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
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