★ 美國亞馬遜網上書店心理學叢書排行榜第17名

人類自認為是地球上的高等動物，有思考能力、能判斷是非，但為什麼人類會用最惡毒的語言來辱罵同類，如「畜生」、「寄生蟲」、「禽獸」等經常出現在政治、宗教、種族和性別的紛爭上。人類的天性難道是對同類不存在尊重嗎？《Less than Human》一書從歷史、心理學、生物學、人類學和哲學等各方面搜集證據，揭露人類對同類缺乏人性的原因。

環顧過去的歷史，不難發現人類加諸於同類的殘暴行為，從古時的奴隸交易到二戰時期的大屠殺、盧安達的種族滅絕，甚至到了21世紀，皆可找到我們對於不同國籍人的無理仇視、對同性戀者的憎惡及種族歧視等。哲學家暨本書作者David Livingstone Smith在新書《Less than Human》中，結合豐富的歷史資料，告訴讀者人類失去人性的例子到處可見，並從心理學到生物學來研究這些喪失人性的模式，以及試圖解釋當中的原因。

作者發現，人類經常殘忍對待同類，其實是根深蒂固的生物特徵，是人性發展的展延性。作者列舉出多個實例加以說明這種展延性在漫長人類史的發展和改變，以致於出現種種令人心寒的暴行。透過簡明表達和詳實說明，我們可以從第三者的角度看待人性的不同層面。

David Livingstone Smith 是新英格蘭大學的哲學系教授，又是該大學認知科學和環境心理學中心的聯合創辦人和主管。他的著作有《Why We Lie and the Most Dangerous Animal》。

"Smith's compelling study and his argument that the study of dehumanization be made a global priority to prevent future Rwandas or Hiroshimas is well-made and important." -- Publishers Weekly

“David Livingstone Smith produces a clear and illuminating vision of why human beings are the way we are and how we got this way. The scholarship is broad, the insight is deep and the prose is compelling. Less Than Human will change the way you think about things that matter profoundly. This is dazzling stuff.”-- Steven E. Landsburg, Ph.D., author of The Big Questions

"This is a beautiful book on an ugly topic. David Livingstone Smith uses the newest research in cognitive science to address the problems of racism, genocide, and atrocity, presenting a provocative theory as to why we come to see others as less than human. There are deep and important ideas here, and this engaging book should be read by anyone interested in the worst aspects of human nature -- and how we can come to transcend them." -- Paul Bloom, author of How Pleasure Works: The New Science of Why We Like What We Like and professor of psychology, Yale University