Genomic Data Reveals the Biggest Human Ancestral Tree of 231 Million Lineages

In an effort to deliver a rough draft of the human genome, two groups of researchers joined forces in June 2000. What began as an incomplete map of the human chromosomes has now bloomed into a trove of individualized sequences from various corners of the globe and stretching as far back as possible in several cases.

Human Genome: A History of the Human Race

Researchers faced several obstacles to reaching a unified interpretation. The sheer mass of data alone proved to be a worthy opponent. The subtle differences in retrieved samples, diverse formats, and analysis techniques that prioritized different errors were difficult for researchers to cross.

Now in a recent study published in the journal Science, titled "A unified genealogy of modern and ancient genomes," researchers from the University of Oxford's Big Data Institute have made a great step towards the ultimate goal by merging more than 3,600 individual genome sequences from 215 populations across the globe into one enormous tree - the biggest human ancestral tree.

The branches of the human genome ancestral tree comprise 231 million ancestral lineages. At the tree's base, a spread of roots was represented by eight ancient human genome sequences, including thousands of smaller snippets used to confirm their place deep in humanity's past.

Among the eight roots, three Neanderthal genomes were placed. One of which came from a Denisovan, a small family of early humans living in Siberia roughly four thousand years ago.

Anthony Wilder Wohns, a geneticist that led the study, explains that essentially researchers were reconstructing genomes of humanity's ancestors and used the samples to form links in the evolutionary tree to complete the 'tree sequence.'

He adds that we can now estimate when and where our human ancestors lived using the data.

Ancestral Family Tree

For the researcher's case, a tree sequence better finds the correlations between various tree branches to make the large pools of sequences and information easier to analyze.

By turning the immense number of data into graphs with nodes representing the various lineages and mapping the mutations along the edges, a massive genetic database was squeezed into a smaller space while still being easily accessible by algorithms designed to search for noteworthy statistics and reports ScienceAlert.

In a statement with Big Data Institute, Wohns explains that the power of the team's approach is that it makes significantly fewer assumptions regarding the underlying data and can include both ancient and modern DNA.

Incorporating geographical location labels on the sequences allowed the team to estimate where common ancestors might have thrived and how they moved during their era. Not only does the study reveal events that many researchers have suspected, such as how humans initially migrated from Africa, it also hints at changes in population densities of human ancestors that we're still learning about, like the Denisovans.

Thanks to the process's efficiency, the largest human ancestral tree has a lot of room to grow as more genomic data becomes available in the near future. Adding millions more genomic sequences will only make any further results more accurate in pinpointing where novel sequence fits in a genealogy that stretches across the globe.

Yan Wong, a BDi evolutionary geneticist, says that genealogy allows researchers to see how a person's genetic sequence relates to others and pinpoint the similarities of all genomes.