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Tuesday, May 12, 2015

4mix: four-way mixture modeling in R


Thanks to Eurogenes project member DESEUK1. A zip file with the R script, instructions and a couple of data sheets is available here.

So let's model Poles as a bunch of ancient genomes from Central and Eastern Europe using output from my K8 analysis.

Copy & Paste: source('4mix.r')

Hit ENTER

Copy & Paste: getMix('K8avg.csv', 'target.txt', 'HungaryGamba_EN', 'HungaryGamba_HG', 'Karelia_HG', 'Corded_Ware_LN')

Hit ENTER

After a few seconds you should see the results...

Target = 19% HungaryGamba_EN + 14% HungaryGamba_HG + 2% Karelia_HG + 65% Corded_Ware_LN @ D = 0.0062






Obviously the script can use ancestry proportions and/or population averages from any test, provided they're formatted properly. The accuracy of the modeling will depend on the quality of the input.

Update 19/05/2015: A new version of the 4mix script that can run multiple targets is available here, courtesy of Open Genomes.

Sunday, December 28, 2014

The fateful triangle


Not long ago Lazaridis et al. proposed that most present-day Europeans were derived from three distinct ancestral populations: Ancient North Eurasians (ANE), Early European Farmers (EEF) and Western European Hunter-Gatherers (WHG).

However, this is essentially a stop-gap model, which will in all likelihood be replaced by a partly revised and more robust model once someone manages to sequence a genome or two from the Neolithic Near East. That's because EEF is clearly a hybrid component, largely made up of ancient Near Eastern ancestry and something very WHG-like, sometimes in very different proportions depending on the location and archeological context of the EEF genomes being analyzed.

So what will this new model look like, you might ask? Probably like this, where EEF is replaced by an Early Neolithic Farmer (ENF) component from the ancient Near East, or something very similar:


The diagram above is basically a Principal Component Analysis (PCA) based on output from my new West Eurasia K8 test (see here), in which the Near Eastern component is synonymous with ENF.

I'm quite certain that these results are very close to the truth. However, just in case the Near Eastern ancestry proportions are a little bit too high (and we won't know until we see those ancient genomes from the Near East), I've got another version that offers lower bound Near Eastern estimates.


It might be useful to keep in mind that I rotated the plots to fit geography. As a result, Component 1, which packs around 85% of the variance on both plots, appears smaller than Component 2, which only carries around 10% of the variance.

A spreadsheet with West Eurasia K8 results for a wide variety of populations is available here. Please note that there are two sheets, with the second sheet showing the lower bound Near Eastern ancestry proportions.

We'll probably learn of more ancient European meta-populations as many more genomes are sequenced from across Eurasia. Nevertheless, I doubt this will affect the model outlined above. That's because I'm expecting all such meta-populations to be mixtures of ANE, ENF and/or WHG, as well as, in some cases, extra-West Eurasian components.

However, I suspect that West Eurasia will have to be modeled in a different way from Europe, with, amongst other things, the so called Basal Eurasian component replacing ENF. But for this to happen we'll need at least one ancient genome that is in large-part of Basal Eurasian origin. In any case, that's a whole different subject.

See also...

4mix: four-way mixture modeling in R

ANE is the primary cause of west to east genetic differentiation across West Eurasia

Bell Beaker, Corded Ware, EHG and Yamnaya genomes in the fateful triangle

Sunday, November 30, 2014

Short clip: The making of modern Europe


Simple but, I think, very cool animation: ten ancient genomes analyzed with the Eurogenes K15. More elaborate clips are on the way.



And this is basically the same thing, but restricted to samples from Hungary.

Monday, September 8, 2014

Eurogenes ANE K7


Update 01/01/2015: Crowdfunding for 2015 + new K8 test. See here.

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As its name implies, the Eurogenes ANE K7 is specifically designed to estimate Ancient North Eurasian (ANE) ancestry. It's based on a series of supervised runs with the ADMIXTURE software, and freely available at GEDmatch under the Eurogenes Ad-mix tests tab.

The ANE component is not modeled on the Mal'ta boy or MA-1 genome, the main ANE proxy in scientific literature, because this sample didn't offer enough high quality markers for the job. So instead, I used the non-East Asian portions of several Karitiana genomes from the HGDP.

I wasn't sure what was going to come of that, but it actually seems to have worked out really well. Below are the results for several individuals that were not used in the making of the test, and clearly their ANE scores look pretty damn solid going by recent papers. For instance, both Lazaridis et al. and Raghavan et al. estimate the Karitiana Indians at just over 41% ANE (see here and here).

Karitiana_HGDP00998
ANE 41.56%
ASE 0.41%
WHG-UHG 0%
East_Eurasian 58.01%
West_African 0%
East_African 0.01%
ENF 0%

Lezgin_GSM536850
ANE 26.74%
ASE 3.88%
WHG-UHG 14.65%
East_Eurasian 0%
West_African 0.01%
East_African 0%
ENF 54.72%

Bedouin_HGDP00651
ANE 0%
ASE 0%
WHG-UHG 0.05%
East_Eurasian 1.49%
West_African 0%
East_African 8.19%
ENF 90.27%

Sardinian_HGDP01067
ANE 0%
ASE 0%
WHG-UHG 49.49%
East_Eurasian 1.8%
West_African 0.01%
East_African 0.01%
ENF 48.69%

You can also cross-check your ANE score with the results in this spreadsheet and table. The spreadsheet includes ANE estimates for more than 2,000 individuals that I tested with the ADMIXTURE software in supervised mode (see here).

