I’m going to write a few things about a paper on the relationship between body size and longevity. Here goes, mates.
First of all, here’s The Paper. I’m going to write about some interesting facts therein. And from the papers it cites that are interesting enough to look up.
Here’s a cite from this paper. In this study in Sardinia, soldiers had a greater survival if they were short. At 70 years of age, the shorter men (<160 cm, or about 5’3″) lived 2 years longer than men taller than 5’3″.
For reference, the difference in life expectancy of 75-year-olds in 1900 and 75-year-olds in 1999 is only 1.5 years. So the difference in height causes a bigger difference in longevity on average than modernity does. How’s that for effect size.
I have never felt so bad being so tall and handsome as right now.
The author of the same paper directly above makes the point that Staffan Lindeberg’s Kitavan males were on average 5’3″ and the females 4’11”.
A seriously confounding factor when we’re talking about diet and longevity among Kitavans, exemplars of a disease-free lifestyle. What other groups of especially long-lived people might be long-lived simply because they are short? Hint: most or all.
This one is cool. The authors compared the mortality from cardiovascular disease in the five tallest countries with the five shortest countries. Being in the tallest vs. shortest countries increased risk >2X.
Also compare Japan to Finland. 6X the risk being Finnish compared to being Japanese.
What about centenarians? The bummer knob gets turned up a few notches here. Average height of Okinawans, who have the highest rate of centenarians. Male height? 4’10”. Female? 4’6″.
So short you could accidentally step on them.
Average Okinawan centenarian male height is 4’10”, female 4’6″, right?. Well, Okinawans that are 73 years old: 10 cm taller than this. This implies that short people are overwhelmingly overrepresented among centenarians.
Between species, smaller animals live shorter lives. But within species, the smaller animals live longer.
Mice food-restricted as they grow become smaller mice but have an extended lifespan.
Genetically smaller mice live longer, and vice versa. Reference.
The association between size and longevity even holds for trees. Trees that grow on cliffs and are nutrient deprived and much shorter than their tree colleagues have lifespans that are much longer.
Willcox found that among Japanese living in Hawaii, mortality continues decreasing all the way down to 1000 calories, when it starts increasing with further cal restriction.
Anyone want to go on a 1000 cal/d diet with me? Oh wait, I’m too tall.
Willcox did note that the equivalent for a tall European would be about 1400 cal/d. I’m guessing at 6’1″, I’m closer to about 1600 cal/d, which is about half of what the average American male consumes.
What are the mechanisms giving a longevity advantage to smaller body size?
1. Fewer cells = lower cancer risk.
2. Lower food intake = lower IGF and insulin levels.
3. Organs of smaller animals are larger proportional to body size = greater functionality into older age.
4. Reduced toxin intake because decreased food/water intake.
5. Lower left ventricular size and lower blood pressure because less blood pressure necessary to distribute blood.
6. Lower all bad blood biomarkers.
These are the ones I understand anyway.
In this paper, Samaras then takes on the idea that taller people live longer and healthier lives. He says that this relationship is confounded.
Interesting fact: before the 1930s, American blacks had lower rates of chronic disease, until they began to match whites for height and then experienced increased rates of cardiovascular disease, diabetes, stroke, etc.
Let’s return to some of the specific population studies cited in the original paper. Here we will discuss Holzenberger et al’s 1991 paper on Spaniards.
Here is a graph plotting mean survival an additional 70 years at age 18 in each Spanish province against mean height at age 18 in that province.
According to the analysis, each cm of additional height costs 0.7 years of life.
Samaras then goes on to discuss a study conducted by Dennis Miller in Ohio.
Two figures from this paper by Miller are interesting. First, a table showing an analysis done by none other than Samaras, with accompanying text, showing the point clearly.
Miller then discusses the observations that he made in Cleveland, measuring the heights of corpses at the County Coroner’s office. He found that each additional 1.2 inch in height corresponds to a reduction of a year in average age of death.
Interestingly I found a chart with some of this information in a book called Trends in Nutrition Research published in 2005.
In his paper, Miller makes the interesting suggestion that the difference between male and female life expectancy, especially in terms of cardiovascular disease and cancer, is in large part attributable to height.
Back to the original paper. Also cited is one by Rantanen et al showing among Japanese men living in Hawaii a statistically significant trend (p=0.015) toward decreased height at later age of death, with ~2cm difference between >100 and <80.
Let’s detour, because I want to explain something I stumbled across. We briefly touched on it early, but there’s something called Laron’s syndrome, where mutations cause a person to be entirely insensitive to growth hormone. People with Laron’s syndrome are dwarves.
Not THAT kind of dwarf. THIS kind.
Not only are people with Laron syndrome short in stature, they are also virtually immune to diabetes and cancer.
Here’s a paper showing the cancer rate in people with Laron syndrome versus first-degree relatives, co-authored by the man Laron himself.
No cancer in 230 individuals = 0% cancer rate.
Here’s another paper looking at diabetes. Much higher insulin sensitivity, lower insulin levels, lower rate of diabetes, and so forth, despite higher obesity caused by the syndrome. (This is because growth hormone causes elevation in blood glucose; absence of the receptor as exists in these patients therefore causes lower blood glucose.)
Patients with Laron syndrome have similar mortality to controls, however, because Laron syndrome patients have seizures due to periodic hypoglycemia and die more frequently from accidents. They also tend to have developmental abnormalities.
Why am I going on about people with Laron syndrome? Here’s why. Mice with a similar defect–not a GH receptor defect but a growth hormone deficiency–show a similar phenotype, but this time, with enhanced life expectancy. They are also dwarves and are called Ames mice.
Now the interesting thing about Ames mice is if you give them growth hormone in early life, you increase the adult size but cut the lifespan extension by ~1/3. EVEN if you stop giving the growth hormone after the 7th week.
This implies that a substantial part of the long-term longevity advantage of Ames mice may not be lifetime low GH but lifetime low body-size. And that for best results, you want to restrict calorie intake during the growth period.
Elephant in the room:
“Should I starve my kids?”
We will address this issue head-on later in part 2. But since we haven’t definitively established it yet, be sure not to starve your kids until we’ve finished part 2.
OK 9am and I haven’t slept and I drank like 5 coffees to do this. Time to go to sleep with disrupted circadian rhythms and significantly increased systemic inflammation. I’m probably going to die earlier for staying up late writing about longevity.
Series will continue later. Spoiler: this is a prolegomenon to the Okinawa thread to be finished in a few years. #CantFinishAnything
And about the starving kids thing. That was a joke, and I am seriously concerned about the effects of calorie restriction during childhood growth on brain development. We will look at the evidence for that and try to see what tradeoffs there might be between increased longevity from body size restriction versus brain development and other possible issues.
If we can’t find tradeoffs, though, we would then want to rethink our valorization of height and body-size and growth during childhood. But if we can find tradeoffs, we will need to more carefully consider the issue.
See you in the next wonky post. And if you enjoyed this, please subscribe to this blog, sign up for my Discord, listen to my podcast, and/or become a Patreon subscriber. Your support matters. All links are available below or on my Twitter profile.