Natural Causes: An Epidemic of Wellness, the Certainty of Dying, and Killing Ourselves to Live Longer

by Barbara Ehrenreich

Perhaps one of the examples best known to biologists is the phage lambda, a virus that preys on that familiar resident of our guts—the bacterium E. coli. A virus is a strand or two of nucleic acid, usually DNA, coated with protein, visible only through an electron microscope, yet in the course of their development phage have a crucial choice to make: When one of them penetrates an E. coli cell, it can either remain there in a state of dormancy, passively reproducing its nucleic acid when the cell divides, or it can immediately lyse the cell—splitting it open and releasing a swarm of progeny to invade other E. coli. Acres of paper have been filled with differential equations in an effort to predict which way an encounter between phage and E. coli will go, with the result that the outcome seems to depend on decision making by individual phage.