AHS 2012

What a great conference!  I had heard such high praise for the inaugural meeting of the Ancestral Health Symposium last August, but I was too late to register in 2011.  This year I submitted an abstract that was accepted as a poster presentation.   For those who missed it, I’ve attached a copy of my presentation below.

What an edifying and uplifting experience! We just wrapped up three days of excellent talks, panels, poster presentations and plenty of informal networking and socializing. This conference is really the hub of the Paleo movement. The emphasis was on the most recent developments in the scientific, cultural, political, and practical approaches to overcoming the contemporary health epidemics that derive from a mismatch between contemporary lifestyles and the biology of our evolutionary heritage.  The talks and panels were diverse, covering nutrition, cholesterol, cancer, immune health, farming, exercise, and many other topics.

My previous post of July 15 contains links to the webpage of the Ancestral Health Symposium, where you can read about its purpose and review the program of speakers and other presenters.  The conference certainly did not disappoint.

The program was composed of formal podium presentations, panel discussion and poster presentations. There were formal poster presentation sessions right after lunch on Friday and Saturday, where the poster presenters stood by their posters, provided a short overview, and then engaged in extensive Q&A. I liked this format very much because it maximized interaction and allowed me to meet many long time followers and newly interested people.  I was also able to continue discussions next to the poster throughout the day at various times.

Many of you who could not attend may be interested in learning more about my presentation and how it was received.

My talk was a very high level summary of what I’ve written about on this blog over the past two years.  It very well received and I was overwhelmed by the level of interest in hormesis.  My presentation started with a general overview of hormesis and a number of practical examples of how to apply it.  Since it would have been impossible to cover every application, I selected three to focus on:

  • Calorie restriction and intermittent fasting
  • Allergen immunotherapy
  • Vision improvement

While there was interest in all of these topics, one topic in particular generated the greatest interest. Can you guess which one?

Vision improvement!

This was an audience that  was on the whole unusually physically fit, and there was intense interest in looking to the wisdom embodied in human evolution and pre-industrial and pre-agricultural society as a source of ideas for improved health.  Yet a significant number of attendees were wearing glasses — not exactly a “paleo” practice.   So there was acknowlegement when I pointed out that myopia is not in our genes, but has become prevalent because of environmental factors — primarily intensive schooling, near work and poor visual habits. (Many thanks to Otis Brown for the analysis and reference to the Eskimo study I referenced in support of this point). Yet there was shock — and intense interest — when I pointed out that myopia can be prevented and even reversed by the techniques I discuss in my blog.  Several of you discussed this with me and expressed a desired to embark upon a program to reverse myopia, and in some cases hyperopia or presbyopia.

I’m attaching here a link to a pdf copy of the poster.  Keep in mind that the actual poster size was 48″ wide by 36″ tall, so it does not fit on a normal computer screen. But you can easily adjust the zoom and use the arrows on your keyboard to scroll around, or print it out in a reduced size format if you have good eyesight:

Hormesis: A New Lens for Understanding Health and Improving Resilience

For those who have trouble reading the poster, or want an easier read, I present below the full text and set of images in the form of a standard blog article.  Most of the content will be familiar to those of you who have read this blog over the past few years.  But for those of you who are new to the topic of hormesis, I think it provides a good overview. I’ve also hyperlinked  to articles on a number of the topics that are discussed, for further reading.




Overstressed – or understressed?  What explains the recent pandemic rise in “diseases of civilization” like obesity, diabetes, cardiovascular disease, autoimmunity and cancer – conditions much less prevalent in ancestral populations?

One common answer is that contemporary life is too stressful. The prescription is to minimize exposure to certain chemicals, foods, UV, or psychological stress.  But stress is a double-edged sword.  While chronic or excessive levels of stress can indeed cause illness, so can a “deficiency” of stress.  Exposure to stress at the right intensity and frequency activates the body’s natural defense and repair mechanisms, improving health and resilience. The hardier life of our ancestors had benefits.

This poster presents the case for judicious application of progressive, intermittent stress to overcome conditions as diverse as obesity, addiction, depression, allergies and even myopia.

What is hormesis?  Hormesis is a  biological phenomenon whereby a beneficial effect (improved health, stress tolerance, growth or longevity) results from exposure to low doses of an agent that is toxic or lethal at higher doses.

The LNT (linear no-threshold) model of conventional toxicology assumes that toxic effects are inhibitory even at very low doses.  But many examples have been found of “hormetic” chemicals or stimuli with a “biphasic”  or “inverted U” dose response curve, illustrated below.  At low doses, the “toxic” or inhibitory agent actually becomes stimulatory or beneficial to the organism. [1]

Hormesis appears to work by activating endogenous defense and repair mechanisms found in all organisms, thereby improving resistance to stress and disease.

