Charles Darwin, author of the Theory of Evolution, was born in 1809, the son and grandson of physicians. At age 16, he was sent to study medicine at Edinburgh University in Scotland, but he was more interested in beetles than medicine. At age 22, he was invited to join the HMS Beagle for a five-year sail around the earth, where he collected specimens of plants and animals from around the world. He made lots of friends at school, was the life of the party in college, met all sorts of people when he traveled around the globe, and he was an active hiker and camper.

However, in 1837, at age 26, one year after returning to England from his boat trip around the world, he became terrified to meet people because he would develop, in his own words, a "sensation of fear accompanied by troubled beating of the heart, sweat, trembling of muscles." He no longer went to parties and began to withdraw from society, he was afraid to meet people, and spend his time entering notes in a special journal. He consulted many physicians who at various times diagnosed him as having bad nerves, tropical disease, arsenic poisoning, intellectual exhaustion, dyspepsia, and "suppressed gout".

Today he would be diagnosed as having panic disorder, a condition that usually starts between late adolescence and the mid-thirties. This condition affects an estimated 13 million Americans, manifests itself in unexpected attacks of extreme anxiety, with symptoms including rapid heartbeat, shortness of breath, trembling, sweating, nausea and dizziness. Some victims feel they are losing their minds or are about to die. Many become so obsessively worried about subsequent attacks that they make major changes in their behaviors, shunning whatever situation may have prompted the panic.

Darwin might never have revolutionized biology with his theory of evolution if he had not suffered from chronic mental illness that turned him into a scholarly recluse. When he died in 1882, he was buried at Westminster Abbey next to another giant named Isaac Newton.