Posted by on September 12, 2013 in DNA, Science

The AncestryDNA science team presented the results of their latest research today at the Smithsonian Institute’s symposium on The African Diaspora in Washington D.C. Using unique proprietary DNA samples and a variety of statistical approaches, our science team has been able to separate West Africa into six separate population groups based on genetic data.  This advancement will provide a finer-resolution genetic ethnicity estimate for individuals with West African ancestry.

West African ethnicity

AncestryDNA’s six new ethnicity regions of West Africa include Senegal, Mali, Ivory Coast/Ghana, Benin/Togo, Nigeria, and Cameroon/Congo, each of which has a distinct set of tribal affiliations.  The division of West Africa into these groups marks the first time that West African genetic ethnicity estimates can achieve this level of detail, bringing AncestryDNA’s total number of reported genetic ethnicity regions in Africa to ten.

The announcement of the new genetic ethnicity regions were presented at The African Diaspora event earlier today by Dr. Jake Byrnes, population genomics senior analyst on the AncestryDNA science team.  Although these new ethnicity updates will not be made available to all AncestryDNA users for a few more months, we wanted to give the inside scoop on Jake’s Smithsonian presentation detailing the West African ethnicity update as well as additional research findings on the genetics of African Americans.

It can be extremely difficult to research one’s African ancestry using historical records alone, as most African American individuals in the U.S. are unable to find detailed records of their ancestors before the 1870s. Our AncestryDNA test can help family historians use genetics to pick up where the paper trail ends.

AncestryDNA leverages a unique proprietary collection of DNA samples from individuals with well-documented family trees to conduct innovative research in population genetics, human evolution, and migration. The science behind AncestryDNA is continually evolving and improving. During this ongoing process, the science team demonstrated that genetic data reliably shows population structure in Western Africa.  What this means is that the DNA of individuals from Western Africa clusters into a number of distinct groups. As a result, AncestryDNA can now more finely define genetic ethnicity regions in Western Africa. (See the visual representations below.)

 Caption: The graph on the left depicts the distinct genetic clusters of individuals from West Africa. Each point is an individual with deep ancestry in West Africa from our proprietary sample database. The color of each point corresponds to the country (shown in the map on the right) where a majority of that individual’s ancestors lived. The x and y axes indicate two primary axes of genetic differentiation (called principal components, or PCs) as inferred from sample DNA. Points closer together on the plot are more similar genetically. Comparison of the graph on the left and the map on the right reveals the similarity of the genetic and geographic structure.


Caption: The graph on the left depicts the distinct genetic clusters of individuals from West Africa. Each point is an individual with deep ancestry in West Africa from our proprietary sample database. The color of each point corresponds to the country (shown in the map on the right) where a majority of that individual’s ancestors lived. The x and y axes indicate two primary axes of genetic differentiation (called principal components, or PCs) as inferred from sample DNA. Points closer together on the plot are more similar genetically. Comparison of the graph on the left and the map on the right reveals the similarity of the genetic and geographic structure.

Population structure such as this is not new, and even exists in the U.S today.  Here’s an example from the 2010 census data.  Each point is an individual, colored by their self-reported ethnicity.

West African ethnicity 3

You’ll notice that people of similar backgrounds tend to stay and live in the same general geographic areas.  Imagine now if we could roll this map back in time to see where an individual’s ancestors immigrated to the U.S.!

The AncestryDNA science team is looking toward a future where we could reveal, in the absence of a family tree, the most probable locations where one’s ancestors lived – both in the U.S. and abroad.  To do this, the science team hopes to harness the power of collectively analyzing family trees of individuals with similar genetic profiles.

Though this project is still in its infancy, the science team has made some progress. First, we looked at the birth locations of individuals in the trees of all African Americans. Then, we looked for locations where, relative to all African Americans, there appeared to be an over-representation of birth locations in trees of individuals with a particular West African ancestry.  For individuals with Senegalese genetic ethnicity, we found what seems to be an over-representation of birth locations in South Carolina and Georgia in the 1700’s and 1800’s.

This might be an example where the genetics matches up with history.  In the 18th century, plantation owners in South Carolina and Georgia knew little about rice cultivation and preferred to import slaves from Sierra Leone, Gambia, and Senegal (the Windward Coast), where rice is a commonly grown crop. It is thought by some scholars that the Gullah people, who today live in coastal Georgia and South Carolina, descend from slaves imported from the Windward Coast to work specifically on rice plantations.

Providing more detailed ethnicity estimates for West African populations is crucial for American family historians.  Approximately 85-90% of today’s African Americans are descendants of enslaved Africans brought to America between 150 and 450 years ago – leaving many African Americans without a known family history prior to this time. AncestryDNA’s new West African ethnicity update will help to link African American individuals to specific locations in West Africa. In the future, more detailed analyses of genetic data and family trees have the potential to reveal important historical stories.

