How your DNA can reconstruct history

DNA contains genetic segments inherited from groups that interbred in the past. Scientists have mapped some of the intermixing.

Story highlights

  • Genetic admixure: When people from different groups interbreed
  • There have been many instances of this happening
  • Researchers used DNA to track historical mixing
Most people are carrying around historical records in their DNA, with clues to how people from genetically distinct groups intermingled over the last 4,000 years. That's the conclusion of a new study in the journal Science.
Researchers set out to pinpoint which groups intermixed, and when, over thousands of years, using modern DNA. They thought this information could complement other historical records.
"The results suggest DNA is indeed a powerful means of reconstructing history, which then might be used to identify the genetic legacies of historically well-attested events ... and highlight surprising events with a less clear historical context," authors Garrett Hellenthal and Simon Myers wrote in an e-mail.
The scientists have created an interactive map showcasing their findings. You can explore the map in detail on the researchers' website, admixturemap.paintmychromosomes.com.
The technical term for people from genetically different groups having babies together is "genetic admixture." This has happened throughout history when people migrated into a new geographic region where others were already living.
Researchers say there have been many such admixture events among people from populations that were separated by thousands of miles. Sometimes populations adjacent to each other have distinct ancestry and history.
Did you know that your DNA contains genetic segments you've inherited from groups that intermingled in the past? Researchers can look at these signatures for clues about major historical mixings of populations.
DNA from a person today can also give scientists an idea of how long ago two groups genetically mixed.
The more time that has passed since the admixture event, the shorter the inherited DNA segments from the original groups are likely to be. That's because there would have been more generations in between, and there would have been reshuffling of genetic material in each generation.
There are limitations to the method, however. When genetic mixing involves more than three groups, the researchers can't identify those specific events. The researchers were also limited in how well they could estimate when the same, or very similar, groups interbred on multiple occasions in one descendant group's history.
The researchers looked at a genetic data set of 1,490 people who come from 95 genetically distinct groups worldwide. Their software, Globetrotter, was able to describe