A fracture beneath Tibet

If there's one thing I've learned from my forty-plus years of dabbling in science, it's that the universe is a weird and complex place.

It's why I frequently heard the complaint from my students that "in every science class, the first thing the teacher tells us is that everything we learned in the previous science class is wrong."  This, of course, is inaccurate and not particularly fair; it's not that the earlier tier of information was untrue so much as it was incomplete.  After all, you need a basic grasp of the underlying principles before you can understand the twists, complications, and exceptions.

Take, for example, the paper that appeared last week in Science about a strange phenomenon involving the plate tectonics under the Himalayas.

The simple model of plate tectonics is that there are three types of boundaries between plates: (1) a divergent zone or rift, where two plates are moving apart; (2) a convergent zone or thrust fault, where two plates are coming together, and one plunges beneath the other; and (3) a strike-slip fault or transform boundary, where two plates move in opposite directions alongside each other.  This broad-brush depiction can have an additional layer of complication added right away, when you consider the relative directions of motion (two colliding plates aren't necessarily, or even usually, going to be moving at right angles to the boundary, for example), and whether the plates in question are thin, dense, brittle oceanic plates or thick, lightweight, rigid continental plates.

To narrow in on the location in question, the junction between the Indian Plate and the Eurasian Plate is a convergent zone between two chunks of continental crust.  When this happens, the conventional wisdom is that the two big blocks of rock are too cold and thick to subduct, so they basically just ram into each other and crumple, forming a mountain range.  (Besides the Himalayas, another place this is happening is the Alps.)

[Image is in the Public Domain courtesy of the United States Geological Survey]

But it turns out that this picture of what's happening under Tibet is neither complete nor all that accurate.

A study out of Utrecht University looked at the seismic waves produced by earthquakes in the region, and found that they were consistent with a bizarre scenario; as it crashed into Eurasia, beginning about sixty million years ago, India has delaminated.  The bottom slice of the Indian Plate has peeled apart from the top, and that lower, denser piece is subducting, while the rest has simply smashed against the larger mass of the Eurasian Plate, creating two focal points for earthquakes, one shallow and one deep.

The real tipoff came when the researchers analyzed the gas bubbles in hot springs in the region.  Helium comes in two isotopes -- a light isotope, helium-3, and a heavier one, helium-4.  Helium-3, being less dense, tends to offgas more quickly in surface rocks, soils, and water, so a high He-3/He-4 ratio indicates a source lower in the mantle.  And springs in the southern parts of the Himalayas are depleted in helium-3, whereas northern parts have a higher than expected amount of the lighter isotope -- indicating that the bubbles coming from southern parts of the fault zone have a shallower source, but when you cross into the northern parts, suddenly the bubbles are originating from much deeper mantle material that has flowed in over the split section of the fractured plate.

A cross-section of the Himalayas, from south (left) to north (right)

So once again, we have a situation way more complex than the model you were taught in high school.  But that's the way it goes, you know?  Every time we think we have things figured out, the universe turns around and astonishes us.

And those of us who love science wouldn't have it any other way.

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An MRI built for two

Some years ago, I injured my left knee doing martial arts, and a couple of weeks later found myself inside an MRI machine.  The technician, who would be the odds-on favorite for the least personable medical professional I've ever met, started out by telling me "strip down to your underwear" in tones that would have done a drill sergeant proud, then asking me if I had any metal items on my person.

"I don't think so," I said, as I shucked shirt, shoes, socks, and pants.  "Why?"

His eyes narrowed.  "Because when I turn these magnets on, anything made of metal will be ripped from your body, along with any limbs to which they might be attached."

I decided to check a second time for metal items.

After reassuring myself I was unlikely to get my leg torn off because I had forgotten I was wearing a toe ring, or something, I got up on a stretcher, and he cinched my leg down with straps.  Then he said, "Would you like to listen to music?"

Surprised at this unexpected gentle touch, I said, "Sure."

