Out of your mind

One of the most striking pieces from neuroscientist David Eagleman's brilliant TED Talk "Can We Create New Senses for Humans?" centers around what is really happening when we experience something.

Regardless what it feels like, all that's going on -- the internal reality, as it were -- are some fairly weak voltage changes bouncing around in the brain.  The brain is locked inside the skull, and on its own is blind and deaf.  It needs the sense organs (Eagleman calls them our "peripherals") to send electrical signals in via input nerves to the right places in the brain, and that stimulates changes in the voltage in those areas.

That's it.  Everything you've ever experienced -- good and bad, pleasant and unpleasant -- boils down to that.  And if something messes around with any step in that process, that altered electrical state in the brain becomes the basis of what you see, hear, feel, and think.  If the wiring is faulty (thought by some researchers to be the cause of the peculiar disorder synesthesia), if there's a problem with the levels of neurotransmitters, the chemicals that either pass signals along or else block them (probably involved in schizophrenia, depression, and anxiety, among others), or if you've taken drugs that change the electrical activity of the brain -- that becomes your reality.

I was reminded of this sobering observation when I read an article sent to me my a friend and loyal reader of Skeptophilia.  Entitled, "Have Scientists Found the Source of Out-of-Body Experiences?", it describes research into a part of the cerebrum called the anterior precuneus, which appears to be involved in our sensations of conscious awareness.  Neuroscientist Josef Parvizi of Stanford University was working with epilepsy patients who were experiencing drug-resistant seizures, and found that when the anterior precuneus was electrically stimulated (the patients already had electrodes implanted in their brains to try to reduce the frequency and severity of their seizures), they had sensations of floating, and of dissociation and disorientation.

"All of them reported something weird happening to their sense of physical self," Parvizi said in an interview in Scope, Stanford Medicine’s blog.  "In fact, three of them reported a clear sense of depersonalization, similar to taking psychedelics."

Luigi Schiavonetti, The Soul Leaving the Body (1808) [Image is in the Public Domain]

What it made me wonder is if the anterior precuneus might be involved in other types of dissociation.  It's one thing when you artificially trigger a part of the brain to malfunction (or at least, alter its function) using electrodes or chemicals; but what about when it just kind of... happens?  I know I've had this experience while listening to music.  When I was about twelve, my grandma gave me a little portable radio, and I listened to it constantly.  One evening, I happened upon a radio station playing classical music, and just as I tuned in, I heard the wild, joyous trumpets and violins of the overture to J. S. Bach's Magnificat in D.

Then the chorus came in.

Three minutes later, I remembered where (and who) I was.  My face was wet with tears.  I don't know where I'd been during that time, but it wasn't in my attic bedroom in my grandma's house, with its creaky wood-plank floors and pervasive smell of dust and old books.

It was such a powerful and overwhelming event in my life that I wrote it into one of my novels, The Hand of the Hunter -- with setting and character changes, of course -- but to this day when someone says they had a "spiritual experience," this is what I think of.  It's happened to me more than once since then, always associated with music (the first hearings of Ralph Vaughan Williams's Fantasia on a Theme by Thomas Tallis, Stravinsky's Firebird, Debussy's The Drowned Cathedral, Arvo Pärt's Spiegel im Spiegel, and Mozart's Requiem had similar effects on me), but that first encounter was by far the most striking.

I wonder if the mental and physical sensations that accompanied it had something to do with the anterior precuneus?  And if, by extension, it might be the source of all such transcendent experiences?

If so, what possible purpose could this serve?

Figuring that out is considerably above my pay grade, but considering the similarities -- a loss of awareness of where your body is, dissociation, the feeling of a "time slip" -- it did bring the question up.

In any case, finding a part of the brain that, when stimulated, it makes you lose connection to the outside world is pretty staggering.  I recall one of my mentors Cornell University Professor Emeritus Rita Calvo (of the Department of Human Genetics) saying that if she were going into biology today, she'd choose neuroscience instead of genetics.  "With respect to the brain, we're right now where we were with the gene a hundred years ago.  We have an idea of some of the 'wheres' and 'hows,' but little understanding of the mechanisms behind them.  Think of what was on the horizon for geneticists in 1923 -- that's what the neuroscientists have to look forward to."

