(1) After you log into into your 23andMe account, click on your Ancestry Reports and then Ancestry Composition. Next scroll down and (if you have it) you will see "Your Ancestry Timeline" located right under your "Ancestry Composition" results. At the top of the feature you will see a horizontal list of circled numbers, which represents a generation. Immediately below this are corresponding dates at 30-year intervals (30 years = 1 generation) and presumably driven by the birth date you listed on your 23andme account --- for me Generation 1 starts at 1940 and goes back to Generation 8(+) at the year 1700. Below this you will see colorful modules, each one representing an ethnicity component present in your Ancestry Composition results --- each module is of a different length based upon the time and generation range your proposed ancestor with 100% of a certain admixture (ie West African) might have actually existed. It looks like this:
(2) Next click on any of the ethnicity modules, a pop-up box will open showing the probable time when your ancestor with 100% of a singular admixture lived. I clicked on the RED module "West African" as seen here:
The pop-up box shows: "You most likely had a parent, grandparent or great-grandparent who was 100% African. This person was likely born between 1880 and 1940."
(3) To learn how the new feature works, you should (actually MUST) click on the blue link "Learn more about how to interpret this result" (located underneath the feature's ethnicity tabs). It includes a link to the 23andMe Admixture Date Estimator White Paper which goes into the "logic" and "science" behind the new feature. The blue link reveals the following information:
I like the 23andMe new Admixture Date Estimator ("Your Ancestry Timeline") feature because I use these sort of statistical inheritance predictions when I analyze people's ethnicity admixture results. However my immediate impression is a lot of people will be confused and misinterpreting the information. To this point, the Admixture Date Estimator White Paper states the feature will "enable customers to find out, for each of the ancestries they carry, when they may have had an ancestor in their genealogy who was likely to be a non-admixed representative of that population." This is because genetic inheritance is much more complicated and ... well there has been very few ethnically "pure" or non-admixed populations in modern history. The population structure of most ethnic groups includes ancestry from "outside" groups. Also based on random genetic recombination we inherit any of our parents admixture in DNA chunks of varying sizes, with some of those DNA chunks remaining intact over several generations. This is problematic because the feature assumes a singular admixture component from one ancestor/ancestral event. Further note this estimator does not include your X-chromosome(s) in its calculations.
Now I'm African-American, which means my admixture profile is going to be complex and colorful. I know that my West African admixture @ 78% comes from both of my parents and all of my grandparents in various amounts; this new feature automatically assumes my West African inheritance comes just one parent. In fact I descend from numerous indigenous populations living in western and other African subregions that entered my bloodline at different times and places in my genetic history. Further my results were phased with a parent and I've received "West African" from both of them in varying amounts. Therefore it is highly unlikely I had "a parent, grandparent or great-grandparent who was 100% West African that was born between 1880 and 1940." Or what if like me, you have Malagasy ancestry and you show a small Southeast Asian percentage @ 0.9%? Well Malagasy populations have been admixed with Asian and African for thousands of years so even if this Southeast Asian came one predicted ancestor he or she may not have been 100% Southeast Asian for a very long time. And what if you have Southeast Asian ancestry from both parents?
In my optimistic opinion these admixture date predictions may work better with people from more homogenous populations ("West Africa" is not one of them), or with smaller distinguished admixture amounts (ie Native American) that can be attributed to one ancestor (ie Choctaw grandmother) or ancestral couple. Of course I'd much rather 23andMe work on improving/updating its Ancestry Composition (West Africa is a much too broad category) and Haplogroup predictions, including the build platform; restoring our ability to see the chromosome paintings of the people we're sharing with; implementing an in-house family tree utility, as well as expanding its fantastic In Common With/triangulation tool to include all of our DNA relatives. I would also like to see an ethnicity element added to 23andMe's chromosome browser/mapper tool where customers can see the location, size and ethnicity(s) of the shared segments displayed.
You're absolutely right. My ancestry is almost all British, Irish and Western Europe. Their chart says my British ancestors date to 1910-1930....its more like 1620-1770, they just married among the folks from the old country.ReplyDelete
Same here! Most of my ancestors were in the USA from before it's founding so my British is coming from all my ancestors who kept marrying other people who were predominantly British. But it was correct on my German ancestor. I think it is completely off base on my South Asian which I believe is actually Romany Gypsy and not Indian. Very interesting though.Delete
I appreciate how you bring it all down to layperson definitions and explanations. Thank you for all you do.ReplyDelete
Yeah I just checked this out. It said that "You most likely had a grandparent,great-grandparent, or second-great grandparent who was 100% African. This person was likely born between 1860 and 1920."ReplyDelete
I have no doubt that they're talking about my grandfather who was born in 1898.
I am sure it is a good tool, but 23andMe should be prioritising the transfer of those of us not yet on the new set up . It's insulting to produce these new tools for a select few when many of us have been waiting over a year to be transferred.ReplyDelete
They describe the caveats quite well in the whitepaper:ReplyDelete
However, there are several caveats to this
direct interpretation. In many cases, individuals from some world-wide population
may themselves be highly admixed, obfuscating the time to when this ancestry
may have first been introduced. The admixture date provided is based on
the ancestry segments estimated by Ancestry Composition, and is, consequently,
dependent on their accuracy and specificity for accurate date estimation. Any
genealogical history or ancestries that are not well captured by Ancestry Composition
estimates may result in poor admixture date estimation, which typically
results in older estimated dates of admixture.
Secondly, the admixture date is based on all segments of a particular ancestry.
If multiple genealogical ancestors contributed independently, the admixture date
may reflect these multiple ancestors in a complex way. If many segments, from
independent ancestors, recombine to form longer segments, the estimated admixture
date may be shifted towards a more recent date. This is especially likely in
the case when segments cover over 50% of a genome. On the other hand, if many
older genealogical ancestors contribute discrete, shorter segments, the estimated
admixture date may be pushed back, reflecting a weighted average over the multiple
This was an excellent review!ReplyDelete
Is thus available in the Canadian version. I don't see itReplyDelete
I just logged on and was immediately underwhelmed. Like you stated, it may work better for some individuals. I believe this can be misleading. Mine states I have a ancestor born between 1850-1910 that is 100 % African. Roughly 68% of my ancestry is African. Of that 64% is West African. I immediately started thinking of the African brought to Cuba during the late 1800's. But that does not take into account the Africans that did not mix with Europeans or Native Americans that came to new world during a longer time frame. I too would rather see an update to the Ancestry Composition. But at least there is some activity.ReplyDelete
To me the site has been de-humanized. The old site had more character and more personality. I do not buy the whole invasion of privacy. There was a disclaimer for everyone to agree to, before joining. The old site , for better or worse, put people in more personal situations. Especially when there were disagreements. The new site seems to have toned down interaction among users.
Thanks for an interesting read. As for me, I'd like 23andMe to advance downstream ancestry. Maybe, even offer Next Generation Sequencing.ReplyDelete