Its volume is estimated at four hundred million cubic kilometers.)  The eruption would have burned everything in its wake, pumping tons of carbon dioxide into the atmosphere, and it would have released huge amounts of sulfur dioxide -- not only a poison, but one of the most powerful greenhouse gases.  The result; massive global warming and a catastrophic change in ecosystems worldwide.
• The lockup of Pangaea.  The collision of smaller continents to form a supercontinent has a number of effects -- the eradication of coastline along the colliding margin, ecological changes from shifting ocean currents, and collapse of mid-ocean ridges (resulting in a huge drop in sea level) among them.
• A "methane burp."  This sounds innocuous, but really, really isn't.  There's a tremendous amount of methane locked up in the form of clathrates -- a network of water ice with methane trapped inside.  These "frozen methane hydrates" coat the entire deep ocean floor.  The stuff is stable under cold temperatures and high pressures, but if something disturbs them, they begin to come apart, releasing bubbles of methane gas.  The bubbles expand as they rise, displacing more and more water, and when they hit the surface it causes a tsunami, not to mention releasing tons of methane into the atmosphere, which is not only toxic, it's also a greenhouse gas.
• Bombardment by swarms of comets and/or meteorites.  The problem with confirming this hypothesis is that any geological evidence of meteorite collisions would be long since eroded away.  If the object(s) that impacted the Earth were metallic meteorites, it's possible that you could use the same technique Luis Alvarez pioneered to explain the Cretaceous Extinction, which wiped out most of the dinosaurs -- enrichment of a layer of sediment by dust that's high in metallic elements not found in large quantities elsewhere.  But if it was a comet (mostly ice) or a rocky meteorite, we might not see much in the way of evidence of the event.

We just got a new piece of the puzzle last week, from research that also took place in China at a rock outcropping called the Penglaitan Section.  This formation dates from just before and just after the Permian-Triassic Extinction, and has the advantage of being 27 meters thick -- the sediment was being deposited rapidly when it formed, which means that you can see fine gradations in composition and narrow down the time range for when things happened.  (By comparison, the previous formation used is only 30 centimeters thick.)

Part of the Penglaitan Section [Image by Shuzhong Shen]

And what Penglaitan tells us is rather alarming.  The Permian-Triassic Extinction, which wiped out 95% of life on Earth and dwarfed the more familiar Cretaceous Extinction, happened in a relative flash.  And it wasn't (or wasn't solely) caused by temperature rise; the main pulse of extinctions happened suddenly, without any warning, and occurred when the temperature had only started its upward trajectory.  There was a five-degree temperature increase that occurred at the same time as the extinctions, but a much larger increase followed that, after the vast majority of the extinctions had already taken place.

Right now, the leading hypothesis is that the eruption of the Siberian Traps is the most likely cause.  But that in itself is horrific; it means that this colossal outpouring of lava not only happened suddenly, it happened with no warning.  Immediately prior to the extinction event, life was doing just fine -- the biodiversity was high, and there were no minor die-offs to presage the big one that was coming.

"We thought we would see a gradual decline in the diversity of life forms or, for example, certain species that are known to be less resilient than others, we would expect them to die out early on, but we don’t see that, said Jahandar Ramezani, of MIT's Department of Earth, Atmospheric, and Planetary Sciences.  "We can say there was extensive volcanic activity before and after the extinction, which could have caused some environmental stress and ecologic instability.  But the global ecologic collapse came with a sudden blow, and we cannot see its smoking gun in the sediments that record extinction...  The key in this paper is the abruptness of the extinction.  Any hypothesis that says the extinction was caused by gradual environmental change during the late Permian — all those slow processes, we can rule out.  It looks like a sudden punch comes in, and we’re still trying to figure out what it meant and what exactly caused it."

So that's pretty scary.  The idea that something on this scale could strike with essentially no warning whatsoever makes me realize how precarious life is, and how easily the interconnections between ecosystems that keep everything going could be disrupted -- not to mention the scale of the destruction if that happens.

Anyone out there still wondering why I'm so alarmed at the rate at which we're pouring fossil-fuel-derived carbon dioxide into the atmosphere?

Anyhow, that's our cheery message for today.  Monkey around with the ecosystem, and you could kill 95% of life on Earth.  I mean, I don't think it's likely to happen day after tomorrow, or anything, but the fragility of it all should give you pause.

