Sunday, September 17, 2017

Drum Roll Please.....

Today's post is going to be long, because it's about my favorite annual nerd event: the awarding of the Ig Nobel Prizes.  This annual prize honors the ridiculous, absurd, and hilarious findings of the past year.  Improbable Research, which gives out the award, describes their goal as making people laugh as well as think, and "raising the question [of] How do you decide what's important and what's not, and what's real and what's not".  The Ig Nobel prizes were given out on September 14 at Harvard's Sanders Theater by actual Nobel laureates- because why be brilliant if you can't also have fun?  I highly recommend watching the webcasts of their ceremonies- there's an opera, paper airplanes, 24 second technical lectures with 7 word lay explanations, and at the end of the evening, the traditional disappearance of the audience.  I have taken the liberty of reading all of the winning papers to report on them for your intellectual benefit.

Before we get into that, because it's not an award ceremony without opening remarks, please follow Reviewer Three on Facebook to get notified about all my recent posts and on Twitter to learn fun science things.  My goal is to get 100 Twitter followers by the end of the month, so please spread the word! And, as always, I love seeing my view count creep up as I obsessively refresh the page, so feel free to share my stuff and help make me a big-time blogger.  And now, on with the awards!

PHYSICS: "On the Rheology of Cats," Marc-Antoine Fardin1
Rheology is the branch of physics that deals with the flow of matter.  Cats are notoriously flowy, as Figure 1 in the paper demonstrates.
The author uses the Deborah number, a measure of the fluidity of matter determined by a relaxation time value representing how long it takes a substance to adjust to applied stress divided by the time of the experiment.  Using the Deborah number, it was determined that, as in (a) above, sometimes cats qualify as a solid, and sometimes, as in (b)-(d), cats are a liquid.  One of the limitations of the approach as detailed in the paper is that all of the research subjects were kittens, and older cats may have different relaxation times.  Response to applied stresses was determined in a number of different scenarios.
The author also points out that it must be noted that cats are not isolated fluid systems, because they can transfer and absorb stresses from their environment, as demonstrated by cat cafes where you can pet cats to relieve stress.

PEACE: "Didgeridoo Playing as Alternative Treatment for Obstructive Sleep Apnoea Syndrome: Randomised Controlled Trial," Milo A. Puhan, Alex Suarez, Christian Lo Cascio, Alfred Zahn, Markus Heitz and Otto Braendli2
After a didgeridoo instructor with sleep apnea reported decreased daytime sleepiness after jam sessions on the Australian aboriginal instrument, science was born.  If you are unfamiliar with the didgeridoo, here's a video of someone playing one.  Twenty-five patients with moderate sleep apnea were randomized into a didgeridoo lesson group or a control group who swore not to start taking didgeridoo lessons for the duration of the study, which I can only assume was quite the sacrifice.  The didgeridoo group practiced for at least 20 minutes, five days a week, for four months.  The intervention group improved significantly in daytime sleepiness as compared to the control group, as well as improvements in the sleep quality of partners who shared a bed with the apnea patient, as well as improvements in apnea episodes recorded in the course of a sleep study.  The improvements were slightly less than when patients are treated with CPAP machines, though CPAP treatment is typically prescribed in more severe cases.  For those who are interested, didgeridoos can be purchased for ridiculously cheap on Amazon.

ECONOMICS: "Never Smile at a Crocodile: Betting on Electronic Gaming Machines is Intensified by Reptile-Induced Arousal," Matthew J. Rockloff and Nancy Greer3
The idea behind this study is that previous research has suggested that if someone is highly aroused or excited before gambling, they will often gamble longer or with larger amounts.  If the person is a pathological gambler, however, being highly aroused actually moderates gambling behavior.  Studies unrelated to gambling have demonstrated that people are apt to misinterpret positive or negative feelings when being highly aroused to an unrelated stimulus, so the researchers hypothesized that if people are exposed to a high arousal, negative valence situation, they may associate that feeling with the gambling, causing them to place smaller bets as they feel unlucky.  It logically follows that the ultimate way to test this is by exposing people to live crocodiles. So that's what they did.  Tourists visiting a crocodile farm in Australia were recruited to participate in an electronic gambling task.  They either performed the task when they first arrived at the farm, or after an hour long tour where they had the opportunity to hold a one meter juvenile crocodile. The crocodile's mouth was taped shut, but "tourists were cautioned that it could still harm them due its sharp claws and protruding teeth."  For participants who had no gambling problems, the crocodile group placed smaller bets than the control group, regardless of the intensity of negative affect.  For participants with gambling problems, however, the crocodile group placed smaller bets than controls if they were high in negative affect, but placed larger bets than controls if they were low in negative affect.  The take away for the researchers was that low intensity negative moods or high arousal non-negative moods contribute to large bets for at-risk gamblers.  The take away for me was that casinos probably shouldn't use crocodile tanks as decoration.

ANATOMY: "Why Do Old Men Have Big Ears?" James A. Heathcote4
In this classic study from 1995, four British doctors asked all of their patients who came in if they could measure their ears. The age range of patients was 30-93, and after the data were entered into a computer (a point the paper is clear to make), it was discovered that, indeed, ear length correlates with age.  It appears that ears grow at an average rate of 0.22 millimeters per year.  I take great issue with the presentation of the Ig Nobel to this study, as it is a completely misnamed and misleading title.  The paper itself states that "Why ears should get bigger when the rest of the body stops growing is not answered by this research."  It also included women, therefore actually emphasizing that old PEOPLE have big ears.

BIOLOGY:  "Female Penis, Male Vagina and Their Correlated Evolution in a Cave Insect," Kazunori Yoshizawa, Rodrigo L. Ferreira, Yoshitaka Kamimura, Charles Lienhard5
Let me begin by saying the graphical abstract for this paper is absolutely horrifying.  I couldn't tell what was where and who was what and why there was something that looked so much like a scrotum on my screen.  I've included the picture for your viewing pleasure.
On the very off chance that that doesn't tell you everything you need to understand this paper, I'll go into more depth.  In Brazilian caves, there is a genus of barklice called Neotrogla, that consists of four species.  The defining feature of this genus is that they have reversed sex roles that accompany reversed sex organs.  Namely, females have an erectile structure that protrudes from the body, accompanied by a second structure that stores sperm.  The males, on the other hand, have simple arc genitals that don't have any type of protruding organ. The female gynosome penetrates the phallosome in order to receive "voluminous spermatophores" from the male.  Once inserted into the male, a membrane inflates to hold it in place with help from a whole bunch of spines.  If you try to separate two insects during the act of copulation, you will only succeed in ripping the male's abdomen from his body, as it is so firmly anchored to the gynosome, so that's pretty awful. It is suggested that this unique arrangement may have arisen from females competing for, I kid you not, this is how it's worded, "nutritious seminal gifts" (objectively the worst Hanukkah present), which increase the female mating rate. In this situation, the gynosome "may have a premating function grasping reluctant mates or a postmating function holding mates to ensure prolonged copulation".  And with that, I don't want to have to read about insect sex again for a long, long time. 

