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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A cosmic slide whistle

In 1894, physicist Albert Michelson said, "It seems probable that most of the grand underlying principles [in science] have been firmly established …  An eminent physicist remarked that the future truths of physical science are to be looked for in the sixth place of decimals."

The irony of this statement is twofold.  First, within thirty years, the entire field of physics would be upended twice, by Einstein's Special and General Theories of Relativity, and from the development by Niels Bohr, Louis de Broglie, and Erwin Schrödinger of the Quantum Model.  Second, it was the null result from the experiment Michelson himself performed with Edward Morley that disproved the existence of the luminiferous aether and directly led to Einstein's revolutionary theories about the nature of light and motion.

The fact is, there is still a ton of stuff we don't fully understand, and then there are all the things that we don't even know we don't know.  The universe is full of mystery, and there will be plenty to keep scientists occupied for a very, very long time.

Take, for example, a paper last week in Monthly Notices of the Royal Astronomical Society about a bizarre twist on an already poorly-understood phenomenon -- the fast radio burst.  These sudden explosive blasts in the radio region of the spectrum, lasting between 0.001 and 3 seconds, pack as much energy in that time as the entire Sun emits in three days.  Some are transient, but others -- like the euphoniously-named FRB 180916.J0158+65 -- have a regular periodicity, in this particular case 16.35 days.

[Image licensed under the Creative Commons ESO/M. Kornmesser, Artist’s impression of a fast radio burst traveling through space and reaching Earth, CC BY 4.0]

Since their discovery in 2007, hundreds of fast radio bursts have been observed.  Given their unpredictability and ephemeral nature -- you have to have your radio telescope aimed at exactly the right place in the sky at exactly the right time, and you have a window of under three seconds to see them -- it's probable that they are insanely common, and we just miss 99% of them.  Canadian astrophysicist Victoria Kaspi estimates that over ten thousand fast radio bursts happen somewhere in the sky every single day, so there's potentially a huge amount of data out there to study if we can only figure out a way to observe them.

Explanations for what these things could be are all over the map, and include hitherto-unknown behavior of neutron stars, magnetars, black holes, collapsing/dying supergiant stars, or some combination thereof.

Or an alien intelligence trying to signal us.  Admit it, you knew this had to come up.

The bottom line is the astrophysicists still don't know what causes fast radio bursts, much less why some repeat and some don't.  And the whole thing just got a lot weirder with the discovery by observers at the SETI (Search for Extraterrestrial Intelligence) Institute, who found a fast radio burst that had 35 explosive outbursts -- and each one slid up the frequency scale before it ended, drawing comparisons to an enormous outer space slide whistle.

What could cause a fast radio burst to sweep up the frequency scale in that fashion is, at the moment, beyond guessing.  All we know is that is that what was already a mystery just became a hell of a lot more mysterious.

So I think Michelson may have been a wee bit hasty in proclaiming science to be settled except insofar as calculating things to six decimal places.  I suspect that a closer estimate -- if it were possible to do such a thing -- is that the bits of the universe we understand well are hugely outnumbered by the bits we still haven't a clue about.  I prefer the assessment made by Carl Sagan: "Out there, something incredible is still waiting to be known."

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Hello Dolly

Despite my tendency to fall into the "dubious" column with respect to most paranormal claims, I'm always appreciative of anyone who is more of a believer who nevertheless wants to see any evidence analyzed the right way.

That's my impression of The Anomalist, a website I check regularly for news of the weird.  It acts as a sort of clearinghouse for recent stories of odd or unexplained phenomena, but is really good about presenting all sides of the story -- and for calling out bogus claims as such.

Take, for example, some stories that appeared there having to do with the alleged phenomenon of "haunted dolls."

For a lot of us, dolls are right up there with clowns in the "oh, hell no" department.  Their blank, unresponsive faces and fixed expressions land right in the middle of the uncanny valley -- we tend to perceive a face that is human-like, but not quite human enough, as being more frightening or repellant than a face that has fewer distinctly human features.  (Think of a doll's face as compared to a teddy bear's, for example.)  So we're already in scary territory for a good many folks.