"What style?"

"Something soothing.  Classical, maybe."  So he gave me some headphones, tuned the radio to a classical station, and the dulcet tones of Mozart floated across me.

Then, he turned the machine on, and it went, and I quote:

BANG BANG BANG CRASH CRASH CRASH CRASH *whirrrrrr* BANG BANG BANG BANG BANG BANG BANG BANG BANG etc.

It was deafening.  The nearest thing I can compare it to is being inside a jackhammer.  It lasted a half-hour, during which time I heard not a single note of Mozart.  Hell, I doubt I'd have heard it if he'd tuned in to the Rage Against the Machine station and turned the volume up to eleven.

The upshot of it was that I had a torn meniscus, and ended up having surgery on it, and after a long and frustrating recovery period I'm now mostly back to normal.

But the MRI process still strikes me as one of those odd experiences that are entirely painless and still extremely unpleasant.  I'm not claustrophobic, but loud noises freak me out, especially when I'm wearing nothing but my boxer briefs and have one leg tied down with straps and am being watched intently by someone who makes the T-1000 from Terminator 2 seem huggable.  I mean, call me hyper-sensitive, but there you are.

So it was rather a surprise when I found out courtesy of the journal Science that the latest thing is...

... an MRI scanner built to accommodate two people.

My first thought was that hospitals were trying to double their profits by processing through patients in pairs, and that I might be there getting my leg scanned while old Mrs. Hasenpfeffer was being checked for slipped discs in her neck.  But no, it turns out it's actually for a good -- and interesting -- reason, entirely unconnected with money and efficiency.

They want to see how people's brains react when they interact with each other.

Among other things, the scientists had people talk to each other, make sustained eye contact, and even tap each other on the lips, all the while watching what was happening in each of their brains and even on their faces.  This is certainly a step up from previous solo MRI studies having to do with emotional reactions; when the person is in the tube by him/herself, any kind of interpersonal interaction -- such as might be induced by looking at a photo or video clip -- is bound to be incomplete and inaccurate.

Still, I can't help but think that the circumstance of being locked into a tube, nose to nose with someone, for an hour or more is bound to create data artifacts on its own.  I mean, look at the thing:

One of the hardest things for me at the men's retreat I attended a couple of years ago, and about which I wrote a while back, was an exercise where we made sustained eye contact at close quarters -- so you're basically standing there, staring into a stranger's eyes, from only six inches or so away.  I'm not exactly an unfriendly person, per se, but locking gazes with a guy I'd only met hours earlier was profoundly uncomfortable.

And we weren't even cinched down to a table with a rigid collar around our necks, with a noise like a demolition team echoing in our skulls.

So as much as I'm for the advancement of neuroscience, I am not volunteering for any of these studies.  I wish the researchers the best of luck, but... nope.

Especially since I wouldn't only be anxious about whether I'd removed all my metal items, I'd have to worry whether my partner had, too.  Although I do wonder what would show up on my brain MRI if I was inside a narrow tube and was suddenly smacked in the face by a detached arm.

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Ghost cities

I just finished reading The Long Summer: How Climate Changed Civilization by Brian M. Fagan, and what struck me over and over again was an astonished thought of how we managed to survive at all.

For most of human history (and prehistory), the human species lived in communities of various sizes that were constantly teetering on the brink of mass starvation.  Fagan makes the point again and again; for the majority of humanity, all it took was one bad season to spell complete disaster.  There was no Plan B.  Except for the small number of civilizations that lived in areas with sufficient wild foods to forage, a drought or a flood or a freeze at the wrong time and you were in deep, deep trouble.

Size and power were no guarantors of safety.  The Mycenaeans, the Indus Valley Civilization, the Mayan Empire, the Pueblo Culture, the Tiwanaku People, and the Sumerians all declined and collapsed at least in part due to the vagaries of the climate.  More recently, the Little Ice Age contributed to the Great Famine of 1315-1317 which affected most of Europe and killed millions; and repeated crop failures during the eighteenth century, coupled with the monarchy's seeming inability to deal with them, almost certainly were part of what gave momentum to the French Revolution.

