Santa Fe Institute Collaboration Platform

COMPLEX TIME: Adaptation, Aging, & Arrow of Time

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Contact: Caitlin Lorraine McShea, Program Manager,

Towards a Multi-Scale Theory of Birth and Death Pattern II

From Complex Time

Category: Core Theory

Date/Time: September 15, 2021 - September 15, 2021

Location: Hybrid - Virtual and In-person at Miller Campus, Thaw library

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Wednesday, September 15, 2021
9:00 am - 9:30 am Opening Remarks - David Krakauer (SFI)
9:30 am - 10:00 am Potential Modeling Approaches - Annette Baudisch (Univ. Southern Denmark) Download Presentation
10:00 am - 10:15 am Coffee Break
10:15 am - 11:00 am Ontological Considerations - Chris Kempes (SFI)
Thursday, September 16, 2021
9:00 am - 9:30 am Social Individuals - Annette Baudisch (Univ. Southern Denmark) Download Presentation
9:30 am - 12:00 pm General Discussion

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Meeting Synopsis

A universal feature of adaptive systems is that individual agents come into existence—are born—experience a variety of forms of aging or senescence, and then pass out of existence—die—or are outcompeted. This is true for organisms, lineages, companies, cities, and even theories and beliefs. Within this common “life-history” sequence we observe a range of differences in mechanisms and timescales, from oxidative damage and apoptosis in cells, through to the obsolescence of technologies in companies, and the replacement of ideas in science. We also observe commonalities among many of these areas at the level of population dynamics, energetic and informatic constraints, and scaling phenomena.

The universality of life-history raises a number of intriguing questions. How do we identify the individual and how do we decide when it was born and when it died? These will not always be discrete events. At what rate does the individual age, and what sets the upper bound on its longevity? Is aging and death a physical necessity or an evolved or designed complex trait? And how do changes in the selective environment modify the aging process? Perhaps birth, aging and death constitute a critical part of any comprehensive definition of complexity?

Venki Ramakrishnan provided these questions to consider in advance of the meeting. 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.

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