Off the chart

Way back around 1910, Danish astronomer Ejnar Hertzsprung and American astronomer Henry Norris Russell independently found a curious pattern when they did a scatterplot correlation between stars' luminosities and temperatures.

The graph, now called the Hertzsprung-Russell Diagram in their honor, looks like this:

[Image licensed under the Creative Commons Richard Powell, HRDiagram, CC BY-SA 2.5]

Most stars fall on the bright swatch running from the hot, bright stars in the upper left to the cool, dim stars in the lower right; the overall trend for these stars is that the lower the temperature, the lower the luminosity.  Stars like this are called main-sequence stars.  (If you're curious, the letter designations along the top -- O, B, A, F, G, K, and M -- refer to the spectral class the star belongs to.  These classifications were the invention of the brilliant astronomer Antonia Maury, whose work in spectrography revolutionized our understanding of stellar evolution.)

There is also a sizable cluster of stars off to the upper right -- relatively low temperatures but very high luminosities.  These are giants and supergiants.  In the other corner are white dwarfs, the exposed cores of dead stars, with very high temperatures but low luminosity, which as they gradually cool slip downward to the left and finally go dark.

So there you have it; just about every star in the universe is either a main-sequence star, in the cluster with the giants and supergiants, or in the curved streak of dwarf stars at the bottom of the diagram.

Emphasis on the words "just about."

One star that challenges what we know about how stars evolve is the bizarre Stephenson 2-18, which is in the small, dim constellation Scutum ("the shield"), between Aquila and Sagittarius.  At an apparent magnitude of +15, it is only visible through a powerful telescope; it was only discovered in 1990 by American astronomer Charles Bruce Stephenson, after whom it is named.

Its appearance, a dim red point of light, hides how weird this thing actually is.

When Stephenson first analyzed it, he initially thought what he was coming up with couldn't possibly be correct.  For one thing, it is insanely bright, estimated at a hundred thousand times the Sun's luminosity.  Only its distance (19,000 light years) and some intervening dust clouds make it look dim.  Secondly, it's enormous.  No, really, you have no idea how big it is.  If you put Stephenson 2-18 where the Sun is, its outer edge would be somewhere near the orbit of Saturn.  You, right now, would be inside the star.  Ten billion Suns would fit inside Stephenson 2-18. 

If a photon of light circumnavigated the surface of the Sun, it would take a bit less than fifteen seconds.  To circle Stephenson 2-18 would take nine hours.

This puts Stephenson 2-18 almost off the Hertzsprung-Russell Diagram -- it's in the extreme upper right corner.  In fact, it's larger than what what stellar evolution says should be possible; the current model predicts the largest stars to have radii of no more than 1,500 times that of the Sun, and this behemoth is over 2,000 times larger.

Astronomers admit that this could have a simple explanation -- it's possible that the measurements of Stephenson 2-18 are overestimates.  But if not, there's something significant about stellar evolution we're not understanding.

Either way, this is one interesting object.

There's also a question about what Stephenson 2-18 will do next.  Astrophysicists suspect it might be about to blow off its outer layers and turn either into a luminous blue variable or a Wolf-Rayet star (the latter are so weird and violent I wrote about them here a while back).  So it may not be done astonishing us.

Puts me in mind of the quote from Richard Dawkins: "The feeling of awed wonder that science can give us is one of the highest experiences of which the human psyche is capable."

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The kludge factory

Know what a kludge is?

Coined by writer Jackson Granholm in 1962, a kludge is "an ill-assorted collection of poorly-matching parts, forming a distressing whole."  Usually created when a person is faced with fixing something and lacks (1) the correct parts, (2) the technical expertise to do it right, or (3) both, kludges fall into the "it works well enough for the time being" category.

[Image licensed under the Creative Commons Zoedovemany, Screen Shot 2015-11-19 at 11.54.48 AM, CC BY-SA 4.0]

Evolution is essentially a giant kludge factory.