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

This week's Skeptophilia book recommendation is a fun one.  If you've never read anything by Mary Roach, you don't know what you're missing.  She investigates various human phenomena -- eating, space travel, sex, death, and war being a few of the ones she's tackled -- and writes about them with an analytical lens and a fantastically light sense of humor.  This week, my recommendation is Spook, in which she looks at the idea of an afterlife, trying to find out if there's anything to it from a scientific perspective.  It's an engaging, and at times laugh-out-loud funny, read.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

Insect rebound

I vividly recall my first visit to the American Museum of Natural History in Washington, DC, perhaps fifteen years ago.  Having a fascination for evolutionary biology and paleontology, I was thrilled to take a walk down the hallway with exhibits of each biological taxon, in phylogenetic order -- put simply, all the groups of living things in the order they come on the family tree of life.

So I'm walking up the hall, and things are progressing the way I'd expect -- bacteria to protozoans to plants to primitive animals, and within Kingdom Animalia, jellyfish to flatworms to roundworms to more complex invertebrates, and then on to fish, amphibians, reptiles, birds, and mammals.

But that wasn't the end of the hall.  The usual approach to the "Great Tree of Life" -- with, of course, mammals at the top of the heap and humans at the top of the mammals, as befits the pinnacle of evolution -- wasn't applied here.  If you progress past mammals, you're into Phylum Arthropoda, those animals with jointed legs and an exoskeleton, which include arachnids, crustaceans, centipedes, millipedes, and the most successful creatures on Earth...

... insects.

Being that it's the end of summer in upstate New York, I can verify that insects are highly successful life forms, given that there are millions of mosquitoes in my back yard alone, every single one of which divebombs my wife whenever she goes outside.  Something about Carol just attracts biting insects.  In fact, she claims that I bring her along to tropical destinations just to draw the mosquitoes away from me.

Which is not true.  Honestly.

In all seriousness, there is incredible diversity amongst insects, and many taxonomists believe that the number of insect species outnumbers all other kinds of animals put together.  Just beetles by themselves -- Order Coleoptera -- represents over 400,000 species, or about 25% of the total animal biodiversity on Earth.

This is the origin of the famous story about biologist J. B. S. Haldane, who was not only a vocal proponent of evolution but was an outspoken atheist.  Haldane frequently had hecklers show up at his talks, and one such asked him at the end, "So, Professor Haldane, what has your study of biology told you about the nature of God?"

Without missing a beat, Haldane replied, "All I can say is that he must have an inordinate fondness for beetles."

Metallic Shield Bug (Scutiphora pedicellata) from Australia [Image licensed under the Creative Commons Benjamint444, Metallic shield bug444, CC BY-SA 3.0]

It's curious that such a diverse and ubiquitous group still has a great many questions unresolved about its origins.  It's known that the big jump in insect diversity came after the Permian-Triassic Extinction of 252 million years ago, the "Great Dying" that wiped out (by some estimates) 95% of life on Earth.  There's a common pattern that a sudden burst of species formation always follows a mass extinction, but in this case, because of a poor fossil record following the event, it's been hard to connect later biodiversity to speciation amongst the survivors.

We just got a huge boost in what we know about insect evolution because of the discovery of a fossil deposit in China dating from 237 million years ago, or only ("only!") fifteen million years after the extinction itself.  The site had eight hundred fossils representing 28 different insect families that had survived the bottleneck, including the ancestors of modern beetles, flies, and cockroaches.

The study, done jointly by Zheng Daran and Wang Bo of the State Key Laboratory of Paleobiology and Stratigraphy in Nanjing, China and Chang Su-Chin of the University of Hong Kong, is only a preliminary analysis of the fossils at the site, and has already helped to connect the dots between pre-Permian-Triassic insects and more modern ones.  As Elizabeth Pennisi, senior correspondent for Science magazine, writes:

The sites underscore that this burst of evolution took place much earlier than researchers had thought, particularly for water-loving insects.  Among the remains are fossil dragonflies, caddisflies, water boatmen, and aquatic beetles.  Until now, paleontologists had thought such aquatic insects didn’t diversify until 130 million years ago.  These insects—which include both predators and plant eaters—helped make freshwater communities more complex and more productive... moving them toward the ecosystems we see today.

It's always fascinating when we add something to our knowledge of past life, and even more impressive when it's about one of the most diverse groups that has ever existed.  Seeing how life rebounded after the Permian-Triassic Extinction should also give us hope -- that even after a cataclysm, the survivors can still come back and rebuild Earth's biodiversity.

