October 21, 2009

European admixture on the Micronesian island of Kosrae

Kosrae has a population of about 7 thousand, so the finding that most of the European ancestry in this population can be traced to one 19th c. European individual, shows the reality of reproductive inequality I mentioned in a previous post.

European Journal of Human Genetics advance online publication 21 October 2009; doi: 10.1038/ejhg.2009.180

European admixture on the Micronesian island of Kosrae: lessons from complete genetic information

Penelope E Bonnen et al.


The architecture of natural variation present in a contemporary population is a result of multiple population genetic forces, including population bottleneck and expansion, selection, drift, and admixture. We seek to untangle the contribution of admixture to genetic diversity on the Micronesian island of Kosrae. Toward this goal, we used a complete genetic approach by combining a dense genome-wide map of 100 000 single-nucleotide polymorphisms (SNPs) with data from uniparental markers from the mitochondrial genome and the nonrecombining portion of the Y chromosome. These markers were typed in 3200 individuals from Kosrae, representing 80% of the adult population of the island. We developed novel software that uses SNP data to delineate ancestry for individual segments of the genome. Through this analysis, we determined that 39% of Kosraens have some European ancestry. However, the vast majority of admixed individuals (77%) have European alleles spanning less than 10% of their genomes. Data from uniparental markers show most of this admixture to be male, introduced in the late nineteenth century. Furthermore, pedigree analysis shows that the majority of European admixture on Kosrae is because of the contribution of one individual. This approach shows the benefit of combining information from autosomal and uniparental polymorphisms and provides new methodology for determining ancestry in a population.



Kepler said...

It seems indeed there was a very lucky Briton there!

AWood said...

Maybe he was stranded and was living it up with the locals. Apparently...not exactly a bad way to grow old and die. Seems like he had some fun :)

Maju said...

Simple maths: 39% of individuals with some Euro admixture, 77% of those with less than 10%. I get some 4% of European admixture at most.

This (if a single individual was at the origin) would tell us something about the population at the time that "lucky European" individual had some children there: they were around 25-50 effective population (unless other data disproves it - but doesn't seem this study made such reality check), what would mean not more than 200 people (not so unlikely as today they are just 7000).

However it is also possible (likely I'd say) that other Europeans contributed to the gene pool but that only one of them managed to get his Y-DNA transmitted. This would increase the population size proportionally.

As the children and remote descendants of the white guy were surely raised as locals (probably the random sailor was never to be heard again of) they would not have any particular advantage, so the argument for "reproductive inequality" stands as mere wishful thinking.

Anonymous said...

Island populations are not representative of any populations not even the island. Leave 1000 attractive nubile Chinese women on that island, and the genetic structure of the island would change dramatically and quickly. Do that in Rome or even San Antonio TX, and the result would be hardly detectable. No one seems to have factored in the desirability of light skin (almost global) on a small island of mostly dark skinned islanders. The Euro man's daughters would be highly desirable as mates, as light skin is desired by all including those people who are mostly light skinned. The same thing would happen in Spain or Italy if many buxom light eyed women were available instead of the boring black eyed peas typical of those countries.

Maju said...

... as light skin is desired by all...

Not really. I find that too light skin looks unnatural, kind of an indicator of illness. I don't find blond hair attractive either (red hair instead is cool). However if the rest is nice...

This is all matter of personal preferences, it seems to me.

Dana Lee Ling said...

No, not a random sailor. Probably someone like a Fritz Weilbacher who married and had eight children many of whom in turn founded large families. The genealogies of Kosrae are fairly well known within the respective families of Kosrae, tracking foreign pedigrees is theoretically possible although there are a number of privacy issues. I cannot say I understand the reproductive inquality hypothesis nor genetics well enough to comment on whether the data cited supports the theory. Disease played a massive role in the history of Kosrae with the population falling to something on the order of 274 adults in the late 1800s - the second genetic bottleneck some papers refer to.

Maju said...

I cannot say I understand the reproductive inquality hypothesis...

I think it'd be best if Dienekes explained his own hypothesis. But for what I've read, he basically seems to believe that some Mycenaean age hero (Herakles or whatever) is the sole ultimate responsible for all the E1b1b1-V13 in Greece, which is like 25%, (and elsewhere in Europe, including Albanians, where it's c. 40%, and even the remote Portuguese, it seems). For that he needs to estabilish this hypothesis as a viable theory and hence he argues (roughly) that people of higher social status and their offspring (even many generations later, and regardless of any turmoil and social change) would have some clear advantages, both socio-economical and apparently also biological (superior genetics).

