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Maggie Koerth-Baker

Featured • Science • Africa • archaeology • food • genetics • human origins • Nobel Conference

How shellfish saved the human race

A couple hundred thousand years ago, the planet became a much colder and drier place. In Africa, deserts expanded, species were wiped out and the human race was in deep trouble.

See, humans today may look pretty different from one another but, genetically speaking, there's not much diversity at all within our species. In fact, chimpanzees, which look pretty much the same from one individual to the next, are much more genetically diverse than we are. To scientists, that suggests that humans have come through a genetic bottleneck--a point where our numbers shrunk dramatically, and a relatively small population had to rebuild the species. For about 20 years, genetic anthropologists have been comparing the genes of modern human populations. Over time, they've used bigger and bigger samples, and better and better analysis, to hone in on when our bottleneck likely happened, and how many humans managed to slip through it.

Turns out, somewhere between 130,000 to 190,000 years ago, the human species was reduced to less than 1000 breeding individuals--just a few thousand people in total. Ancient, naturally driven climate change pushed our species to the brink, said Curtis Marean, Ph.D., a professor with the Institute of Human Origins and the School of Human Evolution and Social Change at Arizona State University.

What saved us? According to Marean, the answer may be "shellfish".

"They're a great source of protein," he said. "And shellfish are immune to colder ocean temperatures. In fact, when the water gets colder, those populations go up."

Marean used climate models to pinpoint locations in Africa where human hunter-gatherers could have hunkered down during a long glacial period that dried out the continent and expanded deserts. Of the four-to-six possible locations, he focused in on an area along the coast of South Africa.

"That area has a super high diversity of below-ground tuberous plants, which have high carb loads. People are excellent foragers for them. You need a digging stick and there wouldn't be a lot of animal competitors," he said. "And the tuberous plants are adapted to arid environments."

His team eventually found a site, dating to 164,000 years ago, that shows evidence of humans eating shellfish, working with natural pigments and creating technologically sophisticated tools. He thinks this could be the remnants of the humans of the bottleneck--ancestors of everyone alive today.

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WOD 091218

"Mary"

As Many Rounds As Possible in 20 minutes:

5 Handstand Push-Ups
10 Pistols (5 each leg)
15 pull-up

Post rounds completed to comments.

James C. One-Arm Push-Ups

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People have a very strong reaction to challenges to what they believe about food. It is much like peoples reaction to challenges to their religious belief, and I think it is no accident that in "Gulliver's Travels" the satirical religious conflict is framed as a dispute between "Big-End" and "Little-End" Indians who cut their eggs from different ends. It makes sense, as short of air and water, there is nothing more essential to our survival than food.

I should say that as your eminently moderate moderator, I find value in myriad opinions expressed here, and while there is value in humor and some good-hearted ribbing, I don't wish to see the level of discourse even remotely approach that of the recent troubles in the broccoli-vs-bread brou-ha-ha. Keep it respectful, and don't confuse someone's opinions on food with their general value as a person, intelligence etc. Any comments of this nature will be removed.

I do agree that from a marketing standpoint, science has been done a disservice by some less-than-rigorous thinking on the part of those involved in selling services and products based on the "paleo" diet. However, I believe that despite this there is a lot of value to such a diet, or a similar one that accentuates such foods, without banning all others altogether. I will be writing more about this and presenting more arguments from both (or more) sides of the paleo coin. Here is my present thinking about diet (I don't have a fancy name, but if anyone has any ideas how I can make millions from this let me know).

Max's rules for healthy eating:

1. Focus first on food quality: eat whole foods such as meat, fish, fowl, eggs (and possibly dairy based on genetic ability to tolerate it), vegetables, fruits, nuts and seeds, little starch (all from whole-grain sources or favoring yams and lower-GI foods over potatoes and higher-GI foods) and no sugar (or any sweeteners at all).
2. Eat animal protein with every meal and snack.
3. Eat 4-5X a day, small meals.
4. Eat general zone proportions. Eat in a balanced way.
5. Weigh and measure your food.
Supplemental: stay hydrated, take fish oil and a multivitamin. Don't drink juice.

Below is a study, which I, and the author of the blog post, do acknowledge was done with shoddy protocols, but raises interesting questions.

