Why death? Is death an inextricable consequence of life? If not, where did death come from? In Sex and the Origins of Death, William R. Clark looks at life and death at the level of individual cells to address questions such as why we age, why cells die, and why sex and death seem to go hand in hand. Dr. Clark examines two kinds of death: "accidental death," caused by physical injury, starvation, or extreme cold or heat, and "programmed cell death," controlled by genes written into our DNA. We learn that every cell in our body has a self-destruct program written into it, and that cell suicide is a fairly common event throughout life.

But why do our cells have such programs? Why must we die? To shed light on this question, Clark reaches far back in evolutionary history, to the moment when "inevitable death" (death from aging) first appeared. For cells during the first billion years, death, when it occurred, was accidental; there was nothing programmed into them that said they must die. But fierce competition gradually led to multicellular animals - size being an advantage against predators - and with this change came cell specialization and, most important, germ cells in which reproductive DNA was segregated from the DNA used to operate individual cells. When sexual reproduction evolved, it became the dominant form of reproduction on the planet, in part because mixing DNA from two individuals gemerates altogether new germline DNA. During this process, most mutations that have crept into germline DNA are corrected. But this does not happen in the other (somatic) cells of the body; the mutations are not corrected, and continue to accumulate. The somatic cells become, from a genetic point of view, both superfluous and dangerous. Nature's solution to this dilemma, Clark concludes, was programmed death - the somatic cells must die. Unfortunately, those somatic cells are us. Death is necessary to exploit to the fullest the advantages of sexual reproduction.

In Sex and the Origins of Death, Clark ranges far and wide over fascinating terrain. Whether describing a 62-year-old man having a major heart attack, and how his myocardial cells rupture and die, or discussing curious life forms that defy any definition of life (including bacterial spores, which can germinate after decades of inactivity, and viruses, which are nothing more than DNA or RNA wrapped in protein), this brilliant, profound volume illuminates the miraculous workings of life at its most elemental level and finds in these tiny spaces the answers to some of our largest questions.

All human death begins with the death of individual cells, the smallest units of which we can say, "These are alive." To understand the death of a cell is, in an ultimate biological sense, to understand the death of a human being. How does a cell die? What is it missing in death? Why do cells die? The study of death is full of surprises - for example, the widespread existence of cell suicide. The necessity for cells to die seems to have arisen at about the same time that cells began experimenting with sex as a means of reproduction. It may have been the ultimate loss of innocence.

"Traversing the microcosm where sex is easily untangled from reproduction, Clark's book, an exciting voyage to the center of death, is full of life."
- Lynn Margulis, Distinguished University Professor
University of Massachussetts, Amherst

"An exemplary job."
The Washington Post Book World