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PsychicGPT

Well... we should have seen this coming.  Or at least, they should have.

According to a recent report, visits to psychics are way down because people are paying to use online "psychic chatbots" to make predictions about their future.

Because the AI fortunetellers use "sophisticated algorithms and machine-learning techniques... and are unaffected by human emotions and preconceptions," there's been a sudden surge of the worried and/or lovelorn turning to what amounts to ClairvoyantGPT.

"In the digital age the convergence of ancient wisdom and cutting-edge technology has given rise to new possibilities," writes Jerry Lawton.  "One such innovation is AI Tarot reading where the age-old practice of Tarot cards meets the power of artificial intelligence...  Through natural language processing and data analysis AI algorithms aim to mimic the intuition and insight traditionally associated with human Tarot readers.  This fusion of technology and divination opens up new possibilities for individuals seeking guidance and self-reflection.  AI Tarot reading brings the wisdom of Tarot cards to your fingertips anytime and anywhere.  With just a few clicks you can access Tarot readings from the comfort of your own home or even on the go.  Digital platforms and mobile applications make it easy for individuals to receive instant guidance and insights eliminating the need for in-person consultations.  AI algorithms follow a set of predefined rules and principles providing objective interpretations of Tarot cards.  These algorithms analyze vast amounts of data, taking into account various factors and symbolism associated with each card.  By eliminating subjective biases AI Tarot readings offer consistent and reliable insights that remain unaffected by human emotions or preconceptions."

[Image is in the Public Domain]

Well, that all sounds pretty amazing, so I had to try it out.

I was restricted in my choices given that I am not going to give some random fortunetelling website my name and email address (this eliminated about half of them) and I was damn sure not going to pay for it (eliminating most of the other half).  I finally settled on EvaTarot.net, the home of Eva Delattre, "tarologist," which met my criteria of being free and not condemning me to a lifetime of getting spam emails from psychics.

Anyhow, after doing the "pick a card, any card" thing, here's what it told me about my future.  I've abbreviated it somewhat, because it was kind of long, but otherwise, it's verbatim.

The cards show that you are now in a period favorable to personal development.  This idea of getting better is highlighted by the cards you have selected which show that at work, and in your personal projects, you are adopting a new attitude and a new way of looking at things.  Nowadays you tend to think more about the consequences of your acts; there is no question of doing things at random, and making the same mistakes as in the past.  This new dynamic opens many doors that go beyond your personal projects.

That's good to hear.  I do feel that repeating mistakes from the past is a bad idea, which is why I have a lifelong commitment to making all new and different mistakes.

A proposal will be made that will surprise you for two reasons.  First because of the person who will do it: you didn't expect that from her.  Then by the proposal itself, which will be just for you and which will be totally unexpected.  It will make you very happy, and you will be overwhelmed to be the subject of this proposal.  "The innocent will have their hands full", as they say!  Innocent because you were not expecting this. Hands full because it will fill you with joy.

Then it's up to you to think about the consequences of this request: to accept? to refuse?  It's up to you.  Whatever happens, you'll have to give an answer.  Take the time to think, because the answer you give will engage you for months in a pattern that you will not be able to get out of easily.

Huh.  If the proposal is to turn my upcoming book release into a blockbuster movie, I'm all for it.  But the decision-making part worries me a tad.  It's never been my forte.  In fact, I've often wondered if I have some Elvish blood, given Tolkien's quip, "Go not to the Elves for advice, for they will say both yes and no."

You need calm and tranquility at the moment.  You have been tried by long-lasting problems that never seem to get better, it plays on your morale and your daily life goes by so quickly you never seem to get a grip on it.  You must have patience, create a bit of distance from a system that is going too quickly for you, and get some perspective on your situation.  The card shows a character whose head is buried in the present, trapped by the rhythm of their life, unable to escape.

Well, once again, patience has never been one of my strengths.  So this is accurate enough with regards to my personality, but at the same time I'm struck by how generally unhelpful it is.  "You need to be more patient, so develop some patience!  Now!" doesn't seem like a very good way to approach the problem.

