Humans have long thought of their bodies and minds as separate spheres of existence. The body is physical—the source of aches and pains. But the mind is mental; it perceives, remembers, believes, feels, and imagines. Although modern science has largely eliminated this mind–body dualism, people still tend to imagine their minds as separate from their physical being. Even in research, the notions of a “self” that is somehow distinct from the rest of the organism persists. But such ideas are increasingly barriers to discovery and understanding, and a new framework is needed. I propose that a human being can be characterized as a composite or ensemble of four fundamental, parallel, entwined realms of existence that reflect our evolutionary past and account for our present ways of being—biological, neurobiological, cognitive, and conscious. All four are, deep down, biological. But the neurobiological realm transcends the biological, the cognitive transcends the neurobiological, and the conscious transcends the cognitive. We each exist uniquely within our own realms every moment of adult life, and together our realms account for all of what and who we are. The four realms also give us a way to evaluate how we, as an individual person, social group, culture, or species is similar to and different from other individuals, social groups, cultures, or species. Even if two species both have cognitive or conscious realms does not mean they think, feel or experience quite the same. Yet, they are more similar to one another than organisms that lack those realms.

The biological realm makes life possible. Hence, every living thing exists biologically. Animals, uniquely, supplement biological existence with a nervous system. This neural component enables them to control their bodies with speed and precision unseen in other forms of life. Some animals with nervous systems possess a cognitive realm, which allows the creation of internal representations of the world around them. These mental models are used to control a wide range of behaviors. Finally, the conscious realm allows its possessors to have inner experiences of, and thoughts about, the world.
Together, LeDoux shows, these. They cooperate continuously and underlie our capacity to live and experience ourselves as beings with a past, present, and future. The result, LeDoux shows, is not a self but an “ensemble of being” that subsumes our entire human existence, both as individuals and as a species.


Joseph LeDoux is a University Professor and Henry and Lucy Moses Professor of Science at New York University, where he also directs the Emotional Brain Institute. His work is focused on the brain mechanisms of emotion, memory, and consciousness. LeDoux, who has received a number of awards for his research, he is an elected member of the American Academy of Arts and Sciences and the National Academy of Sciences USA. He is also the author of several books, including The Emotional Brain, Synaptic Self, Anxious (2016 APA William James Book Award), and The Deep History of Ourselves (finalist for the 2020 Pen America E.O. Wilson Award for Literary Science Writing). LeDoux is also the 2023 President of the Association for the Scientific Study of Consciousness, as well as the lead singer and songwriter in the rock band, The Amygdaloids, and in the acoustic duo So We Are.