As a young boy, Charles Darwin made friends easily but preferred to spend his time taking long, solitary nature walks. (As an adult he was no different. “My dear Mr. Babbage,” he wrote to the famous mathematician who had invited him to a dinner party, “I am very much obliged to you for sending me cards for your parties, but I am afraid of accepting them, for I should meet some people there, to whom I have sworn by all the saints in Heaven, I never go out.”)