The lifelong illness suffered by the great biologist Charles Darwin (1809 - 1882) has been long puzzled-over and mis-diagnosed. Some diagnoses are incomplete, accounting for just a few symptoms, and some are plain wrong. Others have attributed it to psychiatric illness. Darwin's Chronic Illness is a medical detective story: one that offers an entirely new account of this mysterious illness and a novel solution to its nature.

In the first five chapters, Adam Wilkins and John Hayman sketch the history of the illness and how its symptoms developed over many years, surveying previously proposed explanations and their inadequacies. The authors then explore, for the first time, a pattern of related illnesses in Darwin's maternal family tree, the Wedgwood family, tracing its roots back to an event that occurred a billion years ago.

In the second half of the book, Wilkins and Hayman discuss the basics of mitochondrial biology, demonstrating how Darwin's specific symptoms may well have reflected a mitochondrial deficiency. They explore how this idea might be tested and the difficulties of doing so; definitive proof, one way or the other, may not be possible. Finally, the authors return to Darwin: the man, his creativity, his interest in evolution, and how this illness and prognosis relate to all three. What would Darwin have made of the plethora of hypotheses about his illness? Chronic conditions in the world today and the centrality of mitochondrial function to health and disease are linked back to Darwin's illness in the concluding chapter.