Over the years our DNA has undergone multiple mutations. The longer the DNA has been active in our environment, the more time it has been exposed to the causes of mutation. A population group that has many of these changes would indicate that it has been around a lot longer that a population group that has few. This simple logic has been used to figure out which population group has been around the longest, even since the beginning of the human experience. Today, these changes, snips (SNPs), have been identified. Each single nucleotide change that has been found, has been coded and grouped. In essence, each mutation that has been found, has been given a genetic address that can be tested repeatedly. When enough of a population group shares a mutation, this mutation (SNPs) help define that part of the DNA that has been transmitted from one generation to the next. This change (SNPs) then becomes the "label" (haplogroup) for that family group. Today there are around 20 haplogroups know to exist. They are given the simple coding of the alphabet, beginning with the letter A, going to the letter T. It is believed that haplogroup A is the oldest.
Understanding the concept of the "snip" is the bases of moving on in the understanding of how DNA has been examined and these gene addresses have been used. Knowing where the "snips" occur along the DNA chain of codons (three nucleotide bases), and the type of "snips" present, tell the history of this DNA. It might be helpful to go back and review the blogs that discuss the dinning room and bucket trucks. A snip is a change in only one dinning room. The bucket at the end of the truck has been changed. This change will of course produce a change in the other side of the nucleotide pair (base pair). Go back and run through this mental concept until you have a clear understanding of the SNPs! This becomes our DNA address book.