Kayaking with Alligators and Other Calculated Risks

Jonathan Dickinson Park is a Florida State Park located in Martin County, Florida; the Loxahatchee River runs through it.

Last Friday, accompanied by my wife and another couple, I kayaked down the river to view pristine nature. Watching us from the sidelines were a number of alligators, with some appearing as large as ten feet long. One actually swam under my friend's kayak.


Stroking the water in my single kayak, I couldn't help but think what possessed me to go down a river surrounded by ferocious, life-altering creatures with my only defenses a paddle and a pocket-knife. Coupled with the knowledge that death had come to a young boy on this very same river from a similarly situated alligator only added to my puzzlement.

I am not a risk taker by nature, particularly when it comes to nature. True, I was a boy scout for three years, but supervised hikes in the woods was the extent of my trailblazing. Skydiving, motorcycle riding, hang-gliding, parachuting, bungee jumping etc. are simply not part of my repertoire and never have been. So what was I doing on that river? I was taking a calculated risk.

The Merriam Webster dictionary defines a calculated risk as "a hazard or chance of failure whose degree of probability has been estimated before some undertaking is entered upon." I think you will agree that boating down a river inhabited by alligators, one of which already killed someone, without any rescue in site in order to enjoy a unique patch of nature is by all means a calculated risk. Why did I do it and why should my adventure be of any concern to you?

Patients often told me that if they had to give up the foods they loved, there would be no reason to live. Clearly such people live to eat as opposed to eat to live. Even when faced with the risks of heart disease, cancer, stroke, diabetes, etc,, food means too much to them to give up. More importantly, they know there are no guarantees that if they actually gave up their pizza, cakes, burgers, french fries, milk-shakes, pasta, etc. that they would necessarily stay healthy or even live longer. For them, their calculated risk has their favorite foods trumping over potential health risks. 

Many people often make the same calculation about exercising regularly and managing their stresses more effectively. For example, if you spend one hour a day exercising for sixty years, you would have spent the equivalent of over three years of awake time (at an average of 17 hours a day) of your life exercising. It is estimated that people who exercise one hour a day, ignoring diet and other longevity factors, will on average live a few years longer. By some calculations, that seems like a wash. I say some, but not mine. 

When I think about the consequences of eating the right diet or staying physically active over the course of your life, I think in terms of both possible gains as well as losses. Although there are no guarantees that exercise will keep you alive longer, as Jim Fixx the runner proved by his passing, staying physically active has been clearly associated in every study I ever read with a healthier healthspan, the measurement of how long in life you feel well. So it's not just a matter of living longer, it's also about feeling better during the years you live. In addition, many studies also show that eating healthy when coupled with other healthy lifestyle choices is highly correlated with avoiding the chronic diseases often associated with aging. 

To eat what you want and to live a sedentary lifestyle is a calculated risk that you are free to take. It's your life after all. You may think that it is not as foolish as kayaking with alligators, but it's actually far worse given that millions of people have died prematurely from eating too much of the wrong foods while since the 1970s there are only twenty three recorded alligator deaths in the U.S. I prefer those odds. While alligators are a frightening topic and when they kill, they garner major headlines for the gruesomeness, the risk of dying early from an unhealthy lifestyle is far greater than death by alligator even when they are swimming nearby. So if you aren't brave (or stupid, depending on your perspective) enough to go kayaking with alligators, why do you keep eating the way you do? It's a calculated risk to eat unhealthy and the odds are not in your favor. 

Now that's something to chomp on (pun intended).

Monkeying Around With Longevity

The search to extend human longevity spans the ages. More recently, scientists have repeatedly shown that restricting the intake of calories while continuing to supply essential nutrients extends the lifespan of flies and yeast by as much as 40 percent. An additional research vector that captured much attention were animal studies with rodents that suggested similar benefits from caloric restriction. 

Although positive results were not seen with all strains of rodents, some rodents were shown to live significantly longer when their calories were limited.  As with all animal studies, scientists wanted to know if these benefits extended to more complex creatures that more closely resemble humans--such as primates--better known as monkeys.

When the National Institute of Aging (NIA) completed their studies with monkeys in 2012, the NIA's conclusion was that that caloric restriction made no difference. This hardly put the controversy to bed, but it did seem to dampen some enthusiasm for this approach to extending human longevity.

