OK, so now imagine yet another person who goes by the label of… yes, you guessed it, Person 3. You can probably also guess that Person 3 lives one day longer than person 2. Once again, I can think of no reason why, where we have two people who live meaningful lives but one lives one day longer, that extra day would not seem worth experiencing. Put another way: If possible would persons 2 and 1 rather not be dead on Wednesday (the last day for person 3) when Monday and all preceding days were worth experiencing? So far as I can see, the answer to that question is, ‘yes’.
There seems to be no reason why this argument should not hold for any number of hypothetical people, each one of which lives one day longer than the last. Person 1 billion lives one more day than person 999,999,999 and we have no reason to suppose that this one extra day should be devoid of meaning.
But how much longer did Person One Billion live compared to good old Person 1 with whom we began our thought experiment? Well, Person One Billion lived for one billion days or, to put it another way, Person One Billion lived for 2.7 million years. That is quite a bit longer than most speculations on life extension ask us to imagine an individual persisting for (‘what if you could live to be 150’?). A person who was one billion days old today would have been born in the Pliocene Epoch when North America was becoming linked to South America via the formation of the Isthmus of Panama and the first recognisable hominins (the species australopithecine) evolved in Africa.
If humanity could achieve biological immortality (which is not true immortality but rather liberation from death through malfunctions of the body due to accumulation of damage over time which manifests as the visible signs of ageing, which obviously leaves one vulnerable to other existential threats like being struck by a falling meteor) or if substrate-independent minds are feasible, perhaps one day, there may indeed be a ‘person one billion’- somebody who experienced 2 million years of life. We imagined a person One Billion alive today would be a human just like us, but we can see from evolutionary history that this would not be the case*. Our ancestors from 2 million years ago were not modern humans, but small apelike creatures. Similarly, a person born today who goes on to experience a further 2 million years of life would likely not remain recognisably human, but rather evolve through technological intervention and the sheer amount of life experience accrued, into another sort of being altogether. Where we are post-ape, this hypothetical person would be post-human. And Person One Billion’s life seems to have no reason to be less meaningful than yours or mine. If anything, it seems extraordinarily privileged to have experienced so much history.
*Actually, an immortal australopithecine would remain an australopithecine rather than transform into a Homo Sapiens Sapiens. This is because evolutionary change occurs over generations as genes are copied and useful mutations accumulate, rather than transform the individual. But in the case of a person born today who went on to live for one billion days, a transformation into another being altogether seems likely, as this would come about thanks to increasingly powerful bio, nano, information and cognitive technologies which today are just beginning to enable us to redesign ourselves and not just our environments. At least, this is the assumption underlining the term ‘Transhuman’.