The Ancient Origins of Addiction and Its Implications for Today

Why do so many individuals find it difficult to stop drinking, quit smoking, or resist endless social media scrolling? Addiction affects millions worldwide and is often misinterpreted as a personal weakness or moral failing. However, scientific research reveals that addiction is deeply rooted in the ancient structure of the human brain.

Stanford Medicine researchers are investigating how our evolutionarily designed reward system can be hijacked by addictive substances and behaviors.

"We have an old brain in a new environment," explains Keith Humphreys, Ph.D., an addiction expert at Stanford Medicine. "This vulnerability wasn't significant for most of human history until modern commerce and industrial chemicals made highly addictive substances easily accessible."

Addiction is not a defect but an unintended consequence of survival mechanisms built to seek rewards. When we engage in beneficial actions, such as eating or seeking shelter, our brain releases dopamine, reinforcing those behaviors. These reward pathways have been conserved across millions of years and species, driving us to pursue what makes us feel good.

In the past, when survival depended on scarcity, seeking pleasures that released dopamine was crucial. Today, however, our exposure to highly stimulating foods, nicotine, alcohol, drugs, gambling, and digital media triggers rapid and intense dopamine surges, often more powerful than natural rewards.

This overstimulation can cause the brain to adapt by reducing dopamine receptor sensitivity, leading to difficulty experiencing pleasure from everyday activities—a phenomenon known as tolerance. For example, nicotine use initially boosts focus and mood, but over time, the brain compensates by creating more receptors, making users need more nicotine simply to feel normal, not to get high.

Genetics, impulsivity, emotional regulation issues, and early exposure all influence addiction susceptibility. Younger individuals are more vulnerable, as their brains are still developing until about age 25, making early substance use particularly risky.

Understanding these neurobiological foundations is transforming addiction treatment. Abstinence-based strategies, such as a 30-day reset, help re-establish neural balance. Medications like nicotine patches, varenicline, and emerging therapies including plant-derived drugs and psychedelics are part of evolving treatment options.

Furthermore, medications initially designed for other conditions, like GLP-1 receptor agonists, have shown promising benefits in reducing cravings for alcohol, food, and nicotine.

Recovery involves rewiring the brain’s reward system—an often slow and persistent process. Withdrawal symptoms and cravings can last months or years, influenced by "addiction memories" linked to routines and environments. Successful treatment necessitates understanding that these adaptations are not about lack of willpower but about the brain's deep-seated changes.

With appropriate support, the brain's capacity to recover is remarkable. Restoring natural reward responses can bring joy back into daily life, reconnecting us with meaningful activities, relationships, and well-being. The ongoing research at Stanford offers hope for more effective strategies to combat addiction rooted in our ancient brains.