Scientists say they have discovered the oldest DNA on record. It was found in the teeth of mammoths that lived in northeastern Siberia up to 1.2 million years ago. A mammoth was a kind of early elephant that lived during the Ice Age. The discovery may lead to a greater understanding of the long-dead species. DNA is the substance that carries genetic information in the cells of living things. The researchers say they recovered and sequenced DNA from the remains of three mammoths. The remains, which were contained in permanently frozen ground, were discovered beginning in the 1970s. But scientists at the time did not have the ability to find and remove the DNA. The oldest of the three mammoths was discovered near the Krestovka River in Siberia. It was about 1.2 million years old. Another, from near the Adycha River, was between 1 to 1.2 million years old. The third, from near the Chukochya River, was around 700,000 years old.