In this post Ray Peat argues that intelligence is not a fixed genetic trait but a dynamic process shaped by metabolism, physiology, and the environment. Drawing on research from neuroscience, psychology, and animal studies, he contends that chronic stress, social isolation, and rigid educational systems suppress curiosity, learning, and emotional development by increasing serotonin, cortisol, and other stress mediators. In contrast, stimulating, supportive environments promote brain development, resilience, and lifelong cognitive health.

Throughout the article, Peat returns to the idea that healthy brain function depends on healthy energy metabolism. He links excess serotonin and stress hormones to impaired mitochondrial function, reduced neurosteroid production, brain atrophy, depression, learned helplessness, and accelerated aging. While some of his proposed interventions—such as using fruit sugars to support thyroid function—differ from the MetFix approach to carbohydrate intake, both perspectives share the broader view that cognitive function, aging, and chronic disease are rooted in metabolism rather than fixed genetics, and that improving cellular energy production is essential for long-term health.