Biographies sometimes separate people from their work or, conversely, that work from the people concerned. It is as if home life (family, children, hobbies, friends) is quite irrelevant to the daily toil (9 to 5, laboratory, office, colleagues). Nature’s obituaries are written as if the scientists did nothing else with their time on earth than science. Apparently the recently departed whose work it celebrates never had parents, childhoods, schools, wives, offspring, diseases or vacations, let alone interests and activities quite distinct from the role that earned them their salary, the honours, the fame, and their status in society.

Consequently, after only flicking through Marek Kohn’s book, I was hooked. Called, somewhat excessively (and even misleadingly), A Reason for Everything, it is more about the reasons for, and reasoning behind, selected evolutionists, those who have taken Charles Darwin’s views on natural selection and honed them as they thought fit. The chosen individuals are Alfred Wallace, Ronald Fisher, J. B. S. Haldane, John Maynard Smith, Bill Hamilton and Richard Dawkins, but others are encountered as the book proceeds, such as Julian Huxley, E. B. Ford, David Lack, Bernard Kettlewell, and Philip Sheppard. In fact think of a name likely to be there, and it is there.

These scientific lives are portrayed as a splendid medley of personal idiosyncracy, wrongful turnings, bizarre or crucial thinking, and steady nudging towards a greater understanding of their chosen goal. At once I should declare a personal interest. I first met Bill Hamilton within Amazonia (and therefore read his chapter first). This man, both large and impish, careful and yet casual, strode through the forest determined to find wasps. He hit the vegetation vigorously, and the insects then found him, stung him, and were promptly captured. He also, in that place where even the botany strikes back, put his hand down holes ‘to find out what was there’. I longed to ask him how he had lost some finger joints, and also why he had not lost the lot.

In Kohn’s deeply researched volume I met many of the answers to the questions I had not dared ask, and also, quite gently, how Hamilton’s remorseless thinking made others say he was the greatest evolutionist since Darwin. Alas, but he died aged 62 from cerebral malaria caught in Africa. (Of course he had not been taking prophylactics. Putting hands down holes, and blowing fingers off with home-made fireworks, are not likely to be followed by taking anti-malarials.)

The science within this book is not tackled head on. It percolates, slowly at first, and then wholeheartedly, much as an idea gains ground within a head. There is a mammoth index, which helps, but the book is best read as an adventure story, with the people developing, the ideas growing (or subsiding), and everything intermingled. Biographies, in my opinion, should blend work, ambitions, foibles, advances, retreats, and the whole panoply of lives well lived. Of course Kohn's book is not a reason for everything, but it makes a particular branch of science most reasonable, along with its principal – and often unreasonable – advocates.

Extreme Measures by Martin Brookes is less wide-ranging and concentrates almost entirely on Francis Galton. There is no index, and the book can be read most easily, it reaches page 103 before its hero settles down (from travelling, and the honours this had awarded him) in order to pursue, more determinedly, his zest for numbers, for measurements, and for conclusions to be drawn from such analysis. His undoubted energy, vitally stimulated by his half-cousin’s publication concerning the origin of species, sends him fearlessly into the unknown. If something could be measured, he seemed to say at every turn, it could be better understood. He did not greatly care if his opinions were resented. After all, Charles Darwin’s views were bitterly attacked, and Galton’s clashes with the Church, in particular, did not displease him.

This book states, even in its blurb, that Galton often let his obsessions run away with him. Indeed they did. One trouble was, being a polymath, he had so many of them. Of course our Society applauds the man for he did initiate so much, and it is undoubtedly intriguing to learn more in Brookes' most attractive account how Galton used the simple fact of measuring to learn, to formulate, to irritate, and also to educate in so very many different areas.

Anthony Smith