Species, types, and the "No True Scotsman" fallacy

One of the most frustrating of logical fallacies is the No True Scotsman fallacy.

It gets its name from an almost certainly apocryphal story, in which a serial rapist and killer is being pursued by the police in Glasgow, and a Scottish MP encourages the police to search amongst the immigrant population of the city.  "No Scotsman would do such a thing," the MP said.

When the criminal was caught, and turned out to be 100% Scottish, the MP was challenged about his remark.

"Well," he said, drawing himself up, "no true Scotsman would have done such a thing!"

The crux of this fallacy is that if you make a statement that turns out, in view of evidence, to be false, all you do is shift your ground -- redefine the terms so as to make your original point unassailable.

Very few other fallacies have such a capacity for making me want to smack my forehead into a wall as this one.  Someone who commits this fallacy can't be pinned down, can't be backed into a corner, can't receive his comeuppance from the most reasoned argument, the most solidly incontrovertible evidence.  The dancing skills of a master of the No True Scotsman fallacy are Dancing With The Stars quality.

All of this comes up because of an online discussion that I read, and (yes) participated in, a couple of days ago, on the topic of the demonstrability of evolution.  Someone, ostensibly a supporter of evolution but seemingly not terribly well-read on the subject, was using such evidence as the fossil record as a support for the idea.  A creationist responded, "The fossil record, and fossil dating, are inaccurate.  You evolutionists always think that bringing us a bunch of bones and shells proves your point, but it doesn't, because no one can really prove how old they were, and none of them show one species turning into another.  You can't show a single example, from the present, of one species becoming another, and yet you want us to believe in your discredited theory."

Of course, I couldn't let a comment like that just sit there, so I responded, "Well, actually, yes, I can.  I know about a dozen examples of speciation (one species becoming another) occurring within a human lifetime."

Challenged to produce examples, I gave a few, including the ones that I described in an earlier post (Grass, gulls, mosquitoes, and mice, February 9, 2012), and then sat back on my haunches with a satisfied snort, thinking, "Ha.  That sure showed him."

Well.  I should have known better.  His response, which I quote verbatim: "All you did was show that one grass can become another grass, or a mosquito can become another mosquito.  If you could show me a mosquito that turned into a bird, or something, I might believe you."

Now, hang on a moment, here.  You asked me for one thing -- to show one species turning into a different species, in the period of a few decades.  I did so, adhering to the canonical definition of the word species.  And now you're saying that wasn't what you wanted after all -- you want me to show one phylum turning into a different one, in one generation?

I sat there, sputtering and swearing, and not sure how to answer.  So I said something to the effect that he'd pulled a No True Scotsman on me, and had changed the terms of the question once he saw I could answer it, and he'd damned well better play fair.  He humphed back at me that we evolutionists couldn't really support our points, and we both left the discussion as I suspect most people leave discussions on the internet -- unconvinced and frustrated.  So I was pondering the whole thing, and after taking my blood pressure medications I had a sudden realization of where the confusion was coming from.  It was from the idea of a type of organism.

Most people who aren't educated in the biological sciences (and I'm not including just formal education, here; there are many people who have never taken a single biology class and know plenty about the subject) really don't understand the concept of species.  They think in types.  A bird is one type of thing; a bug is a different one.  If you pressed them, they might admit that there were a few types of birds that seemed inherently different.  You have your big birds (ostriches), your medium-sized birds (robins), and your little birds (hummingbirds).  I've had students that have thought this way, and when they hear I'm a birdwatcher, they seem incredulous that this could be a lifelong avocation.  Wouldn't I run out of new birds to see pretty quickly?  When I tell them that there are over 10,000 unique species of birds, they seem not so much awed as uncomprehending.

The phylogenetic tree of birds (Class Aves) [credit: Dr. Gavin Thomas, University of Sheffield, UK]

I suspect that the source of this misapprehension is the same as the source of the general misapprehension regarding the antiquity of the Earth and the origins of life: the Bible.  In Leviticus 11, where they go through the whole unclean-foods thing that eventually would be codified as the Kosher Law, they split up the natural world in only the broadest-brush terms; you have your animals that have hooves and chew the cud, various combinations of ones that don't, creatures that have fins and scales and ones that don't, insects that jump and ones that don't, and a few different classes of birds (which, to my eternal amusement, includes bats).  And that's pretty much it.  Plants were sorted out into ones that had edible parts (wheat, figs, olives), ones that had useful wood (boxwood, cedar, acacia), and ones that had neither of the above (thorn bushes).  And these distinctions worked perfectly well for a Bronze-Age society.  It kept you from eating stuff that was bad for you, told you what you could build stuff from, and so on.  But as a scientific concept, the idea of "types of living things" kind of sucks.  And yet it still seems to live on in people's minds, lo unto this very day.