Examples of Hormesis



Diets with calories reduced by 30-65% versus free feeding have been shown to extend lifetime and reduce degenerative disease in a wide variety of animals. [2].  What explains this?  Several proposed mechanisms have been demonstrated:

Autophagy: A cellular “recycling” process. Calorie restriction dramatically lowers the concentrations of insulin, IGF-1 and growth hormone, activating enzymes that degrade damaged intracellular macromolecules and use them for energy.

Mitohormesis: A defense response initiated in the mitochondria.  Calorie restriction turns on sirtuin genes that code for endogenous antioxidant enzymes and neurotrophic factors like BDNF, neutralizing reactive oxygen species (ROS), slowing the aging process, and protecting against neurodegenerative diseases like Alzheimer’s.

Receptor upregulation.  Brain scans in rats (below) show that after 3 months of restricted eating, D2 dopamine receptors in the brain are upregulated. [3]. This in effect lowers body fat “set point”. Calorie restriction also upregulates GLUT-4 and insulin receptors in muscle and liver.

Fasting and weight loss increase dopamine receptors [3]


Intermittent Fasting (IF). Fasting for 12-24 hours intervals per dayproduces similar health benefits as general calorie reduction, without activating a starvation response or risk loss of lean muscle.  A “cycling” approach may optimize the secretion of (and sensitivity to) hormones such as insulin, leptin, ghrelin, cortisol, and thyroid hormones.  For many, eating less frequently is easier than eating less at each meal; with time it naturally suppresses between-meal hunger. [4]


The allergy epidemic is frequently blamed on the profusion of pollutants and toxic man-made chemicals in modern industrial society.  But historical studies indicate allergies have become pandemic as our environment has become cleaner.

The Hygiene Hypothesis holds that inadequate exposure to allergens in childhood may be depriving our adaptive immune system from developing properly, failing to develop normal tiers of IgG, IgA and IgM antibodies.  The undertrained immune system tends to rely on the “emergency” IgE system, resulting in allergic response when confronted with normally harmless foreign bodies like pollen, dog hair, or peanuts. [5]

How to eliminate allergies. The conventional advice given to allergy sufferers is to avoid exposure to allergens and use antihistamines. Allergen immunotherapy takes the diametrically opposite approach:  Patients are given tiny amounts allergen in shots or sublingually.  Exposure is then slowly increased in a systematic way.  The emergency IgE response is thus dampened by stimulating production of an allergen specific IgG that blocks the IgE response and modulates the helper T cell response.  Allergen immunotherapy has reversed allergies to peanuts and other foods in children. [6]


Is myopia a result of nature or nurture?  While certain populations may be genetically predisposed, studies show that nearsightedness is tied to environmental factors like increased schooling and close work.  A multi-generational study of a Eskimos revealed a statistically significant downshift in mean refractive state, from +1.8 diopters (hyperopic) in the older (unschooled) generation to -2.1 diopters (myopic) in the younger (schooled) generation. [7]

The Incremental Retinal Defocus Theory (IRDT) provides a plausible explanation for myopia induced by near work. [8] Effort by the retina to focus on near objects slows the rate of retinal neuromodulator proteoglycan synthesis in scleral tissues, causing axial elongation of the eye.  Repeated cycles of “near work” induce axial growth that leads to permanent myopia. This has been further confirmed in studies of chicks and other animals in which axial elongation and myopia could be rapidly induced or reversed by respectively fitting them with plus or minus lenses.

How to reverse myopia.  Conventional “correction” of myopia by fitting the eye with concave (minus) lenses provides short term relief, but at the cost of inducing progression of the underlying myopia. It is as futile as trying to “strengthen”  a weak leg by prescribing crutches.

Anti-corrective lenses are the hormetic solution.  Myopia is reduced by inducing a slight myopic defocus or “underaccommodation”. This can be done using reduced prescription minus lenses for distance viewing, and using plus lenses (or the naked eye) to read text at the “blur point” – the maximum distance beyond which the printed word just begins to blur. [9]

Myopic defocus induced by a convex (+) lens on a myopic eye. From DeAngelis [9], p. 38


Getting Stronger is a blog about the philosophy of Hormetism, based on the application of progressive, intermittent stress to overcome challenges and grow stronger physically, mentally and emotionally.