At its heart, it's the "law of whatever works."  It's why the people who advocate Intelligent Design Creationism always give me a chuckle -- because if you know anything about biology, "intelligently designed" is the last thing a lot of it is.  Here are a few examples:

• Animals without hind legs -- notably whales and many snakes -- that have vestigial hind leg bones.
• Primates are some of the only mammals that cannot synthesize their own vitamin C -- yet we still carry the gene for making it.  It just doesn't work because it has a busted promoter.
• Human sinuses.  Yeah, you allergy sufferers know exactly what I'm saying.
• The recurrent laryngeal nerve in fish follows a fairly direct path, from the brain past the heart to the gills.  However, when fish evolved into land-dwelling forms and their anatomy changed -- their necks lengthening and their hearts moving lower into the body -- the recurrent laryngeal nerve got snagged on the circulatory system and had to lengthen as its path became more and more circuitous.  Now, in giraffes (for example), rather than going from the brain directly to the larynx, it goes right past its destination, loops under the heart, and then back up the neck to the larynx -- a distance of almost five meters.
• Our curved lower spines were clearly not "designed" to support a vertically-oriented body.  Have you ever seen a weight-bearing column with an s-bend?  No wonder so many of us develop lower back issues.
• One of the kludgiest of kludges is the male genitourinary tract.  Not only does the vas deferens loop way upward from the testicles (not quite as far as the giraffe's laryngeal nerve, admittedly), along the way it joins the urethra to form a single tube through the penis, something about which a friend of mine quipped, "There's intelligent design for you.  Routing a sewer pipe through a playground."  It also passes right through the prostate, a structure notorious for getting enlarged in older guys.  C'mon, God, you can do better than that.

The reason all this comes up is that the kludging goes all the way down to the molecular level.  A study from a team at Yale, Harvard, and MIT that appeared last week in the journal Science looked at the fact that when you compare the human genome to that of our nearest relatives, you find that one of the most significant differences is that our DNA has deleted sections.

That's right; some of why humans are human comes from genes that got knocked out in our ancestors.

The researchers found that there are about ten thousand bits of DNA, a lot of them consisting only of a couple of base pairs, that chimps and bonobos have and we don't.  A lot of these genetic losses were in regions involved in cognition, speech, and the development of the nervous system, all areas in which our differences are the most obvious.

The reason seems to have to do with gene switching.  Deleting a bit of switch that is intended to shut a gene off can leave the gene functioning for longer, with profound consequences.  Often these consequences are bad, of course.  There are some types of cancer (notably retinoblastoma) that are caused by a developmental gene having a faulty set of brakes.

But sometimes these changes in developmental patterns have a positive result, and therefore a selective advantage -- and we may owe our large brains and capacity for speech to kludgy switches.

"Often we think new biological functions must require new pieces of DNA, but this work shows us that deleting genetic code can result in profound consequences for traits make us unique as a species," said Steven Reilly, senior author of the paper.  "The deletion of this genetic information can have an effect that is the equivalent of removing three characters -- n't -- from the word isn't to create the new word is...  [Such deletions] can tweak the meaning of the instructions of how to make a human slightly, helping explain our bigger brains and complex cognition."

So yet another nail in the coffin of Intelligent Design Creationism, if you needed one.  Of course, I doubt it will convince anyone who wasn't already convinced; as I've observed more than once, you can't logic your way out of a belief you didn't logic your way into.

But at least it's good to know the science is unequivocal.  And, as astrophysicist Neil deGrasse Tyson said, "The wonderful thing about science is that it's true whether or not you believe in it."

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Pitch perfect

Consider the simple interrogative English sentence, "She gave the package to him today?"

Now, change one at a time which word is stressed:

• "She gave the package to him today?"
• "She gave the package to him today?"
• "She gave the package to him today?"
• "She gave the package to him today?"
• "She gave the package to him today?"