So, anyway, that was my brief excursion into that least useful of endeavors, the Online Argument.  It gave me a nice example of the No True Scotsman fallacy to write about here.  And it really didn't affect my blood pressure all that much, but it did make me roll my eyes.  Which seems to happen frequently when I get into conversations with creationists.

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Viral reality

If you are of the opinion that more evidence is necessary for demonstrating the correctness of the evolutionary model, I give you: a paper by biologist Justin R. Meyer of the University of California-San Diego et al. that has conclusively demonstrated speciation occurring in the laboratory.

The gist of what the team did is to grow populations of bacteriophage Lambda (a virus that attacks and kills bacteria) in the presence of populations of two different potential food sources, more specifically E. coli that had one of two different receptors where the virus could attach.  What happened was that the original bacteriophages were non-specialists -- they could attach to either receptor, but not very efficiently -- but over time, more of them accrued mutations that allowed them to specialize in attacking one receptor over the other.  Ultimately, the non-specialists became extinct, leaving a split population where each new species could not survive on the other's food source.

Diagram of a bacteriophage [Image is in the Public Domain]

Pretty amazing stuff.  My response was, "If that isn't evolution, what the hell is it?"  Of course, I'm expecting the litany of goofy rejoinders to start any time now.  "It's only microevolution."  "There was no novel gene produced."  "But both of them are still viruses.  If you showed me a virus evolving into a wombat, then I'd believe you."

Nevertheless, this sticks another nail in the coffin of the anti-evolutionists -- both Intelligent Design proponents and the young-Earth creationists, the latter of whom believe that all of the Earth's species were created as-is six thousand or so years ago along with the Earth itself, and that the two hundred million year old trilobite fossils one sometimes finds simply dropped out of God's pocket while he was walking through the Garden of Eden or something.

So as usual, you can't logic your way out of a stance you didn't logic your way into.  Still, I have hope that the tide is gradually turning.  Certainly one cheering incident comes our way from Richard Lenski, who is justly famous for his groundbreaking study of evolution in bacteria and who co-authored the Meyer paper I began with.  But Lenski will forever be one of my heroes for the way he handled Andrew Schlafly, who runs Conservapedia, a Wikipedia knockoff that attempts to remodel the world so that all of the ultra-conservative talking points are true.  Schlafly had written a dismissive piece about Lenski's work on Conservapedia, to which Lenski responded.  The ensuing exchange resulted in one of the most epic smackdowns by a scientist I've ever seen.  Lenski takes apart Schlafly's objections piece by piece, citing data, kicking ass, and taking names.  I excerpt the end of it below, but you can (and should) read the whole thing at the article on the "Lenski Affair" over at RationalWiki:

I know that I’ve been a bit less polite in this response than in my previous one, but I’m still behaving far more politely than you deserve given your rude, willfully ignorant, and slanderous behavior.  And I’ve spent far more time responding than you deserve.  However, as I said at the outset, I take education seriously, and I know some of your acolytes still have the ability and desire to think, as do many others who will read this exchange.

Sincerely, Richard Lenski

And if that's not spectacular enough, check out one of the four P.S.s:

I noticed that you say that one of your favorite articles on your website is the one on “Deceit.”  That article begins as follows: “Deceit is the deliberate distortion or denial of the truth with an intent to trick or fool another.  Christianity and Judaism teach that deceit is wrong.  For example, the Old Testament says, ‘Thou shalt not bear false witness against thy neighbor.’”  You really should think more carefully about what that commandment means before you go around bearing false witness against others.

I can only hope that there was a mic around after that so that Lenski could drop it.

So there you have it.  Science finding out cool stuff once again, because after all, that's what science does.  The creationists, it is to be hoped, retreating further and further into the corner into which they've painted themselves.  It's probably a forlorn wish that this'll make Ken Ham et al. shut up, but maybe they'll eventually have to adapt their strategy to address reality instead of avoiding it.

You might even say... they'll need to evolve.

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Splitting the difference

One of the most misunderstood pieces of the evolutionary model is that natural selection is almost always a compromise.

Very few changes that could occur an organism's genes (and thus in its physical makeup) are unequivocally good.  (Plenty of them are unequivocally bad, of course.)  Take, for example, our upright posture, which is usually explained as having been selected for by (1) allowing us to see farther over tall grass and thus spot predators, (2) leaving our hands free for tool use, (3) making it easier to carry our offspring before they can walk on their own, or (4) all of the above.  At the same time, remodeling our spines to accommodate walking upright -- basically, taking a vertebral column that evolved in an animal that supported itself on all fours, and just kind of bending it upwards -- has given us a proneness to lower back injury unmatched in the natural world.  The weakening of the rotator cuff, due to the upper body no longer having to support part of our weight, has predisposed us to shoulder dislocations.

