Steve, Steve, Jennifer, and Onesimus

I remember running into the idea of changing trends in name popularity when I saw a New Yorker comic back in the seventies.  It showed a typical first grade class photo, including the teacher, and the caption said, "Top row: Steve, Steve, Jennifer, Jennifer, Steve.  Middle row: Jennifer, Steve, Jennifer, Steve, and Steve.  Bottom row: Jennifer, Jennifer, Steve, Steve, Jennifer, and Mrs. Bertha Q. Wackenhorst."

Interestingly, as that particular trend goes, during my last ten years of teaching, I had only a handful of Jennifers in my classes, and barely any Steves.  But I bumped into a more recent iteration of the same phenomenon with a photo of five handsome, affluent-looking white college guys, all smiles and tans and perfect hair.  The caption read, "Left to right: Hayden, Trayden, Kayden, Grayden, and Brayden."

In my own case, I was named after my father, but he was named by his mom, who allegedly said -- and having known her well, I can easily hear her saying it -- "He may be stuck with a French last name, but he damn sure is going to have a Scottish first name!"  Which is how I ended up with an odd amalgam that is still strangely fitting of my actual roots.

Things get even more complicated when you start throwing in other languages.

Names come and go, something that really became apparent when I started doing research into genealogy.  Various relatives and ancestors from my family tree include Ulysse, Anicet, Roxzella, Orsa, Laodice, Odressi, Donathilde, and Hiram.  A friend of mine, for whom I did some genealogical digging, descends from a guy named Onesimus Futch, which sounds like an insult.  ("How dare you, you onesimus futch!")  

My wife's family is largely Eastern European Jewish, and she has Avish, Baruch, Gittel, Scholem, Chaia, Dvora, and Mordechai.  The really weird ones, though, are in my wife's non-Jewish ancestry, which hailed from England and goes back to the Anglo-Norman nobility.  She has an ancestor named, I kid you not, Marmaduke de Thweng.  Another was Johanna Ufflete.  But by far my favorite is Benedicta de Shelving, which would make a great name for the patron saint of interior decorators.

Always keep in mind that however strange your name is, it could be worse.

The topic comes up because of some recent research out of the University of Michigan which looked at naming trends both in children and in pets, and found that it could be modeled using a concept from evolutionary genetics called frequency-dependent selection.  The idea here is that the success of a specific phenotype -- and thus its trending toward becoming more or less common -- depends on how common it already is.  It can go either way; in positive frequency dependence, the trait has better success the more common it is.  (A good example is warning coloration, where a poisonous or venomous species advertises its presence with bright colors; the tactic only works if there are enough dangerous, brightly-colored individuals that predators learn to leave them alone.)  There's also negative frequency dependence, where the success of common phenotypes is poorer.  (An example is apostatic selection in a species of common British garden snails that have a variety of color patterns; studies showed that predators favored the more familiar-looking ones, so rare color patterns had a better survival rate.)

Naming trends tended to show a negative frequency dependence; when names become common, new parents (or new pet owners) tend to choose something more distinctive (or else spell it differently, which is why I had students named Michaela, Mikayla, Mikaela, Makayla, and Mekayla, fortunately not all in the same class).  Names become trendy for a while, but following the time-honored principle of "I want to be unique, just like everyone else," if the trend peaks too high, it goes into an equally precipitous fall.

"This is really a case study showing how boom-bust cycles by themselves can disfavor common types and promote diversity," said study co-author Mitchell Newberry.  "If people are always thirsting after the newest thing, then it's going to create a lot of new things.  Every time a new thing is created, it's promoted, and so more rare things rise to higher frequency and you have more diversity in the population."

Still, something that is too odd never does catch on.  I've seen the name Trasimond in nineteenth century Cajun French records, but I've never known one in real life, and that particular name seems to have always been a bit of an outlier.

You have to admit, though, that it's kind of euphonious.  Better than Onesimus Futch, anyhow, not to mention the unfortunate Mr. Zopittybop-Bop-Bop.  Given those as choices, I'll stick with Gordon.  I might even stick with Marmaduke de Thweng.  At least that one has a certain insouciance.