Add to that the possibility of the doll being possessed, and you're looking at "scream like a little child and run away."

It's no wonder that the recent creepy Doctor Who episode, "The Giggle," featured a doll called Stooky Bill.  Stooky Bill was real enough -- he was a ventriloquist's dummy that was used by Scottish electronics pioneer John Logie Baird as a subject for the first-ever image transmitted over a television signal -- but in the episode, Stooky Bill (and his wife and "babbies") are brought to life by an evil alien called the Toymaker (played to perfection by Neil Patrick Harris).  The scariest scene in the entire episode was when the wife and children dolls first talk to, then attack, companion Donna Noble in an empty room as she and the Doctor are trying to escape the labyrinth where the Toymaker has trapped them.

Something about their still, expressionless faces, that even so are moving and speaking, is absolutely terrifying.

A while back The Anomalist looked at a couple of examples of the haunted doll phenomenon.  The first is a World War II-era ventriloquist's dummy head called "Mr. Fritz" kept in a glass cabinet by its owner.  The owner started getting suspicious when he'd get up in the morning to find the cabinet door open, so he set up a camera to film it when he wasn't around.

The result, even if you're suspicious it's a fake, is pretty fucking creepy.  The glass door swings open, Mr. Fritz's eyes pop open -- and then his mouth moves.

After this, the owner apparently took the doll head out of the case and put it in a cabinet "secured by heavy chains."  Why this was necessary, given all that happens is the door opens and the face moves, I don't know.  It's not like it had arms and legs and was walking about unassisted, or anything.

Still, I understand the apprehension.  Skeptic though I am, I don't think I'd want to sleep in the same room as that thing, heavy chains or no.

Then we have a British doll named Scarlet, who has been recorded using an "Electronic Voice Phenomena" (EVP) recorder -- and what she supposedly says indicates she should have her prim little porcelain mouth washed out with soap.

In a video of the doll, we get to hear playback of the alleged EVP.  Not only does she supposedly say her owner's name (Linzi), she says such things as "fuck off," "you're fucked," "shut the fuck up," and "fuck this."

So apparently Scarlet is even more fond of the f-word than I am, and that's saying something.

Anyhow, I listened to the recording several times -- and I'm just not hearing it.  I could barely make out "Linzi," but all of the alleged obscenities sounded like white noise to me.  And that's the problem; as is pointed out in The Anomalist, there's a good explanation for a great many alleged EVP claims, and that's apophenia.  The human mind is a pattern-finding machine, which means that sometimes we'll see patterns when there's nothing there but chaos. (You can think of our tendency to see faces -- pareidolia -- as a special case of apophenia.)

With Scarlet, people are already primed to hear something meaningful, so the static pops, clicks, and hums the EVP recorder plays back are interpreted with this bias.  Especially when we already know what the doll allegedly said -- it's all listed right there in the article.

Put simply, you can't miss it when I tell you what's there.

The Anomalist provides a link to an article in The Skeptical Inquirer about this very tendency -- looking at particular cases of EVP claims and analyzing why they're probably nothing more than our tendency to impose order on chaos.

So unlike a lot of sensationalized sites about alleged paranormal phenomena, I can hold up The Anomalist as a place that has the exact right approach.  I'm probably still a bit more dubious than the site owners are, but by and large, we both have the same touchstone for accepting a claim -- logic and evidence.

And a bit of healthy skepticism about humanity's capacity both for getting things wrong... and for engaging in fakery.

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The mystery of the Etruscans

One of the unresolved mysteries of European anthropology is where the Etruscans fit into the big picture.

The Etruscans lived in northwestern Italy, in the region now called Tuscany -- in fact, the name Tuscany comes from the Latin Tusci, one of several names they had for the people who lived there.  The Greeks called them the Τυρσηνοί -- the Tyrrhenians -- etymologically related both to Etruria (the region where they lived) and, obviously, the Tyrrhenian Sea that still bears their name.  They called themselves the Rasenna, a word which, like most of their language, is of uncertain origin.