Some popular blog posts:

  1. Calabrese, E.J. and Baldwin, L.A. “Hormesis as a biological hypothesis”. Environ. Health Perspect. 106 (Suppl 1): 357-362, 1998.
  2. McCay, C. M.; Crowell, Mary F.; Crowell. “Prolonging the Life Span”. The Scientific Monthly. 39 (5): 405–414, 1934.
  3. Thanos, et. al. “Food restriction markedly increases dopamine D2 receptor (D2R) in a rat model of obesity…”. Synapse. 62 (1): 50-61, 2008.
  4. Herring, Bert W.  The Fast-5 Diet. http://www.fast-5.com
  5. Ruebush, Mary.  Why Dirt is Good. New York: Kaplan Publishing, 2009.
  6. Groopman, Jerome. “The Peanut Puzzle: Could the conventional wisdom on children and allergies be wrong?”. The New Yorker, p. 26ff,  Feb. 7, 2011.
  7. Young, Francis A., Leary, George. A. “Ocular Biometry of Eskimo Families”, Primate Research Center, Washington State University, Pullman, Washington, 1973.  (Statistical analysis courtesy of Otis Brown).
  8. Hung, George K. and Ciuffreda, Kenneth J., “Incremental retinal-defocus theory of myopia development”. Computers in Biology and Medicine. 37 (7): 930-946, 2007.
  9. DeAngelis, David. The Secret of Perfect Vision. Berkeley: North Atlantic Books, 2008.
I’d love to hear from any of you who met me at the conference.   I really enjoyed our discussions and would like to stay in touch.



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  1. Hi Todd,

    I know it takes a considerable effort to get a paper accepted at these conferences – not to mention the personal time it takes to fly to Harvard to present the concept of the natural eye’s behavior – in a Paleo World, versus our Modern World.

    I am in total agreement – that by moving our eyes indoors, our refractive state changes naturally from plus-to-minus. In my judgment, Dr. Young’s publications proves that point.

    But it is very difficult to explain this issue to a person in an office when the person expects to receive a strong minus (that is impressive) and will not take the time to understand the implications of Dr. Young’s scientific work and analysis.

    I am pleased you had the time to review Young’s objective work, and perhaps others can understand the issue of a self-induced negative status for our natural eyes – and what the wise individual could do to prevent it from developing.

    Probably the only real proof you need – is your sustained wearing of a plus – with ultimate success confirmed by you objectively passing the required line on your Snellen eye chart.

  2. Stephen


    I am buying into the hormesis model hook, line, and sinker. Though I stumbled across your writings only a few weeks ago, I’ve already started taking cold showers, practicing reverse procrastination, and winning against a 20-year-old joint-cracking habit through cue exposure. I know it’s best to go gradually, but the results have been great nonetheless.

    The general nature of the principles of beneficial stress are impressive. I was wondering, do you still stumble across new areas of application? For example, the parallels between the timing of cue exposure therapy and the timing involved in spaced repetition exercises led me to think of spaced repetition as a hormetic application of stress to memory training. Would this qualify? I imagine there are many more applications out there waiting to be put in concrete form.


    • Todd


      Glad to hear that you are having some success in applying hormesis to your own situation. Including extinguishing a joint-cracking habit. :-)

      You are astute to observe that hormesis is a very general phenomenon, with virtually unlimited applications. As you point out, the very process of learning itself can be conceptualized as a hormetic phenonenon that is subject to the general principles that apply to all forms of hormesis. On my Overview page, I summarized these as: simulation, constraint, intensity, recovery and gradualism. There is a lot of research on learning and memory that examines the optimum intensity, frequency and recovery time to maximize short term and long term memory and learning. I also think that the other principles are important — using the applied stress to simulate or approximate the actual behavior as closely as possible (you perform what you train for), and gradualism (progressing too quickly or too slowly both result in suboptimum results).

      I do have several new applications I’m actively researching. One that I’m particularly excited about is the use of hormesis to moderate pain. You’ll be hearing about that soon.


  3. Todd, I’m looking forward to the posts you mention. Keep it

  4. Todd,

    I really admire what you’re doing with this blog.

    You’ve effectively started to tie together ancient ideas (Stoicism) with our modern knowledge of the brain and biochemistry. (At least in part. I do realize that some of the protocols you’re discussing go far beyond anything the Stoics proposed.)

    For example, it’s fascinating how the fasting/simple eating/caloric restriction advocated by Senaca in Letter XVIII might be operating at a deep biochemical level by upregulating dopamine receptors.

    In any case, I’d like to think that your work, the biohacking of Ferriss/Asprey/QS, and the ancestral health movement (what could be closer to “Live According to Nature”!?), is sort of a re-emergence of practical philosophy.

    Are we discovering how to live?

    • Todd


      Yes, I think we are discovering how to live. Seneca, Epictetus, Musonius Rufus, and Marcus Aurelius were able to put together a good framework based upon their observations of human nature. Now we can use science to fill in the details, and to inspire new lines of investigation.


