Talk to the hand

I used to tease my poor, long-suffering mother because of her habit of talking with her hands.

It wasn't even necessarily when the person she was talking to was physically there in the room with her.  She talked with her hands (well, with one hand) while she was on the phone.

"Mom, they can't see you," I told her.

"I know," she said in an exasperated tone.  "I can't help it."

I got my comeuppance when I started teaching, and a student -- more than one, actually -- pointed out my habit of sculpting the air while I was explaining something.  One of them challenged me to deliver a lecture with my hands clasped behind my back.

That lasted approximately two minutes, much to the class's amusement.

So Mom, if you're listening right now, you get the last laugh.  I don't know that I can explain it any better than you did, but if I sit on my hands, I become completely tongue-tied.

[Image licensed under the Creative Commons Wikimania2009 Beatrice Murch, Talking with the hands, CC BY 3.0]

Apparently it's more or less universal, and the reason may be more than just introducing expressive body language into our conversation.  A study from the University of Connecticut released this week in Proceedings of the National Academy of Sciences found that hand gestures change the quality and intonation of our voices -- therefore communicating subtle information even if the listener can't see what our hands are doing.

In "Acoustic Information About Upper Limb Movement in Voicing," by Wim Pouw, Alexandra Paxton, Steven J. Harrison, and James A. Dixon, we read about a simple experiment -- volunteers were instructed to make a continuous vowel tone ("aaaaaaa....") into a microphone, simultaneously making rhythmic motions with the arms, while listeners in another room tried to synchronize their own arm movements with those of the vocalizers.

The ability to do that was nearly universal, even though the changes in the tonal quality were very subtle.

The authors write:

Co-speech gestures, no matter what they depict, further closely coordinate with the melodic aspects of speech known as prosody.  Specifically, gesture’s salient expressions (e.g., sudden increases in acceleration or deceleration) tend to align with moments of emphasis in speech.  Recent computational models trained on associations of gesture and speech acoustics from an individual have succeeded in producing very natural-looking synthetic gestures based on novel speech acoustics from that same individual, suggesting a very tight (but person-specific) relation between prosodic–acoustic information in speech and gestural movement.  Such research dovetails with remarkable findings that speakers in conversation who cannot see and only hear each other tend to synchronize their postural sway (i.e., the slight and nearly imperceptible movement needed to keep a person upright).

Because the entire skeletomuscular system is connected, movement of the arms and hands alters the shape/position of the chest cavity and throat, creating small changes in our vocal quality.  That, apparently, is enough to convey information to our listener, even if they can't see the gestures.

"Some language researchers don't like this idea, because they want language to be all about communicating the contents of your mind, rather than the state of your body," said study co-author James Dixon. "But we think that gestures are allowing the acoustic signal to carry additional information about bodily tension and motion.  It's information of another kind."

So add this to the long list of subtleties affecting our communications.  I still remember my Intro to Linguistics professor telling us about tonal languages like Thai, in which the pitch and/or pitch changes in vocalizing a syllable change its meaning, and he asked if we thought information in English was altered by changes in tone or stress.  One person came up with the rising pitch at the end of a sentence communicating a question, and increasing stress to indicate emphasis, but that was about it.

"Really?" he said.  "Then tell me why the following all mean something different."  And he read us this list of sentences:

• She gave the money to him today?
• She gave the money to him today?
• She gave the money to him today?
• She gave the money to him today?
• She gave the money to him today?

Minor alterations in the way a sentence is uttered can entirely change the meaning of the words.

I guess I shouldn't have picked on my mom for talking with her hands.  Human communication is complex, and what we end up saying to our listeners can depend on a great many things beyond the exact words used.  So be careful how your hand moves when you're talking to a friend on the telephone.

You may be telling them more than you realize.

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

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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

Mind the gap

In 1869, explorer John Wesley Powell did the first systematic study of the geology of the Grand Canyon.  As impressive as it is, the Grand Canyon's not that complicated geologically; it's made of layers of sedimentary rock, most of them relatively undeformed, one on top of the other from the oldest at the bottom to the newest at the top.  A layer cake of billions of years of Earth history, and a wonderful example of the principle of superposition -- that strata form from the bottom up.