The big question is whether the Etruscans were autochthonous (academia-speak for "they'd always been there") or allochthonous (migrants from somewhere else -- and if so, from where?).  Of course, the truth is that all Europeans are ultimately allochthonous, because we all started out in east Africa -- it's just that some of us have been in place for a lot longer than others.  We know the Etruscans were already in that region when the Romans got there, who encountered them in something like 500 B.C.E. and ultimately absorbed them completely.  (An occupation the Romans excelled at.)

The historian Thucydides said they were related to the Pelasgians, a bit of a catch-all term ancient Greeks used to describe the inhabitants of Greece prior to the arrival of the classical Greek-speaking Dorians, Ionians, Achaeans, and Aeolians.  The word Pelasgian was almost synonymous with barbarian -- the ancient Greeks and ancient Romans shared a rather off-putting self-congratulatory bent, summed up as "if you're not us, sucks to be you."  

Of course, they're hardly the only civilization to feel that way.  I could name a modern one or two that still haven't gotten over that attitude.

In any case, there's good evidence that the Etruscans had already been there a while when the Romans encountered them, and that they were not closely related to the people in the neighborhood.  Their language, for example, is still a mystery, and has only been partly deciphered by linguists.  The general consensus is that, like Euskara (the language of the Basque people), it is non-Indo European.  There are two other languages it seems to be related to -- the Rhaetic language, an extinct language once spoken by people in what is now eastern Switzerland and western Austria, and Lemnian, spoken on the distant island of Lemnos in the Aegean Sea prior to their being conquered by speakers of Attic Greek in the sixth century B.C.E. 

The latter suggests that Thucydides may have been right on the money in connecting the Etruscans to the Pelasgians.  Together, Etruscan, Rhaetic, and Lemnian seem to be related to no other known languages, and are tentatively classified as a linguistic isolate family (Tyrsenian).

None other than the Roman Emperor Claudius wrote a twenty-volume set on the history and language of the Etruscans -- apparently he himself was a fluent speaker, and was fascinated by their culture -- but tragically, no trace of that extensive manuscript remains.  It's one of a long list of works we only know by their titles, and through references in other books.

The Monteleone Chariot, bronze inlaid with ivory, from sixth century B.C.E. Etruria [Image is in the Public Domain]

A genetic study of Etruscan remains found that they seemed to be related to the central European Urnfield Culture -- so named because of their practice of cremation and burial in ceramic urns -- which probably originated on the steppes of eastern Europe.  But as this path was a pretty common one -- the ancestors of the Celts, Slavs, Hungarians, and Germanic peoples all came that way -- it might not tell us all that much about how or when the Etruscans arrived.

At least their later history was happier than that of many people who bumped into the Romans.  There was some warring and jockeying for power, which the Etruscans ultimately lost, but they were eventually subsumed into the Roman Republic, becoming full Roman citizens.  Many Etruscan towns went on to make large amounts of money as middlemen between the Romans and the conquered Celtic tribes to the north and west.  Several prominent families who were to rise to position of power in the Republic (and later Empire) had Etruscan roots, including the Caecinia, Urgulania, Tarquinia, and Volumnia families, all names that will be familiar to aficionados of Roman history.  Most of the people from modern Tuscany have Etruscan roots, indicating their ancestors have been living in the same place for over three thousand years.

In the end, though, we're left with a mystery.  A people who left behind buildings and works of art and an only partly-understood language, whose connections to other ancient peoples are lost to the shadows of time.  And a mystery is always fascinating -- even if we might never fully discover the answers to all the questions.

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Going to the dogs

I understand dogs a great deal better than I understand my fellow humans.

Dogs are straightforward.  They interact with their world in a direct way, whether it be motivated by love, anger, curiosity, hunger, enthusiasm, or fear.  There's nothing feigned about a dog's emotions or the way they express them.  I've sometimes misinterpreted one of my dogs' signals, but that's on me; the signals were there, even if I only recognized them in retrospect.  Once you grok dog behavior, it's much less fraught than the complex, confusing morass of human interaction.

This is why when I'm invited to social events, I'm always hoping the host will have a dog so there'll be someone for me to have a conversation with.

