How Jumping Genes Alter Our Wiring Why are no two human brains alike?
Medical geneticists say it could be that jumping genes rearrange our mental structure.Jumping genes, or transposons, are bits of DNA that can move freely about the genome. For unknown reasons, they either travel to a new spot or paste copies of themselves into random stretches of DNA, sometimes wreaking havoc. Transposons are already thought to be responsible for some mutations in sperm and eggs, such as the genetic changes that cause hemophilia. But scientists had no clue that these restless genes might be active elsewhere. University of Michigan geneticist Fred Gage and his colleagues found that a transposon called LINE-1 readily moves around in the brains of mice, suggesting that the same gene may do likewise in humans. The reshuffling seems to take place starting before birth and continuing throughout life in places like the short-term memory center. According to Gage, not only do humans have a much higher proportion of transposons in their genomes than other animals but the LINE-1