Not, honestly, that I have any better ideas.  Unsurprising, I suppose, given that "my head is buried in the present."

What stands out about all this is how generic my reading is.  That's how it works, of course; you may remember James Randi's famous demonstration of that principle in a high school classroom, where students were told that a detailed horoscope had been drawn up for them using their birthdates, and they were asked to rate how accurate it seemed for themselves personally on a scale of zero to ten.  Just about everyone rated it above seven, and there were loads of nines and tens.

Then they were asked to trade horoscopes with the person next to them... and that's when they found out they were all given the exactly same horoscope.

We're very good at reading ourselves into things, especially when we've been told that whatever it is has been created Especially For Us.  Add to that a nice dollop of confirmation bias, and you've got the recipe for belief.

Of course, maybe my overall dubious response was because I chose the no-strings-attached El Cheapo psychic reading.  You get what you pay for, or (in this case) didn't pay for.

In any case, I suppose it was just a matter of time that the AI chatbot thing got hybridized with psychic readings.  What I wonder is what's going to happen when the AI starts to "hallucinate" -- the phenomenon where AI interfaces have slipped from giving more-or-less correct answers to just making shit up.  You pay your money, and instead of a real psychic reading, all you get is some AI yammering random nonsense at you.

That, of course, brings up the question of how you could tell the difference.

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Magnetic nonsense

Loony people are hardly a new invention.  Any claims that "people are crazier now than they used to be" generally springs from one of two things, the first of which is a bad memory.

The other, though, is more interesting, as well as more troubling.  In the past, when Great-Aunt Ethel started babbling in public about being visited at night by a sexy alien who wanted to take her up to his spaceship and bring her back to Zeta Reticuli to be his immortal love slave, we had the option of saying, "That's wonderful, auntie, but let's go inside and get you a nice cup of tea and watch The Beverly Hillbillies, okay?  Wouldn't that be fun?"

Now, the Great-Aunt Ethels of the world have computers with internet access, where they can connect with all the other Great-Aunt Ethels.  And influence people who are already on the borderline, so as to create the next generation of Ethels.  And because a lot of social media sites now allow you to monetize your content, they're able to make tons of money off it, extending their reach even further.

We're in a world where the Ethels have just as great a capacity for being heard as the scientists do.

And this brings us to Sherri Tenpenny.

Tenpenny is an anti-vaxx activist who was identified by the Center for Countering Digital Hate as one of the "Disinformation Dozen" -- the twelve people who, put together, are responsible for 65% of the vaccine misinformation out there online.  (Other shining lights on this list are Joseph Mercola, Robert F. Kennedy, Jr., and Christiane Northrup.)  Tenpenny, though, brings things to a whole different level, way beyond the usual "vaccines cause autism" nonsense.  Here's one example:

The stated goal is to depopulate the planet and the ones that are left, either make them chronically sick or turn them into transhumanist cyborgs that can be manipulated externally by 5G, by magnets, by all sorts of things.  I got dragged through the mud by the mainstream media when I said that in May of last year in front of the House Committee in Columbus, [Ohio].  Well, guess what?  It’s all true.

The whole issue of quantum entanglement and what the shots do in terms of the frequencies and the electronic frequencies that come inside of your body and hook you up to the "Internet of Things," the quantum entanglement that happens immediately after you’re injected.  You get hooked up to what they’re trying to develop.  It’s called the hive mind, and they want all of us there as a node and as an electronic avatar that is an exact replica of us except it’s an electronic replica, it’s not our God-given body that we were born with.  And all of that will be running through the metaverse that they’re talking about.  All of these things are real...  All of them.  And it’s happening right now.  It’s not some science fiction thing happening out in the future; it’s happening right now in real time.

Sure it is, Great-Aunt Sherri.  Here, have a nice cup of tea.

The trouble is, Tenpenny and others like her are getting rich off this stuff.  Some social media sites -- notably Facebook and YouTube -- have taken steps to stop her from spreading her insane lies, but even so, her message is still getting out there.  Business management information provider Dun & Bradstreet reported that her clinic, the Tenpenny Integrative Medical Center, has an average annual sales total of a bit over four million dollars.

