http://www.oldwayspt.org/med_pyramid.html

http://health.usnews.com/articles/health/diet-fitness/2009/08/24/foods-surprisingly-high-in-added-sugar.html

http://health.usnews.com/articles/health/living-well-usn/2008/04/07/diets-that-promote-health-and-always-have.html

http://health.usnews.com/articles/health/healthday/2009/08/25/as-waistlines-widen-brains-shrink.html

Richard Wrangham, a primatologist and anthropologist, has spent four decades observing wild chimpanzees in Africa to see what their behavior might tell us about prehistoric humans. Dr. Wrangham, 60, was born in Britain and since 1989 has been at Harvard, where he is a professor of biological anthropology. He is about to publish another book, “Catching Fire: How Cooking Made Us Human.” He was interviewed over a vegetarian lunch at last winter’s American Association for the Advancement of Science meeting in Chicago and again later by telephone. An edited version of the two conversations follows.

Q. In your new book, you suggest that cooking was what facilitated our evolution from ape to human. Until now scientists have theorized that tool making and meat eating set the conditions for the ascent of man. Why do you argue that cooking was the main factor?

A. All that you mention were drivers of the evolution of our species. However, our large brain and the shape of our bodies are the product of a rich diet that was only available to us after we began cooking our foods. It was cooking that provided our bodies with more energy than we’d previously obtained as foraging animals eating raw food.

I have followed wild chimpanzees and studied what, and how, they eat. Modern chimps are likely to take the same kinds of foods as our early ancestors. In the wild, they’ll be lucky to find a fruit as delicious as a raspberry. More often they locate a patch of fruits as dry and strong-tasting as rose hips, which they’ll masticate for a full hour. Chimps spend most of their day finding and chewing extremely fibrous foods. Their diet is very unsatisfying to humans. But once our ancestors began eating cooked foods — approximately 1.8 million years ago — their diet became softer, safer and far more nutritious.

And that’s what fueled the development of the upright body and large brain that we associate with modern humans. Earlier ancestors had a relatively big gut and apelike proportions. Homo erectus, our more immediate ancestor, has long legs and a lean, striding body. In fact, he could walk into a Fifth Avenue shop today and buy a suit right off a peg.

Our ancestors were able to evolve because cooked foods were richer, healthier and required less eating time.

Q. To cook, you need fire. How did early humans get it?

A. The austrolopithicines, the predecessors of our prehuman ancestors, lived in savannahs with dry uplands. They would often have encountered natural fires and food improved by those fires. Moreover, we know from cut marks on old bones that our distant ancestor Homo habilis ate meat. They certainly made hammers from stones, which they may have used to tenderize it. We know that sparks fly when you hammer stone. It’s reasonable to imagine that our ancestors ate food warmed by the fires they ignited when they prepared their meat.

Now, once you had communal fires and cooking and a higher-calorie diet, the social world of our ancestors changed, too. Once individuals were drawn to a specific attractive location that had a fire, they spent a lot of time around it together. This was clearly a very different system from wandering around chimpanzee-style, sleeping wherever you wanted, always able to leave a group if there was any kind of social conflict.

We had to be able to look each other in the eye. We couldn’t react with impulsivity. Once you are sitting around the fire, you need to suppress reactive emotions that would otherwise lead to social chaos. Around that fire, we became tamer.

Q. Your critics say you have a nice theory, but no proof. They say that there’s no evidence of fireplaces 1.8 million years ago. How do you answer them?

A. Yes, there are those who say we need archaeological proof that we made fires 1.8 million years ago. And yes, thus far, none have been found. There is evidence from Israel showing the control of fire at about 800,000 years ago. I’d love to see older archaeological signals. At some point, we’ll get them.

But for the meanwhile, we have strong biological evidence. Our teeth and our gut became small at 1.8 million years. This change can only be explained by the fact that our ancestors were getting more nutrition and softer foods. And this could only have happened because they were cooking. The foraging diet that we see in modern chimps just wasn’t enough to fuel it.

For Carole Carson, the golden years weren’t so shiny when it came to her mental clarity.

“I was sort of a retired lump on a log,” said 67-year-old Carson, referring to herself seven years ago.

But after going on a restricted calorie diet, along with an exercise regime, Carson, who lives in Nevada City, Calif., lost about 50 pounds. Her life — and her mind — perked up again.

“Every kind of mental function improved,” Carson said.

Many people who have cut calories experience the “mental clarity” and increased creativity Carson said was an unexpected benefit of a healthier lifestyle.

Now, researchers have shown a definite link between caloric restriction (CR) and mental function, according to a study published Monday in the journal Proceedings of the National Academy of Sciences.

Researchers from the University of Munster in Germany divided 50 normal and overweight adults with an average age of 60 years into three groups. Group 1 cut their normal daily caloric intake by 30 percent, group 2 increased their normal daily consumption of unsaturated fatty acids, such as those found in fish and olive oil, and group 3 did not alter anything in their diets.

The volunteers had their memories tested at the start of the study and again three months later. Results showed that those who reduced their calorie consumption improved their scores on a word-learning task, suggesting a boost in verbal memory. Other types of memory were not affected, and the other two groups showed no significant cognitive improvements.