  5. Margot

    Hi Todd,

    I met you at your poster presentation at AHS12. I have myopia and hope to be able to improve my vision using your method. I’ve started with not wearing my glasses when I am doing computer work or reading, and holding the book / computer screen at a distance such that the text is slightly blurry. I am thinking of buying reduced prescription glasses, since there are some activities, like driving or playing tennis, that I can’t do without wearing glasses. The vision in my left eye is much worse than the vision in my right eye. If I buy reduced prescription glasses, should I buy different prescriptions for each eye? Or should I use the same prescription in each eye, so that my left eye has more of a challenge, which might make it improve faster?


    • Todd

      Hi Margot,

      Yes, it was nice to meet you at AHS. If you can provide your prescription (the correction in each eye), that would be helpful. Also, you should determine your Snellen score for each eye by printing out one of these eye charts or using the computer version if you prefer:


      If you can provide that information, I’ll try to provide some specific suggestions on eye exercises and prescriptions for lenses.


      • Margot

        Hi Todd,

        Thanks for the reply. I can read the second line on the Snellen chart with my right eye (20/100). Even the first line on the Snellen chart (20/200) is a bit too blurry to read with my left eye.

        The prescription of my current glasses (which I obtained 2 years ago) is -1.75 and -1.5. When I wear my glasses, I can see down to the 8th line (20/25).

        If I hold a book at an arm’s length, I can just read it with my right eye. I have to hold it at half an arm’s length to read it with my left eye.

        • Todd

          Hi Margot,

          Thanks for the information about your myopia correction.

          I would recommend the following:

          1. For distance vision, get a weaker prescription by reducing each lens 0.5 diopters. So in your case: -1.25, 1.0.

          2. Read and do computer work without glasses.

          3. Because your left eye is weaker, the focus of the right eye will dominate. This means that as long as your right eye is doing the work, the left eye will be deprived of any stimulus to improve. (I actually have the reverse situation, where my left eye is dominant). The solution is simple: find a way for the weak eye to work on its own, at least part of the time. I suggest at least two 30-minute sessions a day reading with your right eye “blocked” and the left eye reading at the edge of blur. The simplest way to do this is to find some non-corrected cosmetic glasses, like lightly tinted sunglasses, and tape some thin paper over the right lens. It is better to use thin white paper, like tracing paper, to diffuse any image but still allow enough light into the right eye so that it doesn’t have to adjust back and forth from dark to light when you put the glasses on and off. I know this looks a bit awkward, but it works.

          Another option is to order a pair of custom glasses from zennioptical.com. You want to “handicap” the right eye so that it is at least as “myopic” as the left eye. Go to the drug store and try hold some weak plus lenses (perhaps +1) in front of only your right eye, with the left eye uncovered, and try to read text. Find a lens that allows the left eye to focus just slightly closer than the right eye. Then order from zennioptical a pair of glasses that is “plano” (no correction in the left eye and has the plus lens for the right eye. Wear these glasses while reading at the blur point. Once your left eye has strengthened, you can work without lenses, or you can order a new pair of glasses with equal plus lenses over both eyes. Keep increasing the plus lens strength until it gets to about +2 or +2.5 for both eyes. After that, your distance vision will be very clear!

          I realize that this method may seem somewhat surprising or counterintuitive. The principle to keep in mind is that you want to exercise the weaker eye until it catches up with the stronger eye. Then push both eyes, in very gradual steps, to continually focus at the limit of their range — but never beyond. It’s the Goldilocks principle — not too easy, not too hard, but just the right amount of challenge. Your eye will not change if you overstress it or understress it. The stress must always be “at the threshold of ability.”

          Hope that helps.


        • Hi Margot,

          I do have a question. When you read at “arms length” is that with your minus glasses on? One advantage to being a -1.5 diopter myope, is that you can take your glasses off, and read at 20 inches with no glasses at all – because your eyes are in-focus for about 25 inches as your prescription indicates. It would be good to know if you can read OK with no lens. Thanks for your answer.


  6. Margot

    Hi Todd,

    Thanks for the detailed suggestions! I will try training my left eye to improve by blocking my right eye as you suggested.

    Otis, I meant that if I don’t wear any glasses, I can read text if it is less than an arm’s length away with my right eye and less than half an arm’s length away with my left eye.


  7. Nate

    Quick question. In one of your previous posts, you state that cold showers raise the dopamine receptors in the brain. (I can’t find the exact quote). Do you have any references for that?


    • Todd

      Hi Nate,

      I’m not sure my self where in my blogging I specifically connected cold showers to dopamine receptor level. In my article “Change your receptors, change your set point” I did cite research demonstrating the impact of other metabolic challenges such as intense exercise and calorie restriction on upgregulating dopamine receptors.

      It wouldn’t surprise me if cold showers increased the levels of dopamine receptors, but I cannot readily locate any research that specifically documents that connection.



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