Mummy's foot. Close-up of the foot of an Egyptian mummy on autoradiograms. The autoradiograms are X- ray prints made from DNA extracted from the foot. DNA (deoxyribonucleic acid) is the molecule responsible for carrying the genetic code. It holds the code as a series of pairs of bases along the length of the molecule. The dark bands on the autoradiogram represent the positions of specific bases in the DNA, and thus the genetic code. This DNA fingerprint" is different for every individual, and familial traits can be traced by studying it. Taking DNA from preserved humans gives a good account of how humans spread across the world from the point of their evolution."