Food for Thought

But while this study does show a link, the number of participants was small, making it difficult to determine how the dietary programs would affect a wider population. Past studies have not shown a clear relationship between cutting calories and memory.

“We do not yet know if this response is sustained over time and whether it is meaningful enough to benefit our everyday activities,” said Dr. P. Murali Doraiswamy, professor of psychiatry and medicine at the Duke University Medical Center.

But experts agreed that the phenomenon makes sense from a physiological standpoint. Dr. Ken Fujioka, director of Nutrition and Metabolic Research at the Scripps Clinic in San Diego, offered an evolution-based explanation.

“Humans used to die from starvation all the time,” he said. “Insulin is a messenger to the brain of carbohydrate reserves, and as we restrict calories, we will drop the insulin and signal to the brain we will be going into ‘starvation.’ It would be adaptive to have better verbal memory to find food or calories in order to survive.”

In addition to increased insulin sensitivity, the researchers proposed that better neuron function and reduced inflammatory activity, as a result of caloric restriction, could have resulted in better verbal memory.

Chew On This

Along with her overall well-being, Carson said she noticed clear cognitive benefits from CR after just a few months of her new diet.

“Is my verbal memory improved? Absolutely,” she said.

In the past several years, Carson has organized a community weight-loss effort, gives talks about her own weight loss — from memory — and has published two children’s books.

“I have to use my memory in incredible ways,” said Carson, who just bought a new laptop on which she receives about 500 e-mails a week due to her busy schedule, far busier than when she ran her own business prior to retiring. “Something has shifted.”

Further research on CR and cognition could have implications for those with Alzheimer’s or stroke-related memory loss.

“Our study may help to generate novel prevention strategies to maintain cognitive functions into old age,” the authors wrote in the paper.

By LAUREN COX

A study that showed men and women’s brains work differently when they’re tempted with food has experts debating the reasons behind the gender gap in obesity rates.

Doctors asked 23 men and women of healthy weight to go on a three-day fast and then tempted them with morsels of their favorite foods and trips to buffets where study subjects were told they could not partake.

Brain scans of the test subjects showed men’s brains looked calmer and worked less when they consciously faced temptation, but women’s brains lit up in emotion and hunger desire areas, according to the study published in the Proceedings of the National Academy of Sciences.

The researchers behind this study suggest that the gender difference in the PET brain scans may explain the two percentage point lead women have over men in rising obesity rates.

However, other diet experts think environment and culture, not biology, explain the roots of obesity.

“When people move from the U.S. to other countries, they lose weight. When people move here to the U.S. from other countries, they gain weight,” said Kelly Brownell, director of the Rudd Center for Food Policy and Obesity at Yale University.

“Is it that we can’t control what we are eating that makes us obese, or is it that we are eating the wrong things and not moving around?” Brownell asked.

Dr. Gene-Jack Wang, lead author of the study, did his best to mimic a person’s struggle with food in his lab to address the question.

Wang first asked each study subject to rate their favorite foods from a long list, and then start fasting for three days.

When the test subjects returned, he used their favorite foods to tempt them.

“We’re going to show it to you, and you’re going to put a small piece in your mouth for taste. And then we’re going to talk about it with you,” said Wang, who admitted he had to eat before each case to stop his own temptation.

“It’s the actual food, and you’re in the bed and you cannot escape,” he said. After each temptation, which included a trip to a buffet at the end of the day, Wang and his colleagues did a PET (positron emission tomography) scan of each subject to see which parts of the brain are active during temptation.

Is Suppressing Hunger a Gender Issue?

Men and women’s PET scans did not differ very much when Wang and his colleagues simply tempted them with food. It was only after the researchers asked their subjects to deliberately ignore the food and repress hunger that a gender difference appeared.

Both men and women reported success at repressing thoughts about food. “But in women, their brain and what they’re saying is not necessarily the same,” said Wang. “I hear them say they suppressed their appetite, but their brain is doing something else.”

Neither the men nor women ever actually caved in and took the food, but Wang said the different PET scans could be a sign that women have a harder time suppressing their hunger in general, and that this could be a biological explanation for higher obesity rates among women.

According to the U.S. Centers for Disease Control, 33 percent of men and 35.3 percent of women were obese in the United States in 2006 — a small, but consistent difference over of 2 percent over the years.

Elisabetta Politi, the nutrition director at the Duke Diet and Fitness Center in Durham N.C., thought the PET study was an interesting idea, but doubted it would change how people fight obesity.

“In my practice, we never worry about men or women, we just try to treat obesity — for both their rate is alarming,” said Politi. “The thing with obesity is that it is so multi-factorial and so complex that it’s hard to pinpoint what makes a gender or ethnicity more prone.”

Politi could name several possible explanations for the gender difference in obesity right off the bat — the number of women who are around food preparing it, the natural biologic tendency for women to have higher body fat for pregnancy, the struggle to lose weight after pregnancy, and more stationary work in careers.

“I thought that the PET design was really, really interesting,” said Politi. “But it’s really a piece of the whole picture when you’re trying to treat obesity.”

For example, Politi would never recommend someone try to fast or suppress their appetite as the study subjects did.

“I’d say try to eat more frequent meals,” said Politi. “To say that people who control their weight have more will power is simplifying. It’s maintaining healthier behavioral changes over time.”