Then there are the bad changes that have beneficial features.  One common question I was asked when teaching evolutionary biology is if selection favors beneficial traits and weeds out maladaptive ones, why do negative traits hang around in populations?  One answer is that a lot of maladaptive gene changes are recessive -- you can carry them without showing an effect, and if you and your partner are both carriers, your child can inherit both copies (and thus the ill effect).  But it's even more interesting than that.  It was recently discovered that being a carrier for the gene for the devastating disease cystic fibrosis gives you resistance to one of the biggest killers of babies in places without medical care -- cholera.  It's well known that being heterozygous for the gene for sickle-cell anemia makes you resistant to malaria.  Weirdest of all, the (dominant) gene for the horrible neurodegenerative disorder Huntington's disease gives you an eighty percent lower likelihood of developing cancer -- offset, of course, by the fact that all it takes is one copy of the gene to doom you by age 55 or so to progressive debility, coma, and death.

So the idea of "selective advantage" is more complex than it seems at first.  The simplest way to put it is that if an inheritable change on balance gives you a greater chance of survival and reproduction, it will be selected for even if it gives you disadvantages in other respects, even some serious ones.

The reason the topic comes up is because of a cool piece of research out of the University of California - Santa Barbara into a curious genetic change in the charming little Colorado blue columbine (Aquilegia caerulea), familiar to anyone who's spent much time in the Rocky Mountains.

Colorado blue columbine (Aquilegia caerulea) [Image licensed under the Creative Commons Rob Duval, Heavycolumbinebloom, CC BY-SA 3.0]

Both the common name and scientific name have to do with birds; columba is Latin for dove, aquila Latin for eagle.  The reason is the graceful, backwards-curved tubular petals, which (viewed from the side) look a little like a bird's foot.  The tubes end in nectar glands, and are there to lure in pollinators -- mostly hummingbirds and butterflies -- whose mouthparts can fit all the way down the long, narrow tubes.

Well, the researchers found that not all of them have these.  In fact, there's a group of them that don't have the central petals and nectar spurs at all.  The loss is due to a single gene, APETALA3-3, which simply halts complete flower development.  So far, nothing too odd; there are a lot of cases where some defective gene or another causes the individual to be missing a structure.  What is more puzzling is that in the study region (an alpine meadow in central Colorado), a quarter of the plants have the defective flowers.

You would think that a plant without its prime method of attracting pollinators would be at a serious disadvantage.  How could this gene be selected strongly enough to result in 25% of the plants having the change?  The answer turned out to be entirely unexpected.  The plants with the defective gene don't get visited by butterflies and hummingbirds as much -- but they are also, for some reason, much less attractive to herbivores, including aphids, caterpillars, rabbits, and deer.  So it may be that the flowers don't get pollinated as readily as those of their petal-ful kin, but they are much less likely to sustain energy-depleting damage to the plant itself (in the case of deer, sometimes chomping the entire plant down to ground level). 

If fewer flowers get pollinated, but the ones that do come from plants that are undamaged and vigorous and able to throw all their energy into seed production, on balance the trait is still advantageous.

Even cooler is that the two different morphs rely on different pollinators.  Species of butterfly with a shorter proboscis tend to favor the spurless variant, while the original spurred morph attracts butterflies and hummingbirds with the ability to reach all the way down into the spur.  What the researchers found is that there is much less cross-pollination between the two morphs than there is between plants of the same morph.

For speciation to occur, there needs to be two things at work: (1) a genetic change that acts as a selecting mechanism, and (2) reproductive isolation between the two different morphs.  This trait checks both boxes.

So it looks like the Colorado blue columbine may be on the way to splitting into two species.

Once again, we have an example from the real world demonstrating the power and depth of the evolutionary model -- and one that's kind of hard to explain if you don't buy it.  This time, it's a pretty little flower that has vindicated Darwin, and shown that right in front of our eyes, evolution is still "creating many forms most beautiful and most wonderful."

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Viral reality

If you are of the opinion that more evidence is necessary for demonstrating the correctness of the evolutionary model, I give you: a paper by biologist Justin R. Meyer of the University of California-San Diego et al. that has conclusively demonstrated speciation occurring in the laboratory.

The gist of what the team did is to grow populations of bacteriophage Lambda (a virus that attacks and kills bacteria) in the presence of populations of two different potential food sources, more specifically E. coli that had one of two different receptors where the virus could attach.  What happened was that the original bacteriophages were non-specialists -- they could attach to either receptor, but not very efficiently -- but over time, more of them accrued mutations that allowed them to specialize in attacking one receptor over the other.  Ultimately, the non-specialists became extinct, leaving a split population where each new species could not survive on the other's food source.

Diagram of a bacteriophage [Image licensed under the Creative Commons GrahamColm at English Wikipedia, Phage, CC BY-SA 3.0]

Pretty amazing stuff.  My response was, "If that isn't evolution, what the hell is it?"  Of course, I'm expecting the litany of goofy rejoinders to start any time now.  "It's only microevolution."  "There was no novel gene produced."  "But both of them are still viruses.  If you showed me a virus evolving into a wombat, then I'd believe you."

"Anti-evolutionists," see "Goalposts, Moving the."