Despite all this, our intrepid ancestors not only survived, but in many places, thrived.  Sometimes even in regions where it's hard to imagine.  For example, consider two archaeological discoveries of hitherto-unknown cities -- one in the desert of northwestern Arabia, and the other in the Amazonian lowlands of Ecuador.

A study led by Guillaume Charloux of the Centre National de la Recherche Scientifique found the remains of a fortified complex surrounding the Khaybar Oasis dating to the fourth and third millennium B.C.E., giving evidence of a permanent settlement that persisted for at least several centuries.

The authors write:

The multidisciplinary investigation carried out between 2020 and 2023 by the Khaybar Longue Durée Archaeological Project (CNRS-RCU-AFALULA) demonstrates that the Khaybar Oasis was entirely enclosed by a rampart in pre-Islamic times, like several other large regional walled oases in north-western Arabia (Tayma, Qurayyah, Hait, etc.).  The cross-referencing of survey and remote sensing data, architectural examinations and the dating of stratified contexts have revealed a rampart initially some 14.5 km long, generally between 1.70 m and 2.40 m thick, reinforced by 180 bastions.  Preserved today over just under half of the original route (41 %, 5.9 km and 74 bastions), this rampart dates back to the Bronze Age, between 2250 and 1950 BCE, and had never been detected before due to the profound reworking of the local desert landscape over time.  This crucial discovery confirms the rise of a walled oasis complex in northern Arabia during the Bronze Age, a trend that proved to be central to the creation of indigenous social and political complexity.

A different study that also came out this week looked at the ruins of a city complex with buildings, gardens, streets, and plazas, now buried in the tangle of the Ecuadorian rain forest near the Upano River.  This one is even more mysterious than the Arabian settlement; we knew there were people living in northwestern Arabia back then, even if we didn't know they had built a city.  Here, archaeologists have found the remains of a complex, settled civilization, its beginnings contemporaneous with the Roman Republic and which lasted for a thousand years, and we have no idea who the people were that inhabited it -- neither what language they spoke nor how they were related to other Indigenous groups in the area before and afterward.

[Image licensed under the Creative Commons James Martins, Amazon rainforest - panoramio, CC BY 3.0]

Sacha Vignieri, writing for Science, commented about the research:

When intact, the Amazonian forest is dense and difficult to penetrate, both on foot and with scanning technologies.  Over the past several years, however, improved light detection and ranging scans have begun to penetrate the forest canopy, revealing previously unknown evidence of past Amazonian cultures.  Rostain et al. describe evidence of such an agrarian Amazonian culture that began more than 2000 years ago.  They describe more than 6000 earthen platforms distributed in a geometic pattern connected by roads and intertwined with agricultural landscapes and river drainages in the Upano Valley.  Previous efforts have described mounds and large monuments in Amazonia, but the complexity and extent of this development far surpasses these previous sites.

Of course, the fact that both the Arabian and the Amazonian cities were ultimately abandoned indicates that they too fell prey to the capriciousness that characterizes much of human history.  Whether the cause was war, famine, drought, disease, or some combination -- all too often those come together -- the Khaybar Oasis and Upano Valley civilizations left their intricately-constructed towns, either dispersing into other communities or else dwindling and finally dying.

Whichever it was, all we have are the ghostly remains of cities once inhabited by thriving populations -- a stark reminder of our own tenuous grasp on survival, something we often forget about because of the hubris of modern society.  I'm reminded of Percy Bysshe Shelley's haunting and poignant poem "Ozymandias," which seems a fitting place to end:

I met a traveller from an antique land,
Who said—Two vast and trunkless legs of stone
Stand in the desert.  Near them, on the sand,
Half sunk a shattered visage lies, whose frown,
And wrinkled lip, and sneer of cold command,
Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things,
The hand that mocked them, and the heart that fed;
And on the pedestal, these words appear:
"My name is Ozymandias, King of Kings;
Look on my Works, ye Mighty, and despair!"
Nothing beside remains.  Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.