However, Powell also noted something rather peculiar.  It's called the Great Unconformity.  In geologic parlance, an unconformity is a break in the rock record, where the layer below is separated from the layer above by a gap in time when either no rocks were deposited (in that location, at least), or the rocks that were laid down were later removed by some natural process.  At that stage in the science, Powell didn't know when exactly the Great Unconformity occurred, but it was obvious that it was huge.  Something had taken away almost a billion years' worth of rocks -- and, it was later found out, that same chunk of rock was missing not only at the future site of the Grand Canyon, but across most of North America.

It was an open question as to why this happened, but one leading hypothesis was that it was massive glaciation.  Glaciers are extraordinarily good at breaking up rocks and moving them around, as I find out every time I dig in my garden and my shovel runs into the remnants of the late Pleistocene continental glaciation.  At that point, where my house is would have been under about thirty meters of ice; the southern extent is the Elmira moraine, a line of low hills thirty miles south of here, left behind when the glaciers, pushing piles of crushed rock and soil ahead of them like a backhoe, began to melt back and left all that debris for us gardeners to contend with ten thousand years later.

There was a time in which the Earth was -- as far as we can tell -- completely covered by ice.  The Cryogenian Period, during the late Precambrian, is sometimes nicknamed the "Snowball Earth" -- and the thawing might have been one contributing factor to the development of complex animal life, an event called the "Cambrian explosion," about which I've written before.

The problem was, the better the data got, the more implausible this sounded as the cause of the Great Unconformity.  The rocks missing in the Great Unconformity seem to have preceded the beginning of the Cryogenian Period by a good three hundred million years.  And while there were probably earlier periods of worldwide glaciation -- perhaps several of them -- the fact that the Cryogenian came and went and didn't leave a second unconformity above the first led scientists away from this as an explanation.

Now, a new paper in Proceedings of the National Academy of Sciences, written by a team led by Francis Macdonald of the University of Colorado - Boulder, has come up with evidence supporting a different explanation.  Using samples of rock from Pike's Peak in Colorado, Macdonald's team used a clever technique called thermochronology to estimate how much rock had been removed.  Thermochronology uses the fact that some radioactive elements release helium-4 as a breakdown product, and helium (being a gas) diffuses out of the rock -- and the warmer it is, the faster it leaves.  So the amount of helium retained in the rock gives you a good idea of the temperature it experienced -- and thus, how deeply buried it was, as the temperature goes up the deeper down you dig.

What this told Macdonald's team is that the Pike's Peak granite, from right below the Great Unconformity, had once been buried under several kilometers of rock that then had been eroded away.  And from the timing of the removal -- on the order of a billion years ago -- it seems like what was responsible wasn't glaciation, but the formation of a supercontinent.

But not Pangaea, which is what most people think of when they hear "supercontinent."  Pangaea formed much later, something like 330 million years ago, and is probably one of the factors that contributed to the massive Permian-Triassic extinction.  This was two supercontinents earlier, specifically one called Rodinia.  What Macdonald's team proposes is that when Rodinia formed from prior separate plates colliding, this caused a huge amount of uplift, not only of the rocks of the continental chunks, but of the seafloor between them.  A similar process is what formed the Himalayas, as the Indian Plate collided with the Eurasian Plate -- and is why you can find marine fossils at the top of Mount Everest.

[Image is in the Public Domain]

When uplift occurs, erosion increases, as water and wind take those uplifted bits, grind them down, and attempt to return them to sea level.  And massive scale uplift results in a lot of rock being eroded.

Thus the missing layers in the Great Unconformity.

"These rocks have been buried and eroded multiple times through their history," study lead author Macdonald said, in an interview with Science Daily.  "These unconformities are forming again and again through tectonic processes.  What's really new is we can now access this much older history...  The basic hypothesis is that this large-scale erosion was driven by the formation and separation of supercontinents.  There are differences, and now we have the ability to perhaps resolve those differences and pull that record out."

What I find most amazing about this is how the subtle chemistry of rock layers can give us a lens into the conditions on the Earth a billion years ago.  Our capacity for discovery has expanded our view of the universe in ways that would have been unimaginable only thirty years ago.

And now, we have a theory that accounts for one of the great geological mysteries -- what happened to kilometer-thick layers of rock missing from sedimentary strata all over North America.

John Wesley Powell, I think, would have been thrilled.

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

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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

Danger down under

Following hard on the heels of Saturday's post, which started with a description of the cassowary -- Australia's killer bird -- today we follow up with a paper in Nature Communications just yesterday that falls under the "You think things are bad now?" department.

