Should we try to live forever? (with Ariel Zeleznikow-Johnston)

Human lifespan is influenced by an evolutionary trade-off between the speed of reaching reproductive age and overall longevity. Species facing high early mortality tend to reproduce quickly and live shorter lives, while those in safer environments can invest in slower development and longer lifespans.

There's an evolutionary trade-off where genes that favor earlier development and reproduction often come at the cost of later-life longevity. This is due to a limited set of genes that must be calibrated to either accelerate growth or enhance lifespan, a phenomenon called antagonistic pleiotropy.

Evolutionary history shows human lifespans expanded as early-life mortality from violence, starvation, and disease reduced. While genetic changes are slow, continued reduction of early deaths over millennia could theoretically lead to further genetic adaptations for longer lifespans, but modern medical advancements offer faster, non-evolutionary paths.

Preservation techniques exist today that offer a reasonable chance (e.g., a double-digit percentage) of future revival, even though revival itself is still decades away. The preservation part is considered much easier than the revival part, which lacks current validation.

Historically, death was defined by the cessation of heart and breathing, but with modern life support, the definition shifted to 'irreversible cessation of all brain functions.' However, even this is complex, as some brain functions can persist, and reversal of brain function loss is slowly becoming possible.

While minor brain damage like a concussion likely doesn't change a person's identity, extreme damage leading to significant, lasting changes in memory and personality (like in the case of Phineas Gage) raises philosophical questions about whether the original person still exists, even if the individual is still conscious.

Yes, reducing temperature directly slows down the rates of chemical reactions within biological systems. This effectively means less 'stuff happens' over the same period of time, making it analogous to slowing or pausing biological time, as seen in induced hypothermia.

The 'glass state' refers to an amorphous solid formed when biological tissue is cooled with cryoprotectants, preventing the formation of damaging ice crystals. In this state, molecules are jumbled together rather than forming ordered crystals, effectively halting chemical reactions and decay.

While effective for small tissues, cryoprotectants are problematic for larger tissues because they can be toxic, cause dehydration, and do not penetrate large structures like whole brains well. This can lead to significant shrinkage and potential damage, making biological viability difficult to maintain with current technology.

Fixation involves introducing preservative chemicals (fixatives) that permeate all tissues and lock molecules in place, preventing decay and maintaining fine structural integrity without shrinkage or dehydration. This method provides very high-quality structural preservation, though it currently makes direct biological revival impossible.

Brain uploading conceptually involves scanning a high-quality preserved brain at very high resolution to capture all neural connections and properties. This information would then be used to recreate the brain's functions in a virtual, digital format, potentially restoring the original person's consciousness.

Philosophically, this is debated, but a psychological view of personal identity suggests that if an upload retains all memories, personality, goals, and consciousness, it would indeed be the same person. The argument is that physical material constantly changes, and consciousness can have breaks, so the continuation of psychological properties is key.

Neuroscientists surveyed suggest a mouse brain might be uploadable by the 2040s or 2050s, and a human brain by around 2125. However, AI researchers often propose much shorter timelines due to the potential for AI to accelerate scientific discovery.

The historical inability to prevent death has led to 'palliative philosophies' that normalize or even valorize it. However, if technologies emerge to extend life, it's argued that death should be viewed as a problem to be solved, similar to how pain in surgery was once accepted but is now avoided with anesthesia.

People readily support curing specific diseases like cancer or dementia because they are seen as discrete problems. However, discussing lifespan extension in the aggregate can feel 'weird and scary' because it challenges fundamental ideas about human life and raises concerns about societal issues like overpopulation or wealth accumulation.

The hope is that it would foster a stronger connection to the future, encouraging people to take seriously the long-term consequences of their actions. Believing they might live in 2150 or 2200 could motivate them to address current problems like climate change or poverty more proactively.