Mapping the human genome was a daunting task. Starting in the early 1980s, The Human Genome Project began depositing enormous amounts of known DNA sequence information in very large computer databases. Over the next 20 years, the "big picture" became clearer. Most, if not all, of the human genome was successfully map around 2002. Since that time, this mapping has been used to help explore the "genetic" history of our human race. It became clear that the genes are DNA segments that encode information about an individual's heritable traits. Mutations are the original source of variation among these heritable traits. It ended up that most of these "mutations" (changes) are substitutions of one base pair (a single nucleotide, remember standing in your dinning room), for another. Once a mutation (SNP)is established, it is past down from one generation to the next. It has been estimated that about 10 million of these SNPs have occured in our human population. [see National Center For Biotechnology Information (NCBI)] Each SNPs is thought to have arose during the passage of time since our human history began.
Basic concepts have been developed that believe the greatest genetic diiversity of the human species is found in the the geographic area which it orginated. [known as Valilov's Concept] A mutation (change) found in the Y-DNA/mtDNA of a large number of people in various parts of the world most likely happened in a common ancestor. These changes can be "marked" and followed as "genetic markers". These genetic markers can be used to place that population group into a "haplogroup". More to come.