It's not like modern Australian wildlife is anything to trifle with.  The country is where you can find some of the world's most dangerous snakes, including the taipan, the brown snake, and the tiger snake.  The north coast is home to the enormous and aggressive saltwater crocodile, while the south coast has a sizable population of great white sharks.  The eastern coast, not to be outdone, is where you can run into the harmless-looking box jellyfish, which is in contention for winner of the most-potent venom contest; it injects its victim with a substance that has an LD-50 of 0.04 milligrams per kilogram of body weight, and can kill in under five minutes if an antidote isn't administered.  Even the plants bear watching.  The north coast has the beach spinifex grass, which reinforces the pointed tips of its leaves with silica drawn from the soil, essentially turning the plant into a cluster of tiny glass shards.  Worst of all is the gympie-gympie, which is like the humongous nettle from hell, inflicting an excruciating sting that can last for years.

(The Wikipedia article I linked says that the fruit of the gympie-gympie is "edible if the stinging hairs are removed first."  To which I respond, "Do I look like a fucking lunatic to you?"  I'll stick with fruit that's not attempting to murder me, thanks.)

But the paper "Extinction of Eastern Sahul Megafauna Coincides with Sustained Environmental Deterioration," by a team led by Scott Hocknull of the University of Melbourne, gives you a good feeling for how much worse it could be.  It describes a treasure-trove of fossils from Walker Creek in northeastern Australia that had the remains of hitherto-unknown species of fauna, including:

• a thus-far unclassified kangaroo that was four meters tall and weighed just shy of three hundred kilograms
• a new species of the genus Diprotodon, which was basically a wombat on steroids -- it's estimated to have been two meters tall at the shoulder and had a mass of 2,500 kilograms
• a new species of the horrific carnivorous marsupial Thylacoleo, which was slightly smaller than your average African lion, but is estimated to have had the most powerful bite of any known mammal, living or extinct
• a six-meter-long goanna and two never-before-seen species of monitor lizards
• a land-dwelling crocodile, because apparently the water-dwelling ones weren't bad enough

Artist's reconstruction of Thylacoleo carnifex [Image licensed under the Creative Commons Nobu Tamura (http://spinops.blogspot.com), Thylacoleo BW, CC BY 3.0]

The kicker is that these things were around after the colonization of Australia by humans, and in fact, by some estimates there was a fifteen thousand year overlap where the ancestors of today's Native Australians had to contend with a nightmarish megafauna.  Me, I wonder why they stuck around, you know?  If I was one of them, and landed in my boat on the shores of Australia, and saw land crocodiles and six-meter-long lizards and a lion-sized Tasmanian devil, I would have used the words of the inimitable Eric Cartman: "Screw you guys, I'm goin' home."

Of course, home was Papua-New Guinea, which honestly wasn't all that much better.

It's an interesting question as to what finally did in these formidable critters.  Hocknull et al. write the following, in an article in The Conversation:

Why did these megafauna become extinct?  It has been argued that the extinctions were due to over-hunting by humans, and occurred shortly after people arrived in Australia. 

However, this theory is not supported by our finding that a diverse collection of these ancient giants still survived 40,000 years ago, after humans had spread around the continent. 

The extinctions of these tropical megafauna occurred sometime after our youngest fossil site formed, around 40,000 years ago.  The timeframe of their disappearance coincided with sustained regional changes in available water and vegetation, as well as increased fire frequency.  This combination of factors may have proven fatal to the giant land and aquatic species.

As magnificent as these creatures undoubtedly were, it's probably better that they're gone.  I've heard Australia is a pretty cool place, even considering its dangerous flora and fauna, but if the animals of Walker Creek were still around, it'd be hard to understand how anyone could manage to live there.  Just taking a short walk to the grocery store would be risking getting dismembered by enormous carnivorous marsupials.

Makes today's snakes and crocodiles and whatnot seem tame by comparison, doesn't it?

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

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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

Quick takes

Today I'd like to look at three topics that came up for one reason or another in the last few days.

First, have you ever thought about catnip?  It's peculiar stuff.  A member of the mint family, Nepeta cataria (no, I didn't make up the species name) is a rather un-showy plant with gray-green stems and off-white flowers.  Its strangest characteristic, as I'm sure you know, is that it produces what amounts to kitty drugs.  The chemical nepetalactone is produced in significant quantities by the plant, and is responsible not only for its musky smell but for its apparent psychedelic effects on cats.  Cats who are susceptible to it -- and some, I understand, are not, although every cat I owned was a total catnip junkie -- purr, roll around in it, become playful and frisky, and their eyes dilate.

