Aubrey de Grey Versus David Brin on Engineered Longevity
This interview with Aubrey de Grey and David Brin encapsulates the divide in longevity science. On the one side, people who see repair-based methodologies like SENS and the reversal of aging as the best way forward, and who foresee great progress within a few decades after major funding is achieved. On the other, people who look towards changing metabolism to slow aging, and who foresee little progress over the next few decades because the challenge of building a new, viable human metabolism is very, very hard. From de Grey's side of the article: "I think we have a 50% chance of achieving medicine capable of getting people to 200 in the decade 2030-2040. Presuming we do indeed do that, the actual achievement of 200 will probably be in the decade 2140-2150 - it will be someone who was about 85-90 at the time that the relevant therapies were developed. There will be no one technological breakthrough that achieves this. It will be achieved by a combination of regenerative therapies that repair all the different molecular and cellular degenerative components of aging." As a counterpoint, from Brin's side of the article: "I do not expect this any time soon. There are way too many obstacles. First, there is no low-hanging fruit. Simple switches, like the ones that are flipped in many animals, by caloric restriction or celibacy, are there to give creatures a delayed chance at reproduction, if it cannot happen earlier. These switches have already been thrown in humans. All of them! Because we had genuine darwinistic reasons to evolve longest possible lifespans. When the lore held by grandparents helped grandchildren to survive, we evolved a pattern where the tribe would always have a few grandparents around, who remembered stuff."
It seems to me that Mr. Brin isn't really addressing SENS. Calorie restriction is something Aubrey is likewise skeptical of, and tinkering with metabolism is specifically rejected by him.
This isn't quite a debate yet. Instead, it is two theses passing in the night.
Agreed. Let's get some engineers working on this, who want to solve a problem instead of understanding it to death.
Brin not only not discussing SENS at all, he is not discussing any molecular biological argument at all. His discussion is nothing more than hand-waving.
Neurons of rats(which have short lifespans) are said to have similar metabolic rates as those of humans. Yet some human neurons last at least up to 120+years, all while the entire body is breaking down around them.
Assuming whale brains have mostly permanent neurons and similar metabolic rates, these seem to last rumored nearly 200 years.
Now the question is, since these are non-dividing cells, and seem to have high metabolism. What sort of SENS-like related changes has evolution performed? Clearly to go from an animal lasting a few years to centuries something had to be done, especially if the metabolic rate is indeed similar.
Interesting question Flash Program. SENS is all about heavy handed repair interventions. Evolution has created some repair mechanisms, but not all that we might like to have, thus the needs for SENS. We don't know if the differences in the durations of neurons between rats, humans, and whales are due to different repair mechanisms or different metabolic pathways. If the answer is repair mechanisms then that could be useful for SENS, if the answer is metabolic then it's probably useless to us because of the trade-off differences between being human and being a whale.
These do need to be verified.
But if it is true that rat and human have similar metabolic rates, and neurons have been successfully maintained for longer. This presents something very suggestive. We can see that neurons being allowed to function over a century, by whatever means, does not appear to have introduced penalties in the potential functionality of the tissue(e.g. human compared to shorter lived rat).
We have no reason to assume that humans are the ceiling of optimization or that any further enhancements seen in other animals have come at an irreversible cost to potential functionality.