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Grubbe
05-05-13, 14:30
I have read about I1 here at the Eupedia and also Ken Nordtvedt's notes. It seems to be conflicting views on the age of I1 and subclades. For instance, Nordtvedt has both I1a2 (SNP L22) and I1a2a (SNP P109) as 3100 years old, but Eupedia estimates I1a to be only 2000 years old. If so, L22 and P109 must be considerably younger. What is correct?

Also, the bottleneck I1 experienced is said to be both 5-10 000 years old and 7-10 000 years old here at Eupedia. (The first is written in the "Origins, spread and ethnic association of European haplogroups and subclades" page, the other in the "Haplogroup I1" page). What is correct?

Maciamo
05-05-13, 21:07
Age estimates change all the time. As you can see the range is very wide. For some haplogroups the range can vary by over 10,000 years for top level haplogroups. The reason is that the age of haplogroups cannot be determined for sure based on the current population because of many factors:

1) age estimates depend on the historical population sizes, which can vary a lot from century to century. Mutations are 10 times more frequent in a population of 10 million than in a population of 1 million. That's why people who only looked at genetic diversity among on haplogroup of subclade often got ages completely wrong. Until a few years ago many "geneticists" thought that R1a originated in South Asia because there was far more STR diversity there than in Europe. The SNP phylogeny disproved that completely and showed that all South Asian R1a belongs to just one branch of European R1a. The diversity was artificially caused by the vastly superior historical population of South Asia. The same is true for mtDNA. Most subclades of U2 are found in South Asia, yet it is almost certain that U2 originated in Russia because it was found there (http://www.eupedia.com/europe/ancient_european_dna.shtml) in 30,000-years ago.

2) age estimates depend on the average number of years by generation, and this also varies enormously depending on the culture and number of children per family. For example, from the 15th to the 19th century it was common for Japanese girls to be married between the age of 12 and 15, while at the same period north-western Europeans typically got married in their mid-twenties. Therefore it is impossible to know how many years each generation count for. Is it 15 years or 30 years ? That alone can make a haplogroup's age twice older or twice younger.

3) many branches have probably gone extinct at some point in (pre)history due to population bottlenecks. It was surely the case with I1 or pre-I1 subclades, which makes it extremely hard to date with accuracy.


Conclusion: the only reliable way to know a haplogroup's age is to test many ancient samples and see the evolution of subclades through time.

nordicwarrior
06-05-13, 02:06
...Conclusion: the only reliable way to know a haplogroup's age is to test many ancient samples and see the evolution of subclades through time.

That's what I've been saying...

Grubbe
06-05-13, 15:44
Thank you very much for your thorough explanation, Maciamo. Let's hope for more ancient DNA sequencing!

sparkey
07-05-13, 17:40
Nordtvedt's own estimates are constantly changing, although that's not necessarily because STR estimation is hopelessly flawed. The error bars resulting from STR dating are known and usually provided if you're looking at a good study, and they converge if the same mutation rate estimates are used. The real reasons they seem to change are many, including refinement of mutation rates, improvement of algorithms, and most importantly, inclusion of SNPs in the tree. Adding SNPs to the tree will force branches that occurred around similar times to be locked into the correct order, so we know which nodes to calculate instead of having to guess and give bigger error bars. The flood of SNPs into the I1 tree has particularly refined it.

STR dating is not perfect, but it has strong predictive power. All Haplogroup I found in ancient DNA so far has been predictable based on STR dating.

Grubbe
07-05-13, 20:01
All the new SNPs found in R1a since about 2011 has helped a lot to determine age estimates for R1a (but they will undoubtedly change over time, like everything else), but I have not seen such good age estmates based on SNP for hg I yet.

nordicwarrior
08-05-13, 04:10
Nordtvedt has done much admirable work in determining the journey of hg. I and specifically I1.

I do liken the tracing of hg. I movements using only STR results to building a cedar deck using a very limited tool selection-- say a butter knife and a hammer. It can be done, but it ain't going to be fun, and it's going to be a pretty lengthy slog. Luckily Nordtvedt has the brain power to actually pull it off.

As SNP data points come online, and as ancient remains are found (with carbon dating and archeological findings further cementing each haplogroup in the place/time matrix)... Nordtvedt's efforts will prove all the more valuable.

His STR findings will serve as detailed "carvings" in the I and I1 structural lines... and the SNP results will make sure each genetic post is anchored in the appropriate footing.

It is my opinion that in two hundred years (or even a thousand years) from now, historians will pour over Nordtvedt's work, Well's work, Paabo's work... like we study maps from the ancient world today. Future scientists will smirk at how little we knew of our DNA landscape, while at the same time being perplexed at how much we were actually able to figure out using our limited means (comparatively limited anyway-- considering what hundreds of years of future advancements will surely bring mankind).

nordicwarrior
08-05-13, 13:45
To recap the above statement, basically what I'm saying to the .000001% of the world population that's into this haplogroup stuff and who read and participate in these threads-- be happy in the knowledge that you are trailblazers.

We are helping to craft the earliest genetic maps that will guide future humanity back through it's DNA travels.

And we do it for free! Wait a minute, now that I recognize the import of my writings... I demand a 50% increase in pay, effective immediately. :)

**EDIT**
How could I have forgotten Terry Robb in my above comment? My apologies to Mr. Robb-- his research involving hg. I1 has proven to be very helpful.

Grubbe
12-05-13, 14:35
As of 9 May there is a new I tree at ISOGG: http://www.isogg.org/tree/ISOGG_HapgrpI.html

Grubbe
13-05-13, 20:41
How could I have forgotten Terry Robb in my above comment? My apologies to Mr. Robb-- his research involving hg. I1 has proven to be very helpful.

I was previously not familiar with Terry Robbs work, but in this thread http://www.eupedia.com/forum/threads/26941-The-elusive-non-Germanic-I1 I found a link to it. The thread also addressed the difficulties of estimating the age of I1 - very interesting!

Greying Wanderer
26-01-14, 21:46
I have read about I1 here at the Eupedia and also Ken Nordtvedt's notes. It seems to be conflicting views on the age of I1 and subclades. For instance, Nordtvedt has both I1a2 (SNP L22) and I1a2a (SNP P109) as 3100 years old, but Eupedia estimates I1a to be only 2000 years old. If so, L22 and P109 must be considerably younger. What is correct?

Also, the bottleneck I1 experienced is said to be both 5-10 000 years old and 7-10 000 years old here at Eupedia. (The first is written in the "Origins, spread and ethnic association of European haplogroups and subclades" page, the other in the "Haplogroup I1" page). What is correct?

Funnelbeaker 6000 years BP

(imo)