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Tracing the lapse of ages

The evolutionary model is one of the most powerful explanatory devices in biology.  It has led to discoveries that simply blow the mind -- such as the fact that dinosaurs didn't go extinct after all (we still have 'em -- we just call 'em birds).  As Richard Dawkins has demonstrated, all you need is an imperfect replicator (DNA) and a selecting agent (the environment) and you can create massive changes in way fewer generations than you'd think.

Of course, sometimes that may not result in an improvement.

I want to tell you today about two fascinating examples of evolutionary conundrums, both about our friends the erstwhile dinosaurs -- and similar occurrences which had nearly opposite results.

First, let's look at scrub jays.

These smart, pretty birds, bright blue with gray markings, are made up of two populations.  The first (and largest) is represented by Woodhouse's Scrub Jay (Aphelocoma woodhouseii):

[Image licensed under the Creative Commons Peter Wallack, Western Scrub Jay, Santa Fe, CC BY-SA 3.0]

The second is the Florida Scrub Jay:

[Image licensed under the Creative Commons Mwanner at the English language Wikipedia]

Pretty similar, right?  Odd, then, that these two photographs were taken 2,700 kilometers apart -- and there are no scrub jays of any kind in between.

Given the fact that the western scrub jays (which include three other species besides Woodhouse's) are a much larger and more diverse population than their Floridian cousins, it's likely the Florida Scrub Jay's ancestors came from the west rather than the reverse.  But how?  They're not migratory, so they didn't get blown off course on migration (which happens -- for three years running a Pacific Loon showed up in Cayuga Lake in upstate New York).  So what caused the split -- and when?  There's apparently been little drift in the populations since the division occurred, given the fact that they're pretty similar still, but that might be low selection, not short time spans.

The bottom line is, we don't know.  The scrub jays are a textbook example of allopatric range distribution -- related populations that have no range overlap.  And while in some cases these peculiarities have been explained, this one has not.

Even odder -- and virtually the opposite in end result -- came out of a genetic study of skeletons of the adzebills (Aptornis spp.), a pair of species native to New Zealand which went extinct from overhunting after the colonization of the islands by the Maoris.  They were impressive birds -- flightless, predatory, just under a meter tall, with the heavy, sharp, downcurved bills that gave them their common name.

Skeleton of Aptornis defossor in the Auckland Museum [Image licensed under the Creative Commons Auckland Museum, Aptornis defossor (AM LB544) 601651 (cropped), CC BY 4.0]

Their general shape led scientists to think they may be related to moas -- enormous flightless birds that went extinct right around the same time as the adzebills did.  But here, appearance and size are misleading.  The study, published last week in Diversity, has shown the genetics of the adzebills indicates their closest living relatives are a group of birds in Africa...

... the flufftails.

White-spotted Flufftail (Sarothrura pulchra)  [Image licensed under the Creative Commons Francesco Veronesi from Italy, White-spotted Flufftail near Kakum NP - Ghana 14 S4E2889 (16010066588), CC BY-SA 2.0]

"A lot of past genetic research and publicity has focused on the moa, which we know were distant relatives of the ostrich, emu, and cassowary," said study co-author Dr Kieren Mitchell of the University of Adelaide.  "But no one had analysed the genetics of the adzebill, despite a lot of debate about exactly what they were and where they came from."

Study co-author Trevor Worthy of Flinders University added, "We know that adzebills have been in New Zealand for a relatively long time, since we previously discovered a 19 million-year-old adzebill fossil on the South Island...  A key question is whether they've been present since New Zealand broke away from the other fragments of the supercontinent Gondwana or whether their ancestors flew to New Zealand from elsewhere later on."

But... look at these two.  (The birds, not the researchers.)  Even the most diehard scientific type might raise an eyebrow at these being closely related.  However, consider my first example -- the wolf and the pug.  Selective breeding of cats and dogs has produced enormous differences in only a few hundred years.  Imagine you were an alien biologist, come to Earth to catalog all the species of life on this planet, and you ran across a chihuahua and a Saint Bernard.

