In this insightful conversation, neuroscientist Lisa Feldman Barrett reveals her groundbreaking research on brain evolution. She challenges the outdated triune brain theory popularized by Plato and Carl Sagan, arguing for a unified brain design shared among all mammals. Listeners will discover how hunting and predation spurred an evolutionary arms race that shaped brain development. Barrett also emphasizes the brain's ultimate purpose and the metabolic costs of intelligence, inviting a profound reconsideration of our understanding of this intricate organ.
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insights INSIGHT
Brains Are Extremely Costly
Brains consume ~20% of human metabolic energy despite being ~3 pounds in size.
Lisa Feldman Barrett emphasizes that brains are metabolically expensive organs shaped by energy constraints.
insights INSIGHT
Triune Brain Model Is Misleading
The triune brain idea posits three layered brains: lizard, limbic, and cortex.
Lisa Feldman Barrett explains this layered model doesn't match evolutionary relationships among species.
insights INSIGHT
A Common Brain Plan Explains Differences
Molecular genetics showed brains didn't evolve in sedimentary layers but follow a common plan across mammals.
Variation arises from differing developmental timing that scales brain regions, not adding layers.
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Plato famously described the human psyche as two horses and a charioteer: One horse represented instincts, the other represented emotions, and the charioteer was the rational mind that controlled them. Astronomer Carl Sagan continued this idea of a three-layer, “triune brain” in his 1977 book The Dragons of Eden.
But leading neuroscientist Lisa Feldman Barrett challenges this idea of the brain evolving in three layers, instead revealing a common brain plan shared by all mammals and vertebrates. The development of sensory systems led to the emergence of the brain, and hunting and predation may have initiated an arms race to become more efficient and powerful predators.
Despite advances in neuroscience and genetics, the question of why the brain evolved remains elusive. But Feldman Barrett’s fascinating exploration of the brain’s evolution offers insights into the most important functions of this complex organ, and invites us to think more deeply about the origins of our own intelligence.
0:00 What a brain costs
0:21 The triune brain (aka lizard brain) theory
1:24 Plato, Carl Sagan, and the making of the myth
2:35 Debunking the ‘lizard brain’ theory
3:39 How the first brain evolved
5:49 The brain’s ultimate job
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About Lisa Feldman Barrett:
Dr. Lisa Feldman Barrett is among the top 1% most-cited scientists in the world, having published over 250 peer-reviewed scientific papers. Dr. Barrett is a University Distinguished Professor of psychology at Northeastern University with appointments at Harvard Medical School and Massachusetts General Hospital, where she is Chief Science Officer for the Center for Law, Brain & Behavior. She is the recipient of a NIH Director’s Pioneer Award for transformative research, a Guggenheim Fellowship in neuroscience, the Mentor Award for Lifetime Achievement from the Association for Psychological Science (APS) and from the Society for Affect Science (SAS), and the Distinguished Scientific Contribution Award from the American Psychological Association (APA). She is an elected fellow of the American Academy of Arts and Sciences, the Royal Society of Canada, and a number of other honorific societies. She is the author of How Emotions are Made: The Secret Life of the Brain, and more recently, Seven and a Half Lessons About the Brain.
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