All this is tightly knitted with his complementary hypothesis, shared by some other people it seems, of pedigree mutation rate, by which genetic mutations defining modern lineages would not be in most cases subjects to any random effects but would almost strictly expand geometrically, as if all descendants of the MRCA had many children and the rest nearly none. This talking in effective reproductive success terms, of course: the descendancy of the rest would be struggling all the time for any minimal success while the descendants of these "great men" of his imagination would always reproduce almost at the maximum possible rate, walking on a reproductive red carpet of sorts for many many generations till present day.

Naturally, as you may have guessed by now, I strongly disagree.

terryt said...

"No one seems to have factored in the desirability of light skin (almost global) on a small island of mostly dark skinned islanders".

Probably not the important factor here. The European may have been a trader or something similar. In New Zealand the indigeneous inhabitants usually found it desirable to encourage a European to live with the tribe. This made access to European manufactured goods much easier, even if the particular European was not actually a trader as such. Such men were encouraged to take up residence by pairing then off with a chiefs daughter, thus giving their descendants a long term advantage. In many isolated parts of NZ just one or two European surnames are extremely common amoung the Maori, much the same as demonstrated on this island.

Unknown said...

In its article on Kosrae, that paragon of accuracy, Wikipedia, says:
"The pirate Bully Hayes was shipwrecked on Kosrae on March 15, 1874, and made his home in Utwe for almost a year, during which he allegedly terrorized the local people"

Might this be the patriarch?

Kepler said...

"he basically seems to believe that some Mycenaean age hero (Herakles or whatever) is the sole ultimate responsible for all the E1b1b1-V13 in Greece"

Well, Maju, there are some possible advantages. Such a person may have had a comparative advantage regarding some basic technologies of the time and some customs regarding organization.
Perhaps he taught his children: build the houses so and so, accumulate things like this, plan.

You have seen what has happened in Latin America with the European Y haplogroups: they spread like fire on dry grass and that went on after the invasion proper had taken place.

That still happens in the few places in Venezuela where there are still "pure Indians": Indian women prefer the criollo to the Indian male. In most of the cases it has to do with status (based on the fact Indians did not have the same educational opportunities etc). At the end the appearance is associated with a status.
Also it may have to do with height. Everywhere I have been to women do prefer ceteris paribus taller men.
I am not sure Englishmen back then were really taller than those people though.
It would be interesting to measure the bones of people back then across nations. Perhaps there is some study about that.

Maju said...

Kepler: We have discussed that elsewhere and while I acknowledge that some silverspoons could begin with some advantages, it is very clear that in the mid-run these would vanish, as they lose their property and whatever. What I cannot accept is that these would be a permanent trait for all the lineage forever. Surely that is what all succesful parents hope for but not a realistic expectation in any case. You just have to read Il Gattopardo to understand that successful lineages also decline and that only one or two generations can be provided for such advantages in advance in the best case.

I'd rather adhere to the old conjecture that gives powerful lineages a lifespan of four generations, unless a second "great man" arises at such stage, what is at best quite rare.

When you're raised among cottons, you just don't build up the attributes of a pitbull. And anyhow many historical great men did not even had any surviving male heirs.

Re. Latin America: I don't even question that privileged classes have some (but not such an extreme) reproductive advantage. What I question is that single Chingis Khan style lineages do forever. That's only a convenient mediatic hype. How many people in Peru are direct descendants of Pizarro or Almagro? Probably none or rather some maybe but totally impossible to say, How many people in Venezuela are descended from Simón Bolívar? In fact surely random less known local caciques were the ones having some reproductive advantage but still not to the extremist levels that Dienekes' hypothesis claims. Just an agrarian reform or other kind of power change is enough to totally supress such "advantage", not to mention the tendency of lineages to decline in quality over time, partly because of power struggles between the existing patriarchs and their more able sons (no two roosters in the same corral, even if these are father and son: they tend to prefer "beta" type sons as right hands and heirs, who in turn tend to lose power after the old man is gone precisely because they are a bad choice, not so much as aides but as leaders on their own).

Anyhow, the data provided by Dana Lee Ling, seems to support, at least to a large extent, my early considerations re. population size. Even if the descendants of that Fritzl Weilbacher started on good position, and even if there was a severe bottleneck, their overall impact after more than two centuries has been limited in fact (all that presuming he was the only European to inject Western genetics into the island, what I find somewhat unlikely.

Kepler said...


Firstly: I don't think Bolivar is such a good example, in spite of the whole idolatry there is now for his name. That idolatry is based on historical distorsion. Bolivar was not precisely healthy and he was more of a political/military case in an era where massive raping by a leader was not so much "cool", even in wild South America.