Nevertheless, this sticks another nail in the coffin of both Intelligent Design proponents and the young-Earth creationists, the latter of whom believe that all of the Earth's species were created as-is six thousand or so years ago along with the Earth itself, and that the two hundred million year old trilobite fossils one sometimes finds simply dropped out of God's pocket while he was walking through the Garden of Eden or something.

So as usual, you can't logic your way out of a stance you didn't logic your way into.  Still, I have hope that the tide is gradually turning.  Certainly one cheering incident comes our way from Richard Lenski, who is justly famous for his groundbreaking study of evolution in bacteria and who co-authored the Meyer paper I began with.  But Lenski will forever be one of my heroes for the way he handled Andrew Schlafly, who runs Conservapedia, a Wikipedia clone that attempts to remodel reality so that all of the ultra-conservative talking points are true.  Schlafly had written a dismissive piece about Lenski's work on Conservapedia, to which Lenski responded.  The ensuing exchange resulted in one of the most epic smackdowns by a scientist I've ever seen.  Lenski takes apart Schlafly's objections piece by piece, citing data, kicking ass, and taking names.  I excerpt the end of it below, but you can (and should) read the whole thing at the article on the "Lenski Affair" over at RationalWiki:

I know that I’ve been a bit less polite in this response than in my previous one, but I’m still behaving far more politely than you deserve given your rude, willfully ignorant, and slanderous behavior.  And I’ve spent far more time responding than you deserve.  However, as I said at the outset, I take education seriously, and I know some of your acolytes still have the ability and desire to think, as do many others who will read this exchange.

Sincerely, Richard Lenski

And if that's not spectacular enough, check out one of the four P.S.s:

I noticed that you say that one of your favorite articles on your website is the one on “Deceit.”  That article begins as follows: “Deceit is the deliberate distortion or denial of the truth with an intent to trick or fool another.  Christianity and Judaism teach that deceit is wrong.  For example, the Old Testament says, ‘Thou shalt not bear false witness against thy neighbor.’”  You really should think more carefully about what that commandment means before you go around bearing false witness against others.

I can only hope that there was a mic around after that so that Lenski could drop it.

So there you have it.  Science finding out cool stuff once again, because after all, that's what science does.  The creationists, it is to be hoped, retreating further and further into the corner into which they've painted themselves.  It's probably a forlorn wish that this'll make Ken Ham shut up, but maybe he'll eventually have to adapt his strategy to address reality instead of avoiding it.

You might even say... he'll need to evolve.

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The sad truth of our history is that science and scientific research has until very recently been considered the exclusive province of men.  The exclusion of women committed the double injury of preventing curious, talented, brilliant women from pursuing their deepest interests, and robbing society of half of the gains of knowledge we might otherwise have seen.

To be sure, a small number of women made it past the obstacles men set in their way, and braved the scorn generated by their infiltration into what was then a masculine world.  A rare few -- Marie Curie, Barbara McClintock, Mary Anning, and Jocelyn Bell Burnell come to mind -- actually succeeded so well that they became widely known even outside of their fields.  But hundreds of others remained in obscurity, or were so discouraged by the difficulties that they gave up entirely.

It's both heartening and profoundly infuriating to read about the women scientists who worked against the bigoted, white-male-only mentality; heartening because it's always cheering to see someone achieve well-deserved success, and infuriating because the reason their accomplishments stand out is because of impediments put in their way by pure chauvinistic bigotry.  So if you want to experience both of these, and read a story of a group of women who in the early twentieth century revolutionized the field of astronomy despite having to fight for every opportunity they got, read Dava Sobel's amazing book The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars.

In it, we get to know such brilliant scientists as Willamina Fleming -- a Scottish woman originally hired as a maid, but who after watching the male astronomers at work commented that she could do what they did better and faster, and so... she did.  Cecilia Payne, the first ever female professor of astronomy at Harvard University.  Annie Jump Cannon, who not only had her gender as an unfair obstacle to her dreams, but had to overcome the difficulties of being profoundly deaf.

Their success story is a tribute to their perseverance, brainpower, and -- most importantly -- their loving support of each other in fighting a monolithic male edifice that back then was even more firmly entrenched than it is now.  Their names should be more widely known, as should their stories.  In Sobel's able hands, their characters leap off the page -- and tell you a tale you'll never forget.

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

An alpine gem in China

In order to produce new species -- so goes the evolutionary model -- you need two things: isolation (splitting off the population that will eventually become the new species from the parent population) and selection (environmental conditions that favor different traits in the splinter population than the ones favoring the parent population).  Given those two, and sufficient time, sooner or later you'll have two (or more) separate species.

The classic example of this, of course, is the group of birds called "Darwin's finches," that evolved from a parent population of tanagers from mainland South America (their closest relative is the Dull-colored Grassquit of Colombia, Ecuador, and Peru) something on the order of two million years ago.  Once arrived in the islands, they thereafter fragmented to fill the available niches in a process that has been nicknamed adaptive radiation.

