The Expression of the Emotions in Man and Animals is discussed in detail by Lucille Ritvo.John Bowlby makes extensive reference to Darwin's ideas in his presentations of attachment theory. Constitutional (psychosomatic) theories of personality were elaborated by Paul Schilder (1886 - 1940) with his notion of the body image, by the psychiatrist Ernst Kretschmer and in the (now largely discredited) somato-typology of W H Sheldon (1898 - 1977). The biology of the human emotions was further explored by Desmond Morris in his (richly illustrated) popular scientific book "Manwatching".In 2003, the New York Academy of Sciences published "Emotions Inside Out: 130 Years after Darwin's The Expression of the Emotions in
Emotion in animals as when rolling and rubbing. Therefore, purring can be generally considered as an indicator of "pleasure" in cats. Low pitched bleating in sheep has been associated with some positive-valence situations, as they are produced by males as an estrus female is approaching or by lactating mothers while licking and nursing their lambs. The argument that animals experience emotions is sometimes rejected due to a lack of evidence, and those who don't believe in the idea of animal intelligence, often argue that anthropomorphism plays a role in individuals' perspectives. Those who reject that animals have the capacity to experience emotion do