Largest ever human family tree: 27 million ancestors

Date:
February 24, 2022
Source:
University of Oxford
Summary:
Researchers have taken a major step towards mapping the entirety
of genetic relationships among humans: a single genealogy that
traces the ancestry of all of us.



FULL STORY ========================================================================== [Abstract illustration of | Credit: (c) tai111 / stock.adobe.com]
Abstract illustration of people, world map (stock image).

Credit: (c) tai111 / stock.adobe.com [Abstract illustration of | Credit:
(c) tai111 / stock.adobe.com] Abstract illustration of people, world map
(stock image).

Credit: (c) tai111 / stock.adobe.com Close Researchers from the University
of Oxford's Big Data Institute have taken a major step towards mapping
the entirety of genetic relationships among humans: a single genealogy
that traces the ancestry of all of us. The study has been published
today in Science.


==========================================================================
The past two decades have seen extraordinary advancements in human
genetic research, generating genomic data for hundreds of thousands
of individuals, including from thousands of prehistoric people. This
raises the exciting possibility of tracing the origins of human genetic diversity to produce a complete map of how individuals across the world
are related to each other.

Until now, the main challenges to this vision were working out a way to
combine genome sequences from many different databases and developing algorithms to handle data of this size. However, a new method published
today by researchers from the University of Oxford's Big Data Institute
can easily combine data from multiple sources and scale to accommodate
millions of genome sequences.

Dr Yan Wong, an evolutionary geneticist at the Big Data Institute, and
one of the principal authors, explained: "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. This genealogy allows us to see how every person's genetic sequence relates to every other, along all the points of the genome."
Since individual genomic regions are only inherited from one parent,
either the mother or the father, the ancestry of each point on the genome
can be thought of as a tree. 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.

Lead author Dr Anthony Wilder Wohns, who undertook the research as part
of his PhD at the Big Data Institute and is now a postdoctoral researcher
at the Broad Institute of MIT and Harvard, said: "Essentially, we are reconstructing the genomes of our ancestors and using them to form a
vast network 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 both modern
and ancient DNA samples." 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.

After adding location data on these sample genomes, the authors used the network to estimate where the predicted common ancestors had lived. The
results successfully recaptured key events in human evolutionary history, including the migration out of Africa.

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. Because tree sequences
store data in a highly efficient way, the dataset could easily accommodate millions of additional genomes.

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." ========================================================================== Story Source: Materials provided by University_of_Oxford. Note: Content
may be edited for style and length.


========================================================================== Related Multimedia:
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YouTube_video:_BDI_researchers_create_largest_ever_human_family_tree_
(Oxford_Population_Health) ========================================================================== Journal Reference:
1. 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 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220224140841.htm

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