Paleolithic Diet Clinical Trials Part III

From the blog: Whole Health Source

"I'm happy to say, it's time for a new installment of the "Paleolithic Diet Clinical Trials" series. The latest study was recently published in the European Journal of Clinical Nutrition by Dr. Anthony Sebastian's group. Dr. Sebastian has collaborated with Drs. Loren Cordain and Boyd Eaton in the past.

This new trial has some major problems, but I believe it nevertheless adds to the weight of the evidence on "paleolithic"-type diets. The first problem is the lack of a control group. Participants were compared to themselves, before eating a paleolithic diet and after having eaten it for 10 days. Ideally, the paleolithic group would be compared to another group eating their typical diet during the same time period. This would control for effects due to getting poked and prodded in the hospital, weather, etc. The second major problem is the small sample size, only 9 participants. I suspect the investigators had a hard time finding enough funding to conduct a larger study, since the paleolithic approach is still on the fringe of nutrition science.

I think this study is best viewed as something intermediate between a clinical trial and 9 individual anecdotes.

Here's the study design: they recruited 9 sedentary, non-obese people with no known health problems. They were 6 males and 3 females, and they represented people of African, European and Asian descent. Participants ate their typical diets for three days while investigators collected baseline data. Then, they were put on a seven-day "ramp-up" diet higher in potassium and fiber, to prepare their digestive systems for the final phase. In the "paleolithic" phase, participants ate a diet of:

Meat, fish, poultry, eggs, fruits, vegetables, tree nuts, canola oil, mayonnaise, and honey... We excluded dairy products, legumes, cereals, grains, potatoes and products containing potassium chloride...

Mmm yes, canola oil and mayo were universally relished by hunter-gatherers. They liked to feed their animal fat and organs to the vultures, and slather mayo onto their lean muscle meats. Anyway, the paleo diet was higher in calories, protein and polyunsaturated fat (I assume with a better n-6 : n-3 ratio) than the participants' normal diet. It contained about the same amount of carbohydrate and less saturated fat.

There are a couple of twists to this study that make it more interesting. One is that the diets were completely controlled. The only food participants ate came from the experimental kitchen, so investigators knew the exact calorie intake and nutrient composition of what everyone was eating.

The other twist is that the investigators wanted to take weight loss out of the picture. They wanted to know if a paleolithic-style diet is capable of improving health independent of weight loss. So they adjusted participants' calorie intake to make sure they didn't lose weight. This is an interesting point. Investigators had to increase the participants' calorie intake by an average of 329 calories a day just to get them to maintain their weight on the paleo diet (bolding mine). Their bodies naturally wanted to shed fat on the new diet, so they had to be overfed to maintain weight.

On to the results. Participants, on average, saw large improvements in nearly every meaningful measure of health in just 10 days on the "paleolithic" diet. Remember, these people were supposedly healthy to begin with. Total cholesterol and LDL dropped, if you care about that. Triglycerides decreased by 35%. Fasting insulin plummeted by 68%. HOMA-IR, a measure of insulin resistance, decreased by 72%. Blood pressure decreased and blood vessel distensibility (a measure of vessel elasticity) increased. It's interesting to note that measures of glucose metabolism improved dramatically despite no change in carbohydrate intake. Some of these results were statistically significant, but not all of them. However, the authors note that:

In all these measured variables, either eight or all nine participants had identical directional responses when switched to paleolithic type diet, that is, near consistently improved status of circulatory, carbohydrate and lipid metabolism/physiology.

Translation: everyone improved. That's a very meaningful point, because even if the average improves, in many studies a certain percentage of people get worse. This study adds to the evidence that no matter what your gender or genetic background, a diet roughly consistent with our evolutionary past can bring major health benefits. Here's another way to say it: ditching certain modern foods can be immensely beneficial to health, even in people who already appear healthy. This is true regardless of whether or not one loses weight.

