John Desmond Bernal (1901-71) was a tireless utopian visionary, Communist idealist, peace campaigner and womanizer. He was also a prolific writer, gifted crystallographer, molecular physicist and social scientist. Such a crowded life was colourful and influential, but sometimes enigmatic. Previous biographies of Bernal have been judged either controversial or incomplete, but Andrew Brown has tried hard here to be objective. Clearly, the dust generated by such an ebullient figure takes time to settle.

Bernal’s brilliance dazzled intellectuals, impressed statesmen and intrigued women. His wild shock of hair gave him the appearance of being permanently electrocuted, and emphasized an arrogance that could antagonize those already irritated by his extreme views and unorthodox lifestyle. Able to discourse knowledgeably and coherently about almost any subject, “Sage”, as he was known to friends and colleagues, was a pioneer of X-ray crystallography in the 1920s and helped to create the new science of molecular biology.

Many of those who worked with him went on to become major players in these fields. Imaginative and free with his ideas, Bernal’s mind blazed like a firework, and he probably gave away much scientific credit that was his due. With his attention continually pulled in many directions, he lacked the dedication to see vital scientific problems through to their conclusion.

In his impressionable youth, major events shaped Bernal’s world – the First World War, the Russian revolution and the struggle for Irish independence. (Bernal was Irish, although he lived most of his life in England.) After an early conversion to Communism along with other Cambridge intellectuals, he remained stubbornly committed to this cause for the rest of his life.

Bernal also became legendary for his promiscuity. Almost every woman he met was seen as a sex object, with his partners participating in and/or tolerating peripheral but torrid relationships. While these numerous women must have suffered, his career seemed to have been fuelled, rather than hindered, by such a rampant libido, which bizarrely contrasted with an otherwise ascetic lifestyle.

Beginning at the Royal Institution, London, in 1923 under W H Bragg, Bernal brought a new rigour to X-ray crystal analysis, which continued when he moved several years later to the Cavendish Laboratory, Cambridge. Probably his contributions there would have gained more recognition had it not been for a clash of attitudes with the omnipotent Ernest Rutherford.

One of Bernal’s Cambridge research assistants was Dorothy Crowfoot (later Hodgkin), who almost inevitably became a Bernal sex partner. Less inevitably, she went on to win the 1964 Nobel Prize for Chemistry. Others who came under Bernal’s influence also went on to achieve Nobel status: in 1962 John Kendrew wrote to Bernal “You’ve fathered five Nobel prizes this year alone”. (In light of Bernal’s promiscuity, “fathered” may or may not have been chosen deliberately.) More Nobels came later to other of Bernal’s colleagues.

In 1937 Bernal left Cambridge for Birkbeck College London, where he inherited the chair left vacant following Patrick Blackett’s move to Manchester University. In what was a chain reaction of professorial movements, Blackett took over from Lawrence Bragg, who replaced Rutherford at the Cavendish following the latter’s death. All this led to Cambridge losing its pre-eminence in nuclear physics and resetting its sights on X-ray crystallography and molecular biology. However, its later successes in these fields, which rivalled Rutherford’s earlier achievements in nuclear physics, built on the firm foundation that Bernal had left.

The 1930s also saw Bernal becoming an active Communist. While he knew Guy Burgess, Anthony Blunt and presumably whoever else was working covertly at the time, he does not appear to have become involved in such espionage. Brown points out that Bernal – a prestigious Irish scientist with a US mother – could easily have emigrated to the US at the outbreak of the Second World War. Instead, he preferred to stay in Britain and became fully involved in applying science to the war effort, where he was trusted by Lord Mountbatten, who was then head of Combined Operations. These exciting exploits, with Bernal frequently and literally in the front line, are vividly described.

While Britain and the Soviet Union were allies, Bernal’s allegiances were not questioned. It was only with the outbreak of the Cold War that his unconventional politics stood out. Some of Bernal’s wartime colleagues later thought that his personal accounts of this era had been exaggerated, adding to the controversy surrounding an already enigmatic figure. These claims and counter claims are well documented in Brown’s book.

After the war, Bernal rebuilt the research effort at Birkbeck, despite lamentable funding. It went on to play a major role in UK and world science, attracting among others Rosalind Franklin and Aaron Klug. Intriguingly, a wall at the college was adorned with a mural drawn by visiting peace activist Picasso in 1950.

Meanwhile, Bernal’s love affair with Communism continued. He was a staunch supporter of the fraudulent geneticist Trofim Lysenko, Stalin’s emperor of Soviet science. In 1953 Bernal wrote a grotesque eulogy “Stalin as a scientist” that embarrassed his colleagues, although it led to him being awarded the prestigious Stalin Peace Prize later that year. Bernal was a reliable apologist for Stalin and for Soviet decisions, including the 1956 invasion of Hungary.

In the 1930s Bernal had written several influential books on the impact of science on society. He resumed this effort in the 1950s, producing his monumental Science in History, which went through several editions to keep pace with scientific and political developments. He also wrote the popular The Origin of Life.

Bernal was an impressive and fascinating figure, often for conflicting reasons. Brown’s biography is a vivid and balanced account of this full and colourful life and its times. The book makes compelling reading, whether one is interested in molecular biology or not. The chapter entitled “The physical basis of life” alone provides a good overview of the development of molecular biology, in which Bernal played a vital pioneering role. One pity is that the index is incomplete, which is unfortunate for a book that provides such valuable material on the history of science in the 20th century.