So split off a population and give it some new conditions to contend with, and you'll end up with new species.  Which is what happened to a whole ecosystem's worth of species thirty million years ago -- leading to one of the most biodiverse spots on Earth.

New research into the genetics of the dozens of unique species in the Hengduan Mountains and Qinghai Plateau of western China has given us a fascinating lens into this process.  In "Ancient Orogenic and Monsoon-Driven Assembly of the World’s Richest Temperate Alpine Flora," by Wen-Na Ding, Robert Spicer, and Yao-Wu Xing of the Chinese Academy of Sciences and Richard Ree of Chicago's Field Museum, we read about a biotic province created by mountain building that not only raised the elevation (and thus lowered the average temperature), but altered wind currents to create monsoons -- and isolated the populations trapped there from their relatives on the other side of the mountain range.

"The theory is, if you increase the ruggedness of a landscape, you're more likely to have populations restricted in their movement because it's harder to cross a deeper valley than a shallow valley," said study co-author Richard Ree, in an interview with Science Daily.  "So any time you start increasing the patchiness and barriers between populations, you expect evolution to accelerate...  The combined effect of mountain-building and monsoons was like pouring jet fuel onto this flame of species origination.  The monsoon wasn't simply giving more water for plants to grow, it had this huge role in creating a more rugged topography.  It caused erosion, resulting in deeper valleys and more incised mountain ranges."

This all started back in the Oligocene Epoch, thirty million years ago, and the area has been pretty well isolated ever since.  The result is plants like the Himalayan lantern (Agapetes lacei):

.... which you wouldn't guess is a relative of rhododendrons and azaleas; the alpine monkshood (Aconitum gymnandrum):

... the gorgeous little Paraquilegia microphyllum:

... and literally hundreds of others, species found there and nowhere else on Earth.

The remoteness and general inaccessibility of the area has limited the human impact (fortunately), but scientists are rightly concerned with the effects that climate change will have on these subalpine valleys and plateaus.  Even if we're not directly damaging the ecosystem, our actions elsewhere imperil it, just as our out-of-control fossil fuel use has led to the thawing of the Arctic and the threat of ice sheet collapse in Antarctica -- the latter of which recent research has suggested could add three meters to the average sea level over a very short period, with catastrophic consequences.

But for now, let's just focus on this pristine gem of an ecosystem, and marvel at the processes that created it.  Once again, we see the truth of Darwin's words, with which he ended The Origin of Species: "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."

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This week's Skeptophilia book recommendation is a fun and amusing discussion of a very ominous topic; how the universe will end.

In The End of Everything (Astrophysically Speaking) astrophysicist Katie Mack takes us through all the known possibilities -- a "Big Crunch" (the Big Bang in reverse), the cheerfully-named "Heat Death" (the material of the universe spread out at uniform density and a uniform temperature of only a few degrees above absolute zero), the terrifying -- but fortunately extremely unlikely -- Vacuum Decay (where the universe tears itself apart from the inside out), and others even wilder.

The cool thing is that all of it is scientifically sound.  Mack is a brilliant theoretical astrophysicist, and her explanations take cutting-edge research and bring it to a level a layperson can understand.  And along the way, her humor shines through, bringing a touch of lightness and upbeat positivity to a subject that will take the reader to the edges of the known universe and the end of time.

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

Genes on loan

I wonder what the early pioneers of genetics -- people like Gregor Mendel, Thomas Hunt Morgan, Reginald Punnett, and William Bateson -- would think if they could peruse a modern genetics textbook.

My hope is that they'd be delighted beyond words at where the science has gone since their time.  The simple foundation laid down by the first geneticists has been elaborated and modified into a complex, far-reaching science that has explanatory power from the molecular level to the characteristics of the organisms themselves (the phenotypes, or physical expressions, of the genes).  And now, just over 150 years after the publication of Mendel's book on statistical genetics that showed that inheritance of traits followed natural laws and generated predictable statistics, we're still adding to what we know.

Take the paper that came out in Nature this week, that describes a fascinating exception to Mendel's Law of Independent Assortment (one of his four laws of statistical genetics).  The Law of Independent Assortment says that every gene inherits by its own separate statistics.  Put another way, genes don't inherit in chunks; each one is its own flip of the coin.  Here's an example:

Let's say your mom inherited a type A blood type gene and an Rh negative gene from her father, and a type B blood type gene and an Rh positive gene from her mother.  (This, by the way, would make her AB+.)  Now, she passed on to you her father's type A gene.  Which Rh gene did you get?

Answer: by the Law of Independent Assortment, there's no way to be sure. Knowing she passed on her father's type A gene doesn't make it any more likely you got her father's Rh negative gene; each gene operates by its own statistics, and the inheritance of one gene does not influence the inheritance of any other.