FLUID DYNAMICS:  "A Study on the Coffee Spilling Phenomena in the Low Impulse Regime," Jiwon Han6
First, I'd like to note that the author of this paper was a high school student at the time he wrote the paper, and that this makes me feel bad about myself. I don't think anyone could explain the impetus for this study better than young Jiwon himself, so to quote: " Rarely do we manage to carry coffee around without spilling it once. In fact, due to the very commonness of the phenomenon, we tend to dismiss questioning it beyond simply exclaiming: “Jenkins! You have too much coffee in your cup!”"
Thus, this paper sought to determine why we spill coffee when we walk, and the best way to avoid this universal phenomenon.  A material's resonant frequency is the vibration frequency where you get the most amplification of oscillations, basically allowing for small forces to have big responses.  In the 1940s, this phenomenon led to the collapse of the Tacoma Narrows Bridge, when the wind caused it to vibrate at its resonant frequency to huge disaster.  Check out a video of the bridge to get a better idea of the effect of resonance.  In this study, researchers determined that the resonant frequency of coffee in a coffee cup just so happens to be right around the same frequency of vibrations from normal walking.  In other words, our normal gait makes the coffee slosh around with even more amplitude than it should, leading to spills.  They went on to explore what we can change about how we carry coffee that will reduce spillage.  Walking backwards did change the frequency from human movement enough that it was no longer the same as the resonant frequency of the coffee, however did not necessarily reduce spillage due to increased likelihood of tripping or "crashing into a passing by colleague who may also be walking backwards".  The more effective method was to use what they call the "claw-hand method" to hold the cup.
This also changed the vibration frequency from walking due to the way it transfers vibrations to the cup.  I would assume, however, that your coffee has to be below a certain temperature for this to work, given that the steam on your palm could make carrying your cup this way uncomfortable, but that's research for a future Ig Nobel.

NUTRITION:  "What is for Dinner? First Report of Human Blood in the Diet of the Hairy-Legged Vampire Bat Diphylla ecaudata," Fernanda Ito, Enrico Bernard, and Rodrigo A. Torres7
Vampire bats' name derives from the fact that their food source is other animals' blood.  They are extraordinarily specialized for this, with teeth designed to puncture vascular areas, saliva that contains anti-coagulation compounds, and organs that efficiently process out water and urea.  They also can't store fat, and therefore can't go more than two days without eating.  Two of the species of vampire bats have some variety in the type of animals they feed from, while the third species, the hairy-legged vampire bat, only preys on birds. This is a problem, because if they live in areas that have been disrupted by humans, their options for food sources decrease dramatically.  In this paper, group of researchers found that the hairy-legged vampire bat solved this problem by simply feeding on the humans.  The researchers collected bat fecal samples from an area in Brazil that had around 1,000 families currently living in it.  In these fecal samples, they found DNA from both chickens and humans, suggesting that when birds are not available, the hairy-legged vampire bat is able to (rather vindictively) expand its diet.  Previously, bats in captivity had been shown to starve themselves to death rather than eating pig or goat blood, so this was an unexpected discovery.  It is possible that they're not actually feeding on humans, rather on animals that are in close contact with humans, but it still points the way to more work regarding the public health consequences of bats preying on humans, as well as horror movies.

MEDICINE: "The Neural Bases of Disgust for Cheese: An fMRI Study," Jean-Pierre Royet, David Meunier, Nicolas Torquet, Anne-Marie Mouly and Tao Jiang8
A group of French researchers needed to determine what percentage of the French population is disgusted by cheese, and what that looks like in the brain.  They found that 38 out of the 332 subject s (11.5%) were objectively wrong and were disgusted by cheese.  Cheese also represented 36.9% of all of the "disgusted" answers, higher than any other category of food.  However, they also found that the majority of people rated desserts as below a 6 on a ten point scale, and almost no one claimed to be disgusted by vegetables, so I have some doubts as to the accuracy of these responses.  They found differences in "liking" and "wanting" ratings for pro- and anti-cheese people when provided with a cheese odor and a picture of cheese, as well as a significant difference in liking and wanting ratings for anti-cheese people when they were just smelling cheese as opposed to smelling and looking at cheese.  When smelling and looking at cheese, they found differences in activation in the globus pallidus, substanatia nigra, and ventral pallidum between pro- and anti-cheese people.  Basically, people who are disgusted by cheese aren't motivated by cheese, and areas that code reward also likely code disgust, at least when it comes to cheese.  (Fun personal note: I'm writing this piece on a weekend where I consumed at least half a pound of cheese.)  

COGNITION: "Is That Me or My Twin? Lack of Self-Face Recognition Advantage in Identical Twins," Matteo Martini, Ilaria Bufalari, Maria Antonietta Stazi, Salvatore Maria Aglioti9
As humans, we are very good at looking at human faces.  We're even better at looking at our own faces.  We recognize ourselves more quickly than other people, we pay attention to our own face longer, we use feature information more for our faces than others, and even in cases of prospopagnosia (face blindness), it's very rare for someone not to be able to recognize their own face. Researchers here recruited twin pairs and their friend, and showed all three faces to each set of three, asking them to identify who each face belonged to.  This is a great way to realize your friend can't tell you and your sister apart. Twins were equally good at recognizing them and their twin in terms of reaction time and accuracy, but were worse at recognizing themselves (and their co-twin) than controls were at recognizing themselves.  This result depended on how much twins were reported to look like each other, which indicates that it's more about them not being able to tell themselves apart than any kind of seeing themselves as a single unit phenomenon.  It is important to note that no twin will ever be able to give you a hard time if you can't tell them apart, because they can't either.

OBSTETRICS: "Fetal Facial Expression in Response to Intravaginal Music Emission," Marisa López-Teijón, Álex García-Faura, and Alberto Prats-Galino10
Conventional wisdom says that playing music to your future baby will make it smart (though there are some major flaws with the so called "Mozart Effect").  You might be wondering, though, what the best way to deliver that music is.  You see a lot of images with a pregnant woman with headphones on her belly, but much like an infomercial, there must be a better way!  It turns out that fetuses show increased mouth opening, rotation, and tongue expulsion when a flute melody is played through an intravaginal microphone as opposed to just headphones on the belly.  The researchers had to ensure that the responses were due to music and not just vibration, so as a control condition, they administered intravaginal vibration, which also resulted in fewer facial expressions that the intravaginal music.  There is no report on how many American Pie "One time, at band camp, I stuck a flute up my ...." references were made during the course of data collection.  If this finding sounds like music to your, uh, ears, rest easy, because they marketed Babypod, a vaginally inserted speaker that comes with headphones so you can listen to the same thing your baby is.  

And with vaginal speakers and control vibrators, my tour through this year's Ig Nobel winners is complete.  For past winners, visit Improbable Research's website.  I recommend 2014 as a particularly good year.  