English isn't a tonal language -- where patterns of rise and fall of pitch change the meaning of a word -- but stress (usually as marked by pitch and loudness changes) sure can change the connotation of a sentence.  In the above example, the first one communicates incredulity that she was the one who delivered the package (the speaker expected someone else to do it), while the last one clearly indicates that the package should have been handed over some other time than today.

In tonal languages, like Mandarin, Thai, and Vietnamese, pitch shifts within words completely change the word's meaning.  In Mandarin, for example, mā (the vowel spoken with a high level tone) means "mother," while mă (the vowel spoken with a dip in tone in the middle, followed by a quick rise) means "horse."  While this may sound complex to people -- like myself -- who don't speak a tonal language, if you learn it as a child it simply becomes another marker of meaning, like the stress shifts I gave in my first example.  My guess is that if you're a native English speaker, if you heard any of the above sentences spoken aloud, you wouldn't even have to think about what subtext the speaker was trying to communicate.

What's interesting about all this is that because most of us learn spoken language when we're very little, which language(s) we're exposed to alters the wiring of the language-interpretive structures in our brain.  Exposed to distinctive differences early (like tonality shifts in Mandarin), and our brains adjust to handle those differences and interpret them easily.  It works the other way, too; the Japanese liquid consonant /ɾ/, such as the second consonant in the city name Hiroshima, is usually transcribed into English as an "r" but the sound it represents is often described as halfway between an English /r/ and and English /l/.  Technically, it's an apico-alveolar tap -- similar to the middle consonant in the most common American English pronunciation of bitter and butter.  The fascinating part is that monolingual Japanese children lose the sense of a distinction between /r/ and /l/, and when learning English as a second language, not only often have a hard time pronouncing them as different phonemes, they have a hard time hearing the difference when listening to native English speakers.

All of this is yet another example of the Sapir-Whorf hypothesis -- that the language(s) you speak alter your neurology, and therefore how you perceive the world -- something I've written about here before.

The reason all this comes up is a study in Current Biology this week showing that the language we speak modifies our musical ability -- and that speakers of tonal languages show an enhanced ability to remember melodies, but a decreased ability to mimic rhythms.  Makes sense, of course; if tone carries meaning in the language you speak, it's understandable your brain pays better attention to tonal shifts.

The rhythm thing, though, is interesting.  I've always had a natural rhythmic sense; my bandmate once quipped that if one of us played a wrong note, it was probably me, but if someone screwed up the rhythm, it was definitely her.  Among other styles, I play a lot of Balkan music, which is known for its oddball asymmetrical rhythms -- such wacky time signatures as 7/8, 11/16, 18/16, and (I kid you not) 25/16:

I picked up Balkan rhythms really quickly.  I have no idea where this ability came from.  I grew up in a relatively non-musical family -- neither of my parents played an instrument, and while we had records that were played occasionally, nobody in my extended family has anywhere near the passion for music that I do.  I have a near-photographic memory for melodies, and an innate sense of rhythm -- whatever its source.

In any case, the study is fascinating, and gives us some interesting clues about the link between language and music, and that the language we speak remodels our brain and changes how we hear and understand the music we listen to..  The two are deeply intertwined, there's no doubt about that; singing is a universal phenomenon.  And making music of other sorts goes back to our Neanderthal forebears, on the order of forty thousand years ago, to judge by the Divje Babe bone flute.

I wonder how this might be connected to what music we react emotionally to.  This is something I've wondered about for ages; why certain music (a good example for me is Stravinsky's Firebird) creates a powerful emotional reaction, and other pieces generate nothing more than a shoulder shrug.

Maybe I need to listen to Firebird and ponder the question further.

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Sounding off

Noodling around on Wikipedia, sometimes you run into the oddest stuff.

I was looking something up yesterday and saw an associated link to a page called "List of Unexplained Sounds."  Well, I couldn't pass by something like that, so off I went down that rabbit hole.  As advertised, the page is a compendium of odd noises that have been heard (many have been recorded, so we know that those at least aren't someone's overactive imagination).  There are sound clips for a few of them, so I highly recommend going to the page and checking them out.

