hitting DNA pay dirt

If scientists want to study ancient DNA, they usually extract it from fossils, the remains of ancient plants and animals. But molecular biologists from the University of Copenhagen found DNA in dirt instead. They drilled cores up to 100 feet deep in the Siberian permafrost, analyzed the frozen soil, and hit a jackpot of DNA fragments. As they report in the April 18 Science, they found the oldest authenticated plant DNA and the DNA of animals, some long extinct. The permafrost contained DNA from woolly mammoth, bison, reindeer, and musk ox, dating back 30,000 years, as well as the DNA of herbs, mosses, trees, and shrubs, some of which lived nearly 400,000 years ago — the oldest yet found. Much of the plant DNA is probably from roots, which would have been well protected underground, and the animal DNA is thought to come from cells sloughed off in their feces. The team also looked at samples of silt from New Zealand, and again were able to recover DNA from various plants and animals, showing that soil does not need to be frozen to obtain identifiable DNA. The new technique of analyzing soil may help reconstruct past ecosystems, helping researchers gain a better picture of the prehistoric world.

This news brief appeared in the Random Data column of the Boston Globe’s Health/Science section on 4/29/2003.