Long before humans genetically engineered plants and animals, cells have been using Natural Genetic Engineering to evolve more rapidly.
Biological evolution consists of variation and selection. Variation means change to the DNA. But where does useful variation come from?
In the past, scientists have thought that variation consists of random mutations, that is, errors during replications. Thanks to sequencing of entire genomes, scientists now know that most of the useful variation comes from “Natural Genetic Engineering.” Natural genetic engineering includes several molecular systems within that have emerged over time. These systems cut and paste entire working sections of DNA from one part of the genome into other parts of the genome.
Slides: How Does Natural Genetic Change Happen? Natural Genetic Engineering of Genome Structure