Homeostatic Capacity and Functional Longevity: 3rd Edition

Homeostatic capacity—a concept analogous to resilience, strength, buffer, robustness, antifragility, and antifrailty—is the efficiency of an autoregulatory system to maintain functional homeostasis against ubiquitous stressors and entropy. The interaction of homeostatic capacity and stressors determines health. We envision a model for healthy, functional longevity based on evaluating and improving homeostatic capacity.
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Homeostatic Capacity and Functional Longevity

Homeostasis is a relatively stable state of equilibrium. Homeostatic capacity (or allostatic capacity, buffering capacity, compensatory capacity, or autoregulatory capacity) is the efficiency of an autoregulatory system to maintain functional homeostasis. The interaction of homeostatic capacity and stressors determines health. We envision a model for healthy, functional longevity based on evaluating and improving homeostatic capacity.
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Heart Rate Variability as a Biomarker of Longevity with Dr. Joon Yun

Is Heart Rate Variability the best biomarker of the time to track our longevity? In this episode, we look at why HRV may be the best way to track how well you are aging and the bets being placed on it in Silicon Valley to drive innovation in anti-aging and longevity research.

Previously we’ve looked at using HRV for training and recovery, stress management, and tracking hormesis. If you are new to biohacking, HRV is an easy economical way to start tracking. All one needs is a heart rate strap and phone app.
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Ebola and Secondhand Stress

Fear is contagious. Natural selection has wired us to sense fear in our surroundings and make it our own. Zebras might not get ulcers from chronic stress but those that fail to activate their acute stress response when others around them are stressed are more likely to miss cues of threat and be consumed by a predator. Absorbing secondhand stress from others is a survival instinct—an adaptation shaped by prehistoric environments to promote evolutionary fitness.

However, our culture is evolving faster than our ability to biologically evolve. Too often, we helplessly rubberneck trainwreck events—often sensationalized by media for attracting attention and profit—despite their remote connection to our personal survival.  For example, fear of the Ebola virus in recent weeks has become more viral than the virus itself. In the modern technology age where fear memes can spread around the globe near-instantly, our tendency to absorb secondhand stress from our ubiquitous, 24/7 media culture to activate our own stress response can produce maladaptive responses that are out of proportion to the actual threat.
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Secondhand Stress: It’s Real

You are probably aware of the concept of second-hand smoke, which increases the risk of disease and death. You should probably be aware of another deadly scourge: second-hand stress.

Natural selection has wired us to sense the stress of others and make it our own. If you are a gazelle and you don’t freak out when others around you do, then you might be the one about to be consumed by a predator you haven’t seen yet. Animals detect the stress of others through various sensory signals such as alarm calls, olfactory cues, or visual behaviors. Plants detect distress signals of others in the form of ethylene gas that activates their own stress response (fittingly, second-hand smoke contains ethylene). The ability to detect second-hand stress is a survival instinct that can promote evolutionary fitness.
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Heart Disease and Evolutionary Medicine

Although heart disease is common today, it was likely a far less frequent cause of death than predatory assaults among our prehistoric ancestors. Anyone reading this article is the fortunate descendant of an unbroken lineage of organisms that escaped or survived predatory attacks before reproducing.

The responses that help us survive predatory attacks are collectively called the fight-or-flight system. This system drives three major vascular responses to injury: coagulation (to counter blood loss), vasoconstriction (also to counter blood loss), and inflammation (to combat microorganisms and to promote wound healing). Together they helped our predecessors survive a predator’s bite. These responses are called upon reflexively no matter what the source of injury.
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The Next Black Swan: Global Depopulation

We’ve all heard the thesis on real estate investing: “They’re not making any more land.” It turns out that before too long we may not be making enough people either.

Global population has been expanding since antiquity, interrupted by wars, disasters, pandemics, and famine. Malthusian predictions of overpopulation, unsustainability, and resource depletion have also been a part of conventional wisdom since antiquity and remain popular today (see Paul Gilding’s “The Earth is Full” TED talk). It is, after all, a common trait of the human mind to assume that the past is an accurate predictor of the future.
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Therapeutics as the Next Frontier in the Evolution of Darwinian Medicine

Evolutionary medicine (also referred to as Darwinian medicine) is the application of evolutionary theory to the understanding of human ailments.1 2 3 It explores evolutionary mechanisms of disease, offering a complementary framework to the proximate mechanistic explanations that prevail in medicine today. In this paper, we consider the application of evolutionary theory to the treatment of ailments.

A major contribution of evolutionary medicine is the framing of human diseases as maladaptations of our prehistoric factory settings. Our physiologic processes were shaped during prehistoric evolution to meet the needs of the era, but those same processes may behave maladaptively in the modern environment and produce disease. We take that notion one step further and propose an overarching therapeutic paradigm for human ailments based on evolutionary theory—the induction of adaptations in the body as a way to treat disease. It is the idea of creating somatic traits in the body that evolution might otherwise need to create over many generations through the sheer force of variation and natural selection. In the same way, that evolution has endowed us with traits that shield against biotic and abiotic stress to maintain homeostasis, we propose treating patients by endowing the body with buffers against ailments.
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Darwinian Rubbernecking


This year marks the 50th anniversary of “American Girl in Italy”, Ruth Orkin’s iconic photograph of men ogling Ninalee Craig as she walked down a street. Despite the cultural stigma now attached to its practice, the rubbernecking of young beautiful women is an everyday phenomenon. From an evolutionary perspective, prehistoric males who did not instinctively tune to visual cues of potential mates with beneficial traits and fecundity would face adverse natural selection pressure. Presumably, males living today have inherited the tendency to rubberneck nubile females because such proximate behaviors translated to improved ultimate fitness during natural selection.

In similar fashion, people driving by a car accident turn their heads to look. In nature, an organism that does not tune to signals of carnage is ignoring potential useful cues of threat in their vicinity and could be subject to elimination. Our tendency to rubberneck trauma, thus, is an adaptation inherited through evolution through the survivorship bias of those who attended to cues of stress that can improve our Darwinian fitness.
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Ethylene: The Most Important Molecule You’ve Never Heard Of?

Ethylene is a gaseous hydrocarbon with the molecular structure C2H4. It is commonly produced when hydrocarbons are exposed to oxidative stress, such as that found during lightning, volcanic eruptions, forest fires, and photochemical reactions on the ocean surface. Plants coopted ethylene biosynthesis during evolution to manage their response to oxidative stress from biotic and abiotic sources. Further exaptations of ethylene include modulation of plant life history events such as development, transformation, senescence, and death.

Due to a number of factors described below, humans may be subject to increasing ethylene exposure. The potential health consequences of ethylene exposure are not part of the public consciousness and warrant further exploration.
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