Here are a few of the ones listed -- with some possible explanations.

Upsweep is the name given to a sound consisting of a repeated series of rising tones that sound to my ears a little like a siren.  The source of the sound has been identified as being somewhere near 54° S latitude, 140° W longitude, placing it a little less than halfway from New Zealand and Cape Horn.  This, to put it mildly, is the middle of abso-fucking-lutely nowhere; in fact, it's not far from Point Nemo, also known as the "oceanic pole of maximum inaccessibility," which at 48°52.6′S 123°23.6′W is the point on Earth that is maximally distant from land.  There's a conjecture that Upsweep might be some kind of sound generated by underwater volcanic activity, but it's not exactly convenient to go out there and check, so that hypothesis is unproven.

The Bloop is a famous noise, once again heard in the Pacific Ocean, that is ultra-low frequency and extremely high amplitude -- meaning it can travel thousands of miles from its source.  The guess here is that the Bloop is a sound made by large icebergs breaking up (or scraping the seafloor), but I've heard an alternate hypothesis that I like better, which is that it's Cthulhu snoring.  Cthulhu, as you probably know, is the octopoid Elder God who was put into a charmèd sleep in his underwater city of Rl'yeh, where he's waiting for his followers to summon him back.  Why anyone would want to do so remains to be seen, because if you've read any H. P. Lovecraft, you know that the ones who try to reawaken him always end up dying in nasty ways, so it seems to me it might be better to leave him blooping peacefully in Rl'yeh.

[Image licensed under the Creative Commons Dominique Signoret (signodom.club.fr), Cthulhu and R'lyeh, CC BY-SA 3.0]

Some sounds have only been heard once, but are weird enough to bear mention.  These include Julia, which was given its name because it sounds like someone saying the name in a weird, hooting voice.  This is another one that is probably due to icebergs; its origin was pinpointed to somewhere near Cape Adare, Antarctica, but it was loud enough to be recorded by the entire Equatorial Pacific Autonomous Hydrophone Array.

The Ping is much more local; it's only been reported from the Fury and Hecla Strait between Baffin Island and the Melville Peninsula, Nunavut, Canada.  Although it's likely to be from some kind of marine animal, it's strange enough (and has been reported enough times) that "the Canadian military is investigating."

Not all of them are oceanic sounds.  One of the weirdest is the Forest Grove Sound, heard multiple times near Forest Grove, Oregon in February of 2016.  It was variously described as "a mechanical scream," "a giant flute played off pitch," and "akin to a bad one-note violin solo broadcast over a microphone with nonstop feedback."  There was an investigation, and it was never satisfactorily resolved -- and has not been heard since.

Last, there are the Moodus Noises, heard near Moodus, Connecticut, which unlike the Forest Grove Sound, have been heard for centuries (the indigenous people of the area, mostly from the Narragansett Tribe, supposedly have a long tradition of weird noises coming from nearby Cave Hill and Mt. Tom).  The Moodus Noises have a different Lovecraftian connection -- apparently they were the inspiration for the strange noises that came from Sentinel Hill in the spine-chilling story "The Dunwich Horror."  The more prosaic explanation for the Moodus Noises is that they come from microquakes, but -- needless to say -- there are a lot of people who don't buy that, and think the region is haunted.

So there you have it; a sampler of weird and unexplained sounds.  You should definitely check out the page and listen to some of the clips, which are goosebump-inducing.  While I do think they all have perfectly ordinary natural explanations, being a diehard skeptic doesn't mean I'm immune from getting the creeps now and again.

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Fingerprint of a megaflood

The Camarinal Sill is a curious geological feature that lies twenty kilometers to the east of the narrowest point of the Straits of Gibraltar.  It's an underwater rise that at its top is three hundred meters from the surface, with (much) deeper water on either side.