Or, as Ian Malcolm put it in Jurassic Park, "Life finds a way."

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

This week's Skeptophilia book recommendation is part hard science, part the very human pursuit of truth.  In The Particle at the End of the Universe, physicist Sean Carroll writes about the studies and theoretical work that led to the discovery of the Higgs boson -- the particle Leon Lederman nicknamed "the God Particle" (which he later had cause to regret, causing him to quip that he should have named it "the goddamned particle").  The discovery required the teamwork of dozens of the best minds on Earth, and was finally vindicated when six years ago, a particle of exactly the characteristics Peter Higgs had described almost fifty years earlier was identified from data produced by the Large Hadron Collider.

Carroll's book is a wonderful look at how science is done, and how we have developed the ability to peer into the deepest secrets of the universe.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

Relics of a lost age

If I can be allowed to geek out a little, today's post is about two new discoveries in the field of paleontology.

The mid-Permian period was (1) a challenging time to live, when the climate was rapidly warming and drying, and (2) at 270 million years before the present, was a really long time ago.  Not only was the climate getting dicey, the world was heading for catastrophe -- the lockup of the supercontinent Pangaea, as all the world's land masses fused into one and the rest of the Earth was covered by a giant ocean, is thought to have been the kickoff to the largest wipeout the Earth has ever seen -- the Permian-Triassic extinction.  Not only did the formation of the supercontinent (and superocean) 252 million years ago drastically change the climate, the event coincided with the formation of the Siberian Traps, when four million cubic kilometers of basaltic lava flowed out over what is now eastern Russia.  The resulting massive burning of organic matter spiked the carbon dioxide content of the atmosphere, simultaneously causing the oxygen content to crash and triggering a warm-up that resulted in average ocean surface temperatures of 40 C (104 F).

The result: 95% of the species on Earth became extinct.

Of course, one of the lineages that made it through the bottleneck was our own ancestors.  Back in the mid-Permian -- pre-mass-extinction -- there was a group of protomammals called Gorgonopsians, which included some seriously scary carnivores (one, Inostrancevia, had a 45-centimeter-long skull and saber teeth -- preceding the more famous "saber-toothed tiger" Smilodon by a good 260 million years).

Permian protomammal fossils are quite rare, however.  So it's pretty awesome that paleontologist Christian Kammerer, paleontology curator of the North Carolina Museum of Natural Sciences, discovered fossils of not one, but two new species of mid-Permian protomammals in a small museum in Russia.

Called Gorynychus matsyutinae and Nochnitsa geminidens, the two were drastically different in size.  Gorynychus was probably one of the apex predators of its time, with a 25-centimeter-long skull and big, nasty, pointy teeth.  Nochnitsa, also a predator, was weasel-sized.  The genera were both named after beasts from Russian mythology -- the three-headed dragon Zmey Gorynych and the malevolent, vampiric night spirit Nochnitsa.

Artist's reconstruction of Gorynychus and Nochnitsa [by Matt Celeskey @clepsydrops, from the press release from the North Carolina Museum of Natural Sciences; used with permission]

These lineages both made it through the bottleneck, but not unscathed.  Their descendants, eighteen or so million years later, underwent some rapid evolution during the Permian-Triassic extinction, especially with respect to size.  "In the age before the dinosaurs, when protomammals were the dominant life on land, you had two different groups that switch off on which is the top predator," Kammerer said.  "You have wolf- to lion-sized saber tooth animals wiped out by a mass extinction, and [the Nochnitsa-like animals] take over.  But [Gorynychus-like animals] aren’t wiped out altogether in this extinction, and they take over and become a small insect eating predator, not large carnivores anymore."

Kammerer and his co-author (and co-discoverer of the fossils), Vladimir Matsyutin of the Vyatka Paleontological Museum of Kirov, Russia, were excited not only about having found fossils of two hitherto-unknown species, but about the potential for other discoveries tucked away in museums.  "I would guarantee you there are thousands of undescribed species in museum collections,” Kammerer said.  "Most new species are found in museum collections for the sole reason that there are literally millions of species on Earth today and many more in the fossil record.  When you’re going out and collecting specimens, you won’t know those things.  The people in the museum knew they were protomammals but they didn’t know they were new species."

So that's today's cool science story, about some of our (very) distant relatives.  I've always been fascinated with the early mammals -- for some reason, much more than the charismatic megafauna that were just getting their start at the same time (the dinosaurs, of course).  And the fact that these critters were out doing their thing as the Earth was heading toward the largest catastrophic extinction ever just adds a nice little frisson to the discovery.  You kind of want to warn them about what's coming, you know?

