23andMe announced today that they will soon be adding 120 new geographic regions to their Ancestry Composition report (sometimes called an ethnicity estimate). That’s up from their current number of 31 populations. That’s quite an increase!
The Ancestry Composition in the past was estimated by comparing bits of your DNA (called “markers”) with those of individuals with long historical ties to one of those 31 reference populations. Computer algorithms searched those reference data sets for suites of markers that were characteristic of, say, Southeast Asia, and if you also had some of those markers, you might be assigned a percentage from that region. The Ancestry Composition estimates reflected your genetic lineages back roughly 500 years or so.
This update adds another layer of detail onto the existing Ancestry Composition: “recent ancestor locations”. These locations are determined based on exact matches between your DNA and that of 130,000 individuals with known family histories from those 120 geographic regions. If you have an exact match with five or more people from a given region, you will be assigned to that location, with a confidence level based in part on how much DNA you share with the reference individuals. (This sounds a lot like the Genetic Communities that AncestryDNA introduced last year.)
Here’s a sample report from the announcement on 23andMe‘s website. Note that some of the existing 31 populations have been renamed. In the image below, “Manchurian & Mongolian” seems to be the new name for the region previously called just “Mongolian”.
In the sample report, the “recent ancestor locations” look to be listed directly below the broader 31 populations. That is, “Spain” is the recent ancestor location for the Iberian region and “Peru” for the Native American population.
The updated reports will be available to new customers when they receive their results, and existing customers are being phased into the new system. All 23andMe users should see the new Ancestry Composition update within a few months.
Do you have the new reports yet? If so, please share your thoughts in the comments.