So the tips of the pincers forming the Straits also has a third pincer coming from below.  And to make things ever more interesting, the northern and southern points are on separate tectonic plates -- the Eurasian Plate to the north, the African Plate to the south.  These two plates have different relative motions, which is why around six million years ago, the straits abruptly closed up, and for a time, there was dry land between what are now Spain and Morocco.

The problem is, the region around the Mediterranean Sea is hot and dry (and was back then, too).  With the Atlantic Ocean now cut off, the only inflows of water into the Mediterranean came from all the rivers draining into it.  But the sum total of all that water entering it was still exceeded by the evaporation rate from the parched air passing over it.

So the Mediterranean Sea began to dry up.

Over the next six hundred thousand years, the sea level dropped by several kilometers, leaving behind a desiccated desert and a few widely separated lakes of concentrated brine.  The temperatures in the region rose by an estimated 15 C year-round, creating a climate more like the central Sahara than the pleasant "Mediterranean climate" that places like Italy, Greece, Spain, and southern France now enjoy.  The minerals from the evaporated sea water were left behind, creating layers of salt, gypsum, aragonite, and calcite that can still be seen today. 

Map of western Europe and northern Africa during the "Messinian Salinity Crisis;" the inset is an artist's depiction of the terrain [Image licensed under the Creative Commons Paubahi, Inserciomamifers, CC BY-SA 3.0]

Then, 5.33 million years ago, there was another tectonic shift, and the two sides of the Camarinal Sill pulled apart.

At that point there was a five-kilometer difference in the sea level between the Atlantic and what was left of the Mediterranean Sea; in fact, from the shore of the Atlantic west of Gibraltar to the nearest Mediterranean brine lake was a distance of over three hundred kilometers.

The result was a flood to end all floods.

The "Zanclean Deluge" was so enormous it's hard to visualize.  The waterfall over the newly-created Straits of Gibraltar was so powerful it eroded a nine-hundred-meter-deep gorge in the seabed.  The water level rose by an estimated ten meters a day for a year, ultimately refilling the entire Mediterranean Basin.  

[Nota bene: before any biblical literalists @ me with comments like "Ha-ha, that proves the Great Flood in the Book of Genesis actually happened!", allow me to point out that (1) the Zanclean Deluge had nothing to do with forty days and nights of rain, and (2) 5.33 million years ago our ancestors were small-brained hominins called Ardipithecus that lived in what is now Ethiopia, Tanzania, and Kenya.  There is, I might add, no evidence that Ardipithecus could build giant boats, nor were they capable of going to Australia to fetch a pair of kangaroos so they could be saved from the Flood and bringing them back after God finished smiting the absolute shit out of everyone and the waters receded.  Oh, and (3), don't you people disbelieve in plate tectonics anyhow?] 

Anyhow, the reason this all comes up is that a team of geologists from Utrecht University, the Royal Holloway University in London, and the University of Granada have just found the first unequivocal direct evidence that all this happened -- a deposit of gypsum, sandstone, and marl (lime-rich silt) showing distinct ripple marks from flowing water.  Upon analysis, they showed that the water was traveling really fast (something that can be determined from the wavelength of the ripple marks and the size distribution of the particles), was moving from west to east, and -- the clincher -- the entire formation dated to right around 5.33 million years ago.

Smoking gun, that.

"Now, for the first time, we can directly prove and quantify one of the most catastrophic periods of environmental change on our planet, which until now we had only been able to describe in geophysical models," said Gils Van Dijk, who led the study.  "Moreover, geologists are trained to use contemporary processes on the Earth’s surface to interpret what we observe in rocks.  But here we can’t rely on that knowledge, because we don’t know of any similar phenomena from at least the past one hundred million years."

What's a little sobering is that the tectonic movement that caused the whole thing -- both the closing of the sill and the reopening and subsequent flood -- is still happening.  The African Plate is still inching northward with respect to the Eurasian Plate, so the pattern is going to repeat.  Eventually, Gibraltar will seal up permanently, and the Mediterranean Sea will disappear -- and the coastal regions' pleasant climate will once again become a furnace, like it was 5.5-odd million years ago.