[Image licensed under the Creative Commons AlishaLH, Bee on Catnip Flowers, CC BY 4.0]

Clearly this is an accident; it's hard to imagine a plausible scenario in which the trait of producing this chemical evolved for the express reason of making cats flail around.  There's a presumption that it has a repellent effect on insects, which is certainly true about a lot of the aromatic substances produced by plants, but that's unsubstantiated.

The reason this comes up is that scientists at the Max Planck Institute of Chemical Ecology have decoded the genome of catnip, and they found that the nepetalactone gene apparently evolved more than once.  There are inactive "pseudogenes," stretches of DNA whose function has been lost over time to mutations, nearly identical to the current (functional) nepetalactone gene.  So evidently the gene evolved a second time, probably from another gene for producing chemicals of the class nepetalactone belongs to (the iridioids, which sounds like an alien species on Doctor Who but isn't), and then was advantageous enough that it kind of went into overdrive in catnip.

Apparently whatever its function is, it's important for more than getting kitties high.

So we're not the only species that has a strange psychological reaction to various naturally-produced chemicals in plants.  It's a good thing, though, that there's no such thing as (for example) moosenip, because the idea of a bunch of moose frolicking about and rolling around in your front yard is a little terrifying.


The next story comes from some research released last week by NASA's Transiting Exoplanet Survey Satellite (TESS), which made an interesting discovery about a rather odd kind of star.  Called Delta Scuti stars (after the first star identified in this class), they are a pulsating variable that are more common than astronomers thought at first -- there's good evidence that the bright stars Altair and Denebola, in the constellations Aquila and Leo respectively, are also in this class.

What makes these stars so odd is not their fluctuations -- periodic variable stars are actually rather common -- but that some parts of the star move outward and dim, and other parts pull inward and brighten, at the same time.  The whole star, therefore, seems to ripple.  The astrophysicists believe this is because as parts of the star heat up, more of the helium in the outer shell becomes ionized; ionized helium is more opaque to light, so it blocks light trying to escape from the core and balloons outward.  Once it cools, it falls back inward, and since this happens at different times in different places on the surface of the star, there are pulsations in not only the overall brightness of the star, but which parts of the star are bright and which are dim.

A paper in Nature last week showed that their behavior may not be as chaotic as it seemed at first.  Data from TESS has shown that these surface fluctuations have their own kind of periodicity -- some, for example, seem to contract and expand one hemisphere at a time, not at random places on the star.

"Delta Scuti stars have been frustrating targets because of their complicated oscillations, so this is a very exciting discovery," said Sarbani Basu, a professor of astronomy at Yale, who studies asteroseismology but was not involved in the study, in an interview in Science Daily.  "Being able to find simple patterns and identify the modes of oscillation is game changing.  Since this subset of stars allows normal seismic analyses, we will finally be able to characterize them properly."

Last, I was contacted by a reader regarding last week's post about the presence of iridescence in the fossilized feathers of ancient birds, with a question as to whether this discovery might shed any light on the presence of tetrachromacy in birds.  You probably know that (most) humans are trichromats -- we have three different kinds of color-detecting cones in the retina of the eye, sensitive to blue, green, and red wavelengths.  The combination of these three gives us our perception of color.

Mammals, apparently, descend from animals that were tetrachromats -- they had four different cones, and presumably, a more highly refined sense of color detection than humans have.  But in most mammals, such as dogs, there were mutations that knocked out two of the genes responsible -- similar to the loss of the catnip gene described earlier -- leaving behind two functioning cone types, and poorer color discrimination.

Some humans -- almost all are female -- have a fourth working cone, and are true tetrachromats.  This is undoubtedly why when my wife and I are going out, a common comment from her is, "Seriously?  You think that shirt matches those pants?"  Saying my aesthetic sense, especially when it has to do with sartorial matters, is poorly developed is kind of a massive understatement.

Birds -- at least the species that have been tested -- seem to all be tetrachromats, which may be why so much of their display behavior has to do with flashing bright colors around.  The presence of feather iridescence in birds from 52 million years ago may be an indication that they've been able to do this for a very long time.

It must be said, however, that the record holder for number of different kinds of color-sensitive photoreceptor is the mantis shrimp, which (depending on species) has between twelve and sixteen independent kinds of cones.  You have to wonder what the world looks like to them, don't you?

So that's three quick takes from the world of science.  And thanks to the reader who suggested a post on tetrachromacy -- it's a fascinating subject, well worth a look.  So keep those cards and letters comin'.

