Cancer-Causing Mutations Can Occur By Chance as Millions of Cells Divide

“When the DNA double helix was first revealed by Watson and Crick in 1953, its structure seemed perfect and robust, well-designed to resist most of the disruptive influences that might be present inside living cells. For example, the bases in the double helix are turned inward and thus are not very susceptible to direct attack by chemical mutagens. Moreover, the linkages between adjacent bases were found to be resistant to cleavage by alkaline ions that arise continually in the cell.

“But while the double helix itself is relatively resistant to chemical attack, the process of maintaining a cell’s genetic integrity has a weak link. The vulnerability derives from the need to replicate the cell’s genome each time the cell goes through the process of growth and division. The resulting duplicate copies of the genome enable the mother cell to endow each of its daughters with a genome precisely equivalent to the one that it carries itself.

“This process of DNA replication has flaws. On occasion, a cell will miscopy a sequence of its DNA prior to cell division, and as a consequence, one of its daughters will receive a slightly miscopied genome, in effect a mutated one. Even the best-functioning cells will occasionally miscopy one in a million (or ten million) bases during each cycle of DNA replication. Hence, cell growth and division create vulnerability mutation.

“This imperfection suggested another way cancer formation might be accelerated. Agents that promote cell growth will indirectly create mutations simply because they force cells to replicate their DNA. More DNA copying means more inadvertent copying mistakes, hence more mistakes.”

Testing DNA Function Through Gene Transfer

“By 1979, another strategy for searching for elusive tumor oncogenes came online. This new approach did not depend on the knowledge gained about retroviruses. It was an independent strategy made possible by the experimental technique of gene transfer. Simply put, gene transfer made it possible to extract DNA (and thus genes) from one cell and introduce these genes into a second cell. The genes introduced into the recipient cell might cause it to take on new traits or behaviors. Such a response would indicate that the information specifying the newly displayed trait was present in the donor cell (from which the DNA had been prepared) and that this information could be conveyed to a recipient cell by the transfer of DNA molecules.” (p. 38)

Agency or Personal Choice and Genetics

“There is an inescapable component of heritability to many human behavioral traits. For virtually none of them is heredity ever close to predictive. Environment, particularly childhood experiences, and the prominent role of individual free will choices have a profound effect on us. Scientists will discover an increasing level of molecular detail about the inherited factors that undergird our personalities, but that should not lead us to overestimate their quantitative contribution. Yes, we have all been dealt a particular set of cards, and the cards will eventually be revealed. But how we play the hand is up to us.” (p. 263)

DNA Can Predispose But Not Predetermine Homosexuality

“An area of particularly strong public interest is the genetic basis of homosexuality. Evidence from twin studies does in fact support the conclusion that heritable factors play a role in male homosexuality. However, the likelihood that the identical twin of a homosexual male will also be gay is about 20 percent (compared with 2-4 percent of males in the general population), indicating that sexual orientation is genetically influenced but not hardwired by DNA, and that whatever genes are involved represent predispositions, not predeterminations.” (p. 260)

Finding Peace Between God and Science

“Will we turn our backs on science because it is perceived as a threat to God, abandoning all of the promise of advancing our understanding of nature and applying that to the alleviation of suffering and the betterment of humankind? Alternatively, will we turn our backs on faith, concluding that science has rendered the spiritual life no longer necessary, and that traditional religious symbols can now be replaced by engravings of the double helix on our altars?

“Both of these choices are profoundly dangerous. Both deny truth. Both will diminish the nobility of humankind. Both will be devastating to our future. And both are unnecessary. The God of the Bible is also the God of the genome. He can be worshiped in the cathedral or in the laboratory. His creation is majestic, awesome, intricate, and beautiful–and it cannot be at war with itself. Only we imperfect humans can start such battles. And only we can end them.”