There's one last critical point I'll make about this study. In figure 2, the investigators graphed baseline insulin resistance vs. the change in insulin resistance during the course of the study for each participant. Participants who started with the most insulin resistance saw the largest improvements, while those with little insulin resistance to begin with changed less. There was a linear relationship between baseline IR and the change in IR, with a correlation of R=0.98, p less than 0.0001. In other words, to a highly significant degree, participants who needed the most improvement, saw the most improvement. Every participant with insulin resistance at the beginning of the study ended up with basically normal insulin sensitivity after 10 days. At the end of the study, all participants had a similar degree of insulin sensitivity. This is best illustrated by the standard deviation of the fasting insulin measurement, which decreased 9-fold over the course of the experiment.

Here's what this suggests: different people have different degrees of susceptibility to the damaging effects of the modern Western diet. This depends on genetic background, age, activity level and many other factors. When you remove damaging foods, peoples' metabolisms normalize, and most of the differences in health that were apparent under adverse conditions disappear. I believe our genetic differences apply more to how we react to adverse conditions than how we function optimally. The fundamental workings of our metabolisms are very similar, having been forged mostly in hunter-gatherer times. We're all the same species after all.

This study adds to the evidence that modern industrial food is behind our poor health, and that a return to time-honored foodways can have immense benefits for nearly anyone. A paleolithic-style diet is a very effective way to claim your genetic birthright to good health. Just remember to eat the organs and fat. And skip the canola oil and mayonnaise."

WOD 091214

Three Rounds For Time:

Run 800 Meters
15 Deadlift 275/185

Post loads to comments

Body BY CFEB, Zone Diet and Raph's Parents

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Litinov Workout

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CF V Globo-Gyms

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CF (blue) V Bikram Yoga

In the above graphic from Google Trends, we see continuously increasing search volume in CrossFit. Also note the "January Effect" on the commercial gyms as people make New Year's resolutions, not present in CF.

In the below graphic, we see interest in CrossFit outstripping interest in Bikram Yoga.

Thanks to CrossFit Sweat Shop for pointing this out.

Post thoughts on these trends to comments.

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WOD 091121

Clean 3-3-3-3-3

Post loads to comments.

From a typical nutrition textbook: "When you eat too much you get fat, when you don't eat enough you get thin, everybody knows these simple facts but nobody knows exactly how to account for them". This is an oversimplification with a lot of truth to it.

There are some folks (you see a lot of them at a climbing gym) who have a really hard time adding any muscular mass, and can, for all intents and purposes eat whatever they want in pretty much any quantity without gaining significant bodyfat. These folks are ectomorphs, skinny and often tall: the "98 pound weakling" of yore. They are also known as "hardgainers" and have a difficult time gaining muscle mass or getting strong.

On the other end of the scale is the endomorph, who easily gains fat mass, but generally can easily become strong. Almost all unlimited weight class Olympic lifters seem to be of this type.

Those who are smart enough to have picked the right parents are mesomorphs, like pretty much all of the top males and most females at this years CrossFit Games. They are lean and muscular, a cultural ideal.

These body types can be mixed: meso-endo and meso-ecto. It may be that the different body types have different insulin sensitivity: Dr. Barry Sears in The Zone, thorizes that about 25% of the population have a poor reaction to carbohydrate leading to obesity when consuming a high-carb, especially high glycemic carb, diet. He postulates that significant genetic adaptation may have taken place in about 25% of the population that enables them to eat a high-grain diet with little or no ill effects (they stay skinny and don't get tired even if they eat giant pasta meals). Finally, everyone else is somewhere in the middle: his Zone DIet is designed to work well for all the types.

So what happens in the body to the carbohydrate, protien and fat we eat? It is pretty complicated, but here is what you need to know for fat loss or muscle gain. Please bear in mind the human body is an almost incomprehensibly complex machine: what follows is a vast oversimplification. Additionally metabolism is not fully understood, so this represents what I think is the best understanding we have today.

Our bodies are constantly burning fuel, simply to exist, even when asleep. this is called basal metabolism. Generally this is fueled by a 50/50 mix of fat and glycogen (the product of carbohydrate). Any food over and above metabolic need is converted to bodyfat, or excreted. During moderate-intensity aerobic work, this ratio switches to favor fat burning perhaps 70/30. During intense exercise (short metcon) the body is burning through glycogen at a blistering rate, preferring nearly 100% of energy needs from glycogen. Intense work of this type increases the bodies metabolic need quite a bit subsequent to the actual work, so additional bodyfat may be burned afterward. So given adequate glycogen, fat can be burned through exercise and bodyfat can be decreased. Very little, if any, muscle wasting occurs as long as nutrition is adequate.