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

This week's Skeptophilia book of the week is six years old, but more important today than it was when it was written; Richard Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future.  Alley tackles the subject of proxy records -- indirect ways we can understand things we weren't around to see, such as the climate thousands of years ago.

The one he focuses on is the characteristics of glacial ice, deposited as snow one winter at a time, leaving behind layers much like the rings in tree trunks.  The chemistry of the ice gives us a clear picture of the global average temperature; the presence (or absence) of contaminants like pollen, windblown dust, volcanic ash, and so on tell us what else might have contributed to the climate at the time.  From that, we can develop a remarkably consistent picture of what the Earth was like, year by year, for the past ten thousand years.

What it tells us as well, though, is a little terrifying; that the climate is not immune to sudden changes.  In recent memory things have been relatively benevolent, at least on a planet-wide view, but that hasn't always been the case.  And the effect of our frantic burning of fossil fuels is leading us toward a climate precipice that there may be no way to turn back from.

The Two-Mile Time Machine should be mandatory reading for the people who are setting our climate policy -- but because that's probably a forlorn hope, it should be mandatory reading for voters.  Because the long-term habitability of the planet is what is at stake here, and we cannot afford to make a mistake.

As Richard Branson put it, "There is no Planet B."

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

Look at that shine!

There's this bird called the cassowary, have you heard of it?

I think a better name for it would be the "Giant Blue-headed Australian Death Turkey."  They're ungainly-looking things, but (1) they're big, and (2) they're fast.  An adult GBADT can be two meters tall and weight 55 kilograms.  Not only that, but if they feel threatened, they don't run or fly away as any normal species of bird would do.  No, this is Australia.  What they do is run toward people, jump up, and kick them with razor-sharp talons, attempting -- sometimes successfully -- to disembowel them.

Think I'm joking?  This is an actual (i.e. un-Photoshopped) photograph of a guy trying to avoid being killed by a furious cassowary.

The reason this comes up is that cassowaries have another strange feature besides being, essentially, emus with daggers strapped to their feet.  Their black feathers have the quality of iridescence -- something you might not notice if it was leaping at you -- but from a safe distance, their feathers have an oily rainbow sheen.

This is more than just simple pigmentation.  The structures in the feathers containing the black pigment are called melanosomes, and they come in a variety of shapes and sizes in different species.  The brightly-colored throat patches ("gorgets") in hummingbirds are the color they are because of melanosomes.

But if the pigment they contain is black, how do hummingbirds display their amazing array of colors, and how do cassowaries gain their sheen?

The reason is a phenomenon called optical interference, and has to do with the multiple clear layers of keratin that separate the layers of melanosomes.  Light passing through those clear layers is refracted, and crosses light waves refracted by other layers -- and because of this, some wavelengths of light undergo destructive interference (they cancel each other out) and others constructive interference (they reinforce each other).  In our local Ruby-throated Hummingbirds, the keratin layers are spaced so the wavelengths that reinforce are ones that our eyes see as being in the red region of the spectrum; other colors get cancelled out.  Thus, the ruby throat of the Ruby-throat.

But change the spacing of the layers, and you change what colors reinforce.  So you can get the Violet-tailed Sylph of Ecuador...

[Image licensed under the Creative Commons Joseph C Boone, Violet-tailed Sylph 2 JCB, CC BY-SA 4.0]

... the aptly-named Magnificent Hummingbird of Mexico, Central America, and southern Arizona...

[Image licensed under the Creative Commons Don Faulkner, Magnificent Hummingbird (7047734993), CC BY-SA 2.0]

... and over two hundred others, each with its own different spacing of the keratin layers in the feathers, and thus, each with its own array of spectacular, iridescent colors.

What's fascinating about this evolutionarily is that cassowaries and hummingbirds have been separate lineages for a long time.  Their last common ancestor is estimated at eighty million years ago, so predating the extinction of the non-avian dinosaurs by a good fourteen million years.  And some birds don't have this kind of iridescence -- their feather colors come from ordinary pigments, not a lot different than different colors of paint.  So how did two widely-separated groups of birds end up landing on the same solution for being colorful?

It's a very striking example of convergent evolution, where different organisms end up becoming superficially similar (usually only on one or two traits) because of similar selective pressures.  And apparently the innovation came about a long time ago in both lineages, as I found out in a paper this week in Science Advances that details information about some fossil feathers from relatives of the cassowary that were around 52 million years ago, during the Eocene Epoch.