My guess is if you told the alien biologist they were the same species, he/she/it would laugh in your face.  But they are, in fact, genetically very close, and in fact are even theoretically interfertile.  (Although what a Saint Berhuahua would look like kind of boggles the imagination.  Plus, the mechanics of the conception are a little problematic.  I mean, if it was a male chihuahua and a female Saint Bernard, would they, like, give him a stepladder or something?)

An imperfect replicator plus a selecting agent plus time can create wonders.  It seems fitting to end this post with a quote from Charles Darwin's The Origin of Species which I think sums it up brilliantly:

It may metaphorically be said that natural selection is daily and hourly scrutinising, throughout the world, the slightest variations; rejecting those that are bad, preserving and adding up all that are good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life.  We see nothing of these slow changes in progress, until the hand of time has marked the lapse of ages.

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This week's Skeptophilia book recommendation is a tour-de-force for anyone who is interested in biology -- Richard Dawkins's The Ancestor's Tale.  Dawkins uses the metaphoric framework of The Canterbury Tales to take a walk back into the past, where various travelers meet up along the way and tell their stories.  He starts with humans -- although takes great pains to emphasize that this is an arbitrary and anthropocentric choice -- and shows how other lineages meet up with ours.  First the great apes, then the monkeys, then gibbons, then lemurs, then various other mammals -- and on and on back until we reach LUCA, the "last universal common ancestor" to all life on Earth.

Dawkins's signature lucid, conversational style makes this anything but a dry read, but you will come away with a far deeper understanding of the interrelationships of our fellow Earthlings, and a greater appreciation for how powerful the evolutionary model actually is.  If I had to recommend one and only one book on the subject of biology for any science-minded person to read, The Ancestor's Tale would be it.

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

Escapees from Siberia

As you might expect from someone who is passionately interested in both genealogy and evolutionary genetics, when there's a study that combines both, it's a source of great joy to me.

This week, Nature published a study on the evolutionary history of humans in northern Europe, specifically the Finns.  Entitled, "Ancient Fennoscandian Genomes Reveal Origin and Spread of Siberian Ancestry in Europe," it was authored by no less than seventeen researchers (including Svante Pääbo, a Swedish biologist who is widely credited as founding the entire science of paleogenetics) from the Max Planck Institute, the University of Helsinki, the Russian Academy of Sciences, the Vavilov Institute for General Genetics, and the University of Turku.

Quite a collaborative effort.

It's been known for a while that Europe was populated in three broad waves of settlement.  First, there were hunter-gatherers who came in as early as 40,000 years ago, and proceeded not only to hunt and gather but to have lots of hot caveperson-on-caveperson sex with the pre-existing Neanderthals, whose genetic traces can be discerned in their descendants unto this very day.  Then, there was an agricultural society that came into Europe from what is now Turkey starting around 8,000 years ago.  Finally, some nomadic groups -- believed to be the ancestors of both the Scythians and the Celts -- swept across Europe around 4,500 years ago.

Anyone with European ancestry has all three.  Despite the genetic distinctness of different ethnic groups -- without which 23 & Me genetic analysis wouldn't work at all -- there's been enough time, mixture, and cross-breeding between the groups that no one has ancestry purely from one population or another.

Which, as an aside, is one of the many reasons that the whole "racial purity" crowd is so ridiculous.  We're all mixtures, however uniform you think your ethnic heritage is.  Besides, racial purity wouldn't a good thing even if it were possible; that's called inbreeding, and causes a high rate of homozygosity (put simply, you're likely to inherit the same alleles from both your mother and father).  This causes lethal recessives to rear their ugly heads; heterozygous individuals are protected from these because the presence of the recessive allele is masked by the other, dominant (working) copy.  It's why genetic disorders can be localized to different groups; cystic fibrosis in northern Europeans, Huntington's disease in people whose ancestry comes from eastern England, sickle-cell anemia from sub-Saharan Africa, Tay-Sachs disease in Ashkenazic Jews, and so on.

So mixed-ethnic relationships are more likely to produce genetically healthy children.  Take that, neo-Nazis.

Map of ethnic groups in Europe, ca. 1899 [Image is in the Public Domain]

In any case, the current paper looks at the subset of Europeans who have a fourth ancestral population -- people in northeastern Europe, including Finns, the Saami, Russians, the Chuvash, Estonians, and Hungarians.  And they found that the origin of this additional group of ancestors is all the way from Siberia!

