Sir

Evelyn Fox Keller, in her Essay “A clash of two cultures” (Nature 445, 603; 2007), argues that biology may not have general laws and that the approach that is natural to physics would probably not work in biology.

In the opening of his seminal 1917 book On Growth and Form, D'Arcy Thompson quoted the eighteenth-century philosopher Immanuel Kant, who lamented that the field of chemistry had not yet embraced a mechanistic and mathematical expression of chemical phenomena. As a result, according to Kant, chemistry at that time was just a science, rather than a Science with a capital S. Despite Kant's view, however, as Thompson emphasizes, a great quantitative revolution proceeded to transform chemistry into a capital-S Science every bit as rigorous as physics. Thompson goes on to argue that biology is poised for just such a quantitative revolution.

Today, Thompson's thesis is being borne out; biology is becoming an increasingly rigorous quantitative Science that is finding more generality with each publication cycle. Most would agree that mathematical theories of quantitative genetics (including the modern synthesis), populations dynamics, organism interactions, epidemiology, ecosystem processes and growth and metabolism have together revolutionized biology, transforming it into a capital-S Science. This quantitative revolution would have been greatly muted, though, had investigators not been compelled, by Thompson's explicit advice, to identify general patterns and laws, to describe these quantitatively and to search for underlying mechanisms.

In this light, Keller's thesis that biology is a series of exceptional cases is a great leap backwards.

Instead of following Keller's philosophy, biology needs to adhere to Thompson's original roadmap and continue its transformation into a rigorous and quantitative Science. It is not fundamentally different from the physical sciences. Keller is correct to note that biology is often unique, but historical contingency does not preclude the existence of general patterns or mechanisms, and has not limited the development of the arguably more rigorous and quantitative fields of astronomy, geology and economics.

Before accepting Keller's thesis, one must first reject the alternative hypothesis that there are general patterns and that these patterns have their basis in equally general mechanisms. For example, Keller dismisses metabolic networks as one possible law-like phenomenom because 'power laws' are not as ubiquitous as first thought. This is conjecture: a quick glance at the biological scaling literature associated with organismal metabolism, life-history, ecology and even evolutionary dynamics reveals an impressive series of general power-law-like behaviours apparently interrelated by a common mechanistic framework based on organismal metabolism. If there are general patterns with equally general mechanisms, then arguably biology has laws. With bioinformatics, large-scale research networks and new computational techniques, we can rapidly identify the existence of general patterns and illuminate the mechanisms that underlie them.

Reasons to follow Thompson's roadmap for biology could not be more urgent. The need to understand and predict the response of the biosphere to climate change, the spread of emerging diseases, the collapse of biological diversity and the need to improve the human condition through medicine and agriculture — all these demand the development of a quantitative, mechanistic and predictive biology. The viewpoint espoused by Keller does not advance the development of biology into a Science. The future of biology belongs to those who follow Thompson's roadmap.