Friday, August 25, 2017

The Relative Reich

There weren't really any songs about Nazis that I could tastefully used as a title, so I improvised this week.  I assume that most of you have, at some point, watched a movie where Evil Nazi ScientistTM does Evil Nazi Science.  The Evil Nazi science might have been aimed at creating a devastating new weapon, or a race of super soldiers, or a four dimensional power cube, but regardless, it would change the course of the war and is up to our intrepid (American) hero to stop him.  

Not to be too farcical.  Nazi science was absolutely a real thing, and that's what we're talking about today.  The Nazi party, under the direction of Dr. Josef Mengele, engaged in horrific human experimentation.  I'm not going to go into that, because a) most people are somewhat aware of these experiments and b) I don't want to do the research into that, because there are some things you just don't want to read.  Ever.  So instead, I'm talking about a very different kind of Nazi science (that I'll still be able to sleep after): Deutsche Physik.

"Deutsche Physik" literally means "German physics", and was a direct result of the interaction between ego, scientific controversy, and nationalism.  A lot of the scientific sentiment I'll be writing about today is deeply and inescapably entwined with larger, historical patterns in Germany at the time, and I'll do my best to add historical context as we go.  While ideas of nationalism had been percolating through German elites since the 1600s, nationalism in the form that is usually associated with the World Wars began really spreading through the German population in the late-19th century, driven by Prussian authoritarianism after military unification of Germany in 1871.1 This nationalism emphasized the ideals of the German crusaders of the Teutonic Order (1198-1525) as a basis for a national identity- the ideas of willpower, loyalty, honesty, and perseverance.2  Also important to our story is the emphasis on pro-Protestant, anti-Catholic ideas in nationalist philosophy.3  German nationalists began to use modified scientific theories, such a social Darwinism and the idea that races are fundamentally biologically different, as a way of cementing their beliefs.4  Nationalism, not just of Germany, was one of the major causes of WWI, starting with the building of tensions between ethnic groups within countries, leading up to Archduke Franz Ferdinand being assassinated by a Serbian nationalist that was the spark for the whole thing.

Symbolism of the Teutonic order was integrated into Nazi symbolism

By the start of WWI, these nationalist ideas had found their way into universities, specifically into the fields of physics and math, fueled by disagreements between German and non-German physicists.  On August 25, 1914, the German army burned the library of the Katholieke Universiteit Leuven (Catholic University of Leuven) in Belgium.  This made book lovers everywhere and British scientists very angry.  Eight British scientists, five of whom were Nobel laureates (including Alexander Fleming, who developed the first antibiotics, and JJ Thompson, who discovered subatomic particles), wrote a letter in protest of the burning of the library.  One of the signees was Sir Oliver Lodge, who was exceptionally good at producing children (he had twelve) and being involved in scientific feuds, and this was no exception.5

Sixteen German physicists, led by Nobel Prize winner Wilhelm Wien, reacted to the British document with an appeal of their own, directed not at the British scientists, but rather at German scientists and scientific publishers, stating that they could no longer facilitate productive scientific interactions with British scientists, and urging four main points: 1) that English scientific literature should not "find stronger consideration" than German science, 2) that German scientists no longer publish in English journals, 3) that German journals only accept papers written in German, and 4) that public money is not spent translating articles.6  This was followed up by the "Manifesto of the Ninety-Three", in which 93 prominent German scientists and artists gave their full support to German military action in Belgium.7  Given that the international community had taken to calling the invasion "The Rape of Belgium", that was probably not the right side of the issue to be on, but that didn't stop a further wave of nationalism from sweeping through German universities following the declaration.  This nationalistic movement was just a reflection of what was happening across Germany.  After WWI, there was another surge of nationalism, as many Germans felt wronged by foreign actors through the terms of the Treaty of Versailles.
Burning of "un-German" books
As WWI raged on, there was another intellectual war being fought.  Einstein's special theory of relativity was published in 1905, followed up by his general theory of relativity in 1915.  Special relativity was, for all intents and purposes, revolutionary.  In fact, the abovementioned Wilhelm Wein actually nominated Einstein, along with Hendrik Lorentz, who developed the mathematical equations underlying the theory, for a Nobel Prize (they did not receive it).8  Despite the general acceptance of the theory of relativity, underlying anti-Semitic tensions led to some rejecting the theory on personal, as opposed to scientific grounds.  Galvanizing anti-Semitic publisher Theodor Fritsch wrote about the role of the "Jewish spirit" in relativity, and went on to discuss the negative consequences of this spirit, an idea that was picked up and propagated by the far-right press.9  Engineer Paul Weyland organized an entire society, the aptly named Anti-Einstein Society, based on conservative and anti-Semitic scientists who disagreed with the theory of relativity (though they only had one meeting).10  The Wikipedia page on Weyland has only one line, which reads "Weyland was a key figure involved in organising an anti-semitic campaign against relativity. He was later granted American citizenship.", which, frankly, sounds about right.11  Many believed that the only reason the theory of relativity was becoming so popular, and Einstein himself a celebrity, was that Jews controlled the media.11  Wilhem Muller called relativity a "Jewish affair" that corresponded to the "Jewish essence".  Bruno Thuring emphasized the correspondence between relativity and the Talmud, one of the central texts of Judaism.12

Philipp Lenard
And so, a group of scientists in Germany, led by Philipp Lenard and Johannes Stark, began a movement that would control their Jewish relativity problem- creating a new physics, a German, Aryan physics. Deutsche Physik.  Deutsche Physik emphasized all things German and suppressed all things Jewish.  Lenard contrasted "Aryan physics or physics by man of Nordic kind" with "formal dogmatic Jewish-physics".13  Aryan physics was marked by rigorous experimentation and tangible proof, while the Jewish spirited physics was more based on ideas, theory, and equations.  It was a difference between discovery and proposal.  It was the representation of German nationalism in science, that science that isn't done in done in keeping with the German method, indeed much of theoretical physics, was fraudulent.  It sought to oppose this fraudulent, anti-German thought by simply pretending it didn't exist.  Movement member Rudolf Tomaschek rewrote Grimsehl's Lehrbuch der Physik, to remove all mentions of Jewish physics, even among conversation where it was almost impossible to avoid.  For example, the book discussed Lorentz's mathematical equations, but made no mention of relativity, how the equations were applied, or Einstein himself.14  

As the Nazi party came to power in the 1920s, the movement began to gain even more steam.  A German mathematics journal, Deutsche Mathematik, was published following the same ideals.15  It wasn't just Jewish scientists that were getting left out- "honorary Jews", essentially anyone who agreed with Einstein, were also having their contributions cut from scientific thinking.16  With the endorsement of the Nazi party, Lenard and Stark began a campaign aimed at eliminating Jewish physicists at German universities with Aryan physicists.  This plan never came to exact fruition, though the outcome was identical, due to the implementation of the 1935 Nuremberg Laws, which forbade Jews from working in universities, as well as a number of other businesses.17

In the end, Deutsche Physik fell out of favor, in large part due to the upper echelons of the Nazi party.  Theoretical physics, Jewish physics, turned out to have some extraordinarily important weapons implications- as long as no one mentioned Einstein or Bohr.  

