In 1859, Charles Darwin published a book called On the Origin of Species that completely changed our understanding of how biodiversity arises.
Sitting on the sofa, you flip through a family photo album. You see a young man dressed in a uniform from the 1940s. Your father looks a lot like the man in the black and white photograph. You flip another page and go further back in time. You see a woman in a Victorian style dress, and you think she looks like your sister.