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Aurora stellaris

Today's topic falls into the category of "The More You Think About It, The Weirder It Gets," and comes to us courtesy of my writer friend Andrew Butters.

Before I get to the meat and potatoes of the story, two bits of background.

Auroras occur because of the solar wind, a powerful stream of particles (chiefly electrons and protons) emitted from the upper atmosphere of the Sun.  When they strike the Earth's upper atmosphere and interact with the various molecules in the air, this has the effect of exciting the electrons in the molecules (bouncing them to higher energy levels), and when those electrons fall back into the ground state, they emit the extra energy as light.  Because of the quantization of energy levels, each color (frequency) is associated with a particular transition in a particular element -- the commonest are reds and greens (from oxygen) and blues (from nitrogen).

Auroras on Earth are most often seen in high latitudes because of the shape of the Earth's magnetic field.  The slope of the magnetic field lines increases the closer you get to the poles, so at high latitudes it acts a bit like a funnel, creating spectacular displays in the Arctic and Antarctic regions.

Despite the fact that I feel like I feel like I live in the Frozen North (especially at this time of year), I've only ever gotten to see the auroras once.  It was about ten years ago, and we heard there was a solar storm and the "Northern Lights" were going to be seen a lot farther south than usual.  That night it was supposed to be crystal-clear -- also an unusual occurrence in this cloudy climate -- so once it was dark, my wife and I went across the street into the neighbor's field and watched for a while, with disappointing results of the "Is that a flicker?  I think that's a flicker" sort.

At some point my wife, who is clearly the brains of the operation, realized that we were looking for the Northern Lights, but we were facing south.  In our defense, there were fewer trees obstructing the sky in that direction, but it's still a little like the guy who was searching around the kitchen floor for his contact lens, and his wife joined him, but the two of them couldn't find it.  She finally said, "Are you sure you dropped it in the kitchen?"  And he responded, "No, I dropped it in the bathroom, but the light is better in here."

In any case, we turned around to the north...

.... and wow.

Over our rooftop and beyond the branches of the walnut trees was a light show like I've never seen before -- shifting curtains of green luminescence resembling some kind of gauzy emerald curtain.  It was spectacular.  We watched it for about forty-five minutes before it finally started to fade.

So if you're ever looking for auroras, make sure you're pointed the right way.

The second piece of background is that there is a strange astronomical object called a brown dwarf.  Brown dwarfs are almost-stars -- something on the order of twenty to eighty times the mass of the planet Jupiter.  Since the fusion of hydrogen into helium -- what powers stars' cores -- requires intense pressure to get started, there's a lower limit to the mass a star can have.  Below that mass, the gravity of its contents is insufficient to raise the pressure in the core to the point where fusion can begin, and what you end up with is something midway between a planet and a star.

Well, the link Andrew sent me is about a new discovery by the amazing James Webb Space Telescope -- of a brown dwarf, W1935, which has auroras.

On first glance, you might think, "why not?"  But remember how auroras are created.  They're caused by the interaction of a stream of high-energy particles with the atmosphere of a planet.

So where are the high-energy particles coming from?

Artist's illustration of W1935 [Image courtesy of artist Leah Hustak and NASA/ESA/CSA]

Even odder, the atmosphere of W1935 seems to have a temperature inversion -- a region of the atmosphere that warms, rather than cools, with increasing altitude.  Its upper atmosphere was glowing with the very specific infrared frequency given off when you heat methane.  So not only does it have auroras when there's no reason it should, there's some sort of a heat source that's creating convection in its atmosphere without it receiving an external heat input from a star.