The story of Deutsche Physik is one from the 1910s to 1940s, but similar patterns are cropping up again today.  Extreme nationalism.  Censoring scientific findings due to political ideology.  Believing that the media are controlled by liberals and Jews and only spreading their ideologies.  Politics over truth.  Letting petty squabbles and strained egos drift into policy making.  Rejection of the ideas of "others".  Politics has no place in science.  It's been done.  It failed.  Be different.  Be better. 

Follow me on Twitter and Facebook.  The Facebook page keeps you updated on the blog and new posts, Twitter has links to articles, cool stories, and retweets about the eclipse.  Most importantly, a plea- I'm still getting this blog off the ground, and I'm trying to break into the science communication field.  I would appreciate it so much if you enjoy something you read on here, share it with someone, share the whole blog with someone, retweet me, leave a comment.  Tell someone about me, and tell me about someone you think I might like!  I love what I do, and I would love even more to share it with more people.  

Sunday, August 20, 2017

Ain't No Sunshine When You're Gone

I like space.  Like, a lot.  My living room is actually entirely decorated in a space theme, with NASA's JPL travel posters, glasses that look like planets, LEGO space shuttles and scenes, and some decorative pillows with nebulae on them.  Trust me, it's totally cool and not kitschy at all; I promise.  My love for space leads me to think that the total solar eclipse that will be happening on August 21, 2017 is really cool.  My love for engagement in science, however, makes me think it's one of the coolest things that's ever happened to science in this country. 

The 2017 eclipse is predicted to be the largest mass migration to see a natural event in history.  The Federal Highway Administration estimates that between two and seven million people will be traveling to be able to witness totality (a 70 mile swath reaching from Oregon to South Carolina).1  That's in addition to another 12 million that already live in that path.  Alaska Airlines is offering a special flight to view from the air,2 United Airlines has worked with NASA on its flights, and Southwest has five flights that cross the path, for which they're offering special themed cocktails and viewing glasses.3  Business in the path of totality are shutting down for an hour.  Thousands of eclipse viewing parties have been organized, at locations ranging from universities to bars.  You can't function as a news outlet right now and NOT have an article about the eclipse.  Most outlets have literally sold out of eclipse glasses. The excitement and commitment that people have for this event is incredible to me- and it's not due to a sporting event, or a once in lifetime concert, or a political rally; it's all about a natural, scientific phenomenon.  That's amazing to me.  The United States is currently divided about everything, and we're experiencing what many have called an era of renewed science denialism.4,5,6  And yet, somehow, a scientific event is bringing millions of people together, making us travel, interact, learn together, and experience something wondrous together.  For someone who cares passionately about science literacy and engagement, I wish we, as a society, had this excitement all the time, but I'll take this as a start. 

I'm pretty sure that if you're a science journalist and you don't write something about the eclipse, they take away your Twitter account and force you to go back to the bench.  But as I mentioned, every news outlet has written something about the eclipse. So I feel a burning need to say something about the eclipse, but there aren't many stories that haven't been totally played out.  Today, I'm taking a historical approach, focusing on the the things we've learned about the earth and our universe from similar eclipses in the past. Let's also take a moment to appreciate that I came up with a musical sun themed title that wasn't "Total Eclipse of the Heart".

Babylonian eclipse tablet recording eclipses between 518 and 465 BCE

The Sun
Historically, it has been incredibly difficult to study the sun.  The sun is bright.  Really, really bright.  Bright enough to do severe damage if you're looking directly at it, and bright enough to basically drown out anything around it.  Now, astronomers use telescopes that can filter out specific spectrums of light and allow them to see the normally suppressed features, but for most of history, the only way to observe these features was while the bright part of the sun, the photosphere, was covered up.  These features, specifically the chromosphere and the corona, are actually part of the sun's atmosphere.  Some believe that the earliest recorded reference to the corona was carved into oracle bones in China during the Shang Dynasty (1766 to 1123 BCE), but it's a little ambiguous.  Plutarch described what sounds like a corona during the eclipse of March 20, 71 CE in the book De Facie in Orbe Lunae: "Even if the moon, however, does sometimes cover the sun entirely, the eclipse does not have duration or extension; but a kind of light is visible about the rim which keeps the shadow from being profound and absolute."  Byzantine historian Leo Diaconus reported on the eclipse of December 20, 968 CE in Constatinople: " the fourth hour of the day ... darkness covered the earth and all the brightest stars shone forth. And is was possible to see the disk of the sun, dull and unlit, and a dim and feeble glow like a narrow band shining in a circle around the edge of the disk".7  Pre-filtered telescope astronomers used the differences in the corona between eclipses in subsequent years to study changes over the course of the sun's eleven year cycle from solar maximum to solar minimum, as measured by the number of sunspots.8
The corona photographed in 1871

Eclipses are also responsible for the discovery of Coronal Mass Ejections (CMEs).  CMEs are projections of plasma that snap off from the surface of the sun and go hurtling through space at thousands of miles an hour, carrying with them billions of kilograms of ions.  This happens at least once a day, but most of them don't come anywhere near the Earth.9  When they do, however, they can cause power surges that can result in blackouts and damage electronic equipment.  On the aesthetic side, they can also cause auroras, more commonly knows as the Northern or Southern Lights.10  The first CME was observed during the eclipse of July 18, 1860.  Solar prominences, filaments of plasma that extend from the surface of the sun into the corona, were first described during the Russian eclipse of May 1, 1185.  The observance of the corona and subsequent discoveries of CMEs and solar prominences tells us a lot about the sun's magnetic field.  This magnetic field is a major driver of solar weather patterns, which can have huge effects on the Earth and the astronauts and equipment we have floating around it.  However, just the Earth's magnetic field, the lines of the field aren't visible.  The pattern of a corona is a reflection of the magnetic field, prominences are held in place by the field, and CMEs are a direct result of breaking the magnetic field lines.  Their discovery allows us to better understand the seemingly distant phenomena that affect our world.11

During the solar eclipse of August 7, 1869, two astronomers independently observed an emission line in the corona in the green part of the spectrum.  This line didn't correspond to anything known, so it was believed to be a new element dubbed "coronium".  In the 1930s, it was discovered that this wasn't actually a new element, but rather was just iron.12  I say "just", but in reality, the lines weren't caused by your everyday iron, but incredibly hot iron.  So hot, in fact, that it was much, much hotter than the sun.  These lines indicated that the corona reached temperatures of 3.6 million degrees F, when the actual surface of the sun only reached about 10,000 degrees F.13  We don't know exactly how the atmosphere of the sun is hotter than the sun itself (which is presumably giving off the heat), but it's suspected to be due to "heat bombs", the result of the magnetic field crossing into the corona and realigning.14

Although coronium wasn't really a unique element, the discovery of new elements during eclipses was not without precedent.  A total eclipse in Guntur, India on August 18, 1868 revealed a bright yellow line in the spectrum of the chromosphere that didn't correspond to any known element.  The element was named for the sun where it was first discovered- helium.15  Helium wouldn't be observed on Earth for almost thirty more years.16

