Charles Darwin wrote a brilliant small treatment on Expression of Emotion, not just in Human, but all other creatures, it is a recommend reading; The Expression of Emotions in Man and Animals (1872)
But by the early 1870s he felt confident enough to openly discuss the evolution of humans from animals. He did this in “The Descent of Man” (1871) and in this book, “The Expression of Emotions in Man and Animals” (1872).
In his 1872 book The Expression of the Emotions in Man and Animals, famed naturalist argued that human expressions of emotion were both innate and universal across cultures. Researcher and emotion expert Paul Eckman has found that, for the most part, the used to convey basic emotions tend to be the same across cultures.