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This year marks the 20th anniversary for sequencing the human genome. A research team headed by Prof. FUQiaomei, from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, reviewed the latest progress in the field of ancestral DNA (aDNA), which is DNA extracted from the remains of previous organisms.
The review entitled "Insights in human history from the first ten years of ancient human genomes" was published by Science on September 23rd.
The first steps in ancient DNA research were to analyze short DNA fragments. However, the field has advanced with the widespread application of high-throughput sequencing techniques (HTS). The publication of three drafts of ancient genomes, namely Neanderthal, Denisovan and a modern 4-thousand year (kyr),-old Greenlander, marked a new era in DNA research.
Reconstructed genomes of extinct archaic human species (Neanderthals and Denisovans), have been identified. It is important to note that the Denisovans were identified for the first time using only aDNA data. The two archaic lines were found to have split from modern humans approximately 550 thousand years ago (ka). The two archaic lineages separated again 400 years later.
These aDNA analyses showed that modern and archaic humans were not isolated from one another after the 550-ka separation. Multiple waves of introgression were found between archaic human (i.e. Neanderthals, Denisovans), and modern humans. The archaic lineages also mingled, as demonstrated by Denisova 11, an archaic individual aged 50 years old who was born to a Neanderthal mother, and a Denisovan dad.
Genetic data supports an African origin for the early modern human population. It is difficult to identify a single model that can be used to characterize the African origin of ancestry. In any event, the five main branches that contributed to early modern human history split within a very short period of time in Africa, between 250200 and ka.
Genomic data from Eurasia's early modern human ancestors date back to 45 ka. These data show several human lineages from the early modern era. While some of these data do not show any genetic continuity with later generations, others, such as those from Ancient North Siberians or Ancient Europeans, could be genetically linked with current-day human populations. Eurasia has seen an increase in population, higher population interaction, and greater migration over time.
"During the Last Glacial Maximum (or LGM), a severe period between 2719 and 2719 ka, population shifts are observed in Europe. East Asia, Siberia, and Europe. Professor FU stated that the LGM brought about a more stable and warmer climate, which allowed the human population to expand, migrate, and interact.
Our understanding of human history has been greatly enhanced by ancient DNA research. We have only scratched the surface. We need to do more. Further sampling should be done from genomes older that 30 kyr, and from regions like Africa, Asia, and Oceania. This will further expand the scope of aDNA-related research by utilizing ancient molecular information, such as proteomic and isotopic data, and exploring adaptive variants.
ADNA research has not only helped us understand human history better, but it also provided a deeper understanding of human biology. Understanding how humans have adapted to extreme environments like the LGM or infectious agents in the past can help us tackle new challenges like climate change and other pandemics.
Continue reading to discover the earliest interbreeding event among ancient human populations
Yichen Liu and colleagues, Insights into the history of humankind from the first decade in ancient human genomics, Science (2021). Information from Science Yichen Liu and colleagues, Insights into Human History From the First Decade of Ancient Human Genomics, (2021). DOI: 10.1126/science.abi8202