It won't happen within our lifetimes, of course; we're talking geological time scales, here.  But it always bears keeping in mind that the permanence of our landscapes and climates is an illusion, caused by our vision being limited to our short life spans.  On the larger scales, Tennyson was closer to the mark, in his beautiful poem "In Memoriam":

There rolls the wave where grew the tree.

O Earth, what changes hast thou seen?

There where the long road roars has been

The stillness of the central sea.

The hills are shadows, and they flow

From form to form, and nothing stands,

They melt like mists, the solid lands --

Like clouds, they shape themselves, and go.

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Let's do the time warp

Dear Readers,

I will be taking a short break -- this will be my last post until Thursday, April 27.  Please keep suggesting topics, though!

See you when I return.

cheers,

Gordon

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I find it fascinating, and frequently a bit dismaying, the range that exists in what people consider "sufficient evidence."

There are us hardcore skeptics, who basically say, "Incontrovertible hard data, right in front of my face, and sometimes not even that."  It then runs the whole spectrum down to people who basically have the attitude, "if my mother's first cousin's sister-in-law's gardener's grandma says she remembers seeing it one time, that's good enough for me, especially if it confirms my preconceived beliefs."

I saw a good example of the latter a while back over at Mysterious Universe in an article by Brett Tingley entitled, "Researcher Discovers Time Warp Near Las Vegas."  Tingley, to his credit, treated the whole thing with a scornful attitude, which (when you hear the story) you'll see was fully warranted.

Turns out "noted paranormal researcher" Joshua Warren, whose name you might know from his television work (some of his finer achievements are Aliens on the Moon: The Truth Exposed!, Weird or What?, Inside the Church of Satan, Possessed Possessions, and -- I shit you not -- Inbred Rednecks), claims to have found a spot north of Vegas where he says that time is running slower than in the surrounding areas.

Okay, let me just state up front that I have a degree in physics.  I certainly wasn't God's gift to the physics department by any stretch, but I did complete my degree.  (I didn't graduate summa cum laude, or anything.  More persona non grata.  But still.)  I bring this up only to say that with all due modesty, I have more knowledge of physics than the average dude off the street.  And because of this, I know that because of Einstein's General Theory of Relativity, there are only two ways to get time to slow down locally; (1) go really really fast; or (2) get close to a powerful gravitational field, such as a black hole.  Even the Earth's gravitational field, huge as it seems to us, causes a time dilation effect so small that it took years simply for physicists to be able to measure it and confirm it exists.  (For reference; your clock here on the surface of the Earth ticks more slowly, compared to a satellite orbiting at 20,000 kilometers, by a factor of 1 in 10,000,000,000.  So being here on Earth is not exactly the answer to lengthening human lifespan.)

[Image licensed under the Creative Commons Kjordand, Treval, CC BY-SA 4.0]

So the whole story is pretty fishy right from the get-go.  But Warren thinks he's proved it.  Here's what he has to say:

At this spot, on June 18 of 2018, I actually measured for the first and only time, time itself slowing down for 20 microseconds.  The weird thing, the real holy grail here, was what we picked up with this brand-new piece of technology.  That signal is always supposed to travel at the same rate of time at any particular place.  The only way that could change is if a black hole approached Earth or something like that, which is never supposed to happen.

You could substitute "never supposed to happen" with "hasn't happened," or "almost certainly never will happen," or "we'd all be fucked sideways if it did happen."  Now, twenty microseconds may not seem like very much, but that kind of discrepancy is not only many orders of magnitude greater than any expected relativistic time dilation effect, it is also well within the range of what would be easily measurable by good scientific equipment.  (Cf. the previous example of the physicists measuring a one-part-in-ten-billion slowdown.)  In other words, if this were real, it not only would be bizarre that it hadn't already been discovered, it would be simple to confirm -- or refute.