Well, we've known about some exceptions to that law for years; in fact, the aforementioned Bateson and Punnett were the ones who figured out what was going on with the discovery of linked genes, genes that lie near each other on the same chromosome.  In my earlier example, if the ABO blood type gene and the Rh+/- gene were close together on the same chromosome (they're not), then inheriting the A gene from her dad would make you more likely to also get the negative gene from her dad.  (You may be wondering why, if they're on the same chromosome, it doesn't make the likelihood of their inheriting together 100%; that's a whole 'nother topic, called crossing over, which I won't explain in this post because otherwise we'll never get to the recent research.)

The paper in Nature, called "Massive Haplotypes Underlie Ecotypic Differentiation in Sunflowers," by a huge team led by the trio of Marco Todesco, Gregory Owens, and Natalia Bercovich of the University of British Columbia, describes how the inheritance of huge chunks of DNA -- hundreds of millions of base pairs long, inherited as a single block -- has allowed related species of sunflowers to grab beneficial traits from each other and triggered differentiation and, ultimately, the formation of new species.

[Image is in the Public Domain]

The authors write:

Species often include multiple ecotypes that are adapted to different environments.  However, it is unclear how ecotypes arise and how their distinctive combinations of adaptive alleles are maintained despite hybridization with non-adapted populations.  Here, by resequencing 1,506 wild sunflowers from 3 species (Helianthus annuus, Helianthus petiolaris and Helianthus argophyllus), we identify 37 large (1–100 Mbp in size), non-recombining haplotype blocks that are associated with numerous ecologically relevant traits, as well as soil and climate characteristics.  Limited recombination in these haplotype blocks keeps adaptive alleles together, and these regions differentiate sunflower ecotypes.  For example, haplotype blocks control a 77-day difference in flowering between ecotypes of the silverleaf sunflower H. argophyllus (probably through deletion of a homologue of FLOWERING LOCUS T (FT)), and are associated with seed size, flowering time and soil fertility in dune-adapted sunflowers.  These haplotypes are highly divergent, frequently associated with structural variants and often appear to represent introgressions from other—possibly now-extinct—congeners. These results highlight a pervasive role of structural variation in ecotypic adaptation.

Catch that last bit?  Some of these "supergenes," as they're called, could have come from now-extinct species, whose DNA still exists and is still influencing the evolution of a different species.  How cool is that?

"What we think could have happened is that a species arrives in a new habitat, 'steals' adaptive supergenes from a local related species, and then replaces that species," said study co-lead author Marco Todesco, in an interview with Science Daily.  "We could call this a 'ghost supergene', the lingering contribution of a species that no longer exist."

How Gregor Mendel and the pioneers that followed would have been fascinated by all this!  We've come a tremendously long way from Mendel's mysterious "factors" (what we now call alleles) and the simplistic probabilities that generate the inheritance of flower color in pea plants.  Even the linked genes of Bateson and Punnett now seem like only the prologue to the story.

And what's more mindblowing still is that to geneticists in a hundred years hence, even what we know now will still probably only be chapter one.

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This week's Skeptophilia book recommendation of the week is for anyone who likes quick, incisive takes on scientific topics: When Einstein Walked with Gödel: Excursions to the Edge of Thought by the talented science writer Jim Holt.

When Einstein Walked with Gödel is a series of essays that explores some of the deepest and most perplexing topics humanity has ever investigated -- the nature of time, the implications of relativity, string theory, and quantum mechanics, the perception of beauty in mathematics, and the ultimate fate of the universe.  Holt's lucid style brings these difficult ideas to the layperson without blunting their scientific rigor, and you'll come away with a perspective on the bizarre and mind-boggling farthest reaches of science.  Along the way you'll meet some of the key players in this ongoing effort -- the brilliant, eccentric, and fascinating scientists themselves.

It's a wonderful read, and anyone who is an aficionado of the sciences shouldn't miss it.

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

Species, types, and the "No True Scotsman" fallacy

One of the most frustrating of logical fallacies is the No True Scotsman fallacy.

It gets its name from an almost certainly apocryphal story, in which a serial rapist and killer is being pursued by the police in Glasgow, and a Scottish MP encourages the police to search amongst the immigrant population of the city.  "No Scotsman would do such a thing," the MP said.

When the criminal was caught, and turned out to be 100% Scottish, the MP was challenged about his remark.

"Well," he said, drawing himself up, "no true Scotsman would have done such a thing!"

The crux of this fallacy is that if you make a statement that turns out, in view of evidence, to be false, all you do is shift your ground -- redefine the terms so as to make your original point unassailable.

Very few other fallacies have such a capacity for making me want to smack my forehead into a wall as this one.  Someone who commits this fallacy can't be pinned down, can't be backed into a corner, can't receive his comeuppance from the most reasoned argument, the most solidly incontrovertible evidence.  The dancing skills of a master of the No True Scotsman fallacy are Dancing With The Stars quality.

