This majestic mammal roamed grassy plains of the Northern Hemisphere until it became extinct about 10,000 years ago. The scientific breakthrough allows for the first time comparion of this ancient species with today's populations of African and Indian elephants, not just at the level of mitochondrial sequences, but also encompassing information from the nuclear genome.
Analyzing organellar DNA from mitochondria has been the only method of studying ancient DNA in the past, as it is more tractable due to its 1000-fold higher copy number per cell. However, the mitochondrial genome codes for only a tiny fraction of an organism's genetic information -- 0.0006 percent in the case of a mammal. In contrast, most hereditary information is organized on chromosomes located in the cell's nucleus (nuclear DNA). A mammoth was chosen for study in part because of its close evolutionary relationship to the African elephant, whose nuclear DNA sequence has been made publicly available by the Broad Institute in Cambridge, Massachusetts (USA). Using comparisons with elephant DNA, the researchers identified 13 million base pairs as being nuclear DNA from the mammoth, which they showed to be 98.5 percent identical to nuclear DNA from an African elephant.
The project became possible through the discovery of exceptionally well preserved remains of a mammoth skeleton in the p