Sometime around 150 BCE, Hipparchus of Nicaea realized that the solar eclipse could help the calculation of the distance between the Earth and the moon.  For that particular eclipse, northwestern Turkey experienced totality.  Alexandria, Egypt, about 1,000 km away, reported only 80% totality.  Since a solar eclipse occurs when the moon drifts between the Earth and the sun, this gave him enough information to be able to use trigonometry to figure out the distance between the Earth and the moon.  It should be noted that he was wrong (off by about 20%), but it was still a pretty good estimate for the tools of 150 BCE.17

This one is my personal favorite.  For a long time, scientists predicted that there was a tiny planet in between Mercury and the sun, because Mercury's orbit was a little more unstable than it should be.  They called this planet Vulcan, I assume because it would have to be so hot and Vulcan was the god of fire and volcanoes, and not because the crew of the Enterprise broke the Prime Directive.  During the eclipse of July 29, 1878 two different astronomers reported observing a red planet object very near the sun, and believed this to be confirmation of Vulcan.18  The next year, one of those astronomers, James Craig Watson, along with Maria Mitchell and Thomas Edison (yes, that Thomas Edison), tried again to observe Vulcan during an eclipse and failed, probably because it's not there.  

In 1915, a theory was postulated that could explain the wobbly orbit without needing another planet:  Einstein's theory of relativity.  The basic idea of general relativity is that spacetime curves around mass, which is an exactly useless explanation for anyone who isn't a physicist, and probably many who are. I'm going to try to break this idea down.
  • Spacetime is a model that combines the three dimensions of space (up-down, left-right, front-back) with one dimension of time (which I'll call forward-backward).  It's kind of hard to picture, because we're so used to visually conceptualizing 2D (think about graphing in grade school) or 3D (all objects around us).  But all objects DO have a fourth dimension- time.  The table my feet are propped up on right now has the dimensions that were listed on the website, (length, width, and height), but it also exists in different moments of time, essentially right now.....and right now.....and right now.....and right now.  Graphing the time component of the table would look something like this one dimensional line:

          The time dimension is tricky because for every day objects, it feels less finite than height,                   width, and length.  If you think about the expanse of the universe, though, height, width, and l             length are also decidedly less finite.  If this is still confusing to you, I don't blame you, and                   there are a bunch of videos you can google for visual explanations. 
  • So we have a fabric that we'll call spacetime.  It stretches out in all dimensions.  Think of it like a stretchy trampoline material.  If you place a baseball on a trampoline, it will sag a little under the baseball. If you put a bowling ball on the trampoline, it will sag more, because the bowling ball is heavier.  If you put a really round hippo on the trampoline, it's going to sag a lot.  That sagging is what we mean by spacetime being curved, and just like in our trampoline example, objects with different masses make it curve different amounts.
  • Now imagine you have a marble on the trampoline. Flick it across the surface, and it rolls steadily in a specific path according to Newton's laws: it'll keep going in a straight line at the same speed until it gets pushed or friction slows it down. Now push the marble across the trampoline when the hippo is sitting on it; it doesn't move in a straight line.  When it hits the sag, it starts to spiral inward, like those penny donation cones at the mall.  This is the idea of relativity.

Relativity explains why orbits precess in a way that isn't consistent with classical physics and ideas on gravity, and also predicts that, much like the path of our marble, light itself bends in the gravitational field of a large object.

You might imagine this to be a difficult thing to prove, but fortunately, there was another solar eclipse coming up on May 29, 1919.  This eclipse occurred as the sun was passing the Hyades star cluster.  Light from these stars would have to pass through the sun's gravitational field to reach Earth, and thanks to the eclipse dimming the sun, it would be dark enough to see them.  By comparing measurements of the locations of these stars on a normal day and measurements taken in Principe during the eclipse, Sir Arthur Eddington was able to confirm that the light was was being bent by the gravity of the sun by more than what would be predicted by classical physics and exactly as much as would be predicted by general relativity.  The morning after Eddington reported his findings, Einstein became a scientific celebrity, a position he's never faltered in.19

Historically, eclipses have portended doom and been signs from God.  They've caused fear and hope.  They've inspired astronomers and brought people together.  They've changed the way we view our universe.  There a hundreds of experiments that will be taking place on August 21st, and who knows what they'll change.  

Follow me on Facebook, follow me on Twitter, and for the love of all that is holy, don't look directly at the sun.  

Friday, August 11, 2017

Let's Talk About Sex, Baby

I spend a good deal of time on the Internet.  I'm involved in a variety of online communities, I'm of the age group that was on the cutting edge of Facebook and still haven't moved on to anything cooler, I have an embarrassing familiarity with memes, and my gif game is on point.  Being an "Internet person" means that sometimes you find incredibly amazing content, and sometimes you find absolute trash.  Some of the absolute trash I've accidentally stumbled into has been from communities that rally around men who use biology, psychology, and "biotruths" to justify various forms of misogyny.  When a memo by a Google employee arguing against Google's diversity initiatives was published recently,1 I realized that a lot of people, even people I know, love, and respect, either hold similar beliefs or can be convinced to believe them simply by slapping some peer-reviewed sources and scientific labels on them.  The problem is that a lot of the sources that these arguments cite are often bad science, not supported by the scientific community or by other studies on the topic, or are being misused and misrepresented.

And so, today I'm delving into the land of sexual dimorphism and evolutionary psychology in an attempt to debunk some of these ideas that are spread around.  As a note, this post acknowledges trans* and intersex people, but since most of the research is on male-female differences, I'm going to be focusing on that.  With a deep breath and the knowledge that I will probably invoke the ire of at least one person on Twitter, let's begin.  Full disclosure:  I am a woman.  I'm sure you're shocked.

We know there are many differences between men and women.  The arguments that are often made, that were a central tenet of the Google memo, try to focus on nature as opposed to nurture- ignoring culturally ingrained constructs and socially appropriate behaviors in deference to biology and trans-cultural phenomena.  I'm going to partially address two of the focuses of these debates today: first, sexual dimorphism.  Sexual dimorphism is just the scientific term for the differences between sexes beyond their primary sex organs.  There are definitely physical differences between men and women.  Men are, on average, 9% taller than women.2  On average, women have 40-60% of the upper body strength of men and 70-75% of the lower body strength (I'll blame this for the fact that I only bench press 65 pounds).3  There are average differences in lung capacity,4 pain tolerance,5 and likelihood of catching and severity of illness.6  You'll notice that none of the things I've listed have anything to do with the brain, psychology, or behavior.

So what differences are there in the brain?  Men's brains are, again on average, 10-15% larger than women's.7  There are a few important caveats here: 1) while brain size may be positively correlated with intelligence, it by no means accounts for intelligence, and there are a variety of third variables (nutrition, socioeconomic status, education level) that may influence both,8 and 2) men also tend to weigh 10-15% more than women, so when body weight is corrected for, there actually is no difference.9  A meta-analysis (statistics performed across a number of studies) in 2014 indicated significant differences in volume of the amygdalae, hippocampus, left insula, putamen cerebellum and  anterior cingulate cortex (men larger), as well as the right insula, frontal gyri, and Heschel's gyrus (women larger).10  Many of these structures are part of the limbic system, which is involved with emotion, learning, and memory.  Interestingly, the men had larger volumes in the "emotion areas" that women have traditionally been associated with.