However, when we intentionally deprive the body of calories (fasting) the following comes into play: the body can actually power itself quite well for up to about a day on stored glycogen and fat, which are turned into glucose and fatty acids and flow into cells to power them. (this is assuming you are not doing Murph in addition to fasting), however, the brain needs glucose to work, and in the absence of glycogen, the body will begin breaking down lean muscle tissue to create glucose, a metabolically very expensive process. This is why starving yourself will not work. Anything below 1500 cal a day for men and 1200 cal a day for women, on average, is going to result in significant muscle loss. And this is average: most CrossFitters have more muscle and more metabolic demand.

So: without even considering the protein requirement we see that just the right amount of deficit must be created to lose fat and not muscle. One reasonably simple way to get it right is the Zone Diet, the CrossFit diet of choice. Find your block count, and then take 1-4 blocks off of that depending on how fast you wish to lose weight. Of course the more you take off, the more danger you are in of losing muscle. It is ESSENTIAL to weigh and measure everything on this diet, certainly for the first few weeks.

Next: The Hardgainer

Polly On Her Coffee Run Photo: Tom Campitelli

It's Time to Make a Coffee Run

By GINA KOLATA

WELDON JOHNSON first tried caffeine as a performance enhancer in 1998. He was not a coffee drinker but had heard that caffeine could make him run faster. So he
went to a convenience store before a race and drank a cup of coffee.

For the first time in his life, he ran 10 kilometers in less than 30 minutes.

"I remember being really wired before the race," he said in an e-mail message. "My body was shaking."

From then on, he was a convert.

Mr. Johnson, a founder of LetsRun.com,
would avoid caffeine, even in soft drinks, for a few weeks before he
competed in a race, wanting to have the full stimulant effect.

"It may have been a huge placebo effect, but I swore by it," Mr.

Johnson said. "Having a cup of coffee exactly one hour before the race
was part of my routine."

Or maybe it was not a placebo effect.

Caffeine, it turns out, actually works. And it is legal, one of the
few performance enhancers that is not banned by the World Anti-Doping
Agency.

So even as sports stars from baseball players to cyclists to

sprinters are pilloried for using performance enhancing drugs, one of
the best studied performance enhancers is fine for them or anyone else
to use. And it is right there in a cup of coffee or a can of soda.

Exercise physiologists have studied caffeine's effects in nearly

every iteration: Does it help sprinters? Marathon runners? Cyclists?
Rowers? Swimmers? Athletes whose sports involve stopping and starting
like tennis players? The answers are yes and yes and yes and yes.

Starting as long ago as 1978, researchers have been publishing caffeine studies. And in study after study, they concluded that caffeine actually does improve performance.

In fact, some experts, like Dr. Mark Tarnopolsky of McMaster University
in Canada, are just incredulous that anyone could even ask if caffeine
has a performance effect.

"There is so much data on this that it's unbelievable," he said.

"It's just unequivocal that caffeine improves performance. It's been
shown in well-respected labs in multiple places around the world."

The only new questions were how it exerts its effects and how little caffeine is needed to get an effect.

For many years, researchers thought the sole reason people could
exercise harder and longer after using caffeine was that the compound
helped muscles use fat as a fuel, sparing the glycogen stored in
muscles and increasing endurance. But there were several hints that
something else was going on. For example, caffeine improved performance
even in short intense bursts of exercise when endurance is not an issue.

Now, Dr. Tarnopolsky and others report that caffeine increases the power output of muscles by releasing calcium that is stored in muscle. The effect can enable athletes to keep going longer

or to go faster in the same length of time. Caffeine also affects the
brain's sensation of exhaustion, that feeling that it's time to stop,
you can't go on any more. That may be one way it improves endurance,
Dr. Tarnopolsky said.

The performance improvement in controlled laboratory settings can be

20 to 25 percent, Dr. Tarnopolsky said. But in the real world,
including all comers, the improvement may average about 5 percent,
still significant if you want to get your best time or even win a race.

