Escapees from Siberia

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

This was my reaction to a study in Nature 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, the Nobel Prize-winning 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 forty thousand 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 eight thousand 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 forty thousand 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.

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

Dog travels

The human/dog association goes back a long way.

No one knows for sure how it began.  It may be that our distant ancestors fed scraps to wolves, buying their loyalty in order to gain protection for their dwellings from other predators (and hostile humans).  They might have been utilized for their specific skills -- herding, hunting, pulling sleds.

Or it may be that the dogs themselves gave up their wariness when they discovered that humans have sofas.

I can say from my own experience that my own two canine companions, Lena (L) and Guinness (R), are of fairly dubious utility.  The only things they've successfully defended the house from are squirrels and the UPS Guy.  Whenever we get a package the dogs go into a frenzy of vicious barking, and it always results in the UPS Guy leaving, reinforcing their conviction that they're providing a vital service.  

"Hey, look at that!  He's driving away!  We did it!"  *canine high-five*  "I think we deserve biscuits."

But whatever the reason, humans and dogs have been inseparable for as long as we have records, including genetic ones, as a paper last week in Science showed.  A trio of teams of researchers, one led by Pontus Skoglund of the Francis Crick Institute of London, another by Greger Larson of the University of Oxford, and the third by Ron Pinhasi of the University of Vienna, joined forces to combine cutting-edge genetics research with archaeology to analyze the genomes of dogs from 100 to 11,000 years ago.

Amongst the many cool features of this study is the window it gives us into human migration, in some cases movements which occurred before there were any written records to keep track.  When human groups moved, they took their dogs with them, so the relationship between domestic dog populations over time acts as a proxy record for the wanderings of their owners.  The study identified different, genetically-distinct lineages, each of which followed humans pretty much wherever they went.

"Dogs are a separate tracer dye for human history," said study co-author Pontus Skoglund.  "Sometimes human DNA might not show parts of prehistory that we can see with dog genomes...  Already, 11,000 years ago, there were at least five different groups of dogs across the world, so the origin of dogs must have been substantially earlier than that."

One interesting outcome of the study is that one of the lineages studied -- European dogs -- became less diverse as time went on.  I wonder if that's due to selection, and the gradual shift of dogs from workers to companions.  Working dogs have to have skills compatible with their jobs, be it herding, hunting, pulling sleds, or whatnot.  Companion dogs just have to be cute and friendly, because honestly, they're mostly home décor items and lap warmers.

Whatever the reason, this analysis of Our Best Friends is pretty fascinating not only for what it tells us about our own history, but the window it gives us into the long relationship between us and our furry friends.  Speaking of which, I gotta go.  Guinness and Lena are barking like hell at something, and I gotta go see if it's a squirrel or the UPS Guy.

He's a cunning one, that UPS Guy.  You gotta watch him like a hawk, or he'll do something awful like put a package on the front porch and then drive away.  

If you can imagine someone doing something that evil.

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

This week's Skeptophilia book recommendation of the week is about one of the deepest mysteries in science: the origin of time.

Most physical processes are time-reversible.  If you looked at a video of a ball bouncing off a wall, then looked at the same video clip in reverse, it would be really difficult to tell which was the forward one and which the backwards one.  Down to the subatomic level, physical processes tend to make no distinction based upon the "arrow of time."

And yet our experience of time is very, very different.  We remember the past and don't know anything about the future.  Cause and effect proceed in that order, always.  Time only flows one direction, and most reputable physicists believe that real time travel is fundamentally impossible.  You can alter the rate at which time flows -- differences in duration in different reference frames are a hallmark of the theory of relativity -- but its direction seems to be unchanging and eternal.

Why?  This doesn't arise naturally from any known theory.  Truly, it is still a mystery, although today we're finally beginning to pry open the door a little, and peek at what is going on in this oddest of physical processes.

In The Order of Time, by physicist Carlo Rovelli (author of the wonderful Seven Brief Lectures in Physics), we learn what's at the cutting edge of theory and research into this unexplained, but everyday and ubiquitous, experience.  It is a fascinating read -- well worth the time it will take you to ponder the questions it raises.

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