Clearer Thinking with Spencer Greenberg Should we try to live forever? (with Ariel Zeleznikow-Johnston)
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Aug 22, 2025 
In this captivating discussion, neuroscientist Ariel Zeleznikow-Johnston shares insights on human longevity and how it compares to other species. He examines the fascinating evolutionary trade-offs in lifespan and reproduction, while speculating on future technologies like stasis and cryonics. The conversation delves into the fluid concept of death, questioning traditional definitions and addressing consciousness and identity in light of technological advancements. Zeleznikow-Johnston challenges us to rethink our relationship with life and death, raising intriguing philosophical questions along the way.
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Surgery Uses Temporary 'Paused Time'
- Deep hypothermic circulatory arrest cools patients to ~18–20°C to pause brain activity for surgery.
- Patients often regain core memories and have high survival rates after rewarming.
Glass-State Cooling Prevents Ice Damage
- Cooling plus cryoprotectants can avoid ice crystals by forming an amorphous 'glass' state.
- Glass preservation halts molecular motion and is analogous to storing embryos for decades.
Fixatives Preserve Structure At Cost To Revival
- Chemical fixation (aldehydes) preserves brain structure across tissues without shrinkage.
- Fixation yields high structural fidelity but likely prevents near-term biological revival.