For years, researchers believed that you needed about 5 to 6

milligrams of caffeine per kilogram of body weight. An 80-kilogram, or
176-pound man, for example, would need about 400 milligrams of
caffeine, or 20 ounces of coffee.

Now, Louise M. Burke, the head of sports nutrition

department of the Australian Institute of Sport in Canberra, reports
that athletes get the full caffeine effect with as little as 1
milligram of caffeine per kilogram of body weight. Instead of 20 ounces
of coffee, a 176-pound man could drink 4 ounces of coffee, or about two
12-ounce cans of Coke.

It's also possible to get diminishing returns.

Terry Graham, chairman of the Department of Human Health and
Nutritional Sciences of the University of Guelph in Canada, found that
at 9 milligrams per kilogram, athletes actually did worse.

Many athletes and coaches are not caffeine fans. Mr. Johnson said he

has tried to spread the word and gets frustrated when runners don't use
caffeine -- so much so, he said, that when he sees the team his brother
coaches at Cornell, he thinks, why aren't they all going to Starbucks?

Mike Perry, a friend who is a sculler who has competed nationally

and internationally, said that, with one exception, the rowers he knew
did not use caffeine.

"People would have psychological issues with using it," he said.

"They would see it as against the spirit of the law, even though it's
not against the law."

Still, Mr. Perry wondered whether caffeine would help him. When he

retired from rowing last July, he decided to do a randomized, blinded,
placebo-controlled experiment on himself.

He noticed that the 200-milligram caffeine pills look exactly like vitamin C

pills, allowing him to code the pills so that he would not know which
one he had taken. For eight months he tested himself once a week,
taking two pills an hour before working out on a rowing machine. Then
he worked as hard as he could for an hour, recording the results, also
recording his guess about whether the pills he took contained caffeine.
Mr. Perry, who also is a runner, said that an hour on the rowing
machine is the equivalent of an hour of very fast running on the road.

When he finished his study and broke the code late last month, he

was astonished to see how much the caffeine had affected him. He was
stronger -- his power output was 3 percent greater -- and faster. In
fact, he said the average speed for his tests when he used caffeine was
faster than his fastest speed when he was not using caffeine.

He also guessed right most of the time about whether the pills he

took were caffeine or vitamin C. Mr. Perry said he is now sorry that he
never used caffeine when he was competing. "It would have been a pretty
harmless way to do better," he said.

Others, including my son Stefan, disagree. I urged Stefan to try caffeine and he did. Once.

He took a caffeine pill before a track workout that involved
running a mile very quickly, resting briefly, and running a mile again,
repeatedly. Like Mr. Johnson, he was wired and shaking. But, Stefan
said, he could not recover between miles. His heart was pounding and
just would not slow down. He said he has no desire to experience that
again.

Then there is the problem my running partner Jen Davis and I have.

We love coffee and probably have caffeine in our blood all the time
except during the middle of the night (it lasts for hours).

SO would we do better if we weaned ourselves from caffeine and then took a pill or two before a race?
 
I asked Dr. Tarnopolsky. It turns out, he said, that you get

habituated to two of caffeine's effects right away. Caffeine can make
you urinate, but only if you are not used to it.

"Athletes do not get dehydrated from caffeine," he added, "contrary to popular myth."

And caffeine does increase the heart rate and blood pressure
in people who are not regular uses. "But after three or four days, that
potentially negative effect is gone," Dr. Tarnopolsky said.

The beneficial effects on exercise, though, remain. Even if you are

a regular coffee drinker, if you have a cup of coffee before a workout
or a race, you will do better, Dr. Tarnopolsky said. "There is no
question about it," he added.

He puts the caffeine research to use when he trains and competes.

Dr. Tarnopolsky is an elite triathlete, ski orienteer and trail runner
who has competed at national and international levels. And, he said, he
loves coffee: "I love the smell. I love the taste. It's heaven."

And before a race? He always has a cup.

Social Climbing at GWPC 6-9PM

Come climb with the CFEB crew. If you don't know how this is a great opportunity to learn to top-rope: you don't need to own equipment, but there is a nominal fee for harness and shoe rental.

Post routes completed or attempted to comments.