But here's the kicker: Warren is basing his amazing, groundbreaking, "holy grail" discovery on...

... one measurement with one piece of equipment.

So my first question is: time ran slower as compared to what?

Of course, even the equipment itself sounds suspicious to me.  It's called a "DT Meter," and no, in this context, "DT" doesn't stand for "delirium tremens," although it might as well.  It's a "differential time meter," and here's how Brett Tingley describes it:

KVVU-TV in Las Vegas reports that Warren made the discovery using a gizmo called a DT Meter, or differential time rate mater.  Warren says the device was created by a Silicon Valley engineer named Ron Heath, who has no discernible presence on the internet.  The device apparently consists of a 100-foot cable with a sensor on one end.  The device sends a signal down the length of the cable and measures the time it takes to reach the other end; theoretically, the device can detect small perturbations or differences in the speed of time itself.

Now, I ask you, which is more likely: that (1) there's a spot in Nevada where time runs slowly, for no apparent reason, or (2) Warren and Heath's gizmo has a glitch?

Of course, that's not slowing down Warren one iota (as it were).  He says that the time warp he discovered is the explanation for all sorts of other things for which he also has no proof:

I think it’s really interesting when you consider that this site where we got this reading, showing this time anomaly, also happens to be one of the most popular UFO hotspots in the area.  The big question at this point is not whether or not we have these anomalies, but what’s causing them?  Is this something natural that gives us a window a gateway into another world or another level of reality?  Or is this the byproduct of some kind of weird technology, be it something secret and man-made or something that’s extraterrestrial?

So the "big question" is not whether the anomaly exists?  I think that's a pretty big question, myself.  But no, we're supposed not only to believe his time warp, but that his time warp explains UFO sightings, and is caused by gateways into another world, etc.

What's baffling is that there are lots of people who apparently find this line of... um... well, I can't call it reasoning... this line of baloney convincing.  Poking about on the interwebz for about ten minutes found lots of places this "discovery" has been posted, mostly by people claiming either that ha-ha, this proves those dumb old physicists are wrong about everything, or that there's clearly a coverup by the government to prevent us from finding out about it, and thank heaven for Joshua Warren bravely posting this online, or even that we should watch this spot closely because it's likely to be where the alien invasion of Earth starts.

All of which left me weeping quietly and smacking my forehead on the keyboard.

Anyhow.  Like I said, I'm glad Tingley scoffed at Warren's claim, because Warren is not even within hailing distance of what anyone with a background in science would find convincing.  It also made me feel marginally better that I'm not the only one scoffing.  But I'd better wrap this up, because for some odd reason I feel like I'm running short on time.

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The genes of the ancestors

When I had my DNA tested two years ago, I found out I have 330 distinctly Neanderthal markers in my genes.  This, apparently, is well above average for people of western European descent, and may explain why I like to run around half-naked and prefer my steaks medium-rare.

In all seriousness, most people of European descent have Neanderthal ancestry; it's less common in people of African and Asian ancestry, and in the indigenous peoples of Australia and North America.  It makes sense, once you know where they lived.  The Neanderthals were a predominantly European species (or sub-species; the experts differ, and honestly, the definition of species is so mushy anyhow that it's probably splitting hairs to argue about it).  They seem to have split off from the main population of hominins in the region something like five hundred thousand years ago.  The first unambiguously Neanderthal bones are 430,000 years old, and they persisted until 40,000 years ago -- and we still don't know why they died out.

What's certain is that it wasn't a lack of sophistication and intelligence by comparison with contemporaneous Homo sapiens, whatever you might have gleaned from Jean Auel's The Clan of the Cave Bear.  The Neanderthals were plenty smart.  They had culture, made paintings on cave walls, and created jewelry.  To judge by the Divje Babe flute they made music.  They ceremonially anointed their dead, and appear to have had some concept of an afterlife.  They had the same version of the FOX-P2 gene we do, suggesting they had spoken language.  So despite my earlier quip, Neanderthals were far from the slow, sluggish, stupid "cave men" we often picture when we hear the name.