A study of over 5,000 individuals using the UK Biobank study found that men tend to display greater variance across brain region volume, and that the effect sizes of volume differences were small.11  Essentially, while they're may be statistically significant differences, they're not very big difference, mainly due to the amount of variance men's brains displayed.  There was some evidence that the connections between brain areas were more complex in women, but as of yet, we don't really know what that might mean, if anything.12

So here we get into two of the major flaws of the people who make MRI and volumetric based arguments for differences between men and women.  The first is that the majority of these studies are in "mature" populations- over 18.  This makes it very difficult to tell whether these morphometry differences are due to inherent, genetically determined blueprints, or if they come about because of experience and exposure.  I'll compare it to studies that have found that people with PTSD tend to have smaller hippocampi: does a lower hippocampus volume predispose you to getting PTSD, or does something about having PTSD shrink your hippocampus?  Cross-sectional study designs make it nearly impossible to tell, and most of the sources that people tend to cite on these points are cross sectional.

The second, and most major, problem with this line of argument is the problem of reverse inference.  Reverse inference happens all the time in MRI research, and it's a thing to be on the lookout for when evaluating studies.  The basic idea is that we show people pictures of fearful faces.  Their amygdala shows increased activity. "Awesome", we say.  "They amygdala is involved with fear responses.  We have done science!" Then we show people pictures of their dog, and their amygdala shows increased activity.  "Ah ha!", we say. "People are afraid of their dogs!".  It's one of the first logical fallacy most people learn: Red heads have no soul.  Sam Winchester has no soul.  Therefore, Sam Winchester is a red head.
Wrong.  This only applies if red heads are the only people that don't have souls, or if the only the that causes increased amygdala activation is fear.  Claiming that men and women display structural or functional differences in the limbic system does not in any way mean that they are more or less emotional, process emotion differently, or any of the other things that people may claim.  Researchers do this all the time in their papers, and it's a huge problem with functional imaging papers.  Don't let other people get away with applying this crappy science too.

After establishing that there are measurable physiological differences, people tend to turn to personality differences. The Psychology of Sex Differences, published in 1974, considered 2,000 different studies on gender differences in pretty much every domain imaginable: social behavior, abilities, personality traits, memory, etc.  It reported differences in only four domains: verbal memory, mathematical ability, visual-spatial ability, and aggression.13  A meta-analysis published in 2005 looked at the effect size of sex differences across 128 different behavioral variables- academic skills, speech, facial emotion processing, aggression, leadership, helping behaviors, self-esteem, motor behaviors, Neuroticism, Agreeableness, Openness, moral reasoning, and cheating behavior.  It found a small to zero effect size in 78% of the variables.  Large differences were found in physical abilities (not really relevant to women in the workplace) and sexuality (hopefully not relevant to women in the workplace).  The effect size in physical aggression was moderate (still hoping not relevant in the workplace, unless you're an MMA fighter), and effect size of relational aggression, which has gotten a lot of play in the news, was unclear.14

Let's move beyond that into some of the more specific claims- ones that Mr. Google cited coming from the Big Five Personality Scales.  These include Openness to Experience, Agreeableness, Neuroticism, Conscientiousness, and Extraversion.  All of these traits exist on a continuum, where every stage has what we would culturally consider positive or negative attributes to any given point, which means that regardless of findings, you don't have to think more than about thirty seconds to come up with a way to make them support your opinion.  There is a fair body of evidence that indicates that women score higher on Neuroticsm scales across cultures.15  This finding doesn't represent effect size at all though, and small average differences on a personality scale aren't going to create the major disparities we see in the workplace and relationships.  This finding could also be used to argue that women are less well equipped to handle stress, emotionally unstable, often in a bad mood.  On the flip side, you could argue that men are less inspired or unconcerned with things, less dynamic and engaged.  The same is true of any of the Big Five Personality measures.  They're somewhat like (fairly consistently validated) horoscopes: whatever you want to read into it, you can.  If you want to prove that women are (on average) less oriented toward or capable of performing in certain roles, you can find a way to interpret personality measures to do that.

The other field that certain types of people like to use as arguments is evolutionary psychology.  This puts forward the idea that psychological behaviors are adaptive, and have adapted differently for men and women.  It looks for patterns across cultures and species that can be explained as a byproduct of adaptation as opposed to random variation.  The field as a whole is extremely controversial in science.  To start off with, evolutionary psychology is often scientifically sketchy at best.  There are a few problems here: first, evolutionary psychology theories are often not testable, which makes them bad science.  Given how different modern life is from that of our ancestors, it seems likely that personality traits would have evolved for different reasons than we now apply them.  We can't really test that, though, because it's difficult to determine personality from human remains.  It's difficult to tell when and how psychological behaviors developed in the timeline of human evolution, and impossible to determine what was psychologically happening with these individuals.  Even if we do have evidence of behaviors, there is no way to know the underlying reasonings and internal happenings, which is where the important stuff for these purposes is.  If you try to draw across species comparisons, you can't very well ask animals their thoughts and motivations either.  The idea of observing a trait or behavior and saying "That's interesting, it could be because of the fact that women take nine months to reproduce", without the ability to manipulate the gestation period in women, or have a clear analog for the behavior in species that don't have a nine month gestation period is just that- ideas, not science, and doesn't "prove" anything, no matter how much these defenders want it to.

There are assumptions made by many evolutionary psychologists that are just not true.  A major example is specialization of brain areas.  While yes, there is specialization to some extent, those are by no means simple or static.  Look at any of the hundreds and hundreds of studies on neuroplasticity (NOT the kind that supposedly happens with brain training apps) to see how malleable these areas are.  Look at the Wikipedia page for a given chunk of cortex and for most of them, multiple roles or suspected roles will be listed.  We have amazing computational power that wouldn't really be possible if we limited ourselves to one task or ability per chunk.  This goes back to the problem of reverse inference.  It would be nice, but unfortunately doesn't work that way.

In the end, the Google memo, and other manifestos like it, are a bunch of hogwash, or whatever your preferred colloquial form of "bullshit" may be.  Any differences in psychological or personality traits that may be relevant to a work place (or romantic relationships, for the people who use these tactics in those settings) are either not consistently found or have a small effect size, and likely don't really matter in the settings they're applying them.  The "biological differences" theories put out there often ignore the interaction of genes and environment or are misinterpreted and misapplied (possibly out of naivity, possibly intentionally).  The use of evolutionary psychology to bolster a point is a red flag in general, and the reader should proceed with caution.  They're often rife with reverse inferences, cherry-picking data that supports their points (and there usually IS data that supports their point, even when there's a whole lot more that proves it wrong), and coming up with a theory and then attempting to back it up, as opposed to letting the data guide the theory.  Most importantly, slapping the label of "science" on something does not inherently make it true, productive, or worthy of our consideration.  "Peer reviewed" doesn't necessarily mean right, it just means methodologically sound.  "Biological" doesn't mean applied correctly.  Capitalizing on the common misunderstandings of the word "theory" as it is used incorrectly by those arguing against the "theory" of evolution or the "theory" of relativity, doesn't mean that anything with the word theory in it is commonly accepted by scientists. Using "science" to bolster misogynistic, racist, homophobic views (and for those defending this particular memo, please remember that the exact same types of arguments have historically been made to prove that black individuals are less intelligent and capable, more violent, etc.) doesn't make them more worthy of consideration, it just makes them more worthy of using actual science and statistics to smack it down.

