Since the discovery of DNA and RNA, it has been becoming increasingly clear that diversity of living organisms is underlain by a wide spectrum of mechanisms and processes generating genetic variation. The latter causes that individuals representing the same species are different, and that each species can evolve, and thus, adapt to changing environmental conditions. Unfortunately, for many years, studying the mechanisms that generate genetic variation was extremely difficult due to the lack of methods for determining the sequence of whole genomes or transcriptomes. Thus, the development of next generation sequencing technologies became a real breakthrough in biological diversity research. Consequently, the genetic basis of both physiological and pathological processes can now be studied. It has also been shown that by analyzing genetic variation, one can learn about the biological history of individuals and whole populations. As a result, a new research field, called archeogenomics was established and in a short time, became one of the fastest growing branches of genomics. However, in contrast to traditional genomics, the major object of archeogenomic studies is not contemporary, but ancient DNA, extracted from the remains of individuals living thousand years ago.