In "Cassowary Gloss and a Novel Form of Structural Color in Birds," by Chad Eliason and Julia Clarke of the University of Texas - Austin, we read about an incredibly detailed analysis of feather fossils from the Green River Formation in Wyoming.  Using an electron microscope, the authors were able to measure the spacing of the melanosome layers and keratin layers, and determined that the species the feathers came from -- the lithornithid Calxavis (or Calciavis) grandei -- was black, with a deep iridescence on the wings.

The idea that we could actually find out what color an extinct species was using its fossilized feathers is amazing.  When I look at "artist's reconstructions" of prehistoric animals, I have to remind myself constantly that all the colors are just guesses based on analogies (sometimes incorrect ones) to modern species.  But now we actually have a pretty good idea of what a bird looked like who last flew around fifty-some-odd million years ago, which is kind of mind-boggling.

You have to wonder what other characteristics Calxavis shared with its modern cousins.  Unfortunately, we still know next to nothing about the behavior of long-extinct animals, so more than likely we'll never have anything more than guesses about how it acted when it was alive.

Who knows, maybe it even rushed at prehistoric predators and tried to rip them apart with its talons.  I mean, the Giant Blue-headed Australian Death Turkey's bad attitude has to come from somewhere.

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

This week's Skeptophilia book-of-the-week is one that should be a must-read for everyone -- not only for the New Yorkers suggested by the title.  Unusual, though, in that this one isn't our usual non-fiction selection.  New York 2140, by Kim Stanley Robinson, is novel that takes a chilling look at what New York City might look like 120 years from now if climate change is left unchecked.

Its predictions are not alarmism.  Robinson made them using the latest climate models, which (if anything) have proven to be conservative.  She then fits into that setting -- a city where the streets are Venice-like canals, where the subways are underground rivers, where low-lying areas have disappeared completely under the rising tides of the Atlantic Ocean -- a society that is trying its best to cope.

New York 2140 isn't just a gripping read, it's a frighteningly clear-eyed vision of where we're heading.  Read it, and find out why The Guardian called it "a towering novel about a genuinely grave threat to civilisation."

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

Canine teenagers

I love my dogs to pieces, but sometimes they drive me up a tree.

Especially our three-year-old pittie, Guinness.  He's sweet, cuddly, affectionate, playful... and willful, stubborn, mischievous, and frequently a complete pain in the ass.

The issue usually is that we're not giving him our undivided attention 24/7/365.  If you can imagine.  Monsters that we are, there are times when we don't want to play fetch with him or pet him, or when we might have other things we need to do.  When this happens, he usually finds some way of getting a rise out of us, like picking up a shoe and walking off with it, swiping something from the coffee table, or dragging a piece of firewood out of the wood cradle next to the stove.  If just taking it doesn't work, he proceeds to chew up whatever he stole, which is not a big deal if it's an empty cardboard box, but is a somewhat bigger deal if it's the TV remote.

Our usual strategy is to give him lots of one-on-one fun time in the afternoon, with the hope that he'll be so tired he'll stay out of trouble during the evening.  This works maybe fifty percent of the time.  When it doesn't, we fall back on the dubious strategy of chasing him around the house yelling, "DAMMIT GUINNESS GIVE THAT BACK."  Which, of course, means that he won -- we're giving him attention, and even better, playing with him, which is clearly how he interprets our running and flailing our arms.  "You are such a bad dog" usually elicits nothing more than a tail wag, because he knows how to game the system, and that's much better than being a Good Boy.

"I'm ready for my close-up, Mr. DeMille."

Well, because of a paper this week in Biology Letters of the Royal Society, I found out there's a good reason why Guinness acts the way he does.

He's a teenager.

In "Teenage Dogs?  Evidence for Adolescent-Phase Conflict Behaviour and an Association Between Attachment to Humans and Pubertal Timing in the Domestic Dog," animal behaviorists Lucy Asher (University of Newcastle), Gary England and Naomi Harvey (Nottingham University), and Rebecca Sommerville (University of Edinburgh) tell us that adolescent dogs go through a lot of the same sorts of annoying stuff that adolescent humans do -- oppositional behavior, selective hearing, and outright defiance, especially of the owner/parents.