The dogs we've had have nearly all been rescues, and came with all the baggage and bad backstories that rescue dogs have, but one and all were and are wonderful companions, and enriched our lives tremendously.  This latter part is the only possible explanation for why during the holidays, my wife and I were looking around and thinking, "Wow, our house sure has a lot of clutter and dirt and chaos.  We never seem to be able to keep up with the housekeeping.  Hey, I know... let's get a puppy!"

So, without further ado, allow me to introduce to the Skeptophilia readership...

... Jethro.

Jethro is -- and I say this with all modesty and restraint -- the cutest puppy in the whole entire world.  He's five months old, has the sweetest, happiest disposition ever, and soft, silky hair that gathers burs, mud, and debris like some sort of bizarre magnet.  Like many puppies, he has two settings -- "Full Throttle" and "Off."

He's currently set at "Off" and is sleeping at my feet, which is the only way I'm able to write this.  Otherwise I would be engaged in the essential task of Playing With Jethro.

We got him from the amazing Stay Wild Rescue and Wildlife Rehabilitation Center on New Year's Eve.  If you are looking for a wonderful and deserving place to make a donation, please consider Stay Wild.  They do fantastic work on a shoestring budget, and the owners -- Jane George and Dan Soboleski -- work tirelessly to help find rescue pets forever homes, and to rehabilitate wild animals for re-release.  Please check out their website and consider supporting them.

In the few days we've had Jethro, he's already bonded with our other two dogs, Guinness and Rosie.  Rosie is an Australian Cattle Dog mix who pretty much loves everyone, so she was easy.

Guinness is a big galumphing American Staffordshire Terrier/Husky/Chow cross who can be cranky and gets jealous easily, especially when it comes to sharing Carol's attention with anyone, because he's a big ol' Mama's Boy.  He is, however, a very natty dresser. 

But yesterday, all three of them were romping around together in the back yard, and Guinness was letting Jethro chase him like they'd been best friends forever instead of just three days.  Guinness even responded with the doggie "play-bow" before they took off running again.

Like with most rescues, we're not sure what kind of a mix Jethro is.  Jane at Stay Wild said she thought he had some Golden Retriever in him, which makes sense given his silky coat and general head shape, but his striking and beautiful black face and brindle coloration have to come from somewhere else.  He's got huge paws, indicating he's got some serious growing to do, but whether he'll turn out to be long and lanky or barrel-chested and stocky is anyone's guess.  Dog-loving friends of mine have speculated a lot of possible contributions to his ancestry -- suggestions have included various spaniels and setters, Border Collie, Boxer, German Shepherd, even Saint Bernard -- but we won't be sure until we have him DNA-tested.  (The kit has already been ordered.)

A photo of Jethro from five minutes ago, because why not

It's tempting to say his lovable, playful temperament is indicative of his Golden Retriever genes, but a surprising study at the University of Massachusetts just last year found the contribution of breed to behavior is way smaller than most people think.  We often associate particular behavioral traits with certain types of dog -- labs are friendly and loyal, hounds laid-back but stubborn, Dalmatians nervous and prone to biting, and so on -- but the researchers found exceptions to the rule are so common that the rule isn't really a rule.  And while we've had dogs who seemed to conform to the breed expectations, all of them have their own unique characteristics and quirks.

Dogs are as varied in personality as people are, I suppose.

In any case, now we've got three dogs.  I commented yesterday that this means we're outnumbered, and that it's a good thing this is a benevolent dictatorship and not a democracy.  Although a friend of mine responded, "I'm sure your dogs would vote for you anyway."

Given the fact that Jethro is snoozing happily right next to me, I suspect my friend is right.

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The fingerprint of life

Springboarding off yesterday's post, which suggested that -- from a biochemical standpoint, at least -- extraterrestrial life might be way more common than we'd thought, today we look at how we might find out where it lives.

This is a thornier problem than it might seem at first.  Despite hopeful movies like Contact, picking up an alien radio signal makes looking for a needle in a haystack seem like child's play.  Consider the difficulties; you have to have your radio telescope pointed at exactly the right place in the sky, at exactly the right time, and tuned to exactly the right frequency, to pick it up as it sweeps by the Earth at the speed of light.  Even if you posit an extremely simple message, which repeats indefinitely (like Ellie Arroway's string of prime number blips), there's the problem that any kind of electromagnetic signaling follows the inverse-square law, meaning if you double the distance between the sender and the receiver, the intensity of the received signal goes down by a factor of four.  Triple it, and it goes down by a factor of nine, and so forth.