West African ethnicity 4

Thanks to the science team’s findings of genetic structure in West Africa, the new African ethnicity regions will be a breakthrough for many African Americans and may even reunite the origins of disrupted families.  But more is to come, as we are only scratching the surface of what is possible.

About Julie Granka

Julie has been a population geneticist at AncestryDNA since May 2013. Before that, Julie received her Ph.D. in Biology and M.S. in Statistics from Stanford University, where she studied genetic data from human populations and developed computational tools to answer questions about population history and evolution. She also spent time collecting and studying DNA using spit-collection tubes like the ones in an AncestryDNA kit. Julie likes to spend her non-computer time enjoying the outdoors – hiking, biking, running, swimming, camping, and picnicking. But if she’s inside, she’s baking, drawing, and painting.

17 Comments

James 

Wow, this is what me and my father have been hoping for. Awesome!

September 12, 2013 at 11:39 pm
Nia 

Sounds great!!! When will this feature take effect?

September 13, 2013 at 2:36 pm
    Julie Granka 

    Within the coming months AncestryDNA customers will start to see the fruits of our research incorporated into their ethnicity results.

    September 19, 2013 at 7:39 pm
Mase 

Great work, guys!!!! Very excited.

September 13, 2013 at 5:55 pm
HLee 

Wow! Can’t wait to see the results. @Nia from The Genetic Genealogist the next 1 to 3 months. 6,000 lucky random people (i’m not one) got their sneak preview 9/12. See: http://www.thegeneticgenealogist.com/2013/09/12/ancestrydna-launches-new-ethnicity-estimate/

September 14, 2013 at 1:36 am
Ron 

Could this advance help resolve the origination location of E-V13?

September 17, 2013 at 7:12 pm
    Julie Granka 

    Thank you for your interest! This advance in our genetic ethnicity estimates only relates to autosomal DNA — not to Y or mitochondrial DNA.

    September 19, 2013 at 7:22 pm
Quinn Hopkins 

Will the updated information be added automatically to previous DNA tests?

September 28, 2013 at 9:51 pm
    Julie Granka 

    It will. All AncestryDNA customers will receive their new ethnicity results with these updates without having to take the test again.

    September 30, 2013 at 8:11 pm
anthony parker 

I’ve asked Ancestry.com if they will have a raw data upload like Familytreedna has where you can upload raw data from 23andme to them,and they said there are no plans right now. That makes me upset,I would love to have my maternal grandparents 23andme looked at by Ancestrydna since they are the only ones with this new west African breakdown. I promised my grandparents when they did 23andme that they wouldn’t do any more tests (and spitting,even with an assistant collection kit,was rough for them).

October 13, 2013 at 11:50 pm
Unraveling the Science Behind Ethnicity Estimation 

[...] after generation.  Similarly, chance movements of humans across the world allow us to see DNA evidence of this [...]

October 24, 2013 at 3:54 pm
LaKisha David 

Wow. I just want to say THANK YOU! …and keep up the good work. Seriously, please keep it up. There’s some real healing going on from your work. Thank you.

November 23, 2013 at 10:45 am
Asar Imhotep 

I had my test done through another company and it narrowed it down to Mozambique. It looks like your test doesn’t cover that area. Are there plans to expand to that other area where Africans were taken and enslaved in the Americas?

January 18, 2014 at 12:37 am
Should white americans recognize/embrace their African ancestry? - Ancestry research, historical records, genetic analysis, sharing data, locating family - Page 31 - City-Data Forum 

[...] them 2.0 ethnicity results) they posted a blog claiming a big improvement in African DNA testing: AncestryDNA Makes Scientific Breakthrough in West African Ethnicity I had heard rumors of Native American, so thought I might find a bit of that. In my tests I came [...]

January 18, 2014 at 6:20 am
rickey bobbitt 

thanks to ancestry.com I was able to know,
my west and east african roots.
and i WILL BE HAPPY SOME DAY WHEN THEY,
FIND THE NAMES AND TRIBES.

January 24, 2014 at 9:18 pm
Wanda 

Hi Julia,
I have received my results from my DNA test, and I have a question regarding the findings. I was excited to know that West Africa especially the Ivory Coast was where the highest concentration of my genetics found. The other region in West Asia was a bit of a surprise but not entirely, because I have always felt a kindred spirit with the culture of Turkish people. I like the style of clothing, music, etc. I also have some European genes, which was not a surprise. What I would like to know is how did the emigration occur? I live in the Texas in the U.S. thank you for all of the research that you are doing, it really helps in knowing where one is from.
Thanks again,
Wanda

January 29, 2014 at 8:31 pm
    Julie Granka 

    Hi Wanda, thanks again for your interest! I’d suggest looking through the detailed region descriptions on your results pages, as they main help to reveal some interesting history about your possible ancestors from that region.

    March 18, 2014 at 6:47 pm

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