"We expected to see methane, because methane is all over these brown dwarfs. But instead of absorbing light, we saw just the opposite: The methane was glowing," said Jackie Faherty, of the American Museum of Natural History, who led the study.  "My first thought was, what the heck?  Why is methane emission coming out of this object?...  With W1935, we now have a spectacular extension of a solar system phenomenon without any stellar irradiation to help in the explanation.  With the JWST, we can really 'open the hood' on the chemistry and unpack how similar or different the auroral process may be beyond our solar system."

So here we have one more example of a significant mystery out there in space, and yet another brilliant contribution to astronomy and astrophysics by the JWST.  It seems like every new cache of data opens up as many new questions as it solves old ones.  But that's the way it goes with science -- as Neil deGrasse Tyson put it, "As the area of our knowledge grows, so too does the perimeter of our ignorance."

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A message from Vrillon

Eminent astrophysicist Neil deGrasse Tyson made a trenchant and amusing observation apropos of people who see something moving across the night sky and forthwith declare that they've seen an alien spacecraft from another star system:

Remember what the "U" in "UFO" stands for.  It stands for "unidentified."  People see a light in the sky, and they say, "I don't know what it is... therefore it must be a spaceship piloted by an intelligent being from another planet."  Well, if you don't know what it is, that's where the conversation should stop.  You don't go on to say that it "must be" anything.

I was reminded of this when, quite by accident, I ran into an account of something that happened in England in November of 1977, but which is still causing aficionados of aliens to wiggle their eyebrows in a meaningful manner nearly fifty years later.  

[Image is in the Public Domain]

People in southern England watching television on the evening of November 26 suddenly had their regular programming replaced by a deep buzzing noise, followed by a distorted voice claiming to be Vrillon, a representative of the "Ashtar Galactic Command," who said the following (I've shortened it somewhat to keep it to a reasonable length):

For many years you have seen us as lights in the skies.  We speak to you now in peace and wisdom as we have done to your brothers and sisters all over this, your planet Earth.  We come to warn you of the destiny of your race and your world so that you may communicate to your fellow beings the course you must take to avoid the disaster which threatens your world, and the beings on our worlds around you.  This is in order that you may share in the great awakening, as the planet passes into the New Age of Aquarius...  Be still now and listen, for your chance may not come again.  All your weapons of evil must be removed. The time for conflict is now past and the race of which you are a part may proceed to the higher stages of its evolution if you show yourselves worthy to do this.  You have but a short time to learn to live together in peace and goodwill.  Small groups all over the planet are learning this, and exist to pass on the light of the dawning New Age to you all.  You are free to accept or reject their teachings, but only those who learn to live in peace will pass to the higher realms of spiritual evolution...  Be aware also that there are many false prophets and guides at present operating on your world.  They will suck your energy from you – the energy you call money and will put it to evil ends and give you worthless dross in return...  You must learn to be sensitive to the voice within that can tell you what is truth, and what is confusion, chaos and untruth...  We have watched you growing for many years as you too have watched our lights in your skies.  You know now that we are here, and that there are more beings on and around your Earth than your scientists admit.  We are deeply concerned about you and your path towards the light and will do all we can to help you.  Have no fear, seek only to know yourselves, and live in harmony with the ways of your planet Earth.  We here at the Ashtar Galactic Command thank you for your attention. We are now leaving the planes of your existence.  May you be blessed by the supreme love and truth of the cosmos.

Well, first let me just state up front that Vrillon sounds like a pretty swell guy, and frankly, I'm kinda deeply concerned about us, too.  I'd love it if we'd all put away our weapons and live together in peace and goodwill.  But we've been told since the 1960s that the New Age was upon us and soon everyone would ascend to a higher plane and the world would be all rainbows and flowers and fluffy bunnies forever afterward, and if you'll look around you, you'll see that none of that happened.  Worse, it turns out even the astrologers can't agree on when the Age of Aquarius is supposed to start, despite the song by The 5th Dimension making it sound like it was some kind of exact science.  An astrologer named Nicholas Campion did a study of different people's calculations, and found that about two-thirds of the astrologers said we were already in the Age of Aquarius, while the other one-third said it wasn't going to happen until the 24th century.