Then: I do think people with a comparatively speaking much higher education level AND entrepreneurial skills in a poor society will spread their genes more succesfully over several generations, so that the effect is felt 200 years later.
So: men with economic success.

That was the case, I think, in Venezuela and that is the case the post is talking about: XIX century.

Of course, now those descendants of "white, relatively well educated entepreneurs" in Venezuela have a higher education than the rest but less children and the poor have more and the children survive, but this took more than 4 generations

Maju said...

Instead I have the impression that poor uneducated but often sturdy people tend to have many more children and, even if they don't grow with the advantages of the wealthy ones, learning the hard way also has its own advantages because life is short, you know, and poor people tend to be more precocious.

Also they are always the vast majority and hence the chances that any new leaders will come from their ranks are very high (mere odds). I can't even think of many "succesful" individuals, much less whole dynasties: most relevant and powerful people are the descendant of a "self-made man" or such a character themselves. Admittedly in the distant past, lineages mattered more, but they were similarly inefficient (and that's why Spain lost to England, for instance: because it relied on pedigree-based hierarchies, which were highly inefficient). So eventually all lineages get toppled: chaos is the rule, order just a dream.

AWood said...

"But for what I've read, he basically seems to believe that some Mycenaean age hero (Herakles or whatever) is the sole ultimate responsible for all the E1b1b1-V13 in Greece, which is like 25%, (and elsewhere in Europe, including Albanians, where it's c. 40%, and even the remote Portuguese, it seems)."

- I would be a little cautious reading too far in these conclusions. Let's face it. Albania is a tiny little population of 3 million that sampled 114 people and found roughly 40% of them to be E-V13.

Maju said...


Ok but I believe I have seen similar data for Kosovo even before, so I presume it is correct to a great extent (some Greek localities also show such high levels). Also the rest of European E-V13 is concentrated in the Balcans and specially along the Morava-Danube "Neolithic axis". The main exception is West Iberia (Mediterranean Iberia instead is quite low in it), which also had no historical and very limited prehistorical relation with Greece.

It doesn't look to me like Greek Bronze Age clade but a mostly Neolithic marker with some founder effects. The curious FE of West Iberia, in fact, looks like including a "bounce" at North Africa, as both E subclades show a very similar distribution - this could correspond with Neolithic or early Chalcolithic, when NW Iberia is colonized for the first time quite apparently. If Neolithic, an Albanian CIP origin is within the most logical possibilities.

AWood said...

I agree here. Interestingly directly adjacent west of Albania in the foot of Italy are hotspots of E-V13. Yet the subclade is much lower in most other areas. Obviously a genetic relationship there.

T. Kosmatka said...

I think it's plausible that the descendents of a 19th century European traveler could experience a selective advantage in an island population.

Individuals with Eurpean admixture would likely fair better when exposed to the waves of European diseases that tended to decimate island populations.

Dana Lee Ling said...

Having now had the opportunity to read the full text I realize that Fritz is too late an arrival. Buried in the full text is a dating of mid-1800's for the one individual. That would even predate Bully Hayes. Family trees are less certain back before the second bottleneck.

terryt said...

"I'd rather adhere to the old conjecture that gives powerful lineages a lifespan of four generations".

The saying here is, 'shirtsleeves to shirtsleeves in four generations'. I agree with those comments, but that's not the situation with European male descent in NZ. The original male just has to sire several sons. They don't have to be any more upper class or successful than the non Europeans, just have continued access to European materials.

terryt said...

"I think it's plausible that the descendents of a 19th century European traveler could experience a selective advantage in an island population".

Hybrid vigour would also come into the equation, especially for islands. This might, as you say, mean 'Individuals with Eurpean admixture would likely fair better when exposed to the waves of European diseases that tended to decimate island populations'.

Out of Orbit said...

Probably not the best place to post/ask but I am interested in any information concerning the period Bully Hayes and his crew passed through Kosrae.

My ancestor Will Hicks was second mate on Hayes "Leonora" and arrived in Kosrae in March 1874.

Any information shared would be greatly appreciated, thanks.

PhilRitter said...

I haven't read all the discussion and don't know if someone already posted this, and I'm late to this discussion. But it is relatively obvious who the one "white guy" who has the most descendants on Kosrae today was. Many use his surname, which is a typical New England name, and have made contract with relatives in the US. He was married to a Nauruan (not fooling around with Kosraean women, as far as I know), and it was his son who married a daughter of the paramount chief ("King") and had a very large number of descendants. There were lots of other European (and Rotuman, and Chuuk and other) ancestors--e.g. pastor Erafe Tosie's mother was said to be the daughter of an unknown "White" sailor. But I can see why this one Euro-American ancestor would be the best represented genetically today.