The Descent of Man by Charles Darwin

"Man still bears in his bodily frame the indelible stamp of his lowly origin."

In this sequel to Origin of Species, Darwin tackles the subject he avoided in his first book: us. He applies the theory of sexual selection to human evolution, arguing that humans share a common ancestor with the great apes.

It was shocking then and remains powerful now. Darwin explores intelligence, morality, and race (with the biases of his time, which are important to understand historically). A critical text for understanding the biological roots of human behavior.