This year is the 20e anniversary of the sequencing of the human genome. In honor of this event, a research team led by Professor FU Qiaomei from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences reviewed the most recent advances in the field of antiquity DNA (ADNA), that is, DNA obtained from the remains of past organisms.
This review, entitled “Insights into human history from the first decade of ancient human genomics”, was published in Science September 24, 2021.
Ancient DNA research began with short fragments of DNA and then progressed through the wide application of high throughput sequencing (HTS) techniques. In 2010, the publication of three drafts of ancient genomes (ie Neanderthals, Denisovan, and a 4,000-year-old modern human (kyr) from Greenland) marked a new era for aDNA research.
The genomes of extinct archaic humans (i.e. Neanderthals and Denisovans) have been reconstructed. It is important to note that the Denisovans were first identified using only DNA data. These two archaic lineages have been shown to separate from modern humans around 550,000 years ago (ka). They then separated from each other ~ 400 ka.
DNA analyzes showed that archaic and modern humans did not remain isolated from each other after the separation of about 550 ka. Multiple waves of introgression have been found between archaic humans (i.e. Neanderthals and Denisovans) and modern humans. In addition, the two archaic lineages intermingled with each other, as shown by an archaic individual of around 50 kyr (Denisova 11) who had a Neanderthal mother and a Denisovan father.
As for the first modern human populations, genetic data support an origin in Africa. However, it remains difficult to determine a single model to characterize the origin of African descent. In any case, between ~ 250-200 ka, five major branches contributing to modern human ancestry began to separate from each other in a short time in Africa.
In Eurasia, genomic data has been obtained from the first modern humans dating back to around 45 ka. These data reveal several early modern human lineages. Some of them show no detectable genetic continuity with later populations, while others, including those representing ancient North Siberians, ancient Europeans, and ancient Asians, may be genetically related to current human populations. Over time, increasing population structure, greater population interaction, and higher migration have occurred across Eurasia.
“During the last glacial maximum, or LGM, a difficult period between 27 and 19 ka, population changes are observed in Europe, East Asia and Siberia. With a warmer and more stable climate after LGM, the human population expanded, migrated and interacted, ”said Professor FU.
Research on ancient DNA has actually broadened our understanding of human history. However, we only dived below the surface. We have to do more. This should include additional sampling of genomes over 30 years old and regions such as Africa, Asia and Oceania; further expand the scope of DNA research using other ancient molecular information such as proteomic, isotopic, microbiomic and epigenetic data; and further explore adaptive variants.
In addition to expanding our understanding of human history, DNA research has also improved our understanding of human biology. Exploring how humans have adapted to extreme environments such as LGM and infectious agents in the past will help us deal with new challenges such as climate change and other pandemics in the future.
Reference: “Insights into human history from the first decade of ancient human genomics” by Yichen Liu, Xiaowei Mao, Johannes Krause and Qiaomei Fu, September 24, 2021, Science.
DOI: 10.1126 / science.abi8202