Food Reward: a Dominant Factor in Obesity, Part V

Non-industrial diets from a food reward perspective

In 21st century affluent nations, we have unprecedented control over what food crosses our lips.  We can buy nearly any fruit or vegetable in any season, and a massive processed food industry has sprung up to satisfy (or manufacture) our every craving.  Most people can afford exotic spices and herbs from around the world-- consider that only a hundred years ago, black pepper was a luxury item.  But our degree of control goes even deeper: over the last century, kitchen technology such as electric/gas stoves, refrigerators, microwaves and a variety of other now-indispensable devices have changed the way we prepare food at home (Megan J. Elias.  Food in the United States, 1890-1945). 

To help calibrate our thinking about the role of food reward (and food palatability) in human evolutionary history, I offer a few brief descriptions of contemporary hunter-gatherer and non-industrial agriculturalist diets.  What did they eat, and how did they prepare it? 

The Ache of Paraguay

The Ache are recently contacted rainforest hunter-gatherers who live a predominantly traditional lifestyle.  They are more hunter than gatherer, with the large majority of their high calorie intake coming from various game animals, generally killed using a large bow and arrow.  Although the rainforest contains many potential prey animals, they rely predominantly on only a few.  These include armadillos, paca, tapirs, monkeys, peccaries, lizards and a few other species.  Meat is cooked simply on a fire or boiled, typically with no salt or flavorings added (1, Kim Hill and A. Magdalena Hurtado. Ache Life History).  I've never eaten armadillo or tapir, but I know that wild game meat is often very tough and gamey-- with some exceptions.  Gnawing on an unseasoned armadillo leg is probably not very appetizing to the average Westerner. 

Gathered foods also play an important role in the Ache diet, with only a few foods providing most of their calories in this category.  Palm starch is extracted and simply cooked.  Honey also provides a significant proportion of calories, with fruit playing a minor role.  The Ache also eat various insect larvae, including bee larvae that they collect along with the honey.  They drink water almost exclusively, and do not have alcohol.  They are characteristically lean (Kim Hill and A. Magdalena Hurtado. Ache Life History).

Honey is probably the most rewarding/palatable food in the Ache diet, but as delicious as honey is, I suspect honey itself is only moderately rewarding if it's eaten plain.  However, sweetening other foods using honey can increase their reward value considerably. I think most people would rather eat a bowl of ice cream than eat the sugar, cream and vanilla bean separately.  I don't know how the Ache eat their honey-- if anyone knows, please leave a comment.


The !Kung San of Botswana

The !Kung diet is predominantly composed of plant foods.  Among the !Kung groups that I'm familiar with from the work of anthropologist Dr. Richard B. Lee, by far the single largest source of calories is the mongongo nut and the fruit that surrounds it.  The fruit is eaten raw or gently stewed in a metal pot (a relatively recent introduction).  The nuts are roasted, shelled and eaten plain.  During certain parts of the year, they eat almost nothing but mongongo nuts.  Various starchy tubers/corms/roots are cooked on a fire or in its ashes and eaten plain, and Western observers say they have a pleasant flavor.  Leaves are sometimes collected for "salads", although of course no salad dressing is used. They also gather and eat various insects.

Hunted foods are an important part of the !Kung diet.  Men use bows, arrows, spears, hooks and clubs to obtain a variety of large and small game.  They value the liver highly, believing it imparts strength.  Meat is typically boiled in a metal pot until it's tender, then crushed in a mortar and eaten plain.  Before metal pots, it was presumably cooked on the fire or in ashes.

The !Kung don't use salt or seasonings in their food. They mostly drink water, although they also drink the liquid pressed from certain roots.  This liquid is said to have a pleasant flavor.  They do not have alcohol.  They are generally very lean (2, Richard B. Lee. The !Kung San; Jiro Tanaka. The San: Hunter-Gatherers of the Kalahari).