You can find me on Twitter @reviewer3blog for all of the arguments and rebuttals I'm sure will inevitably follow this post.

Thursday, August 10, 2017

Just Another Brick in the Wall

I grew up in deep South Texas.  The part of Texas where, when people ask you which part you're from, you just give a cardinal direction.  The part where people assume you mean Houston, and you have to say "No no, six and a half hours south of there".  The part in red:

I didn't love it.  I won't pretend that I did.  I moved away as soon as I graduated from high school and haven't looked back.  But for all of the tedium, and the poverty, and the fact that not a single bar has ginger ale, it is an interesting place culturally and an important place ecologically.

I grew up in the Rio Grande Valley- not a mountain valley like many assume, but more of a river delta.  It's kind of an ecological wonder- it exists in a shift between the tropical environment of Central America and Mexico and the temperate climate of the United States, as well as the wetter environment of the Eastern US and the drier environments of the West, which results in an unusually high amount of biodiversity.1  There are three refuge complexes in the Rio Grande Valley: The Lower Rio Grande Valley National Wildlife Refuge, Laguna Atascosa National Wildlife Refuge, and Santa Ana Wildlife Refuge.  Between the three, there are 429 species of birds, 44 species of mammals, 115 species of reptiles and amphibians, 31 species of fish, 300 species of butterflies , and 100 species of dragonflies and damselflies.  Eighty-five of these species are currently on the endangered, rare, or threatened species list.2  The area is one of the top birdwatching spots in the country, and plays host to at least half of the butterfly species seen in the United States.3  There are currently fewer than 50 Texas ocelots left in the region,4 and I once saw a jaguarundi there on an elementary school field trip.5

All of this is under threat from a proposed 74 mile long section of the border wall proposed by the Trump administration.  Say what you will about the border wall: racist, waste of money, economic effect on nearby communities, or maybe you're for it; regardless, one of the things that isn't being discussed enough is the ecological impact.

The current proposal for the border wall cuts through three miles of the Santa Ana Wildlife Refuge and an undetermined length of the National Butterfly Center.6
Advocates in this area are looking to other parts of the country and are understandably concerned: for the San Diego portion of the wall, the Department of Homeland Security waived 32 different laws, including the Clean Air Act, Clean Water Act, Solid Waste Disposal Act, a variety of wildlife protection acts, and, ironically enough, the Eagle Protection Act. among others.  Those are just the environmental laws: waivers have also been granted for archaeology laws, antiquities laws, and several laws involving the Native American community.7. Things that we've known were problems for decades, that we've been trying to fix for decades, are now back on the table for border regions.  But what exactly does that mean ecologically for these regions?

We have some idea, because there have been intermittent segments of a border fence in the Rio Grande Valley since 2008.  A study done after these first segments were built came to the conclusions that fences and walls resulted in groups of animals not being as freely connected to mate and interact with others of their species, which, in turn, reduces the population size.8  The same study reported that border barriers have reduced the range for some species by as much as 75%, which means more competition for resources, less to go around, and forcing species into areas where they haven't been seen before (or forcing higher numbers), where the resources available might not be what they need or are used to.  

Rice University professor Scott Egan agreed with these findings.  In an interview with Click2Houston, he emphasized the effects of a population bottleneck that would reduce the number of individuals in a species and risk cutting a single species into isolated populations, as well as the genetic effects and overall weakening of the population caused by the inbreeding resulting from less interconnectivity. He also made the addition of the disruption not just of local populations, but of migratory patterns of animals all along the border.  Disrupting migration patters wouldn't just affect the migratory animals; it would also have potentially disasterous consequences for the plants that rely on those animals for pollination.  On a longer term migratory scale, more and more species are shifting their location distributions northward in response to global warming.  If species are limited by a barrier, they could essentially end up trapped in areas with no resources or inappropriate climates.9

The ecological effects of the border wall are not just limited to impacting fauna.  The majority of the US-Mexico border is a river, and large sections of the US-Mexico border wall are being built in floodplains.  Those familiar with the area have indicated that some of the proposed wall in the Rio Grande Valley is actually on a sandbar.10  During times of heavy rain, a solid barrier in a floodplain will basically become a dam, preventing the flow of water on both sides of the river.  Indeed, this has already happened in Arizona, with two deaths in Nogales, AZ and millions of dollars of damage in multiple floods over the past ten years, primarily due to debris collecting the border wall and having nowhere to go.11  Almost 200 miles away, in a separate incident, the Organ Pipe Cactus National Monument was damaged in a similar flood.12  Intense flooding can not only threaten human lives and damage property, but can result in tainted water supplies, contaminating and spreading contaminated sediment, damaging agricultural, and losses of both plants and animals.  

The final ecological impact I'll briefly mention is the disruption of the actual process of building the wall.  Construction means construction crews, construction equipment, and construction access.  Animals tend to shy away from areas with loud noises and lots of people and development, even if they've been living in the region for decades.  An immediate outcome of building a border wall is likely to be disrupting populations of animals as they leave the area to find safe places.  Cutting down and trampling plants is also pretty much inevitable in the construction process. 

I focused a lot on the Rio Grande Valley in this post, but these issues apply to the entire length of the border wall.  In the Rio Grande Valley specifically though, sections of the wall will go directly through Santa Ana Wildlife Refuge, wreaking environmental havoc on an area specifically set aside to protect species from the effects of urban development.  If the border wall doesn't end kill these animals, the irony certainly will.  For those in Texas, there are protests happening often and campaigns to contact legislatures that you can be a part of.  For those not in Texas, share this article so people know what's going on and how damaging it is.  If you'd like to keep up with these efforts, "Like" the Facebook page for Save Santa Ana Wildlife Refuge.  And, as always, follow me on Twitter @reviewer3blog for science articles, gifs, and retweets of The Atlantic's Ed Yong in between blog posts.  

Sunday, July 23, 2017

Who Wants to Live Forever?

Suffice it to say that I've taken some time off from this blog.  I got incredibly busy with work, finishing and defending my dissertation (wooo!).  I fell into a post-dissertation existential slump, where I just couldn't motivate myself to do anything (burnout is real).  I started a new postdoc in the Department of Psychiatry at the University of Minnesota, studying schizophrenia using fMRI, but it's been taking a little bit of time to settle in there and adjust to new routines (getting to the gym by 6:45 AM is hard).  But now I've officially taken the time I needed to get my groove back, and, armed with a PhD with the ink still wet and a list of topics I want to write on, I'm back with more passion and excitement than ever.  So let's do this.

