Book Review: Life’s Edge by Carl Zimmer

From the beginning of time, humans have been reading life like a book, trying to search for its hidden theme. Scientists have meticulously analyzed all of life’s elements, from the microscopic nucleotide bases that make up our genetic code, to the oxygen and nitrogen found throughout the universe, providing clues to life galaxies away. Psychologists have studied interactions between humans and animals alike, to pin-point the behavioral qualities that distinguish a being as “living”. Even lawyers have questioned societal assumptions in an attempt to define clear borders between life and death. Carl Zimmer’s nonfiction novel Life’s Edge attempts to address the problem that civilization has yet to solve, by guiding readers on a journey through these scientific revelations, and a journey through its author’s own revelations as he discovers the theme of life for himself. Life’s Edge illustrates that life is not a concept that the human race can truly define or understand, but rather one that each individual must define for themselves.

This idea is explored through the questioning of biological discoveries. The novel describes life’s established “hallmarks”- the criteria needed to qualify as an organism. However, the scientific specificity of the criteria can lead to counterintuitive cases that seemingly defy life itself. For example, Planaria is an organism found in lakes that, when cut, can regenerate. Its existence was viewed with both skepticism and awe, because what was once a single form of “consciousness” became two unique, conscious beings. This philosophical difficulty is completely valid scientifically. Another, similarly difficult example is that of a virus. Such a destructive entity as a coronavirus, that multiplies, mutates, and steals the lives of millions of people, is surprisingly simply structured, contains few genes, and is biologically unalive. If an entity that acts like a living being is not, and an organism that seems to defy life is actually alive, how can anyone claim to accurately understand what life truly is?

Zimmer also outlines past scientists’ attempts to prove that they do understand life, though they eventually fail. Theories of life began with religion, and it was believed that life transcended the descriptions of science. Despite the hallmarks that make life identifiable, there is no clear “force” that makes life unique, and separates it from the nonliving matter that it is composed of. Inevitably, composition of life is traced down to physical particles of matter.

In Life’s Edge, Carl Zimmer’s journey through all aspects of life proves that it is a concept beyond the understanding of society. The novel places a familiar concept in unexplored contexts, and views an age-old question through a spectrum of lenses, whether scientific, philosophical, or even political. Zimmer makes one question society’s understanding of one of the most fundamental concepts of humanity. Perhaps the question of the “meaning of life” is a decision that each individual can only make for themselves.