And that's despite the fact that the State Medical Board of Ohio recently revoked her medical license.

What gets me is that nothing she says, however ridiculous, seems to diminish her popularity.  In June of 2021 she stated that she had "spent over ten thousand hours studying the origins and effects of COVID since the pandemic began," despite the fact that at that point only eleven thousand hours had passed since the pandemic was declared.  She also claimed that the vaccine turns you into a human magnet:

I’m sure you’ve seen the pictures all over the internet of people who have had these shots and now they’re magnetized.  They can put a key on their forehead and it sticks…  There have been people who have long suspected there’s an interface, yet to be defined, an interface between what’s being injected in these shots and all of the 5G towers.

Well, I can state definitively that based upon an experiment I just ran with my car keys, this is incorrect. 

And this is considering that I've now had four COVID shots (the original two plus two boosters), and have been vaccinated against all the usual childhood diseases, as well as typhoid, yellow fever, shingles, hepatitis A and B, and a yearly flu shot since (if memory serves) 1995.  Despite all this, as the above highly scientific photograph shows, I am not even a tiny bit magnetic.

I have also not been turned into an electronic avatar or a transhumanist cyborg, which I honestly feel a little disappointed about, because that sounds badass.

Given the fact of the connectivity we have now for information of all sorts, we no longer have the option of hustling Sherri Tenpenny back into the house and getting her settled in the recliner in front of The Beverly Hillbillies.  The best thing we can do is to shine as bright a light as possible on her nonsense.  We can't let her go unchallenged, especially on such subjects as vaccination, where peoples' health and lives are at risk.

It'd be one thing if she was talking about sexy aliens from Zeta Reticuli.  She's not.  Her rhetoric is, literally, killing people.

We're not going to be able to stop her from shouting.  The important thing is that the sane people, the ones who actually know what they're talking about shout back -- louder.

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Inner space

Donald Rumsfeld famously said, "There are known knowns.  These are things we know that we know.  There are known unknowns.  That is to say, there are things that we know we don't know.  But there are also unknown unknowns.  There are things we don't know we don't know."

At the time, much fun was made of his choice of words.  But although I wouldn't choose this as an exemplar of clarity, I have to admit the point he was making is valid enough.  Sometimes discovery starts with determining exactly what it is we don't yet know, with sketching out what astrophysicist Neil deGrasse Tyson (more eloquently) called "the perimeter of our ignorance."

This is the point of the Unknome Project, which is an effort to take our own genome and figure out what parts of it are, at present, unstudied and unexplained.  Cellular biologist Seth Munro and his colleagues at the Medical Research Council Laboratory of Molecular Biology in Cambridge, England, have developed a catalogue of thirteen thousand gene families found in humans (or other mammals that have been sequenced), coding for over two million proteins, and assigned each a "knownness score" -- a number describing to what extent the function of each is understood.  And three thousand of the families -- a little less than a quarter of them -- have a knownness score of zero.

That's a lot of genes that were (at least before Munro et al.) unknown unknowns.

[Image licensed under the Creative Commons Christoph Bock, Max Planck Institute for Informatics, DNA methylation, CC BY-SA 3.0]

What's even cooler is that the group is working to chip away at this bit of the perimeter of our ignorance, and to learn something about the mysteries of our own genetic inner space.  They found 260 genes with low knownness scores that are also present in fruit flies -- a much easier species to study -- and used a technique to suppress the expression of those genes.

Astonishingly, reducing the expression of sixty of these hitherto-unknown genes killed the flies outright.  Dampening others inhibited such important functions as reproduction, growth, mobility, and resistance to stress.

If these poorly-studied genes have analogous effects in humans -- and it's suspected that they do, given that they were evolutionarily conserved since the last common ancestor of humans and fruit flies, something like a half a billion years ago -- that's a lot of critical parts of our genome we don't yet understand.