When it comes down to it, a huge swath of biological research has the end goal of expanding the length and quality of human lives.  Even the most basic research can have an eventual role in curing disease, preventing deficits associated with aging, or providing a healthier environment to live in.  While this seems like it's a valiant and noble goal, it may be, to some extent, for naught.  Back in October 2016, researchers declared that the natural limit to the human lifespan is around 115 years old.1  "Natural limit" means the maximum average age that humans would live without any sort of disease cutting life short or artificial way of prolonging it.  Basically, if everyone died of "old age", what would our lifespan be?

The paper, published in Nature, one of the highest profile scientific journals, looked a various mortality data from developed countries over the past century or so.  All of these countries have shown a steady increase in life expectancy from 1900 to the present, with exceptions for people born in the late 1910's and early 1940's.2  Important lesson to take from these data: try not to be born during a world war.  This, however, just represents average life expectancy, not maximum life expectancy.  There are a lot of data to suggest that this increase in life expectancy over the past century is due to decreases in infant and childhood mortality.3  In the more recent past, there has also been an increase in the number of people reaching late-life, which pulls the average life expectancy up even further.4  None of this, however, is remotely helpful if we want to think about maximum life expectancy.  To really understand this, let's think about how averages work.

Let's say you have five people.

The average life expectancy increases across the three time points, but that only tells us so much about the data.  It says nothing about the range of ages people die at, which, in this case, are all the same.  It says nothing about how much variability there is in the data, which is decreasing across the three time points.  Most importantly, for our purposes, it says nothing about the maximum age.  While the average age is increasing, the maximum is staying constant.

So how did these researchers determine that 115 specifically was the natural maximum of human life?   The most basic analysis looked at the age of death for supercenturians (people over 110 years of age) over a period of time.5  This number increased rapidly from the 1970s to the 1990s, but has mostly held steady since 1995.  People who are living to late-life, the average age of death hasn't increased in the past 20 years, suggesting that we have hit or come close to that maximum lifespan.  The same pattern held true for maximum age at death per year as well as average age, which indicates that there aren't really any outliers.  The conclusion was reinforced when looking at rates of change over time.  When looking at what age has experienced the largest increase in people reaching, between the 1920s and the late 1970s, the age has increased from 85 to 100, and plateaued around that point.  Rates of change over the last 100 years have increased dramatically for points between about 45 and 100 years of age, and then drop off, indicating that there has not been a major increase in the number of people reaching 100 in the last century.6  The authors observed two different trends in the data- one trending upward, the other trending downward, and split the data in order to determine if these were, in fact, different.  The results of this analysis indicated that a positively sloped model of maximum age fits early time-point data, while a slightly negatively sloped model fits the later time point data, indicated that after the mid-1990s, a peak had been reached in the maximum age.  Describing all these data is a little tough, so I've included the figures from the paper so you can visualize.

From Dong et al., 2016

All of the conclusions seem fairly sound from the data, the paper was published and became very popular in the popular news.  You very probably read about it.  And then all hell broke up. 

The June 29th issue of Nature took some issue with the study.  Four rebuttals and a reply from the original authors were published that week, and none of this was covered in the news as follow up.  Essentially, multiple groups took strong issue with the statistical approaches Dong et al., had taken, accusing them of violating multiple good research and statistical practices and virtually nullifying all their findings.  One issue was that the authors fit separate, independent models to each age, ignoring the fact that surviving to any one age isn't entirely independent of surviving to any other age- namely, the probability is higher that you survive to 80 than to 90 by virtue of simply having more time to have something happen resulting in death, but this isn't accounted for when coming up with the lines that fit the data for a single year. Statistics were also heavily biased by the number of supercenturians dying in a certain year, to the point that there was a very strong, extraordinary significant positive correlation between the number of deaths and the average age of those deaths, ranging from 111.39 in years where only one supercenturian died to 116.28 in years where upwards of 30 died.7

Dong et al., separated data into two groups of years, reporting an increase in age at earlier time points, and no change with a trend towards a decrease (though I would argue you could safely call it no change) at later time points.  This lack of change in the second group helped make their case a plateau in maximum age.  However, they never explain why they chose to split the data where they did, and indeed if you look at the data as a whole or partition it at a different point, you find a different result.8  The statistical analyses they performed on these data used only the oldest person who died in each year, meaning that even though the total sample size of supercenturians was 534, the actual sample sizes being included in this split analysis was 21 for one group and 12 for the other, which are pretty small for the type of analysis they're doing.9  Data also appears to potentially be skewed by the outlier of Jeanne Calment, who died in 1997 at the age of 122.10

There was also issue with the data themselves.  The mortality database from which the data warns caution when looking at data for people over the age of 90 due to the data essentially being preprocessed and rounded and not providing raw numbers.  Using the statistical methods that were promoted in the original paper is not necessarily the correct way to unpack these rounded numbers, which leads to some questions in validity.11

Confusingly, single authors at times argue that the results would have been different if they limited the time span they were looking at, or if they had expanded that time span.  For example, how do you determine that a plateau is really a plateau and not just a much slower increase without continuing to look at the data for a longer period of time?12  As evidence of this point, there was also an apparently plateau between the years of 1968 and 1980, but this was followed by another increase.  There is no reason to believe that the current plateau is the finally one.13  

From a basic experimental design perspective, Dong et al. never compare their model fits to other possibilities.  As illustration of this point, another model using the same data suggests that the maximum lifespan might reach 125 by the year 2070.14 Dong and colleagues provide no data on how they determined that the way they modeled the data is the most accurate, and you cannot have a hypothesis that cannot be disproven, thus suggesting that this paper breaks the cardinal rule of science.15

Dong and colleagues then fired back in a brief letter that addressed a very select few of these arguments;  I'll let you determine how compelling you find this rebuttal to be.16  Either way, there is now a war in longevity research, and these scientists are definitely rolling their eyes at each other in the privacy of their own lab meetings.  

I, on the other hand, absolutely love this situation.  It's such a good example of so many things.  The most basic is to always reserve judgment and be skeptical of articles that are being reported in the media.  No one really cares about the methodology and statistics when they're reading something in Discover Magazine, in fact, you're probably not interested in it in this blog, but there is so much valuable information contained in these parts that are being cut out to tell the story.  It's also a beautiful example of the way science should work.  These scientists are volleying back and forth, fighting to disprove the others (it's a very negative and aggressive field), improving, explaining, and questioning.  It beats scientists themselves over the head with the importance of strong statistical knowledge and application, even though we all fell asleep in our first year stats course.  It also demonstrates that when an interesting, sexy piece of science news comes out, it's up to us to stick with it.  See where discoveries go, what develops out of them, how they inspire other science.  Maybe the thing that sounded so interesting is overdramatized or overgeneralized.  Maybe something amazing comes out of it.  Maybe everyone else in the field thinks it's a crock.  Popular science media, unfortunately, doesn't often do this for us, but they should, because it shows how messy the process is and how skeptical and questioning we should be.