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Scientists connect 27 million people through DNA

OXFORD, UK (StudyFinds.org) – The world’s largest family tree connecting about 27 million people was created by scientists. The genetic model combines thousands of modern and prehistoric genomes, providing new insight into key events in human history.

This breakthrough is a major step toward mapping the entirety of human relationships, with a single lineage that traces the ancestry of all people on Earth. The family tree also has wide implications for medical research, identifying genetic predictors of disease.

“We basically built a huge family tree, a genealogy for all of humanity that models as accurately as possible the history that generated all the genetic variations we find in humans today. This genealogy allows us to see how each person’s genetic sequence is related to the other, along all points of the genome,” says lead author Dr Yan Wong in a university outing.

The Oxford University team scoured eight databases containing 3,609 different genomic sequences from 215 populations. They included samples from around the world; some being over 100,000 years old. The resulting network contained nearly 27 million ancestors and 231 million ancestral lines.

Tracing the origins of mankind

The tree reveals how people across the world are connected in unprecedented detail. Individual regions of DNA are inherited from either mother or father. Each point can be considered as a tree.

A set — known as a “tree sequence” — connects them to common ancestors where the mutations first appeared. Computer algorithms explain the patterns, predicting when and where they lived. The study covers migration out of Africa, interbreeding with Neanderthals, and the arrival of early humans in Asia and Oceania.

“Essentially, we reconstruct the genomes of our ancestors and use them to form a vast web of relationships. We can then estimate when and where these ancestors lived. The power of our approach is that it makes very few assumptions about the underlying data and can also include modern and ancient DNA samples,” says lead author Dr. Anthony Wilder Wohns.

“The Next Generation of DNA Sequencing”

The past two decades have generated genomes of hundreds of thousands of people. Many lived tens of thousands of years ago. The variable quality and limitations of the analyzes made it impossible to paint an accurate picture until now. The revolutionary technique described in the review Science allows for missing and erroneous data and uses fragmented old genomes.

“This study lays the foundation for the next generation of DNA sequencing. As the quality of genomic sequences from modern and ancient DNA samples improves, the trees will become even more precise, and we may eventually be able to generate a single, unified map that explains the descent of all human genetic variation we see today,” adds Dr. Wong.

The pedigree map could easily accommodate millions of additional genomes as they become available.

“Although humans are the focus of this study, the method is valid for most living beings; from orangutans to bacteria. This could be particularly beneficial in medical genetics, separating true associations between genetic regions and diseases from false connections stemming from our shared ancestral history,” Dr. Wohns concludes.

South West News Service writer Mark Waghorn contributed to this report.