Genome duplication is the trigger for evolution. Complex multicellular organisms have evolved from simple unicellular organisms by genome duplication and other genome rearrangements. Genome duplication can be of two types: whole genome duplication in which a diploid organism becomes a tetraploid and provide whole set of additional genes i.e for every old gene a new copy is provided. This type of change is considered to be responsible for major changes in organisms including speciation. The second type of duplication is called segmental duplication or copy number variation. Here only a part of the genome gets duplicated and provide additional copies of only those genes in the duplicated regions. This type of variation is considered to be responsible for differences among closely related organisms for example between monkeys and humans. Immediately after sequencing genomes of chimp and other primates Scientists were expecting to find a segmental duplication of genomic regions possessing genes associated with the brain i.e neural system but were not successful.
Recently two groups of Scientists led by Evan Eichler and Franck Polleux have found a part of the missing clue. They identified segmental duplication that led to
