A team of researchers from the Big Data Institute at the University of Oxford has taken a major step toward completing all genetic relationships between humans: a grand family tree that traces all of our ancestry.
The last two decades have brought us great advances in human genetic research , generating genomic data from hundreds of thousands of individuals, even thousands of prehistoric people, offering us the possibility of tracing the origins of human genetic diversity to produce or A comprehensive map of how individuals around the world relate to each other.
Many large databases
Now, this team of researchers has easily combined, thanks to a new method, data from multiple sources and scaled it to accommodate millions of genomic sequences.
“Basically, we have built a grand family tree, a genealogy for all of humanity that models as accurately as we can the history that generated all of the genetic variation that we find in humans today. This genealogy allows us to see how the genetic sequence of each person is related to the others, throughout all points of the genome”, explains Yan Wong, evolutionary geneticist at the Big Data Institute and co-author of the work published in the journal Science.
The experts explain that, although humans are the center of this work, their method could be used in most living beings; from orangutans to bacteria . “It could be particularly beneficial in medical genetics, by separating the true associations between genetic regions and diseases from the spurious connections that arise from our shared ancestral history,” they clarify.
How is this family tree?
The scientists merged more than 3,600 individual sequences from 215 populations into a single tree, with some genes dating back 1,000 years to more than 100,000 years ago. The branches of the tree are part of 231 million ancestral lineages. The algorithms predicted where common ancestors needed to be present in evolutionary trees to explain patterns of genetic variation. The resulting network contained almost 27 million ancestors.
At the base, for example, is a series of roots represented by eight ancient human genome sequences in great detail, thanks to thousands of smaller fragments that have been used to confirm their location deep in our past.
This work confirms existing conclusions about human history, including that most human evolution took place in Africa before a major movement out of the continent around 70,000 years ago. The earliest ancestors the team identified were “most likely” Homo erectus , an extinct species of archaic humans, dating back in time to a geographic location found in present-day Sudan.
Although the genealogical map is already an extremely rich resource, the research team plans to make it even more comprehensive by continuing to incorporate genetic data as it becomes available.
“This study is laying the groundwork for the next generation of DNA sequencing. As the quality of genome sequences from modern and ancient DNA samples improves, the trees will become even more precise and we will eventually be able to generate a single, unified map that explains the decline in all human genetic variation we see today.” Wong concludes.
Referencia: Anthony Wilder Wohns, Yan Wong, Ben Jeffery, Ali Akbari, Swapan Mallick, Ron Pinhasi, Nick Patterson, David Reich, Jerome Kelleher, Gil McVean. A unified genealogy of modern and ancient genomes. Science, 2022; 375 (6583) DOI: 10.1126/science.abi8264
