Saturday, February 27, 2010
You have to watch the video to see the vast difference between the supplemented and the unsupplemented animals. The supplemented animals don't even look or act aged.
This is the first report I have seen documenting extension of lifespan with nutrient enrichment in animals. The scientists are now testing the combination of supplements on crickets, and those fed the supplements apparently have doubled life spans compared to controls.
This supports the hypothesis that a high nutrient density, equatorial analogue (i.e. herb-enriched) paleo diet might extend lifespan in humans without caloric restriction. Take a look at Art DeVany for an example of the possible results.
CBC News - Health - Old mice run faster with supplements
|Tribe||Latitude||% Animal Food||% Plant Food|
|San (!Kung)||20° S||68||32|
|San (!Kung)||20° S||33||67|
Wednesday, February 17, 2010
Biomechanics of Foot Strikes & Applications to Running Barefoot or in Minimal Footwear
Although they focused on running, their findings equally apply to walking. I don't run, but I walk often. Since I have switched to using Vibram Five Fingers shoes almost exclusively, I have spontaneously transitioned from heel striking to mid/fore foot striking when I walk quickly.
When I started this, I could only walk about 5 minutes at a time on concrete in the Five Fingers. My feet and calves got quite sore from the unaccustomed use. Gradually I have increased the time spent walking. After 3 weeks, I can now walk more than 1 mile with a fore/mid foot strike before my feet get too tired to continue and I revert to a midfoot/heel strike (but still softer than what I would have done before Five Fingers). I also feel the my feet building up new cushions/callouses on the forefoot.
This practice also made me aware that I used my left and right sides quite differently in walking. Some years ago, when I got some Feldenkrais Method "Awareness Through Movement" education sessions with Jeff Haller, he noticed that I spent more time on one foot than the other when walking, but I could not detect it myself -- at least not enough to see it correct. Walking on concrete in Five Fingers made me acutely aware of different stride on my left and right foot -- whereas the right foot contacted softly and the heel made minimal contact with the pavement, the left foot came down harder with less control and the heel jarred against the pavement (after midfoot contact). As I walked along for about five minutes spent just noticing this, it gradually diminished and apparently self-corrected. I've noticed more muscular soreness in the left foot and calf than the right, and had some transient soreness in the left groin not present on the right.
I first learned about this way of walking about six or seven years ago from a book titled Tai Chi Walking: A Low Impact Path to Better Health by the physicist and Tai Ch'i Chuan teacher Robert Chuckrow. Chuckrow describes how to walk "softly" as in Tai Chi, even on concrete, wearing minimal footwear (as recommended by Tai Chi masters). He described how he makes his own moccasins and uses them as his exclusive footwear, and he encourages his readers to make the same footwear. I however continued to wear conventional "walking shoes" and found it difficult to practice the low-impact walking in those thick-soled shoes that have cushioned heels. The shoes virtually forced me to heel strike.
So far I consider this experiment positive. I will keep wearing the Five Fingers as my primary footwear for the foreseeable future. I have in the past three weeks (since starting the experiment) worn my New Balance walking shoes only a couple of times. Before wearing Five Fingers I didn't notice that the New Balance shoes confine the front of my foot and feel uncomfortable, compared to the Five Fingers. Now I prefer the Five Fingers even to my Birkenstocks, which have a pretty wide forefoot bed compared to other shoes. I'll update my report as time passes.
Thursday, February 4, 2010
In fact, we can state certainly that paleolithic diets supplied humans with all the nutrients humans require, because if they did not, the human species would have expired due to malnourishment. Further, as I showed in my post Primal Diet On A Shoestring, a paleo diet composed of modern foods can easily supply required nutrients. This means that even if paleo people did have a short life expectancy, it was not due to some nutritional weakness of the paleolithic menu.
In short, "everyone knows" this the same way that "everyone knows" that cereal grains are essential to nutrition -- it is not knowledge, it is simple mythology.
Recent Hunter-Gatherer Evidence
According to Between Zeus and Salmon: The Biodemography of Longevity, a publication of the National Academy of SciencesCommission on Behavioral and Social Sciences and Education (National Academy Press, 1997) (pages 176-179):
"The most reliable estimates of adult mortality rates available for a pre-contact hunting and gathering group are derived from Aché research (Hill and Hurtado, 1996), because of the research focus on producing accurate measures of age and accounting for all adults that lived during the twentieth century."
So what can we learn from the Aché?
Well, among them, 30-40% of people die before the age of 10-15 (most of these before 5).
Among both ancient and modern hunter-gatherers, these and most adult deaths occurred from hazards of childbirth, infections, accidents (e.g. falling from a tree, drowning, etc.), animal attacks (insects, snakes, etc.), poisonings (toxic plants), inclement weather (floods, snowstorms, etc.) and other dangers affecting all age groups but especially children growing up in a wild environment. They did not occur from diseases of civilization, like heart disease, cancer, diabetes, and the like.
“Adult mortality rates remain low and do not rise significantly until the seventh decade of life, where the rate climbs to 5 percent per year and reaches 15 percent per year by age 75.”
So modern hunters live well past 45. What about ancient people?"Although sample size and methods of data collection vary among the four human groups, the survival curves show remarkable convergence, Although infant mortality rates vary, with Hiwi being the highest and Yanomamo the lowest, adult mortality rates between the ages of 20 and 45 are almost identical, about 1.5 percent per year. For that reason the survival curves are parallel to one another during the adult period. Chimpanzee survival curves, however, diverge dramatically from the human curves, due to a quite distinct adult mortality profile. For example, while both Hiwi and chimpanzees have about equal probability of reaching age 15, the conditional probability of reaching age 45, having reached age 15, is near zero for chimpanzees in the wild and about 75 percent among the Hiwi."
Migration and Population Expansion Evidence
In preagricultural times (between 50, 000 and 10, 000 years ago), humans migrated out from Africa around the globe. By 10, 000 years ago, humans had reached and populated the Americas. Given human reproductive function, this could not have occurred if people died at 30 years of age.
The Menopause Evidence
Further evidence that paleo people, at least women, reached ages well beyond 50 years of age exists right now in the phenomenon of menopause, a reproductive milestone unique to humans among primates (elephants also have a menopause, and can live 70 years in the wild).
According to evolutionary theory, menopause would not exist unless it conferred some survival advantage for offspring. The fact that human females go through menopause around 50 years of age tells us that our ancestral mothers did in fact make it to 50 years and beyond, and that those mothers who ceased menstruating at about 50 years of age left more offspring (children and grandchildren) than those who continued to menstruate.
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1. Frisch RE, Fatness and Fertility, Scientific American1988 Mar;258(3):88-95.