The authors write:

[T]he genetic makeup of northern Europe was shaped by migrations from Siberia that began at least 3500 years ago.  This Siberian ancestry was subsequently admixed into many modern populations in the region, particularly into populations speaking Uralic languages today.  Additionally... [the] ancestors of modern Saami inhabited a larger territory during the Iron Age.

The coolest part is that this lines up brilliantly with what we know about languages spoken in the area:

The Finno-Ugric branch of the Uralic language family, to which both Saami and Finnish languages belong, has diverged from other Uralic languages no earlier than 4000–5000 years ago, when Finland was already inhabited by speakers of a language today unknown.  Linguistic evidence shows that Saami languages were spoken in Finland prior to the arrival of the early Finnish language and have dominated the whole of the Finnish region before 1000 CE.  Particularly, southern Ostrobothnia, where Levänluhta is located, has been suggested through place names to harbour a southern Saami dialect until the late first millennium, when early Finnish took over as the dominant language.  Historical sources note Lapps living in the parishes of central Finland still in the 1500s.  It is, however, unclear whether all of them spoke Saami, or if some of them were Finns who had changed their subsistence strategy from agriculture to hunting and fishing.  There are also documents of intermarriage, although many of the indigenous people retreated to the north...  Ancestors of present-day Finnish speakers possibly migrated from northern Estonia, to which Finns still remain linguistically close, and displaced but also admixed with the local population of Finland, the likely ancestors of today’s Saami speakers.

Which I think is pretty damn cool.  The idea that we can use the genetics and linguistics of people today, and use it to infer migratory patterns back 40,000 years, is nothing short of stunning.

Unfortunately, however, I have zero ancestry in Finland or any of the other areas the researchers were studying.  According to 23 & Me, my presumed French, Scottish, Dutch, German, and English ancestry was shown to be... French, Scottish, Dutch, German, and English.  No surprise admixtures of genetic information from some infidelity by my great-great-grandmother with a guy from Japan, or anything.

On the other hand, I did have 284 markers associated with Neanderthal ancestry.  Probably explaining why I like my steaks medium-rare and run around more or less naked when the weather's warm.  Which I suppose makes up for my lack of unexpected ethnic heritage.

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Ever wonder why we evolved to have muscles that can only pull, not push?  How about why the proportions of an animals' legs change as you look at progressively larger and larger species -- why, in other words, insects can get by with skinny little legs, while elephants need the equivalent of Grecian marble columns?  Why there are dozens of different takes on locomotion in the animal world, but no animal has ever evolved wheels?

If so, you need to read Steven Vogel's brilliant book Cats' Paws and Catapults.  Vogel is a bioengineer -- he looks at the mechanical engineering of animals, analyzing how things move, support their weight, and resist such catastrophes as cracking, buckling, crumbling, or breaking.  It's a delightful read, only skirting some of the more technical details (almost no math needed to understand his main points), and will give you a new perspective on the various solutions that natural selection has happened upon in the 4-billion-odd years life's been around on planet Earth.

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

Neanderthal family reunion

Last year, I did a 23 and Me DNA test.

Besides the not-particularly-earthshattering conclusion that I'm mostly French, Scottish, German, and Dutch, I was amused to find that the test showed I have 284 Neanderthal markers.  This puts me in the 60th percentile as compared to the population overall, which probably explains why I like my steaks rare and run around half naked when the weather is warm.

What's fascinating is that some research released last week, a paper in Cell by David Enard of the University of Arizona and Dmitri A. Petrov of Stanford University called, "Evidence that RNA Viruses Drove Adaptive Introgression between Neanderthals and Modern Humans," has shown that some of these genes didn't get passed along the usual way, but by a process called transduction -- when viruses transmitted from one host to another carry novel genes with them.

