The Expression of the Emotions in Man and Animals allows cultural factors only an auxiliary role in the shaping of expression. This biological emphasis leads to an appreciation of the universal nature of expression, with its implication of a single origin for the entire human species; and Darwin points to the significance of emotional communication with children in their psychological development. Darwin sought out the opinions of some leading British psychiatrists, notably James Crichton-Browne, in the preparation of the book which forms his main contribution to psychology. Amongst the innovations with this book are Darwin's circulation of a questionnaire (probably inspired by his cousin, Francis Galton) in his preparatory
Animals' Rights: Considered in Relation to Social Progress Salt is undoubtedly ahead of his age by many years." A new edition of the book was published in 1980 with a preface by the Australian philosopher Peter Singer, who is well known for his work on the ethics of treatment towards animals (specifically in the book "Animal Liberation"). The 1980 reissue prompted a review from Stephen Clark who praised Salt's book with some provisos. He states that Salt's attempt to blame the treatment of non-human animals on the theological doctrine of man having "dominion" over the natural world was mistaken. Animals' Rights: Considered in Relation to Social Progress Animals'