All of this comes up because of an online discussion that I read, and (yes) participated in, a couple of days ago, on the topic of the demonstrability of evolution.  Someone, ostensibly a supporter of evolution but seemingly not terribly well-read on the subject, was using such evidence as the fossil record as a support for the idea.  A creationist responded, "The fossil record, and fossil dating, are inaccurate.  You evolutionists always think that bringing us a bunch of bones and shells proves your point, but it doesn't, because no one can really prove how old they were, and none of them show one species turning into another.  You can't show a single example, from the present, of one species becoming another, and yet you want us to believe in your discredited theory."

Of course, I couldn't let a comment like that just sit there, so I responded, "Well, actually, yes, I can. I know about a dozen examples of speciation (one species becoming another) occurring within a human lifetime."

Challenged to produce examples, I gave a few, including the ones that I described in an earlier post (Grass, gulls, mosquitoes, and mice, February 9, 2012), and then sat back on my haunches with a satisfied snort, thinking, "Ha. That sure showed him."

Well. I should have known better.  His response, which I quote verbatim: "All you did was show that one grass can become another grass, or a mosquito can become another mosquito.  If you could show me a mosquito that turned into a bird, or something, I might believe you."

Now, hang on a moment, here.  You asked me for one thing -- to show one species turning into a different species, in the period of a few decades.  I did so, adhering to the canonical definition of the word species.  And now you're saying that wasn't what you wanted after all -- you want me to show one phylum turning into a different one, in one generation?

I sat there, sputtering and swearing, and not sure how to answer.  So I said something to the effect that he'd pulled a No True Scotsman on me, and had changed the terms of the question once he saw I could answer it, and he'd damned well better play fair.  He humphed back at me that we evolutionists couldn't really support our points, and we both left the discussion as I suspect most people leave discussions on the internet -- unconvinced and frustrated.  So I was pondering the whole thing, and after taking my blood pressure medications I had a sudden realization of where the confusion was coming from.  It was from the idea of a type of organism.

Most people who aren't educated in the biological sciences (and I'm not including just formal education, here; there are many people who have never taken a single biology class and know plenty about the subject) really don't understand the concept of species.  They think in types.  A bird is one type of thing; a bug is a different one.  If you pressed them, they might admit that there were a few types of birds that seemed inherently different; you have your big birds (ostriches), your medium-sized birds (robins), and your little birds (hummingbirds).  I've had students that have thought this way, and when they hear I'm a birdwatcher, they seem incredulous that this could be a lifelong avocation.  Wouldn't I run out of new birds to see pretty quickly?  When I tell them that there are over 10,000 unique species of birds, they seem not so much awed as uncomprehending.

The phylogenetic tree of birds (Class Aves) [credit: Dr. Gavin Thomas, University of Sheffield, UK]

I suspect that the source of this misapprehension is the same as the source of the general misapprehension regarding the antiquity of the Earth and the origins of life: the bible.  In Leviticus 11, where they go through the whole unclean-foods thing that eventually would be codified as the Kosher Law, they split up the natural world in only the broadest-brush terms; you have your animals that have hooves and chew the cud, various combinations of ones that don't, creatures that have fins and scales and ones that don't, insects that jump and ones that don't, and a few different classes of birds (which, to my eternal amusement, included bats).  And that's pretty much it.  Plants were sorted out into ones that had edible parts (wheat, figs, olives), ones that had useful wood (boxwood, cedar, acacia), and ones that had neither of the above (thorn bushes).  And these distinctions worked perfectly well for a Bronze-Age society; it kept you from eating stuff that was bad for you, told you what you could build stuff from, and so on.  But as a scientific concept, the idea of "types of living things" is pretty ridiculous.  And yet it still seems to live on in people's minds, lo unto this very day.

So, anyway, that was my brief excursion into that least useful of endeavors, the Online Argument.  It gave me a nice example of the No True Scotsman fallacy to tell my Critical Thinking classes about.  And it really didn't affect my blood pressure all that much, but it did make me roll my eyes.  Which seems to happen frequently when I get into conversations with creationists.

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

If you are one of those people who thinks that science books are dry and boring, I'll give you a recommendation that will put that misconception to rest within the first few pages: Sam Kean's The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of Elements.

Kean undertook to explain, from a human perspective, that most iconic of all images from the realm of chemistry -- the Periodic Table, the organized chart of elements from the simplest (hydrogen, atomic number 1) to largest and most complex (oganesson, atomic number 118).  Kean's sparkling prose shows us the personalities behind the science, including the notoriously cranky Dmitri Mendeleev; tragic, brilliant Henry Moseley, a victim of World War I; and shy, self-effacing Glenn T. Seaborg, one of only two individuals to have an element named after them while they were still alive.

It's a fun read, even if you're not a science geek -- maybe especially if you're not a science geek.  Because it allows you to peer behind the curtain, and see that the scientists are just like the rest of us, with rivalries, jealousies, odd and misplaced loyalty, and all the rest of the faults the human race is subject to.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

Species, types, and the No True Scotsman fallacy

One of the most frustrating of logical fallacies is the No True Scotsman fallacy.  It gets its name from an almost certainly apocryphal story, in which a serial rapist and killer is being pursued by the police in Glasgow, and a Scottish MP encourages the police to search amongst the immigrant population of the city.  "No Scotsman would do such a thing," the MP said.

