What does it mean to be alive? Breathing, eating, thinking and moving are all evidence of life. But through what mechanism are these activities possible? How do bits of matter come together to make us living beings?
The new book "What Does It Mean to Be Alive" looks for answers in the smallest units that make up living organisms. Starting from electrons and molecules, it traces the principles driving the phenomena of life through proteins and DNA, cells and mitochondria, and on to cancer and aging.
The author, Park Mun-ho, earned a doctorate in electronic engineering from Texas A&M University in the United States and spent 30 years on semiconductor research at the Electronics and Telecommunications Research Institute (ETRI). An electronic engineer who has long explored brain science and life science, Park has an unusual background. Earlier books include "The Brain, the Emergence of Thought," "Everything About Brain Science Read Through Pictures" and "How Life Works."
The cell is the key unit for understanding life. The human body is made up of roughly 200 types of cells, including skin cells and nerve cells, and inside each cell countless proteins are built and broken down. Proteins maintain a cell's structure, speed up chemical reactions and transport materials, taking part in nearly every process of living activity.
What makes this striking is that the basic building blocks for this vast array of proteins number only 20 amino acids. Much as 20 beads can be strung in different orders and lengths to make countless necklaces, living organisms combine amino acids to produce proteins with distinct structures and functions. The structures of 160,000 proteins have been determined experimentally so far, and AlphaFold, the artificial intelligence developed by Google DeepMind, has predicted the structures of more than 200 million proteins — figures that show how intricate and complex the world of life is.
Yet the mere existence of proteins and cells cannot explain life. The author stresses that the chemical reactions and flows of energy constantly occurring among them are the essence of living activity. Cells break down glucose, produce energy in mitochondria and repair damaged parts. Life is sustained only when these processes continue without stopping. That is why the author stresses that "being alive is the performance, not the instrument."
One intriguing section is the author's view of living organisms as beings that constantly predict and correct errors. When something goes wrong in that process, survival is threatened. Cancer is the prime example. In the end, being alive is a process of ceaselessly maintaining one's own order against disorder and collapse.
Also drawing attention are the 202 illustrations the author drew himself to explain complex biochemical reactions. It is a painstaking attempt to connect numerous molecules and metabolic processes into something like a single map. Efforts to unpack difficult concepts through a variety of analogies are evident throughout. Still, for all these accommodating explanations, this is by no means an easy introduction. Properly grasping its sweeping content, which ranges across physics, chemistry and molecular biology, requires considerable background knowledge and persistence. 43,000 won.