The Deep History of Ourselves

June 1, 2019
An in-depth examination of "the place of human beings in the nearly four-billion-year-long history of life." Humans are the only creatures that talk, reason, and reflect on who we are, but all organisms do many of the same things we do to survive, writes LeDoux (Science and Psychiatry/New York Univ.; Anxious: Using the Brain To Understand and Treat Fear and Anxiety, 2015, etc.). Plenty of popular authors describe the history of life, but LeDoux wants readers to remember as well as enjoy, so he divides his book into short, pithy chapters, each explaining a single evolutionary advance. Four billion years ago, something acquired the ability to extract energy from its surroundings and to reproduce, so it fit the definition of "life." To continue living, it had to survive by avoiding dangers and pursuing necessities. The author emphasizes that action and even learning and memory don't require a nervous system. "Behavior is not...primarily a tool of the mind but of survival," he writes, continuing, "the connection of behavior to mental life, like mental life itself, is an evolutionary afterthought." Creatures without nerves did fine for several billion years. Primitive hydra evolved a simple nerve net that enabled much quicker responses, but since the net was generalized, hydra behavior is identical no matter what part of its body is stimulated. Its close kin, jellyfish, developed the first concentrated collections of neurons to control specialized actions such as swimming and prey capture. Nervous systems and then brains gradually grow more complicated, and LeDoux delves into the nature of awareness, perception, deliberation, memory, language, emotion, and, finally, consciousness. Like all good educators, the author begins simply. The first half of the book is a superb overview of evolution; the second half gradually focuses on brain structure and function. Readers will learn a great deal of deep neuroscience, although, despite a generous stream of illustrations, they will need to pay close attention. A dense but expert history of human behavior beginning at the beginning.

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July 1, 2019

Neuroscientist LeDoux (neural science, psychology & psychiatry, New York Univ.; Anxious) draws a hard line in the sand between the human mind and that of all other species. In the first part of this two-part volume he takes readers on a long journey through the evolutionary tree of life, emphasizing the physical features and behaviors that connect all life forms. The second part focuses on those mental faculties that separate Homo sapiens from other animals: cognition, consciousness, memory, and the capacity of the human brain for language, reasoning, and culture. In his view animal brains lack this functionality, and he takes issue with scientists such as Frans de Waal, Marc Bekoff, and Jane Goodall, whose research shows that animals have emotions and other states of consciousness comparable to those of humans. Chapters are short, easily digested essays, but the sections on theories of consciousness and memory are highly technical and, despite helpful illustrations, may cause the general science reader to glaze over. VERDICT Recommended for those with a strong background in evolutionary cognition who enjoyed Daniel Dennett's From Bacteria to Bach and Back. For an alternate viewpoint on animal cognition turn to de Waal's Are We Smart Enough To Know How Smart Animals Are?--Cynthia Lee Knight, Hunterdon Cty. Historical Soc., Flemington, NJ

Copyright 2019 Library Journal, LLC Used with permission.

July 8, 2019
The eons-long development of the mechanics of thought—and other aspects of life—are covered in this sprawling, sometimes indigestible treatise from NYU neuroscientist Le Doux (The Emotional Brain). Surveying the rise and evolution of life-forms out of the primordial soup, he highlights such milestones as the acquisition of neurons by jellyfish and the arrival of mammals with their structured brains. Le Doux then focuses on the neuroscience of how brains process information and control behavior, elaborating on two themes: that, contrary to conventional wisdom, one’s emotions do not cause one’s behaviors and that, contrary to anthropomorphism, nonprimate animals may not have emotions, or even consciousness. The book contains provocative, sometimes unsettling descriptions of experiments, by Le Doux and others, that demonstrate how much seemingly conscious, willed behavior is actually unconscious and automatic, along with detailed discussions of the complex interactions of perception, memory, emotions, and cognition that underlie consciousness. However, Le Doux’s writing tends to bog down in impenetrably dense terminology: “The dorsal and ventral lateral prefrontal cortex regions also receive inputs from the multimodal convergence zone in the neocortical pareital and temporal lobes.” Though this exhaustive study brings up some fascinating concepts, the often arcane presentation will deter all but the most devoted of lay readers. Agent: Katinka Matson, Edge.

Starred review from July 1, 2019
Roger Penrose?much-acclaimed theoretical physicist?predicts that scientists will pierce the mystery of human consciousness by applying as-yet-undiscovered concepts in quantum mechanics. While Penrose hopes for future breakthroughs, LeDoux delves into already-completed evolutionary research to explain the neurobiological origins and dynamics of human consciousness. For LeDoux, the character of human consciousness actually grows clearer if we simply set it aside as irrelevant to the impulses manifest in most of the behaviors necessary for survival. To explain how humans face danger, seek food, eliminate bodily waste, and engage in sex, LeDoux examines biological scripts traceable all the way back to the first one-celled creatures. In this narrative, humans' reflective awareness accompanies but does not govern such fundamental behaviors. Still, LeDoux recognizes that only reflective consciousness (which he discerns in no nonhuman species) could have created the human race's most inspiring ethical and moral principles. Indeed, LeDoux sees humankind in a crisis that the slow process of biological evolution will not resolve. He believes only self-conscious minds willing to resist selfish impulses can avert a species calamity. Though they may wonder how natural selection alone could have forged a consciousness capable of such selflessness, readers have good reason to ponder LeDoux's concluding challenge. Refreshingly lucid treatment of profound questions.(Reprinted with permission of Booklist, copyright 2019, American Library Association.)