Making Sense of Life: Explaining Biological Development with Models, Metaphors, and Machines (review)

Silly Putty® without the word silly was just mundane putty until 1949, when an unemployed ad man named Peter Hodgson added bright colors to the substance and packaged it in plastic eggs. Silly Putty® became one of the most successful novelty toys of the 20th century, grossing hundreds of millions of dollars in sales and achieving name recognition in more than 95% of American households. Evocative metaphors in science are quite like Silly Putty®: colorful, alluring, simply packaged, widely recognized, enduring, and highly moldable. However, they also have a more serious side.

As models, scientific metaphors can be visual, conceptual, linguistic, digital, mechanical, or mathematical interpretations that encapsulate complex phenomena in oft-brilliant images intended to evoke an enhanced sense of cognition or understanding by the finite human mind. But what constitutes understanding? What counts as knowledge? As explanation? As progress in science? What are the ways of knowing? What do scientists want, and how well do metaphors, models, and machines help to meet those desires? Indeed, what is reality as compared to facsimile, analogy, correspondence, or similitude, and to what extent do the lines blur as metaphorical models improve? Such are the provocative intellectual and epistemological topics that Evelyn Fox Keller eloquently addresses in this insightful book.

The theatrical stage for Keller's treatment is the historical study of animal embryogenesis. Trained as a theoretical physicist, Keller had been indoctrinated in the notion that mathematics and logic provide determining arguments, and that experiential evidence, by contrast, is fallible. Later in life, when she moved into molecular biology, she was aghast to discover that most developmental biologists view experiments and observations as far surer paths to truth. Several sources underlie the differing outlooks in these fields, but an early revelation for Keller was that many biologists interpret the supposed benefactions of mathematical models—their economy of explanation, focus on idealized settings, simplifying assumptions, and pursuit of the theoretically imaginable—as weaknesses rather than strengths. Whereas physicists had canonized these attributes as cardinal virtues, developmental biologists often interpreted mathematical descriptions as pointless window-dressing—perhaps elegant in construct, but ultimately sterile for yielding genuine insights into the nature of complex living beings.

Making Sense of Life is an effort to understand what qualifies as scientific knowledge, using the field of embryogenesis as the touchstone. Divided into three parts, the book traces major empirical and conceptual episodes in the history of developmental biology during the 20th century, and explores the changing landscape of what has and what has not counted as scientific enlightenment in that discipline.

Part 1 summarizes the non-genetic orientation of the first several decades by comparing three scientists' extended metaphors of cellular operations and organismal development. Stéphane Leduc's physical models entailed manipulations of inorganic chemicals (e.g., potassium nitrate on glass slides) and material processes (e.g., osmosis and diffusion) to mirror, as artificial fabrications, biological phenomena such as cell division or the emergence of lifelike morphological structures. D'Arcy Thompson's graphical models and Alan Turing's mathematical representations likewise were developed with the broad intent of illuminating developmental processes. Each of these scientists believed his approach to be of great significance in interpreting the ontogeny of form in the real biological world. Indeed, some of the representations were so mimetic of living operations as to be deemed essentially equatable with them. Keller closely examines these metaphorical constructs in the context of their own times and from the perspective of today. She critically asks, for example, why history made an icon ofThompson and an embarrassment of Leduc, when both developed provocative new ways of looking at the problem of individual development.

Part 2 turns to more familiar models of development that emerged from molecular biology and genetics during the latter half of the century.Terms...