The authors write:

...[W]hen dogs reached puberty, they were less likely to follow commands given by their carer, but not by others.  The socially-specific nature of this behaviour in dogs (reduced obedience for their carer only) suggests this behaviour reflects more than just generalized hormonal, brain and reward pathway changes that happen during adolescence.  In parts of this study, the ‘other’ person was a guide dog trainer who may have been more capable of getting a dog to perform a command; however, the results are consistent with parts of the study when the ‘other’ person was an experimenter without the experience of dog training.  We also find the reduction in obedience to the carer and not an ‘other’ person to be specific to the dog's developmental stage and more pronounced in dogs with insecure attachments, which is not easily explained by differences in dog training ability between the carer and other.

I find this fascinating, because it completely parallels my memory of parenting my sons when they were teenagers.  Both of them went through the eye-rolling, good-lord-my-parents-are-stupid phase of development, but while they were in that, we still got consistent stellar reports about their behavior at school.  "They're so sweet and cooperative," their teachers said, over and over.  "Always the first ones to volunteer to help out."

After verifying that yes, we were actually talking about the same teenage boys, Carol and I would just shake our heads and comment that it was better they take their adolescent angst out on us than on their teachers, who heaven knows have enough of that stuff to deal with.  Even if that meant that our request to load the dishwasher was treated as if it were equivalent to turning them into galley slaves and forcing them to row to Scotland.

But it's amazing that dogs go through the same phase.  Makes you wonder what other sorts of parallels they are.  And it gives me some hope that Guinness will grow out of his frustrating, attention-seeking behavior.  Although it must be said that three years old is definitely out of puppyhood, and we're still waiting for improvement.

Maybe it's partly his breed.  One of my friends who is a dog lover came over shortly after we got him (he's a shelter rescue, the best kind of dog to get).  She was greeted enthusiastically by him, and she said, "Oh, a pittie mix!  I love those.  How old is he?"

"A little over a year," I said.

"You do know that pitties only grow a brain when they're four years old, right?"

That was two years ago, and I'm not seeing much sign of it.  Maybe it's a sudden thing, you know?  Maybe next March, when he's three-years-and-eleven-months old, he'll get this shocked look on his face as his skull fills up with actual brain tissue, and immediately he'll start acting like a Good Boy, and perhaps even apologize for all of the household items he's chewed up.

Look, it could happen, okay?  Don't burst my bubble.  At least not until I find my left shoe.

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This week's Skeptophilia book-of-the-week is one that should be a must-read for everyone -- not only for the New Yorkers suggested by the title.  Unusual, though, in that this one isn't our usual non-fiction selection.  New York 2140, by Kim Stanley Robinson, is novel that takes a chilling look at what New York City might look like 120 years from now if climate change is left unchecked.

Its predictions are not alarmism.  Robinson made them using the latest climate models, which (if anything) have proven to be conservative.  She then fits into that setting -- a city where the streets are Venice-like canals, where the subways are underground rivers, where low-lying areas have disappeared completely under the rising tides of the Atlantic Ocean -- a society that is trying its best to cope.

New York 2140 isn't just a gripping read, it's a frighteningly clear-eyed vision of where we're heading.  Read it, and find out why The Guardian called it "a towering novel about a genuinely grave threat to civilisation."

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

Finding the right search parameters

I was making dinner last week, and the recipe called for soy sauce.  I knew we had a bottle of it -- and I was pretty sure it was somewhere in the door shelves of the fridge, amongst the various salad dressings, jellies, jams, sauces, and marinades we'd collected.  But I could not find the damn thing, and was becoming increasingly frustrated.

So instead of a quick scan -- usually sufficient to find what I'm looking for -- I decided on a one-at-a-time, bottle-by-bottle search, and as you've probably already guessed, I found the soy sauce in under thirty seconds.  I realized immediately what the problem was; in my mind I pictured it as having a red cap, and our bottle had a green cap.

You'd think that wouldn't make a difference, given that everything else about it was exactly like what I was picturing, up to and including being full of soy sauce and having a big label on the front that said, "SOY SAUCE."  But one piece of the search parameter was off, and that made me scan right past it, not once but several times.

[Image licensed under the Creative Commons GanMed64, Soy Sauce selection (6362318717), CC BY 2.0]

This is far from the first time this sort of thing has happened to me, and it amazes me how subtle the error can be and still derail my efforts.  It doesn't have to be anything nearly as egregious as in the hilarious anecdote Dave Barry writes about when his mother, groceries in a cart and two small children in tow, spent an hour trying to find her car in the store parking lot.  She looked so pathetic that several kind shoppers pitched in to try to help her.  "It's a black Chevrolet," she said, over and over.  It was only after the search had gone on for a ridiculous length of time, up and down the parking lot lanes, that she remembered that the previous week they'd traded in their old car for a new one, and told the helpers, "Wait!  I just realized, it's not a black Chevrolet, it's a yellow Ford!"

