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December 19th, 2022

The new docu-series on National Geographic Disney with Chris Hemsworth is excellent.

Many of the topics discussed here over the years are explored visually for us all to consume over a few episodes. Chris is challenged to push himself beyond his previous limits and beliefs. Where this series takes a turn for the best is the linkage to health and longevity. They explore how pushing oneself to discomfort is actually health promoting longe term. The science is discussed in parallel to the challenge and the mental/physical drama.

They cover topics that I love. Fear, cold therapy, heat therapy, fasting, aging and much more. Dr. Peter Attia is involved adding a massive layer of scientific legitimacy to it.

Adaptation and Extremes
What do we need to know?

Since the days of Naturalists Darwin and Lamarck, humans have thought about the changes that occur within mammalian species as they attempt to adapt to the ever changing environment. Current times are no different as temperatures and sea levels rise, food has dramatically changed and sedentary attitudes plague humans.

All mammals have cassettes of genes with the sole purpose of dealing with extremes of all environmental inputs. Some genes encode for stress proteins like the class of temperature shock proteins, heat and cold shock proteins. Others encode for adrenal gland cortisol receptors to handle differential psychological and physical stress. Further yet, are groups that encode for receptors that sense any physical perturbations.

Taken all together, we see a picture of mammals having the ability to change as needed to stress or environmental shifts. If stress or shifts do not occur, then logically there will be no adaptation. Whether this is good or bad is now being understood.

Let's look at the hallmark research by Moshe Szyf. He looked at the response of rat offspring to differential social grooming and subsequent stress responses over time. Animals that were poorly groomed by a mother rat had higher long term stress responses because of brain stress receptor changes that occurred. This study showed that a baby is primed epigeneticaly to expect a tough world if his mother was not a loving groomer. Conversely, the groomed offspring had reduced receptors for stress expecting a happier world.

Environmental signals as those above can be positive or negative, but they have an effect nonetheless. It is up to us to figure out which inputs are beneficial.

When we look at this from the perspective of longevity, there is new research that shows that repair mechanisms are turned on more favorably when the body is acutely stressed by exercise, heat, cold and other similar environmental inputs.

Stress proteins like the heat and cold shock proteins have the ability to up-regulate in the face of extreme exposure to heat or cold respectively. The benefit of this adaptation is that the mammalian physiology shifts towards a repair and growth state during these exposures. Sauna use, for example, has been looked at physiologically for its benefits for longevity and health. The heat exposure during sauna use turns on Insulin like growth factor 1 and the heat shock proteins setting up an anabolic growth and repair state. This is very beneficial to an animal as it allows for cellular repair and regeneration as well as hypertrophy of muscles.

These types of biological responses occur similarly with cold stress. Adaptation is necessary for humans to live and survive the cold winters of the north.

Why would this be? Why would a system perform better under these swings in environmental inputs and less well in a euthermic or plateaued input state? The answer lies in the history of mammals and the fact that they have always lived in extremes until recent times. Thus, in order to propagate the species, the biological systems were set to handle the swings of environment in productive ways especially in the growth and repair systems.

When we take this theory and apply it to modern times of limited swings in beneficial environmental signals, we have a human species that is not faring as well. This parallels perfectly with the Hutterite and Amish allergy/asthma study that showed that humans exposed to animal endotoxin through stool and dust had significantly better functioning immune systems with less allergic disease. The more robust bacterial exposure is beneficial as opposed to our belief that a happy clean world is better.

Following on this theme, we now know that parasite consumption also has beneficial effects on us when the parasite is not a killer or hurtful. There are many types of organisms that have effects on us that were previously unknown.

The data keeps mounting that we need to get a little uncomfortable in order to live well and prosper.


1) Learn about about safe sauna therapy(below) or exercise when it is hot. Make sure to hydrate frequently as this is the key to avoid overheating and dehydration. Adapt to heat over time. Never use heat exposure for prolonged times until you are heat adapted. Start with short sauna trips of 5-10 minutes and increase over time. Much of the current research is recommending 20-30 minutes. Young children are not recommended for this activity as the research has not been done.

2) Avoid ever trying anything extreme without first reviewing the risks. Always employ the buddy system to make sure that bad outcomes are avoided.

3) Living a little dirtier will really help to prime our immune system and thus mitigate the risks of modern lifestyle induced diseases of the allergic and autoimmune variety.

4) Challenge yourself in more ways to elaborate more beneficial genes.

Challenge yourself without a worry of others beliefs or thoughts,

 Dr. M

Stress and Gene Expression
McGill Article
Moshe Szyf Ted Talk
Amish Article
Miller Frontiers Neuroscience
Parasite Education