The history of the human race is recorded in each person’s genome. While genetic genealogy goes back hundreds or thousands of years, deep ancestry goes back further, through the spread of humans throughout the earth, to our origins in Africa.
Here’s how it works: men and women each have a type of DNA that is passed down from one parent virtually unchanged. For men, the genetic information on the Y chromosome is passed down from father to son. Women pass their mitochondrial DNA (mtDNA) to their daughters. The mutations on these bits of DNA are so rare that only a few have occurred in hundreds of thousands of years.
Whenever a mutation appears in the Y chromosome or the mtDNA, the person who carries that mutation passes it to their sons (for men) or their daughters (for women) and all their sons or daughters. Each person carries a particular set of these mutations, which gives them membership in a sort of “clan,” along with all the other people, living and dead, who also share that same pattern of mutations. Those patterns are called haplotypes and the “clans” are called haplogroups.
Scientists have sampled DNA from thousands of people around the world, and mapped the haplotypes found in the Y-DNA and mtDNA. From these maps, they have constructed a picture of how and when mankind spread out of Africa, across the rest of the globe. Combined with linguistic and archeological data, this map has become very detailed.
Now you can join in this process, by having your own DNA added to the findings already known. You will discover how you were descended from our earliest forefathers, and how the DNA patterns in your body travelled the earth in our deep history.
Be aware that although this type of DNA testing goes back the furthest in time, it tells you the least about your ancestry. Since only the maternal or paternal line is being tested, results are only available for a small fraction of your ancestors.
Here’s a way to think about it: if you go back one generation, your maternal or paternal lineage is half of your ancestry (for example, your mother is one of your two parents). Going back to your grandparents, this lineage is one-fourth of your ancestors (because your maternal grandmother is one of four ancestors in that generation). Each generation you go back, the maternal/paternal lineage accounts for half as many of your ancestors. It’s possible that your maternal/paternal lineage is not representative of your ancestors as a whole.
