Yes, that Hayflick. RIP.
Interesting article.
https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.0030220
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Interesting (I mean something more akin to deceptive or misguided) to frame an exercise in analytic objective definition (like a dictionary definition that simply unpacks a concept) in terms of a causal empirical explanation. âDefinition of a phenomenonâ and âwhat causes that phenomenonâ should be distinct and separate tasks.
I would expect an objective analytic definition to be agnostic about which empirical scientific explanations best fits the evidence about what is being defined. The definition (not the explanation) should be acceptable prior to any final decision about how to explain what is being defined (in this case either âagingâ or âlongevityâ).
For example, if I defined the physical experience of âbeing shockedâ as the experience of âhaving a ghost touch meâ I would confuse explanation and definition. It would exclude someone saying that the experience of being âshockedâ was caused by electricity passing through your body to the ground.
The definition of âbeing shockedâ needs to not confuse or exclude possible explanations (such as the electricity explanation hypothesis). An agnostic definition of âbeing shockedâ would be more like âan intense physical sensation that tenses the musclesâ.
This definition (the agnostic one) should aim to be acceptable to adherents of either (any) explanation. The person putting forward the ghost hypothesis and the other putting forward the electricity hypothesis.
Hayflick seems to sneak his explanation into his definition crowding out any disagreement as simply definitional confusion.
They changed the second law of thermodynamics and didnât tell me? Entropy is applicable outside of a closed system according to the footnote number 5 of the linked article. I still suspect old Ike Newton might be correct with apologies to Dr. Hayflick.
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I love that the source for âthe recent reinterpretation of the Second Law of Thermodynamics, where the belief that it only applies to closed systems has been overturnedâ is entropysite.com whose URL has now been overturned to some generic sprawl in Mandarin.
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I think you can definitely calculate the entropy of certain cellular states and show they increase in aging. Thereâs plenty of papers doing this with the methylome, for example.
But I donât see this as much of an explanation, because there are clearly âforcesâ that resist this process and slow (or accelerate) aging to various degree within or across species. Life is an open system and thereâs plenty of ânegative entropyâ to go around. Why we become incapable of using it to maintain homeostasis with age is the real question.
Also, the robustness of cellular differentiation and the findings from the cellular reprogramming and rejuvenation fields suggest to me that aging on human timescales isnât due to an irreversible process of increasing entropy. Of course there may be some irreversible loss of information with aging (DNA indels, for example), but I believe we can reverse many of the epigenetic changes that occur in aging, we just have to find the right buttons to push.
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There is an interesting comment in this article from 2009 interviewing Leonard Hayflick (RIP) Life and Health: Physics and Aging | Vision "Repair, synthesis and turnover (i.e., maintenance processes or longevity determinants), keep the balance in favor of more repair than damage until after reproductive maturation, or the species will vanish. After that time, the balance slowly shifts so that maintenance cannot keep up with molecular damage. "
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