Kind of large error bars you got there.

In any case, after the broadcast interruption, the UK's Independent Broadcast Association was understandably torqued that someone had overridden their signal that way and gotten a huge number of television-watchers seriously stirred up, so they launched an investigation, wherein they concluded that someone had used a small unauthorized transmitter to hijack the IBA's Rowridge Transmitter on the Isle of Wight.

In other words: it was a prank.  If that wasn't already obvious.

The problem was, it wasn't obvious to a lot of people, and apparently still isn't.  This story is still making its way around websites, podcasts, and television shows about aliens, usually with the subtext of "What if Vrillon was real?"  One asked, "[How] can the IBA – or anyone else – be sure that the broadcast was a hoax?"

Well, I suppose it depends on what you mean by "sure."  The culprit was never caught, so there is no concrete proof that it was a signal hijack by a waggish human prankster.  And I guess since Vrillon said he was "leaving the planes of [our] existence" it's unsurprising we haven't heard from him again.  But there's the awkward fact that none of the stuff he predicted ended up happening, which is kind of problematic if you believe the voice was coming from a super-intelligent galaxy-traveling alien who had the inside scoop on where humanity was heading.

So the great likelihood is someone with a transmitter on the Isle of Wight read a goofy speech on-air and shook up most of southern England in 1977.  At the very most, all we can say is that the origin of the signal is unidentified.

And recall what Neil deGrasse Tyson said about that word.

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The air that I breathe

A month ago I looked at a geological oddity called banded iron formations -- alternating gray and red bands of iron-rich sediments that have been found all around the world, and all seem to date from about the same time (2.4 billion years ago).  These sedimentary deposits are thought to be the fingerprint of the Great Oxidation Event, when photosynthetic organisms began to pump so much molecular oxygen into the atmosphere that it literally changed the chemistry of the entire planet.

To understand how this happened will take a little bit of explaining.

Photosynthesizers such as plants, phytoplankton, and cyanobacteria evolved a trick for harvesting energy and storing it for use later.  Prior to this, all organisms were heterotrophs -- they required pre-formed organic compounds, which (fortunately for them) were abundant in the early oceans, created by the reducing atmosphere (reduced is chemist-speak for "capable of donating electrons") and sources of energy like lightning and ultraviolet light.  Heterotrophy back then was a fairly inefficient process.  The kind of energy processing they did only produced two ATP molecules, the energy currency of all cells, for every molecule of glucose metabolized.  (Glucose is the most commonly used energy containing molecule.)

Then, around 2.4 billion years ago a new metabolic pathway evolved that could produce ATP directly, driven by the energy in sunlight, rather than by breaking down pre-existing organic molecules.

This process, which probably was created by mutations in a chemosynthesis pathway of the kind we still see today in hydrothermal vent bacteria, used light-capturing pigments like chlorophyll to initiate a chain reaction called photophosphorylation to create ATP by the boatloads.  It required a source of electrons -- nearly all of the energy transfer in cells relies on the movement of electrons in what are called oxidation/reduction reactions -- and the cells performing photophosphorylation found it in abundance.

Water.

The problem was, pulling the electrons from water molecules makes them fall apart.  The result is a pair of hydrogen ions, which can be used for other chemical reactions in the cell -- and free oxygen, which is given off as a waste product.

This led to a huge problem for the rest of life on Earth, because to put not too fine a point on it, oxygen is really freakin' dangerous.  It is, unsurprisingly given the name, a strong oxidizer -- it's really good at pulling electrons away from other substances, which makes them fall apart.  This had the effect of stopping the natural production of food molecules in the ocean; with oxygen in the atmosphere and dissolved in the water, organic compounds now fell to pieces as soon as they were produced.

