Darwin from Descent of Man to Emotions under Domestication" which went on sale on 30 January 1868. He now published his ideas on human evolution and on how beautiful but apparently impractical features could have evolved in "The Descent of Man, and Selection in Relation to Sex". After revising "The Origin of Species" as the definitive 6th edition, his major works on species culminated in "The Expression of the Emotions in Man and Animals". This period was followed by extensive work on insectivorous plants and research into worms. Despite Darwin's concerns that his children were weakened as his wife Emma Darwin was his cousin or had inherited
The Expression of the Emotions in Man and Animals with "ill-temper", sulkiness and determination), Chapter 10 on hatred and anger, Chapter 11 on "disdain, contempt, disgust, guilt, pride, helplessness, patience and affirmation" and Chapter 12 on "surprise, astonishment, fear and horror". In his discussion of the emotion of disgust, Darwin notes its close links with the sense of smell, and conjectures an association with excretory products. In Chapter 13, Darwin discusses complex emotional states including self-attention, shame, shyness, modesty and blushing. Darwin describes blushing as "the most peculiar and most human of the expressions". Darwin closes the book with Chapter 14 in which he recapitulates his main argument: he