I understand DNA companies like 23andMe and Ancestry are able to tell you your ancestry based on many samples from people with known genealogy, but how do they trace it back further? For example, this [article](https://www.greatfallstribune.com/story/news/2019/05/06/blackfeet-man-dna-deemed-oldest-americas-cri-genetics/3145410002/) says this man’s DNA has been traced back several thousands of years to Arizona. How?
In: Biology
Land doesn’t have DNA, people do.
What happens is that they find that a person shares DNA with other people who are confirmed to have ancestry from that area of land.
It’s a bit cyclical because people often take DNA tests to try and find out where they are from and not vice-versa, but they keep rerunning their models as they get more DNA and gain confidence the more data they have.
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