The most intricate choreography in the dance of life occurs within our dividing cells, where proteins and enzymes whirl to a tune we do not entirely understand as they tease apart and then reassemble in duplicate the complex structure of our genetic code.
Each of our cells contains about six billions base pairs—two letter combinations that collectively represent most of nature’s contribution to who and what we are. Between conception and adulthood, these six billion pairs will be duplicated in each one of us several tens of trillions of times.
Missteps are costly in the dance of genetic replication, and we are just beginning to appreciate the intricate, multi-layered error detection, correction, and mitigation strategies that promote most of us reliably from one cell to a hundred trillion, more or less. One thing we know is that the fidelity of genetic replication is astoundingly high, perhaps on the order of one error for every fifty million base pair replications.
Mutations are discouraged. Most mutations are insignificant changes to obsolete codes, random rearrangements of the scrap heaps in the unused portions of our genes. The mutations that are significant are usually harmful—precursors to cancers, genetic diseases, and death. A small fraction of all mutations confer advantages, but the odds so run against these rare genetic jackpots that biology declines the gamble, seeking instead to invest everything in the genetic status quo.