This past week, a new study from the University of Wisconsin stirs up new hope for reconsidering this strategy. Over 25 years, Wisconsin researchers studying rhesus monkeys, considered by some the best proxies for humans, found a significant reduction in mortality and in age-associated diseases among those monkeys fed calorie-restricted diets. The study, begun at the University of Wisconsin-Madison in 1989, is one of two ongoing, long-term U.S. efforts to examine the effects of a reduced-calorie diet on nonhuman primates.

The study of 76 rhesus monkeys, reported Monday in Nature Communications, was performed at the Wisconsin National Primate Research Center in Madison. When the monkeys were 7 to 14 years of age, they began eating a diet reduced in calories by 30 percent. The comparison monkeys, or the control group, which ate as much as they wanted, had an increased risk of disease 2.9 times that of the calorie-restricted group, and a threefold increased risk of death.

So which study is correct?  According to the Wisconsin researchers the reason for the discrepant results is that the NIA monkeys that were in the control group versus the intervention group were actually already on calorie restricted diets and that's why no difference was found in longevity between the two groups. Also, the NIA monkeys were consistently slimmer (and presumably healthier) that the Wisconsin monkeys, who were allowed to eat what they wanted. (I guess even monkeys, particularly captive ones, overeat when enabled to do so.) The NIA was apparently more careful with all their monkeys to limit their food intake regardless of the study.

How did the Wisconsin researchers reach this conclusion? Through their own experience in monkey research, and by reference to an online database recording the weight of thousands of research monkeys, the Wisconsin researchers concluded that the NIA controls were actually on caloric restriction as well. “At all the time points that have been published by NIA, their control monkeys weigh less than ours, and in most cases, significantly so” stated Ricki Colman, a senior scientist at the Wisconsin Primate Center, who presently co-leads the project.

More importantly, the NIA control group monkeys were also found to live longer on average that most other monkeys, and the Wisconsin researchers theorized that this was due to even a small reduction of calories. The big conclusion was that it seems that the small caloric restriction in the NIA control animals had its own benefits, suggesting that a reduction of as little as 10 percent could meaningfully retard aging.

As these studies were very expensive to conduct and will therefore not be repeated any time soon, the question remains do primates benefit from calorie restriction as long as they get all essential nutrients? The Wisconsin study would suggest that for rhesus monkeys, the answer is yes.

So what does that mean for us humans?

According to the Wisconsin researchers, they were“not studying [caloric restriction]...so people can go out and do it, but [rather] to delve into the underlying causes of age-related disease susceptibility...It’s a research tool, not a lifestyle recommendation."

Although the helpful mechanism of why caloric restriction may be beneficial has not been fully identified, it is believed to have something to do with the "reprogramming of the metabolism. In all species where it has been shown to delay aging and the diseases of aging, [calories restriction]... affects the regulation of energy and the ability of cells and the organism to respond to changes in the environment as they age.”

One of the first break-downs in metabolism results in diabetes, which can be seen as “an inability to properly respond to nutrients.” Diabetes damages a whole range of human capabilities including the functioning of muscle, fat and blood vessels. "The Wisconsin scientists began to see diabetes among the control animals while they were still in the prime of life, within six months after beginning their study. The contrast with the restricted animals could not have been more dramatic" Colman said. “Until two years ago, we did not have evidence of diabetes in any caloric-restriction animal, but we had a significant number of diabetes, or pre-diabetes, metabolic syndrome, in the control animals.”

Although it is generally accepted that very few people can tolerate a 30 percent reduction in calories, the study does merit consideration.  Primarily because “the basic biology of caloric restriction in rodents, worms, flies and yeast seems to carry over to primates," it appears worthwhile to identify the underlying mechanism for this result in order to better understand the potential benefit to human primates who are genetically so closely related to rhesus monkeys.

The bottom line here is that as long as they all get their essential nutrients it would appear across multiple species, from simple worms to far more complex primates, that eating less is better than eating more. It's not a large stretch to extend that logic to homo sapiens. Accordingly, even cutting back on 10% of your calories may have a huge effect on your longevity--adding years of healthy living to your life.  And that's not something to monkey around with.