When the criminal was caught, and turned out to be 100% Scottish, the MP was challenged about his remark.

"Well," he said, drawing himself up, "no true Scotsman would have done such a thing!"

The crux of this fallacy is that if you make a statement that turns out, in view of evidence, to be false, all you do is shift your ground -- redefine the terms so as to make your original point unassailable.

Very few other fallacies have such a capacity for making me want to smack my forehead into a wall as this one.  Someone who commits this fallacy can't be pinned down, can't be backed into a corner, can't receive his comeuppance from the most reasoned argument, the most solidly incontrovertible evidence.  The dancing skills of a master of the No True Scotsman fallacy are Dancing With The Stars quality.

All of this comes up because of an online discussion that I read, and (yes) participated in, a couple of days ago, on the topic of the demonstrability of evolution.  Someone, ostensibly a supporter of evolution but seemingly not terribly well-read on the subject, was using such evidence as the fossil record as a support for the idea.  A creationist responded, "The fossil record, and fossil dating, are inaccurate.  You evolutionists always think that bringing us a bunch of bones and shells proves your point, but it doesn't, because no one can really prove how old they were, and none of them show one species turning into another.  You can't show a single example, from the present, of one species becoming another, and yet you want us to believe in your discredited theory."

Well, of course, I couldn't let a comment like that just sit there, so I responded, "Well, actually, yes, I can.  I know about a dozen examples of speciation (one species becoming another) occurring within a human lifetime."

Challenged to produce examples, I gave a few, including the ones that I described in an earlier post (Grass, gulls, mosquitoes, and mice, February 9, 2012), and then sat back on my haunches with a satisfied snort, thinking "Ha.  That sure showed him."

Well.  I should have known better.  His response, which I quote verbatim:  "All you did was show that one grass can become another grass, or a mosquito can become another mosquito.  If you could show me a mosquito that turned into a bird, or something, I might believe you."

Now, wait just a second, here.  You asked me for one thing -- to show one species turning into a different species, in the period of a few decades.  I did so, adhering to the canonical definition of the word species.  And now you're saying that wasn't what you wanted after all -- you want me to show one phylum turning into a different one, in one generation?

So I sat there, sputtering and swearing, and not sure how to answer.  So I said something to the effect that he'd pulled a No True Scotsman on me, and had changed the terms of the question once he saw I could answer it, and he'd damned well better play fair.  He humphed back at me that we evolutionists couldn't really support our points, and we both left the discussion as I suspect most people leave discussions on the internet -- unconvinced and frustrated.  So I was pondering the whole thing, and after taking my blood pressure medications I had a sudden realization of where the confusion was coming from.  It was from the idea of a type of organism.

Most people who aren't educated in the biological sciences (and I'm not including just formal education, here; there are many people who have never taken a single biology class and know plenty about the subject) really don't understand the concept of species.  They think in types.  A bird is one type of thing; a bug is a different one.  If you pressed them, they might admit that there were a few types of birds that seemed inherently different; you have your big birds (ostriches), your medium-sized birds (robins), and your little birds (hummingbirds).  I've had students that have thought this way, and when they hear I'm a birdwatcher, they seem incredulous that this could be a lifelong avocation.  Wouldn't I run out of new birds to see pretty quickly?  When I tell them that there are over 10,000 unique species of birds, they seem not so much awed as uncomprehending.

I suspect that the source of this misapprehension is the same as the source of the general misapprehension regarding the antiquity of the Earth and the origins of life: the bible.  In Leviticus 11, where they go through the whole unclean-foods thing that eventually would be codified as the Kosher Law, they split up the natural world in only the broadest-brush terms; you have your animals that have hooves and chew the cud, various combinations of ones that don't, creatures that have fins and scales and ones that don't, insects that jump and ones that don't, and a few different classes of birds (which, to my eternal amusement, included bats).  And that's pretty much it.  Plants were sorted out into ones that had edible parts (wheat, figs, olives), ones that had useful wood (boxwood, cedar, acacia), and ones that had neither of the above (thorn bushes).  And these distinctions worked perfectly well for a Bronze-Age society; it kept you from eating stuff that was bad for you, told you what you could build stuff from, and so on.  But as a scientific concept, the idea of "types of living things" is pretty ridiculous.  And yet it still seems to live on in people's minds, lo unto this very day.

So, anyway, that was my brief excursion into that least useful of endeavors, the Online Argument.  It gave me a nice example of the No True Scotsman fallacy to tell my Critical Thinking classes about, when we hit that topic in a few weeks.  And it really didn't affect my blood pressure all that much, but it did make me roll my eyes.  Which seems to happen frequently when I get into conversations with creationists.