The helpers apparently were not amused, and his mom spent the rest of her life trying to live down the embarrassment.

So we can be confounded by our brain's preconceived notions of what we're looking for, from the subtle to the (should be) obvious.  And some researchers at Johns Hopkins University have found that finding the right search parameters even extends to characteristics we can't see.

This puzzling result came out of a series of experiments that were the subject of a paper this week in the Journal of Experimental Psychology.  The team, led by cognitive neuroscientist Li Guo, timed how long it took test subjects to isolate a target object from clutter, and they found that knowing characteristics of the object that aren't apparent to the eye -- like hardness or fragility -- significantly improved the speed with which subjects could find the object in question.  The authors write:

Our interactions with the world are guided by our understanding of objects’ physical properties.  When packing groceries, we place fragile items on top of more durable ones and position sharp corners so they will not puncture the bags.  However, physical properties are not always readily observable, and we often must rely on our knowledge of attributes such as weight, hardness, and slipperiness to guide our actions on familiar objects.  Here, we asked whether our knowledge of physical properties not only shapes our actions but also guides our attention to the visual world.  In a series of four visual search experiments, participants viewed arrays of everyday objects and were tasked with locating a specified object.  The target was sometimes differentiated from the distractors based on its hardness, while a host of other visual and semantic attributes were controlled.  We found that observers implicitly used the hardness distinction to locate the target more quickly, even though none reported being aware that hardness was relevant.  This benefit arose from fixating fewer distractors overall and spending less time interrogating each distractor when the target was distinguished by hardness.  Progressively more stringent stimulus controls showed that surface properties and curvature cues to hardness were not necessary for the benefit.  Our findings show that observers implicitly recruit their knowledge of objects’ physical properties to guide how they attend to and engage with visual scenes.

What I find most curious about the results of this experiment is if the characteristic you're given can't be seen, how does it help your brain to locate the object you're searching for?  "What makes the finding particularly striking from a vision science standpoint is that simply knowing the latent physical properties of objects is enough to help guide your attention to them," said study senior author Jason Fischer.  "It's surprising because nearly all prior research in this area has focused on a host of visual properties that can facilitate search, but we find that what you know about objects can be as important as what you actually see...  To me what this says is that in the back of our minds, we are always evaluating the physical content of a scene to decide what to do next.  Our mental intuitive physics engines are constantly at work to guide not only how we interact with things in our environment, but how we distribute our attention among them as well."

So it may be that we're approaching our search from a set theory perspective; searching through "the set of all things in my living room" is more efficient if I can eliminate "the subset of things in my living room that are rigid, heavy, stand upright," etc., so eventually my brain can whittle it down to "the couch throw-pillow my dog dragged behind the recliner."

It's still puzzling to me how our brains actually accomplish this, because it means some kind of interaction is occurring between our visual interpretive systems and our non-visual memories (of such things as texture, durability, and so on).  It'd be interesting to have people perform this task while in a fMRI machine -- and see how their brain firing pattern differs while performing this task as compared to performing a task that simply requires memory retrieval.

So that's our latest look at the fascinating world of cognitive neuroscience.  It doesn't explain, however, the weird phenomenon that happens to me while I'm doing home repair projects, wherein I spend 5% of the time doing actual home repair and 95% stomping around swearing and looking for the tool that was just in my damn hand five seconds ago.  That one's a mystery.

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

This week's Skeptophilia book-of-the-week is one that should be a must-read for everyone -- not only for the New Yorkers suggested by the title.  Unusual, though, in that this one isn't our usual non-fiction selection.  New York 2140, by Kim Stanley Robinson, is novel that takes a chilling look at what New York City might look like 120 years from now if climate change is left unchecked.

Its predictions are not alarmism.  Robinson made them using the latest climate models, which (if anything) have proven to be conservative.  She then fits into that setting -- a city where the streets are Venice-like canals, where the subways are underground rivers, where low-lying areas have disappeared completely under the rising tides of the Atlantic Ocean -- a society that is trying its best to cope.

New York 2140 isn't just a gripping read, it's a frighteningly clear-eyed vision of where we're heading.  Read it, and find out why The Guardian called it "a towering novel about a genuinely grave threat to civilisation."

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