Charles Darwin struggled with significant health problems. Just less than two weeks before publication of The Origin of Species, Darwin described his condition to his cousin Fox in a letter, stating, “I have had a series of calamities; first a sprained ankle, and then badly swollen whole leg and face; much rash and a frightful succession of Boils—4 or 5 at once. I have felt quite ill—and have little faith in this ‘unique crisis’ as the Doctor calls it, doing me much good. I cannot now walk a step from bad boil on knee.”

Things that Darwin once found pleasurable as a young man turned on him. By 1865, at the age of fifty-six, Darwin summed up his problems in writing to a new medical adviser by writing that for twenty-five years he had experienced extreme flatulence, preceded by ringing ears and visual black dots, and vomiting preceded by shivering and crying.

In 1871, one year before the publication of the sixth and final edition of The Origin of Species, in a letter to his natural selection collegue, Alfred Wallace, Darwin confided: “present I feel sick of everything, and if I could occupy time and forget my daily discomforts, or rather miseries, I would never publish another word.”

Time and health took a toll on Darwin’s mind: “I have said that in one respect my mind has changed during the last twenty or thirty years. Up to the age of thirty, or beyond it, poetry of many kinds, such as the works of Milton, Gray, Byron, Wordsworth, Coleridge, and Shelley, gave me great pleasure, and even as a schoolboy I took intense delight in Shakespeare, especially in historical plays. But now after many years I cannot endure to read a line of poetry: I have tried lately to read Shakespeare, and found it so intolerably dull that it nauseated me. I have also lost my taste for pictures or music.”

What caused Darwin’s life-long health problems? To explain why Darwin experienced such poor health, scientists have pointed to a one night event east of the Andes near Mendoza in March 1835—Darwin wrote: “At night I experienced an attack (for it deserves no less a name) of the Vinchuca, a species of Reduvius, the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over one’s body.” Darwin is thought to have been bitten by an insect called the “Great Black Bug of the Pampas” carrying the infectious parasite Trypanosoma cruzi.

For over a period of forty years, Darwin suffered intermittently from various combinations of symptoms such as malaise, vertigo, dizziness, muscle spasms and tremors, vomiting, cramps and colics, bloating and nocturnal intestinal gas, headaches, alterations of vision, severe tiredness, nervous exhaustion, dyspnea, skin problems such as blisters all over the scalp and eczema, crying, anxiety, sensation of impending death and loss of consciousness, fainting, tachycardia, insomnia, tinnitus, and depression. However, since attempts to test Darwin’s remains at the Westminster Abbey by using modern PCR techniques have been refused by the Abbey’s curator, the real cause of Darwin’s health problems remains only speculative.