This interview features Nobel Prize-winning geneticist and cell biologist Paul Nurse exploring the fundamental question, "What is life?" He proposes an answer not through a single definition, but by examining five core biological ideas: the cell, the gene (DNA), evolution by natural selection, life as chemistry, and life as information. Nurse illustrates how these concepts collectively define living organisms as "bounded physical entities" that function as complex chemical and informational machines, possessing a hereditary system with variability that enables them to evolve, adapt, and acquire purpose.
What is Life? A Nobel Laureate's Biological Perspective
0:00 The Fundamental Question: Geneticist Paul Nurse introduces his book "What Is Life?", highlighting the complexity of defining the distinction between living and non-living entities.
1:35 Five Core Biological Ideas: Nurse explains his approach to defining life by dissecting five foundational concepts: the cell, the gene, evolution by natural selection, life as chemistry, and life as information.
2:40 The Cell as Life's Atom: The cell is presented as the simplest, unambiguous unit of life, functioning as both the basic structural and functional entity, capable of growth, division, and reproduction. Nurse shares a personal anecdote of discovering cells under a microscope as a child and credits Robert Hooke with their initial discovery in the 1660s.
7:09 The Ancient Connection Between Yeast and Humans: Nurse's research on yeast cell reproduction revealed that the molecular control mechanisms for cell division are remarkably similar and interchangeable with human cells, indicating an ancient evolutionary origin over 1.5 billion years ago. This demonstrates a deep, shared biological heritage.
13:45 The Gene and DNA's Digital Nature: Gregor Mendel's unappreciated 19th-century work on pea plants introduced the concept of particulate inheritance (genes). Later, Avery's experiment proved genes are made of DNA, and Watson and Crick's discovery of the double helix structure revealed DNA's capacity for digital information storage and precise replication, forming the basis of heredity.
23:50 Evolution by Natural Selection: Described as the "most beautiful idea in biology," Darwin's mechanism of natural selection explains how advantageous variations in hereditary material lead to adaptation and diversification over time, creating "design without a designer."
28:02 Universal Relatedness and Responsibility: A profound consequence of evolution is that all living things are related by descent. Nurse illustrates this through a personal encounter with gorillas in Uganda, fostering a belief in humanity's special responsibility to steward and protect all other life forms on Earth, as they are "all our relatives."
31:12 Life as Chemistry + Information: Life operates through incredibly complex chemistry, with thousands of enzyme-catalyzed reactions occurring simultaneously within compartmentalized cells. This intricate chemical machinery is guided by continuous information management, encoded in DNA, which is vital for coordination, sensing the environment, and maintaining homeostasis (e.g., via negative feedback control).
40:39 Defining Principles of Life: Nurse concludes by summarizing that living things are "bounded physical entities" that function as chemical and informational machines. They possess a variable hereditary system that enables evolution by natural selection, allowing them to acquire purpose through adaptation to their environment.