27 MILLION ANCESTORS: SCIENTISTS CREATE LARGEST HUMAN FAMILY TREE

Sat 26 January 2022:

Scientists have developed the largest human family tree ever, allowing people to learn about their distant ancestors in a major step toward mapping the full of human genetic ties.

Human genomes were constructed from a number of sources — both ancient and modern DNA — by scientists from the University of Oxford’s Big Data Institute in order to better understand human history and evolution.

The study, published on Thursday in the journal Science, predicts common ancestors, including approximately when and where they lived, they said.

“We have basically built a huge family tree, a genealogy for all of humanity that models as exactly as we can the history that generated all the genetic variation we find in humans today,” said Yan Wong, an evolutionary geneticist at Oxford’s Big Data Institute.

“This genealogy allows us to see how every person’s genetic sequence relates to every other, along all the points of the genome,” Wong, one of the principal authors of the study, explained.

The set of trees, known as a “tree sequence” or “ancestral recombination graph”, links genetic regions back through time to ancestors where the genetic variation first appeared, they said.

The research intends to offer a complete map of how individuals across the world are related to each other.

Dr Wong said: “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 accurate and we will eventually be able to generate a single, unified map that explains the descent of all the human genetic variation we see today.”

Dr Wohns added: “While humans are the focus of this study, the method is valid for most living things; from orangutans to bacteria. It could be particularly beneficial in medical genetics, in separating out true associations between genetic regions and diseases from spurious connections arising from our shared ancestral history.”

The study integrated data on modern and ancient human genomes from eight different databases and included a total of 3,609 individual genome sequences from 215 populations. The ancient genomes included samples found across the world with ages ranging from 1,000s to over 100,000 years. The algorithms predicted where common ancestors must be present in the evolutionary trees to explain the patterns of genetic variation. The resulting network contained almost 27 million ancestors.

The study combined data from eight separate databases on present and ancient human genomes, resulting in 3,609 individual genome sequences from 215 populations stretching back over 100,000 years.

To explain patterns of genetic variation, computers projected where common ancestors must be present in evolutionary trees. Almost 27 million ancestors were found in the resulting network.

SOURCE: INDEPENDENT PRESS AND NEWS AGENCIES

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