A team of scientists has combined modern and ancient genomes to build a new genealogy of everyone, which is an achievement that sets the groundwork for future studies into our evolution and global spread. According to new research published in Science, thousands of modern and ancient human genomes have been integrated into a unified genealogy. The largest human genealogy ever created contains nearly 27 million ancestors and is akin to a family tree. The new map could be used to study human evolution and even help with medical research related to hereditary diseases. We have built a huge family tree, a genealogy for all of humanity, that models the history that generated all the genetic variation we find in humans today, according to an evolutionary geneticist at the Big Data Institute. The network shows how individuals around the world are related to each other, and it predicts common ancestors, including when they lived and where they came from. Key events in human history include human migrations out of Africa and dispersals to other parts of the globe. The challenge has been in making sense of it all from a larger,holistic perspective, as researchers have been collecting human genomes for years. Different methods of gathering the data, multiple databases and differing data quality have made it difficult to compare these genomes. The problem is compounded by the fact that each human genome contains segments from multiple ancestries, such as Neanderthals and Denisovans. The challenge is that these ancestries exist across vast timescales. The researchers are claiming that they have achieved what is needed, and that is the use of algorithms that can accommodate these challenges.
Wong and his colleagues applied a non-parametric tree-recording method to modern and ancient human genomes to create a map. I reached out to Sharon Browning, a biostatistician at the University of Washington who wasn't involved in the research, to get her take on the achievement.
The paper is about a new tool for genetic studies called tskit, which is short for tree sequence kit. It's called a tree because if you trace back one small part of the genome in a number of individuals, you can find a single descendant like Eve.
The evolutionary family tree is predicted by looking at genetic variation. Because the genomes are tagged, it predicts where the common ancestors lived.
The lead author of the study said in the Oxford release that they are reconstructing the genomes of our ancestors and using them to form a vast network of relationships. Our approach makes very few assumptions about the underlying data and can include both modern and ancient DNA samples.
The earlier version of tskit had promise, but it turned out to have limitations. She said that the researchers have addressed the limitations and provided a tool that should be extremely useful across many different types of study. Although the authors provide a couple of applications, including their cool visualization of where human ancestors came from, the scope of possible applications is very large, and I would expect to see a flurry of activity from researchers developing these.
Browning cautioned that the trees estimated by tskit don't come with uncertainty measures, so she expects the results to be useful for new hypotheses.
As the system arrives, the team hopes to add new genetic information. The system can accommodate millions more and they don't expect this to be a problem.
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