The team explains that these martyrs' remains were doused in turpentine, then cremated. High temperatures can cause DNA to break into very short fragments or even degrade completely. The shorter the DNA fragments, the more difficult they are to extract and sequence.
To tackle the challenge, Wen's team optimized various aspects of their original solutions to specifically target the shorter DNA fragments and obtain the DNA data used for identification. Eventually, they obtained the DNA profiles from 14 remains. They also found that three of the 16 remains were from one individual, enabling them to identify the families of 12 martyrs from Zunyi.
"The DNA of these martyrs is often severely degraded, highly damaged, and heavily contaminated. Also, many of them died very young with no children. After 90 years, their distant relatives are three to five generations removed," Wen says.
