Darwin biographer Janet Browne contended that the quick and inexplicable way that his mother died had a profound impact on Charles' adult life. Per Scientific American, it was the nature of his loss that Browne said drove Darwin's worries about his and his children's health, which he knew could turn awry at any moment, possibly due to inheriting genetics from his mother's side.
Darwin's anxiety about his own health continued throughout his life and peaked before his 40,000-mile journey from England to South America on HMS Beagle, an expedition that would pave the way for his book "Origin of Species." He was regularly paranoid about physical symptoms that he believed were signs of serious health problems, and described his health issues in his correspondence on the Beagle.
At the end of his life, Darwin had allegedly overcome his fear of death. Before he died of heart disease, he told his wife he was not afraid to die. In a fitting twist of fate, Darwin's theory of natural selection is sometimes used as a way to describe — even rationalize — the inexplicable cycle of life and death and the underlying natural forces that drive it.