The result was that in the flip from a reducing atmosphere to an oxidizing atmosphere, nearly all life on Earth died.

The only survivors were:

1. The photosynthesizers -- i.e., the ones who caused the problem in the first place.  They were able to make their own food, so they didn't give a damn if everyone else starved.
2. A handful of anaerobic heterotrophs who were able to escape the oxygen.  We still have them today -- they live in places like anaerobic mud at the bottom of lakes and ponds.
3. A small number of cells that had a pathway to detoxify oxygen.  This pathway involved essentially reversing photosynthesis, combining oxygen with hydrogen ions to lock it up harmlessly as water.  A side benefit -- which ultimately became its major benefit -- is that this is a powerful energy-releasing pathway, and once you can hitch it to ATP production, it's capable of producing 36 ATP molecules per glucose instead of 2, increasing the efficiency of energy capture by a factor of eighteen.  It has to be done in steps -- oxidizing molecules all at once is called "combustion" -- but if it can be slowed down and harnessed, it's a fantastic way of processing energy.  This stepwise oxidation, called the electron transport chain, was such a tremendous advantage that this group -- the aerobic heterotrophs -- basically went out and took over the entire planet.  In fact, they're our ancestors and the ancestors of all the other life forms on Earth that are dependent on oxygen.

The reason all this comes up is a recent discovery I was alerted to by a friend and loyal reader of Skeptophilia.  Researchers analyzing sedimentary rocks from Australia and Canada found fossils of single-celled organisms dating to 1.75 billion years ago that contain traces of thylakoids -- the layered membranes inside chloroplasts on the surfaces of which the oxygen-releasing photophosphorylation reactions take place.  So what we have here are fossils so finely preserved that they retain details not only of cells, nor the organelles inside cells, but the structures inside organelles inside cells.

And not just any old structures.  These, or ones very like them, are the same things that caused all the havoc during the Great Oxidation Event.

Emmanuelle Javaux, of the Université de Liège, who led the study, said, "Their production of oxygen led to accumulation of oxygen and profoundly modified the chemistry of the Earth’s oceans and atmosphere, and the evolution of the biosphere, including complex life."

It's astonishing that traces of these delicate organelles could last in the fossil record for 1.75 billion years.  It gives us a lens into an Earth we wouldn't even recognize, a time when there was nothing whatsoever living on the land, the most complex life was composed of simple clusters of cells, and the oceans were a rapidly-thinning soup of organic monomers.  In a very real sense these microscopic structures created the Earth we see around us today.  Without these tiny pancake-like membranes, the Earth would be a very different place -- one we would not find survivable.

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Big apple

On August 14, 2003, my wife and I were returning from a trip to Hawaii.  It was a lovely vacation, but the return home was, to put it mildly, fraught with mishaps.  The most spectacular one occurred as we were descending into LaGuardia Airport in New York City.  It was late afternoon and I was watching the lights of the city zooming along below us, when, all of a sudden...

... the entire skyline went dark.

I nudged Carol and asked her to confirm that I was, in fact, seeing what I thought I was seeing.  The pilot landed the plane, but the jet bridges weren't working so we deplaned via a rolling ladder.  The entire airport was dark except for a few lights that were kept on by a generator.  Remember that this is a little less than two years after 9/11, so our immediate (and terrifying) thought was that it was a terrorist attack, but it turned out we'd gotten caught up in the Great Northeastern Blackout, which knocked out the electricity to a huge chunk of the northeastern United States and eastern Canada, and which apparently had been triggered by a software bug.

The upshot was we got stuck in the airport overnight with a bunch of other people who were also trying to get back to the Ithaca area, and one of these was a very nice woman who worked for the Apple Genomics Project at Cornell Orchards.  That evening she and I had a real Nerd-O-Rama about the ins and outs of plant genetics, which was a very peculiar way to make the best of a bad situation.