[Image licensed under the Creative Commons Werner Ustorf, Neanderthal man reconstruction, Natural History Museum, London, CC BY-SA 2.0]

As my own ancestry indicates, there was a good bit of crossbreeding between Neanderthals and "modern" humans.  (I put modern in quotes not only because it's self-congratulatory, but because all organisms on Earth have exactly the same time duration of their ancestral lineages; words like primitive and modern really "less changed since the common ancestor" and "more changed since the common ancestor," but those are clunky.  So I'll continue to use primitive and modern, although with the caveat that they're not value judgments.)

What's interesting, though, is that the genetic input of the Neanderthals was asymmetrical.  Of the Neanderthal markers we carry around, none are on the Y chromosome, indicating that something blocked any contribution of Y-chromosomal genes from our Neanderthal forebears.  It's possible that the answer is simple -- that most inter-species matings were between "modern" human men and Neanderthal women.  But now a new study from The American Journal of Human Genetics, by Fernando Mendez, G. David Poznik, and Carlos Bustamante (of Stanford University), and Sergi Castellano (of the Max Planck Institute for Evolutionary Anthropology) has suggested another reason the Neanderthal Y chromosome didn't survive; mutations that caused male hybrid fetuses to spontaneously miscarry.

The authors write:

Sequencing the genomes of extinct hominids has reshaped our understanding of modern human origins.  Here, we analyze ∼120 kb of exome-captured Y-chromosome DNA from a Neandertal individual from El Sidrón, Spain.  We investigate its divergence from orthologous chimpanzee and modern human sequences and find strong support for a model that places the Neandertal lineage as an outgroup to modern human Y chromosomes—including A00, the highly divergent basal haplogroup.  We estimate that the time to the most recent common ancestor (TMRCA) of Neandertal and modern human Y chromosomes is ∼588 thousand years ago (kya)...  This is ∼2.1 times longer than the TMRCA of A00 and other extant modern human Y-chromosome lineages.  This estimate suggests that the Y-chromosome divergence mirrors the population divergence of Neandertals and modern human ancestors, and it refutes alternative scenarios of a relatively recent or super-archaic origin of Neandertal Y chromosomes.  The fact that the Neandertal Y we describe has never been observed in modern humans suggests that the lineage is most likely extinct.  We identify protein-coding differences between Neandertal and modern human Y chromosomes, including potentially damaging changes to PCDH11Y, TMSB4Y, USP9Y, and KDM5D.  Three of these changes are missense mutations in genes that produce male-specific minor histocompatibility (H-Y) antigens. Antigens derived from KDM5D, for example, are thought to elicit a maternal immune response during gestation.  It is possible that incompatibilities at one or more of these genes played a role in the reproductive isolation of the two groups.

Which is an interesting hypothesis.  It's possible, of course, that there was more than one thing going on, here; there may also have been a skewed distribution of genders in inter-species matings as well as a higher death rate in male children of male Neanderthals and female "modern" humans.   In fact, genetics and culture can sometimes create a feedback loop; the taboo in traditional Basque society against Basque women marrying non-Basque men is thought in part to have come from the high frequency amongst the Basques of the Rh negative blood group allele, resulting in children of Basque women (likely to be Rh negative) and non-Basque men (likely to be Rh positive) having a higher probability of dying of Rh incompatibility syndrome.

So sometimes cultural norms and genetics can intertwine in curious ways.

In any case, that's today's science story, tying together anthropology, genetics, and evolutionary biology, all particular fascinations of mine.  And the fact that it could well be talking about some of my own ancestry adds a nice twist.  Hopefully my forebears will forgive me for my jab about running around naked.  Maybe the most Neanderthal thing about me is that I play the flute.  Kind of turns the "cave man" trope upside down, doesn't it?

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