Darwin suggested the appendix may have been used for digesting leaves. This theory is supported by koala and horse appendixes which do just that.
Charles Darwin married his first cousin and had 10 children. 3 died as infants and 3 were infertile. He was the first to raise the question if incest may cause weaknesses in offspring after studying inbred plants in his garden.
In 1877, Charles Darwin traveled to Stonehenge to conduct research on a subject that had long fascinated him: earthworms.
Charles Darwin suffered from diseases he contracted during his 5-year expedition, and eventually died from a parasitic illness that damaged his heart.
Albert Einstein and Charles Darwin both married their first cousins (Elsa Löwenthal and Emma Wedgewood respectively).