The authors write:

After their divergence 500,000 to 800,000 years ago, modern humans and Neanderthals interbred at least twice: the first time ∼100,000 years ago and the second ∼50,000 years ago.  The first interbreeding episode left introgressed segments (IS) of modern human ancestry within Neanderthal genomes, as revealed by the analysis of ancient DNA from a single Altai Neanderthal individual sequenced by Prüfer et al. (2014).  This first interbreeding event appears not to have left any detectable segments of Neanderthal ancestry in extant modern human genomes.  In contrast, the second interbreeding episode left detectable IS of Neanderthal ancestry within the genomes of non-African modern humans. 

Recent advances in the detection of introgression have led to the discovery that the majority of genomic segments initially introgressed from Neanderthals to modern humans were rapidly removed by purifying selection.  Harris and Nielsen (2016) estimated that the proportion of Neanderthal ancestry in modern human genomes rapidly fell from ∼10% to the current levels of 2%–3% in modern Asians and Europeans.
This history of interbreeding and purifying selection against IS raises several important questions. First, among the introgressed sequences that were ultimately retained, can we detect which sequences persisted by chance because they were not as deleterious or not deleterious at all to the recipient species, and which persisted not despite natural selection but because of it—that is, which IS increased in frequency due to positive selection?  If any of the introgressed sequences were indeed driven into the recipient species due to positive selection, can we determine which pressures in the environment drove this adaptation? 

Recently we found that proteins that interact with viruses (virus-interacting proteins [VIPs]) evolve under both stronger purifying selection and tend to adapt at much higher rates compared to similar proteins that do not interact with viruses.  We estimated that interactions with viruses accounted for ∼30% of protein adaptation in the human lineage.   Because viruses appear to have driven so much adaptation in the human lineage, and because it is plausible that when Neanderthals and modern humans interbred they also exchanged viruses either directly by contact or via their shared environment, we hypothesized that some introgressed sequences might have provided a measure of protection against the exchanged viruses and were driven into the recipient species by positive directional selection.  Consistent with this model, several cases of likely adaptive introgression from Neanderthals to modern humans involve immune genes that are specialized to deal with pathogens including viruses.

Which is amazingly cool.  Viruses are parasites, and as such usually wreak havoc with our systems, but here we have viruses acting as carriers not only for genes that generate diversity, but that protect our cells from the damage viruses can cause.

Great-great grandpa Ugg [Image licensed under the Creative Commons Stefan Scheer, Neandertaler reconst, CC BY-SA 3.0]

"It's not a stretch to imagine that when modern humans met up with Neanderthals, they infected each other with pathogens that came from their respective environments," lead author David Enard said.  "By interbreeding with each other, they also passed along genetic adaptations to cope with some of those pathogens."

"Many Neanderthal sequences have been lost in modern humans, but some stayed and appear to have quickly increased to high frequencies at the time of contact, suggestive of their selective benefits at that time," Petrov said.  "Our research aims to understand why that was the case.  We believe that resistance to specific RNA viruses provided by these Neanderthal sequences was likely a big part of the reason for their selective benefits."

"One of the things that population geneticists have wondered about is why we have maintained these stretches of Neanderthal DNA in our own genomes," Enard added.  "This study suggests that one of the roles of those genes was to provide us with some protection against pathogens as we moved into new environments."

So having Neanderthal DNA isn't something to be ashamed of.  All of this highlights how incredibly cool the evolutionary model is, and the depth of its explanatory power.  Now, y'all'll have to excuse me.  I'm going to go get a snack.  I wonder if I have any roast mammoth left in the fridge?  Probably not.  I guess grilled cheese will have to do.

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This week's Skeptophilia book recommendation is from the brilliant essayist and polymath John McPhee, frequent contributor to the New Yorker.  I swear, he can make anything interesting; he did a book on citrus growers in Florida that's absolutely fascinating.  But even by his standards, his book The Control of Nature is fantastic.  He looks at times that humans have attempted to hold back the forces of nature -- the attempts to keep the Mississippi River from changing its path to what is now the Atchafalaya River, efforts in California to stop wildfires and mudslides, and a crazy -- and ultimately successful -- plan to save a harbor in Iceland from a volcanic eruption using ice-cold seawater to freeze the lava.

Anyone who has interest in the natural world should read this book -- but it's not just about the events themselves, it's about the people who participated in them.  McPhee is phenomenal at presenting the human side of his investigations, and their stories will stick with you a long time after you close the last page.

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