And the fact is, the distances we're talking about here are...

... astronomical.  (*rimshot*)

So the possibility of detecting some sort of radio signal (whether or not deliberately sent to attract our attention) is not zero, but pretty damn small.  And the other downside is that if that's all we're looking for, we're going to miss a huge slice of the living creatures that could be out there -- we'd only see the ones that have a technological civilization that uses radio waves to communicate.  From that approach, Earth itself would have appeared to be barren and lifeless until the use of radio became widespread, back in the 1930s.

Is there another way?

An alternate approach -- one that avoids at least some of these pitfalls -- is to look for biosignatures, chemical traces that might indicate the presence of life on a planet even if it hasn't reached the point of being technological.  The studies done on Mars that attempted to find Martian microbes took this approach; take a sample of soil, add some likely nutrients, and look for a sign of metabolism.  But this, too, has its inherent difficulties.  How do you tell the difference between Martian microbes chowing down on the food you gave them, and some exotic but abiotic chemical reaction?

A team of astronomers and biologists from the University of Birmingham and MIT have come up with a possible answer.  According to a paper in Nature Astronomy last week, there is a pair of dead giveaways; an atmosphere depleted in carbon dioxide but enriched in ozone.

Carbon dioxide is a highly stable compound, and on lifeless, dry planets like Venus and Mars, it makes up a significant percentage of the atmosphere.  (96.5% on Venus, 95.3% on Mars.)  The fact that despite the amount of carbon on the Earth, the quantity in the air is only 0.04%, is due mostly to the fact that the water in the oceans acts as a huge carbon sink, first dissolving the carbon dioxide, then reacting it with dissolved metal ions like calcium and magnesium to form minerals like the calcite and magnesite in limestone.  Without the oceans, all of that carbon would stay in the atmosphere -- and we'd be a lot more like the inferno that is Venus than the temperate world where we reside.

As far as ozone, the real tipoff for the presence of life would be gaseous oxygen, which is a highly reactive substance that, in the absence of something producing it pretty much continuously, would all be bound up chemically.  Ozone -- a chemical relative of oxygen, O3 instead of O2 -- is expected to be present in small amounts in any atmosphere with free oxygen, but is the astronomers' choice because its spectral signature is much easier to detect than oxygen's.

Likewise, carbon dioxide's spectral fingerprint is obvious because of its strong absorption in the infrared (a property that is directly related to the greenhouse effect and carbon dioxide's warming effect on atmospheres).

So it should be possible to analyze the light reflected from the surface of exoplanets that seem to be in the right temperature range, and look for two things -- low carbon dioxide (indicating liquid water on the surface) and high ozone (indicating something, possibly life, keeping molecular oxygen in the atmosphere).  See both of those things, the team said, and you're very likely looking at a planet that is inhabited.

Like I said yesterday, of course, "inhabited" doesn't mean "inhabited by bipedal humanoids with spaceships and laser guns."  But even so, the technique is intriguing in its simplicity.  The team suggested starting with relatively nearby planetary systems like TRAPPIST-1, which has seven known exoplanets and is only a little over forty light years away from Earth.

TRAPPIST-1 and its lineup of seven planets [Image is in the Public Domain courtesy of NASA/JPL]

So this is all tremendously exciting -- that astronomers are now taking the possibility of extraterrestrial life seriously enough to start proposing methods for searching for it other than just scanning the skies and hoping for the best.  After all, to go back to the movie Contact -- "if we're all alone in the universe, it seems like an awful waste of space."

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The biochemical zoo

The human/alien hybrid is a common trope in science fiction.  From the angst-ridden half-Vulcan Mr. Spock, to the ultra-competent and powerful half-Klingon B'Elanna Torres, to the half-Betazoid empath Deanna Troi, the idea of having two intelligent humanoid species produce children together is responsible for dozens of plot twists in Star Trek alone.

