Biology has become more and more quantitative in recent years and the change has brought new insights and new questions. However, not every student of the subject is yet in tune with that kind of thinking, so that, in writing this introduction to quantitative biology, I have made a point of helping those who do not take to it naturally. Thus, I encourage the making of simple ‘back-of-envelope’ calculations, make the most of simple domestic arithmetic and, in mathematical terms, go barely beyond logarithms and exponentials. I have thus written for two extreme kinds of reader, that is to say not only those who take mathematics in their stride and turn to the book for its biology, but also (paradoxically perhaps!) those many people, uneasy with calculations and equations, who have least natural inclination to read about them. I hope the former will not mind if they find themselves led overmuch by the hand, for I know that advanced knowledge does not preclude ignorance of the elementary, and that ability does not stop one liking an easy read. I assume no prior knowledge of logarithms, knowing that readers who are well able to manipulate them in the context of a mathematics class (especially since the advent of calculators) may yet be unsure of their meaning and usefulness.

My title ‘Biology by Numbers’ is intended to suggest both simplicity and numerical emphasis.