What large number? If life expectancy was around 30y that’s the average age of death. I haven’t found a model of the distribution but I’d expect very few to reach more than 50 years. Moreover it’s not clear early humans could afford to have multiple sequential children. If you have a child at 30 you need to survive until 45 to help it reach adulthood, otherwise it’s useless, and maybe that nearly never happened. Sexual selection could also come into play with humans favoring younger.
Though I’ve read the other post about aging being programmed to ensure innovation and it does make sense.
I heard this argument many times and I find it very implausible. What about the large number of organisms that are not killed by predators? Why wouldn’t evolution make sure that they continue reproducing until they are eventually killed?
Reproduction needs to happen at a certain age because organisms die, not from aging, but from other causes and then they can’t reproduce. One example is that pygmy people were selected to mature earlier (and thus reach a smaller height) because of the high mortality and low life expectancy they experience.
I don’t see it as a coincidence that the age at which aging starts to be deleterious is around the life expectancy of early humans (~30 years). The clock works fine until then, but after that most humans would die from predators or disease or something else and thus there would be no selective pressure for the clock to continue working.
Riccardo, thanks! I think the view that reproduction is supposed to happen at a certain age is flawed. If evolution is is really only about maximizing reproduction, evolution would ensure that reproduction happens at any age.
Great article! Another explanation is that aging is the maladapted continuation of normal organism development, i.e. the organism needs changing gene expressions as it grows into adulthood, and needs a mechanism to control this change. The mechanism, however, doesn’t stop once the organism reaches a certain age, because it was not selected for that, given that the majority of reproduction happens before that age.
I agree that this idea that the epigenome stores information in an analog form doesn’t really make sense. It appears to me that Sinclair confuses the distinction between analog/digital and continuous/discrete. It is a common misunderstanding, but a Harvard professor should know better even if this is not his field of expertise. Besides, methyl groups are either attached to the DNA molecule or not. Thus, we have a clear case of “discrete” here.
Perhaps the winding of DNA strands around histone proteins can be seen as “continuous.” However, down there at the molecular level quantum effects already come into play and we realize that “continuous” is an illusion anyway.
Originally, I planned to write an article about this topic, but I guess nothing interesting about aging could be learned here. As far as I know, nobody in the geroscience community picked up this view that the epigenome is analog.
Hello Gary. It will be very usefull if you can show us the difference between your skin before and after some weeks of application of this product. All the cosmetic try to sell us promise that they can’t honorate
It’s a great article and your questions are good questions. What it demonstrates is that Sinclair doesn’t understand epigenetics. What does “the cellular equivalent of TCP/IP” even mean? Most legitimate scientists are highly skeptical of Sinclair’s work, as they should be, and I think, frankly, that he’s causing considerable harm by endorsing junk science and misleading the public.
Gary, thanks! To make sure that it is not wishful thinking I recommend to make pictures (close-ups) once a week under the same light conditions. After a few months, you can show them to friends and ask them which skin looks younger.