The opening pages of Rebecca Stott’s engaging “Darwin’s Ghosts” find Charles Darwin in his study at Down House. It’s December 1859 and “On the Origin of Species” has been on sale in Britain for a month. Darwin holds a letter from the physicist and theologian Baden Powell accusing him of taking credit for a theory developed by others. It provokes, Stott writes, “a prolonged attack of ­anxiety.”

Darwin had anticipated the charge of plagiarism. Buried somewhere in his notes was a list of predecessors he had planned to acknowledge. With so many enemies lining up against him — venting the expected “disgust and outrage” at his theory of natural selection — he could ill afford to offend his allies. So in the first American edition of “Origin,” he appended a “Historical Sketch” crediting 18 others, including Powell. In subsequent editions, the roll expanded. Stott usefully includes as an appendix the version Darwin added to the fourth British edition, in 1866. It cites over 30 names, many now obscure.

Stott, in her absorbing account, shows that Darwin, who had sat on his discoveries for 20 years, had good reason to worry about his book’s reception. Among many other cautionary tales, there was one very close to home: that of the doctor and poet Erasmus Darwin, his talented and outspoken grandfather. Erasmus — having endured attacks against him in the press and seen the jailing of his publisher — felt compelled to hold back his own major work on evolution until after his death. Charles’s publication of “On the Origin of Species” was precipitated only after he received correspondence from the young naturalist Alfred Russel Wallace, who wrote from the Malay Archipelago, detailing his parallel discovery of the mechanism of natural selection.

Yet Darwin’s hesitation over including the “Historical Sketch” stemmed not from fear of conservative reaction, but from insecurity over his competence as a historian. He was confident about staking a claim to natural selection; descent with modification, however — the theory that, in contradiction of biblical literalism, species changed over time (and that Earth was old enough to allow for this) — was another matter entirely. The age of Earth and the development of species had been concerns of natural philosophers and natural historians since ancient times, and Darwin believed he had been careful not to propose the idea as his own. The complaints of Powell and others showed he hadn’t gone far enough. How, then, could he provide a comprehensive accounting?