Oh, well, probably wouldn't have helped.  It's not like you can hide from four million cubic kilometers of lava.

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

This week's recommended read is Wait, What? And Life's Other Essential Questions by James E. Ryan.  Ryan frames the whole of critical thinking in a fascinating way.  He says we can avoid most of the pitfalls in logic by asking five questions: "What?"  "I wonder..." "Couldn't we at least...?" "How can I help?" and "What truly matters?"  Along the way, he considers examples from history, politics, and science, and encourages you to think about the deep issues -- and not to take anything for granted.

Lurking under the ice

So once again I've been sent a link several times with either "Oh, lord, here we go again" or "Ha!  This is real!  You skeptics are so dumb!" notes appended.  The link is to a story in The New York Post about a "massive anomaly lurking in Antarctica."

My first thought was to wonder how an anomaly can lurk, whether in Antarctica or elsewhere, and of course this put me in mind of H. P. Lovecraft's seminal horror story "At the Mountains of Madness."  In this tale some explorers head out to the Frozen Continent after the discovery of certain artifacts of great age, and upon investigation they find a massive city (I believe it's described as "cyclopean" and "eldritch," two of Lovecraft's absolute favorite words), following which they're one by one picked off and eaten by Shoggoths, who apparently lurk quite effectively.

So the usual stuff.  But the particular anomaly referenced in the Post article was discovered not through direct exploration but by use of a magnetometer, and the conclusion was that there is a large metallic object hidden (or lurking, as the case may be) underneath the ice in Wilkes Land, a region of eastern Antarctica.  It's buried at a depth of 900 meters, and is 250 kilometers across.

Which is pretty big.  Cyclopean, even.

Wilkes Land, also known as "Not My Idea of a Vacation Spot" [image courtesy of NASA/JPL and the Wikimedia Commons]

Some scientists have suggested that the anomaly is the remains of a huge asteroid -- perhaps twice as large as the one that created the Chicxulub Crater in what is now the Gulf of Mexico 65 million years ago, and in the process did in most of the species of dinosaurs.  If so, the Wilkes Land Magnetic Anomaly is a good candidate for the smoking gun of the Permian-Triassic Extinction, which occurred 252 million years ago and is estimated to have wiped out 96% of marine life and 70% of terrestrial life in one fell swoop.  The timing certainly seems right, as do the characteristics of the site.

But of course, far be it from your average New York Post reader to accept something like the results of scientific study.  No, the lurking anomaly has to be something more mysterious.  Some of the suggestions have been:

• it's a massive UFO base
• it's an underground (or underice, as the case may be) city where the Nazis escaped to after their defeat in World War II
• it's where they moved HAARP after they decommissioned the one in Alaska.  (Yes, I know that HAARP studies the atmosphere, so it wouldn't do you much good buried 900 meters deep in ice.  Stop asking questions.)
• it's a portal to the inside of the Hollow Earth

Then there's the "UFO-hunting crew" that calls itself "Secure Team 10," which basically combined all of the above into one all-purpose loony explanation.  The Post explains their claim as follows:

Secure Team 10 suggested the Nazis built secret bases in Antarctica during World War II, which were designed to be used by flying saucers. 

The UFO hunters added: “There is some evidence of this coming to light in recent years, with images purporting to show various entrances built into the side of mountains, with a saucer shape and at a very high altitude.” 

“This begs the question: how would you enter these entrances without something that could fly and was the same shape as the hole itself?”

My general opinion is that it begs a great many more questions than that one, but do go on.

Secure Team also suggested the US Navy led a mission to investigate the mysterious continent. 

This expedition was called Operation High Jump, which conspiracy theorists believe was an attempt to find the entrance to a secret world hidden underneath Earth.

Have I emphasized strongly enough that this magnetic anomaly, whatever it is, is covered by a 900-meter-thick sheet of ice?

Anyhow.  Once again we have the woo-woos coming up with bizarre ideas, which of course is what woo-woos do, and tabloid clickbait like The New York Post enthusiastically jumping on the bandwagon to induce readers to provide them with ad revenue by clicking on the link.

And, as a side effect, inducing my readers to send it to me, which they've done (at the time of this writing) six times and counting.  So thanks to all of my loyal readers for keeping me informed on the latest missives from the wingnuts.  As for me, I think I'm going to lurk my way up to the kitchen and get another cup of coffee.