What it got me wondering is how many of these are involved in diseases for which we haven't yet determined the causes.  There are so many disorders -- like, unfortunately, most mental illnesses -- for which the treatments are erratic at best, in part because we don't know for sure what the underlying origin of the condition is.  In my own case, I know for sure that depression and anxiety run in both sides of my family -- my mother and maternal grandmother both suffered from major depression, and a paternal great-grandmother committed suicide after (according to the newspaper article that reported it) "becoming mentally unbalanced by the illness of her husband."  Part of the problem with these sorts of things is, of course, that it's hard to tease apart the genetic from the environmental factors.  Growing up with mental illness in the family certainly doesn't make for an easy childhood; as my wise grandmother once said, "Hurt people hurt people" -- something that was certainly true enough within her own family.

It's fantastic that Munro and his colleagues are working to try and elucidate the functions of these mysterious genes, and I hope that perhaps some of them might turn out to be good targets for medications to alleviate conditions that have heretofore been resistant to treatment.  Certainly, anything we can do to reduce the perimeter of our own ignorance -- to eliminate some of those unknown unknowns -- is a good thing.

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All roads lead to... North Tawton?

You may have heard that upstate New York is called a "four-season climate."  Sounds nice, doesn't it?  What they neglect to tell you prior to moving here is that the four seasons are Almost Winter, Winter, Still Fucking Winter, and Road Construction.

That last bit is a frustrating one, because even though the summers here are quite nice, the constant freeze-thaw cycle of the other three seasons plays absolute hell on our roads.  Ithaca, the nearest decent-sized town to where I live, is a lovely place in many respects, but it often seems like little more than a giant maze of potholes.  So it's no wonder that the road construction crews use our fleeting summers to make what repairs they can before the deluge of snow, ice, and road salt starts once again.

The difficulty we have in maintaining our transportation corridors highlights how amazing it is that there are still largely intact roads from Roman times, nearly two thousand years ago.  To be fair, they didn't have the amount (nor type) of traffic our highways have to endure, but still, it's a testament to Roman engineering prowess that they even still exist.

Blackstone Edge Long Causeway, West Yorkshire, second century C.E. [Image licensed under the Creative Commons Nigel Homer, Looking down the Roman Road - geograph.org.uk - 92590, CC BY-SA 2.0]

The topic comes up because of a cool new study out of the University of Exeter that used LIDAR (Laser Imaging, Detection, And Ranging), a technique that can detect surface structures even through dense undergrowth, to locate traces of a network of Roman roads in Devon and Cornwall that archaeologists didn't even know existed.

What was most surprising is that the hub of the road network wasn't the city of Exeter, but the much smaller town of North Tawton (which currently only has about two thousand inhabitants).  Exeter was a Roman town -- they called it Isca Dumnoniorum, after the Dumnonii, a local Celtic tribe -- but the more centrally-located site of North Tawton (the Roman Nemetostatio) was the center of the radial spokes of the network.

"Despite more than seventy years of scholarship, published maps of the Roman road network in southern Britain have remained largely unchanged and all are consistent in showing that west of Exeter, Roman Isca, there was little solid evidence for a system of long-distance roads," said Christopher Smart, who led the study.  "But the recent availability of seamless LIDAR coverage for Britain has provided the means to transform our understanding of the Roman road network that developed within the province, and nowhere more so than in the far southwestern counties, in the territory of the Dumnonii."

The result was that they were able to identify over a hundred kilometers of roads that were previously unknown to archaeologists, giving them a much better picture of how people moved in Romano-Celtic Britain.  The map they generated suggests that the network not only connected Roman outposts to each other, but incorporated pre-existing Celtic towns -- showing that the conquering Romans preferred to leave intact the settlements of the people they ruled (at least the ones who didn't fight back).

"In terms of chronology, it is likely that the proposed network is an amalgam of pre-existing prehistoric routeways, Roman military campaign roads or 'tactical roads' formally adopted into the provincial communications system, and of those constructed during peacetime in a wholly civilian context," said João Fonte, who co-authored the study.  "This evolutionary model is supported by the fact that the network does not solely connect Roman forts and their hinterlands directly, which are often connected by branch roads, but instead appears to serve a broader purpose than required by military supply."

