A Big History From a Small Piece

Genetic studies with DNA obtained from the remains of organisms lived in the past are called Ancient DNA (aDNA) studies (İyras & Doğan, 2015). Ancient DNA is the subject of study in a multidisciplinary field. It is the collective work of many scientists such as anthropologists, archaeologists, palaeontologists and molecular biologists.

However, these studies are not as easy as they seem, and many problems are encountered during the research, from the excavation area to the laboratory. The biggest problem encountered at the excavation area is difficulty in revealing the sex, pathological conditions, and lifestyles of fossils due to illegal destruction.

Figure 1: METU NEOGENE team in the excavation area (2017).

Figure 1: METU NEOGENE team in the excavation area (2017).

  • The first studies in the field of aDNA began in the 1980s. In 1984, Higuchi and colleagues began working with an extinct zebra species, the Quagga (Equus Quagga Quagga). The Quagga, which became extinct in 1883, was the first creature whose DNA was investigated among the extinct creatures (Higuchi, Bowman, Freiberger, Ryder, & Wilson, 1984).
  • The next study was the 1985 study of an Egyptian mummy by Pääbo et al. Moreover, Pääbo and his team made a wonderful discovery 33 years later. In an article published in Nature in 2018; A bone found in a cave in Siberia made an important contribution to the phylogenetic tree. It was determined that this bone belonged to a girl who died 90,000 years ago. Surprisingly, the girl’s mother is Neanderthal and her father is Denisovan. It was a well-known fact that early human species interbred with modern humans. But what’s great about this exploratory is that Denny is a first-generation ancient human hybrid (Warren, 2018).
  • aDNA studies help us find the roots of diseases, find solutions to them, and learn about ancient lifestyles in the excavated area. One of the most interesting examples of this is Ötzi the Ice Man, found in the Ötztal Alps of Italy (between Austria and Italy) in 1991. Unlike other mummification techniques, Ötzi was mummified with his clothes and belongings without removing any of his internal organs. His autopsy revealed that he had the first Lyme disease in history. It is also seen that the 57 tattoos on his body are not for religious or ornamental purposes, but are the first acupuncture treatment in history by reducing pain in those areas (1). He lived around 5,300 years ago and it makes him the oldest natural mummy in Europe (2).
Figure 2: Researchers sample the contents of Ötzi's stomach to learn about his last meal.

Figure 2: Researchers sample the contents of Ötzi’s stomach to learn about his last meal.

Figure 3: Ötzi at South Tyrol Museum of Archeology in Italy.

Figure 3: Ötzi at South Tyrol Museum of Archeology in Italy.

  • Ancient DNA fragments are ultra-short molecules because they are highly damaged and not preserved under special conditions. The tooth or bones comes to the laboratory from the excavation area or museum. Bones that come to the laboratory with a special sensitivity are placed in separate ziplock bags and stored in the freezer until the next process. Then, DNA is isolated with the help of enzymes with paying attention to things that may endanger the work, such as contamination and degradation. And finally, DNA sequencing begins. After various controls and processes on the DNA, an analysis is made of whether the DNA sequences are the desired sample.
  • Nuclear and mitochondrial DNA analysis provide us with key information in learning about human evolutionary history. While the last common male ancestor is reached by going back only with the Y chromosome given by the father to the son, the oldest female ancestor of the species is reached thanks to the mtDNA given by the mother to the female and male offspring. For this reason, mtDNA is called Eve DNA. The importance of mtDNA in evolutionary studies is undeniable, as mtDNA reaches both sexes. Thanks to mtDNA, we see that evolution exists (3).

Ancient DNA studies have revolutionized many prehistoric and historical events, and are continuing. These researches offer solutions to the evolutionary and anthropological problems of humanity. Moreover, it fills many gaps in human history and corrects mistakes. The transition of modern man from hunter-gatherer nomadic life to agriculture and animal husbandry has been one of the most radical changes in human history. The biggest of those gaps are in there.

I wish to enlighten our history by recognizing the beauty of our differences with such subjects that bring together various scientists from various parts of the world…

References:

  1. Ermini, L., Olivieri, C., Rizzi, E., Corti, G., Bonnal, R., Soares, P., … & Rollo, F. (2008). Complete mitochondrial genome sequence of the Tyrolean Iceman. Current Biology18(21), 1687-1693.
  2. Dickson, J. H., Oeggl, K. D., Kofler, W., Hofbauer, W. K., Porley, R., Rothero, G. P., … & Heiss, A. G. (2019). Seventy-five mosses and liverworts found frozen with the late Neolithic Tyrolean Iceman: Origins, taphonomy and the Iceman’s last journey. PloS one14(10), e0223752.
  3. Tobias, P. V. (1995). The Bearing of Fossils and Mitochondrial DNA on the Evolution of Modern Humans, with a Critique of the’Mitochondrial Eve’Hypothesis. The South African Archaeological Bulletin, 155-167.
  4. İYRAS, H. M., & DOĞAN, Y. Antik DNA çalışmaları ve karşılaşılan sorunlar. Antropoloji, (30), 53-60.
  5. Higuchi, R., Bowman, B., Freiberger, M., Ryder, O. A., & Wilson, A. C. (1984). DNA sequences from the quagga, an extinct member of the horse family. Nature312(5991), 282-284.
  6. Warren, M. (2018). Mum’s a Neanderthal, Dad’s a Denisovan: First discovery of an ancient-human hybrid. Nature560(7719), 417-419.
  7. Tuppen, H. A., Blakely, E. L., Turnbull, D. M., & Taylor, R. W. (2010). Mitochondrial DNA mutations and human disease. Biochimica et Biophysica Acta (BBA)-Bioenergetics1797(2), 113-128.
  8. METU NEOGENE

Figure References:

  1. METU NEOGENE
  2. https://arkeofili.com/wp-content/uploads/2018/07/yemek1.jpg
  3. https://arkeofili.com/wp-content/uploads/2019/11/mose.jpg

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