Toward a Multi-Scale Theory of Birth and Death Patterns II/Caitlin McShea
Notes by user Caitlin McShea (SFI) for Toward a Multi-Scale Theory of Birth and Death Patterns II
1+ paragraphs on any combination of the following:
- Presentation highlights
- Open questions that came up
- How your perspective changed
- Impact on your own work
- e.g. the discussion on [A] that we are having reminds me of [B] conference/[C] initiative/[D] funding call-for-proposal/[E] research group
Reference material notes
- Here is [A] database on [B] that I pull data from to do [C] analysis that might be of interest to this group (insert link).
- Here is a free tool for calculating [ABC] (insert link)
- This painting/sculpture/forms of artwork is emblematic to our discussion on [X]!
- Schwartz et al. 2017 offers a review on [ABC] migration as relate to climatic factors (add the reference as well).
Venki Ramakrishnan's pre-meeting questions for consideration:
1. Evolutionary theories of aging: All predict increase in mortality with age – something Vaupel and Baudisch and others have argued against. Others say that the apparent reduction of mortality or even a plateau is not because the animal has become more youthful or has stopped aging. Rather by growing larger, stronger or simply more experienced, it is better able to feed and protect itself. Some animals continue to grow for some time even after they start reproducing.
Another issue is the plasticity of lifespan, e.g. hunter-gatherers live much less than humans in modern societies. But the counter-argument is that this is not so different from animals protected in captivity generally living much longer than in the wild. One is removing extrinsic causes of death, which is not the same as preventing aging.
2. Elasticity of lifespan: How extendable is lifespan? Clearly, there was a significant buffer because even though average lifespan was about 40 for most of our history, once extrinsic causes (safety, war etc) were removed, and even just diseases that caused infant mortality, lifespan expanded. Further expansion came when causes of adult mortality (cardiovascular disease, diabetes) were reduced or eliminated. Is there a limit and if so, what is it?
In other words can a living system be rejuvenated indefinitely? How similar is this to organizations, eg. companies or larger units? Or a mechanical device – eg replacing parts? Ultimately what is the limit imposed by chemistry and physics (including second law)?
3. Metabolic theory of aging (I believe I heard this from Geoffrey West): Longevity inversely related to metabolic rate. One example was the number of heartbeats per lifetime being roughly the same for different species. Another is that long-lived species seemed to have very low metabolic rate (naked mole rat?). However, I believe there are exceptions to this.