It's astonishing to think that nearly two millennia later, we can still find the remnants of the roads used by the Romans in Britain.  Makes me wonder what future archaeologists will find of our civilization.  Will there be anything left of the asphalt paths we create for our cars?

Hey, if we can still locate the remains of the cobblestone paths put down by the Romans, I think there's an excellent chance the archaeologists of the future will be able to find out a good bit about our highways, too.  "Wow," they'll say.  "Those people in upstate New York sure knew how to repair potholes."

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Deep impact

Tektites are curious, glassy blobs of rock, from millimeters to centimeters in diameter.  At first thought to be similar to obsidian (volcanic glass), formed when silica-rich lava cools too quickly to form crystals, it soon became apparent that tektites were something else entirely.  They have strangely pitted surfaces, are often teardrop-shaped, and (once such studies became possible) they were found to have an entirely different chemistry than obsidian.  Most puzzling was the fact that tektites are most often found in circumscribed geographical regions nicknamed "strewnfields" -- which usually were nowhere near recently-erupted volcanoes.

It wasn't until the 1920s that geologist Franz Eduard Suess proposed the theory now accepted today, and coined the name tektite (from the Greek τηκτός, "molten").  Tektites form when a meteorite strikes the Earth, liquefying the rock on the surface upon impact.  The molten rock is thrown outward from the blast site, creating the circular or elliptical "strewnfield" -- and explaining why the blobs thus created don't match the chemistry of igneous rock.  Their composition is different depending on the nature of the rock at the location where the meteorite struck.

[Image licensed under the Creative Commons James St. John, Indochinite tektite (Pleistocene, 783-803 ka; Australasian Tektite Strewn Field, southeastern Asia) 4, CC BY 2.0]

So, you'd think once Suess said, "These are formed when a bigass rock slams into the ground" (I paraphrase him slightly), finding the crater where the thing landed would be easy, right?  Just draw a circle around the strewnfield and then look in the middle?

Wrong.

There's a relatively recent strewnfield -- on the order of 790,000 years old, which is a snap of the fingers, geologically speaking -- that is abso-freaking-lutely huge.  It extends from southern China to Antarctica (going north-south) and from the floor of the middle of the Indian Ocean to Micronesia (going west-east).  And that's just where the tektites have been definitively identified.  By some estimates, the Australasian strewnfield might cover thirty percent of the Earth's surface.

But the location of the crater proved elusive.  Part of it is that the center of the strewnfield is in Southeast Asia, which is (mostly) impenetrable jungle, and in places the terrain is so steep and rugged as to be nearly impassable.  But despite the difficulties, geologists have finally located the crater, and also determined why it wasn't obvious despite how recently it occurred.

The Australasian meteorite struck a spot in Laos that already had an active volcano.

The heat from the impact did two things -- flung blobs of molten rock all over the place (the tektites geologists later found in the strewnfield), and also triggered a massive eruption, producing a large enough lava flow to fill in and bury the crater.

[Map from Sieh et al.]

What I find most astonishing about all this is that the impact of this gigantic rock, only 790,000 years ago, didn't cause climatic chaos and a resulting extinction event.  Our relatives, Homo erectus, were living and apparently thriving in southern China both during and after the impact, and seem to have been none the worse for the event.  (If some of them were in Laos, they were probably deep-fried; but given that there was an active volcano there anyhow...) 

I wonder if the reason for the relatively low environmental impact had to do with the geology of the place the meteorite hit, which was primarily made of basalt and other hard igneous rocks.  The Chicxulub strike, 66 million years ago, was devastating not only because it was so big, but because it hit a formation of shallow marine limestone, which literally vaporized on impact, creating a shock wave of superheated water vapor and carbon dioxide that incinerated everything within a radius of a thousand kilometers.  There has to be more to it than simply size; the two weren't that different, an estimated two kilometers in diameter for the Australasian impact and between ten and twelve for Chicxulub.

Whatever the reason was for the difference, it's a good thing for us, because another Chicxulub-type event 790,000 years ago, and we'd very likely not be here.