On the other hand, the table comes from the Lazaridis et al. preprint, which I'm sure many of you have read by now several times over. And please pay attention to the range of ANE proportions for each population, rather than just the point estimates.

Obviously, there are also six other ancestral components in this test (hence the K7 in the name). They're basically byproducts of me trying to isolate ANE, and don't necessarily mean anything. Nevertheless, here's a brief rundown of what I think some of them might represent...

Ancestral South Eurasian (ASE): this is a really basal cluster that peaks in tribal groups of Southeast Asia. It's probably very similar in some ways to the Ancestral South Indian (ASI) component described by Reich et al. a few years ago.

Western European/Unknown Hunter-Gatherer (WHG-UHG): this essentially looks like a West Eurasian forager component, and includes the forager-like stuff carried by Neolithic farmers (Oetzi the Iceman has 40% of it).

Early Neolithic Farmer (ENF): I'd say that this is the component of the earliest Neolithic farmers from the Fertile Crescent.

The other three components should be easy to work out from their names. They're almost identical to several components with the same or similar names from my other tests.

Some of you might be wondering why this test doesn't offer an Early European Farmer (EEF) cluster. But the answer to that should be obvious by now. EEF is not a stable ancestral component. It's actually a composite of at least two ancient components, including the so called Basal Eurasian and WHG-UHG. If it really was a genuine ancestral component, like ANE, then I'm pretty sure I'd be able catch it with ADMIXTURE. But I can't.

Indeed, a really important thing to understand about the Lazaridis et al. study is that it doesn't actually attempt to estimate overall WHG-UHG ancestry in Europeans, but rather the excess WHG-UHG on top of what is already present in the EEF proxy Stuttgart.

Also worth noting is that this K7 can be a bit noisy. That's mainly because it's very difficult to correctly assign proportions of ancient ancestry to present-day samples. But like I say above, this test is basically designed to estimate ANE scores. If you're wanting to learn about your overall ancestry then I recommend the Eurogenes K13 and K15 tests.

Missing SNPs might also be an issue for some people. It stands to reason that results will be noisier with more missing markers and no calls.

Have fun and don't forget to make a donation at some point to the Eurogenes cause, via the PayPal tab at the top right of the page. This will help me to keep up with what's going on in the world of Paleogenomics, and continue blogging and running analyses.

Citations...

Iosif Lazaridis, Nick Patterson, Alissa Mittnik, et al., Ancient human genomes suggest three ancestral populations for present-day Europeans, arXiv, April 2, 2014, arXiv:1312.6639v2

Raghavan et al., Upper Palaeolithic Siberian genome reveals dual ancestry of Native Americans, Nature, (2013), Published online 20 November 2013, doi:10.1038/nature12736

See also...

Corded Ware Culture linked to the spread of ANE across Europe


Wednesday, July 16, 2014

Model yourself as a mixture of ancient genomes


Update 12/05/2015: 4mix: four-way mixture modeling in R

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This is really easy and should work well for most personal genomics customers (ie. those of European ancestry and with data files from 23andMe, FTDNA and AncestryDNA).

First of all, make sure you have your Eurogenes K15 ancestry proportions from GEDmatch. Then do the following:

- download the 4 Ancestors Oracle (here)

- download the Eurogenes ancient genomes datasheet (here)

- place everything into the same directory

- double click of the 4 Ancestors Oracle icon (the big red number 4)

- select the Eurogenes K15 ancient genomes datasheet

- type your Eurogenes K15 ancestry proportions into the fields provided

- hit the go button and let it rip

I'm not sure I'm allowed to upload the 4 Ancestors Oracle online, but I couldn't find the original link, so let's assume for the time being that I am. In any case, many thanks to Alexandr Burnashev for this great tool.

You'll also find some modern populations in the datasheet. They're there so that users with ancestry from outside of Europe don't end up with ridiculous results.

Obviously, you can edit the datasheet to explore more options by removing or adding individuals and populations. A spreadsheet of Eurogenes K15 population averages is available here. The oracle settings can also be tweaked in a couple of ways to fine tune the results.

If the calculator crashes, try replacing the periods with commas in both the datasheet and your ancestry proportions.

Please keep checking this post, because I'll attempt to update the datasheet at the link above every time a new ancient genome is published and has enough markers available to be tested with the Eurogenes K15. Eventually we might end up with a tool that covers most of the continents and many periods of history and prehistory.

I've done similar analyses of a variety of ancient genomes. For instance, StoraFörvar11, or SfF11, from Mesolithic Sweden came out 3/4 La Brana-1 and 1/4 MA-1, which translates to 3/4 Western European Hunter-Gatherer (WHG) and 1/4 Ancient North Eurasian (ANE), and lines up well with results reported recently for Swedish hunter-gatherers in scientific literature. You can see the full analysis StoraFörvar11 and a couple of other ancient genomes at the links below.

Analysis of Mesolithic Swedish forager StoraFörvar11

More ancient genomes from Sweden: Pitted Ware forager Ajvide58 and TRB farm girl Gokhem2

I'm still trying to answer a whole lot of e-mails so I won't be monitoring this post for a while. But please feel free to share your results and any tips you might have in the comments below.