Much as I love the idea (and the show), the likelihood of a human being able to engage in any hot bow-chicka-bow-wow with an alien, and have that union produce an offspring, is damn near zero.  Even if the two in question had all the various protrusions and indentations more or less lined up, the main issue is the compatibility of the genetic material.  I mean, consider it; it's usually impossible for two ordinary terrestrial species to hybridize -- even related ones (say, a Red-tailed Hawk and a Peregrine Falcon) are far enough apart genetically that any chance mating would produce an unviable embryo.

Now consider how likely it is to have genetic compatibility between a terrestrial species and one from the fourth planet orbiting Alpha Centauri.

Any hope you might have had for a steamy tryst with an alien was smashed even further by a study that came out of a study from the Tokyo Institute of Technology, Emory University, and the German Aerospace Center.  Entitled, "One Among Millions: The Chemical Space of Nucleic Acid-Like Molecules," by Henderson James Cleaves II, Christopher Butch, Pieter Buys Burger, Jay Goodwin, and Markus Meringer, the study shows that the DNA and RNA that underlies the genetics of all life on Earth is only one of millions of possible information-encoding molecules that could be out there in the universe.

It was amazing how diverse these molecules were, even given some pretty rigid parameters.  Restricting the selection to linear polymers (so the building blocks have to have attachment points that allow for the formation of chains), and three constituent atoms -- carbon, hydrogen, and oxygen, like our own carbohydrates -- the researchers found 706,568 possible combinations (counting configurations and their mirror images, pairs of molecules that are called stereoisomers).  Adding nitrogen (so, hooking in chemicals like proteins and the DNA and RNA nitrogenous bases, the letters of the DNA and RNA alphabets) complicated matters some -- but they still got 454,442 possible configurations.

The results were a surprise even to the researchers.  "There are two kinds of nucleic acids in biology, and maybe twenty or thirty effective nucleic acid-binding nucleic acid analogs," said Henderson James Cleaves, who led the study, in an interview in SciTechDaily.  "We wanted to know if there is one more to be found...  The answer is, there seem to be many, many more than was expected."

Co-author Pieter Burger of Emory University is excited about the possible medical applications of this study.  "It is absolutely fascinating to think that by using modern computational techniques we might stumble upon new drugs when searching for alternative molecules to DNA and RNA that can store hereditary information," Burger said.  "It is cross-disciplinary studies such as this that make science challenging and fun yet impactful."

While I certainly can appreciate the implications of this research from an Earth-based standpoint, I was immediately struck by its application to the search for extraterrestrial life.  As I mentioned earlier, it was already nearly impossible that humans and aliens would have cross-compatible DNA, but now it appears that alien life might well not be constrained to a DNA-based genetic code at all.  I always thought that DNA, or something very close to it, would be found in any life form we run across, whether on this planet or another; but the Cleaves et al. study suggests that there are a million or more other ways that organisms might spell out their genetic code.

So this drastically increases the likelihood of life on other planets. The tighter the parameters for life, the less likely it is -- so the discovery of a vast diversity of biochemistry opens up the field in a manner that is breathtaking.

... but the chance that the aliens will look like this is, sadly, pretty low.

This raises the problem of whether we'll recognize alien life when we see it.  The typical things you look for if you're trying to figure out if something's alive -- such as a metabolism involving the familiar organic compounds all our cells contain -- might cause us to overlook something that is alive but is being carried along by a completely different chemistry.

And what an organism with that completely different chemistry might look like -- how it would move, eat, sense its environment, reproduce, and think -- well, there'd be an embarrassment of riches.  The possibilities are far beyond even the Star Trek universe, with their fanciful aliens that look basically human but with odd facial structures and funny accents.

The whole thing boggles the mind.  And it further reinforces a conclusion I've held for a very long time; I suspect that we'll find life out there pretty much everywhere we look, and even on some planets we'd have thought completely inhospitable.  The "Goldilocks Zone" -- the region surrounding a star where orbiting planets would have conditions that are "just right" for life to form -- is looking like it might be a vaster territory than we'd ever dreamed.

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