In any case, it's pretty cool that we can use the splash patterns of molten debris to identify the location of a meteorite impact almost eight hundred thousand years after it happened, despite the fact that the whole thing was filled in with lava and overgrown by jungle.  Further underscoring my bafflement over how anyone can not find science amazingly cool.

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Glimpse of the dawn

A pair of words biologists (and interested laypeople) have to be careful with are primitive and advanced.

They're often used in place of the generally more appropriate simple and complex.  By that usage, an amoeba is primitive and an aardvark is advanced.  But where it gets confusing is that primitive and advanced are also sometimes used to mean "like something that evolved earlier" and "like something that evolved more recently," respectively -- so they use primitive to describe a stegosaurus and advanced to describe a spider monkey, when in fact both of those are about equally complex.  (It gets even murkier when you throw in questions of relative intelligence.)

It bears keeping in mind that while modern organisms vary greatly on the simple/complex spectrum, they all have lineages that have been around exactly the same amount of time -- 4.3 billion years, give or take a day or two.  All known lineages of terrestrial life converge on a single life form nicknamed LUCA -- the Last Universal Common Ancestor -- around four billion years ago.  To our eyes, LUCA probably wouldn't have looked like much.  It probably resembled species we now classify as bacteria.

But all life on Earth descends from it.  And as far as the primitive/advanced bit, the only difference is in that time, some of the lineages changed a great deal more than others did.

The reason this comes up is because of a link sent to me by a friend and frequent contributor of topics for Skeptophilia, about a species of fairly modern-looking jellyfish that was found in rock strata that are 505 million years old.

The species, named Burgessomedua phasmiformis, was a free-swimming, tentacle-laden predator with a bell on the order of twenty centimeters in diameter.  It, like many of the Cambrian explosion fauna, were found in the exceptionally well-preserved Burgess Shale Formation of the Canadian Rockies in British Columbia.

Artist's impression of live Burgessomedusa in the Cambrian seas [courtesy of artist Christian McCall]

Jellyfish and most of the other members of Phylum Cnidaria are generally scarce in the fossil record, because their bodies are primarily water.  If you've ever seen a dried-up jellyfish on the beach, you know what I'm talking about; there's barely anything left.  (Don't assume that this means they're harmless, though.  Even the dried tentacles of a Portuguese man-o'-war can pack a dangerous sting.)  But you can see how astonishing it is not only to have one create an impression in sedimentary rocks, but to have that impression last for 505 million years.

So the exceptional preservation of this extremely rare fossil animal is amazing enough.  But what I find even more mind-boggling when I think about the life back then is the bigger picture of what the Cambrian Period was like.  At that point, all life was in the water.  There was (more or less) the same amount of land as there is now, albeit configured completely differently -- but on that land was not a single living thing.  No plants, no fungi, no animals.  Nothing.  It was a vast expanse of empty rock, sand, and dust.

At this point, the first terrestrial plants wouldn't make their appearance for another fifty million years, and even then, they were highly water-dependent and very likely clustered along shorelines.  The first vascular plant -- one with the internal plumbing most plants have today -- that appears in the fossil record is Cooksonia, which appeared during the mid-Silurian Period (about 430 million years ago).  It was a strange, rather Dr. Seussian thing:

[Image licensed under the Creative Commons Smith609 Ground texture from Image:Mud closeup.jpg, Cooksonia pertoni, CC BY 3.0]

But when Burgessomedusa was swimming in the Cambrian oceans, all that lay millions of years in the future.  This glimpse of the dawn of time gives us a picture so alien to our current mental image of the Earth it's hard to believe it's the same planet.

What this tells paleontologists, though, is that even in the early Cambrian, there were relatively modern-looking jellyfish -- and that even though today's cnidarians are advanced in the sense of "length of their lineage on Earth," they haven't changed much at all during all those hundreds of millions of years.  The general reason for such stability is that the body plan works; there's little selective pressure to favor alterations in a system that does fine as is, however "primitive" it may look to us.

As a writer friend of mine posted yesterday:

The details might be off a little, but the gist is accurate enough.

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