She and her team had a fascinating job -- going all over Europe, the Caucasus, Anatolia, and Central Asia looking for apple germ line -- basically, anything that can be used to reproduce an entire tree (seeds and cuttings being two of the most obvious examples).  They hired translators to accompany them, who asked locals to point out the best apple trees for various uses -- cooking, cider, making wine or vinegar, drying/preserving, or eating fresh -- and they took samples of germ line (along with copious notes) to bring home to the Orchards for growing and hybridizing.  Besides just looking for good fruit quality, they were also interested in finding strains that are resistant to pests and diseases.

The most diversity they discovered was in Kazakhstan and Uzbekistan, which is where apples originate.  ("American as apple pie" is about as inaccurate as you can get; apples not only aren't native to the United States, they were brought into North America in the mid-1600s by a Frenchman, Pierre Martin -- who settled in Nova Scotia.)  And some research out of the Max Planck Institute for the Science of Human History that appeared last week in Frontiers in Plant Science found that the spread of apples from their homeland, thousands of miles across Europe, was due to two factors; megafauna and the Silk Road.

[Image licensed under the Creative Commons Sandstein, Civni-Rubens apple, CC BY 3.0]

The modern apple is the result of hybridization between at least four wild species, followed by centuries of backcrossing and artificial selection.  Let apples cross-pollinate and plant the seeds, and you'll end up with something like a wild crabapple.  Originally, the bright fruits of apples were eaten by large herbivores like horses and wild cattle, and the seeds dispersed long distances, but with the disappearance of the huge herds that used to exist in central Asia, apple seeds were poorly dispersed.  (Apples aren't the only plants that got into trouble when their seed-disperser disappeared, something about which I wrote in more detail a couple of years ago.)  Fortunately for apples, though, their many uses were noted by humans, and when people moved -- especially along the Silk Road -- they took apple germ line with them, just as my Cornell researcher friend did a thousand years later.

The author, Robert Nicholas Spengler, writes:

Large fruits in Rosaceae [the family apples belong to] evolved as a seed-dispersal adaptation recruiting megafaunal mammals of the late Miocene.  Genetic studies illustrate that the increase in fruit size and changes in morphology during evolution in the wild resulted from hybridization events and were selected for by large seed dispersers.  Humans over the past three millennia have fixed larger-fruiting hybrids through grafting and cloning.  Ultimately, the process of evolution under human cultivation parallels the natural evolution of larger fruits in the clade as an adaptive strategy, which resulted in mutualism with large mammalian seed dispersers (disperser recruitment).

Current archaeobotanical evidence seems to suggest that apple domestication took place over a period of less than 100 generations, much less for the earliest morphological changes.  It seems feasible that rapid domestication through hybridization occurred in as little as one or a few generations, and most of the modern diversity in landraces is probably a recent phenomenon, through directed breeding.  Not only do protracted models of domestication fall short when discussing apples, the concept of a “center” of domestication is misleading. Genetic studies illustrate that wild apple populations across Europe and West Asia collectively contributed to the modern domesticated apple in a hybrid complex of species distributed across a continent and a half.

So that's something to think about next time you bite into a crisp apple -- you're enjoying a fruit that has roots reaching back millions of years, the current shape, color, and taste of which were created by megafaunal seed dispersers and the travel of human populations down the Silk Road.

Oh, and we eventually did get back home.  Carol and I, our geneticist friend, and four other people finally decided to hire a limousine when it became obvious that (1) the power, and therefore the airport, was going to be out of commission for a long time, and (2) there wasn't a rental car to be had anywhere in the New York City area.  We figured that splitting the cost of a limousine all the way to Ithaca seven ways wasn't going to be much more than each of us separately hiring a rental car anyhow.  All was going well until the limousine overheated and died in the middle of nowhere in the Poconos, leaving us stranded by the side of the highway with all our luggage.

By then, even my new friend and I didn't feel much like talking about genetics.

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