Polynesian islanders (and the Melanesian island of Kitava)

The food habits of most traditional Polynesian and certain Melanesian islands centered around starchy staple foods including taro, breadfruit, yams and sweet potatoes (today, additional starchy foods have been introduced, including cassava).  Other important foods included coconut, fish and shellfish, taro leaves and a few fruits (today, they have many more fruits that were introduced).  They had sugar cane, but it was chewed plain as a snack, in moderate quantity.  Pork was a rare treat for most people.  Food was simply cooked in an earth oven, which is between steaming and baking, and typically served plain.  Most islands had virtually no herbs or spices.  One exception is turmeric, although it was mostly used as a dye and not commonly eaten.  They sometimes used seawater to salt their food, either during cooking or as a condiment.

On Kitava, they use chili pepper and ginger as flavorings, which they have had for a few hundred years.  Just recently, they've begun using citrus fruits such as lemons to flavor seafood.  They also frequently use seawater to salt their cooking, particularly when cooking in pots, which may be a relatively recent introduction.  This information comes from Job Daniel, a Kitavan living in Papua New Guinea who has been kind enough to answer my questions.

The food on most islands would have been fairly repetitive and moderately low in fat, with the majority of calories coming from a single starchy food source in most seasons.  Although most islands relied on several starchy staples, they were generally seasonal, so a group might find itself eating mostly Colocasia taro for three months, mostly breadfruit for three months, etc.  A few islands, such as Tokelau, relied on coconut for the majority of calories throughout the year.

On most islands, water was the primary beverage, although they all drank coconut water at times.  On a few islands, coconut water was the primary beverage because there was little or no fresh water.  Coconut water is delicious, and judging by my own reaction to it, highly rewarding (the first thing I thought after I drank some was "where can I get more of this stuff??").  They did not have alcohol.

Feast days included more complex dishes, such as "puddings", which are mixtures of coconut cream and grated or pounded starches.  These are probably quite delicious and rewarding, but not available to the average person on a daily basis. 

High-ranking individuals ate this kind of food more frequently, and in addition were often deliberately overfed to represent the prosperity of the community.  These people were usually overweight and sometimes obese, while the average person was generally lean.  Although frank obesity was uncommon, what we would call overweight was not necessarily rare on some islands.  On Kitava, there is no overweight or obesity whatsoever (Nancy J. Pollock. These Roots Remain; Douglas Oliver. Polynesia in Early Historic Times).

New Guinea highlanders

In the New Guinea highland village of Tukisenta in the 1980s, people ate virtually nothing but sweet potatoes (90+ percent of calories), with small contributions from vegetables, pork and insects.  They drank water and they did not have alcohol.  They were characteristically lean, with female fat mass peaking during reproductive years and declining thereafter.  Male fat mass remained low and constant throughout life.  They were physically fit, showed no sign of malnutrition and had an extraordinarily good glucose tolerance.

They cooked their food in earth ovens, and used no flavorings or salt.  Their diet was extraordinarily bland and repetitive (Hugh Trowell and Dennis Burkitt. Western Diseases). 

The Maasai of Kenya and Tanzania

The traditional Maasai were pastoralists obtaining much all their calories from the milk, meat and blood of the cows they raised.  They also ate starchy foods such as grains and legumes that were primarily obtained by trade.  Much of their calories came from very fatty milk, which was eaten fermented, fresh or cooked with bitter herbs.  Blood was eaten raw or cooked, sometimes with milk.  Meat was cooked on a fire or stewed, sometimes with bitter herbs.  They did not use salt or sweet foods.  They did not have alcohol.

The traditional Maasai were very lean, had low blood cholesterol, low blood pressure and an undetectable incidence of heart attacks (3, 4, 5).  Their diet was relatively bland and extremely repetitive.

Conclusions

Overall, historical hunter-gatherers and non-industrial agriculturalists/horticulturalists/pastoralists ate a diet that most modern people would find bland, and in some cases even unpalatable.  Compared to the modern diet, it would sometimes have been tough, often repetitive, and typically lacking in salt, added sweeteners and other flavorings.  Food items were generally prepared simply by cooking, and eaten plain, mostly without mixing with other foods or adding flavors.  Their diet would have been quite low in rewarding qualities compared to what most people eat today.  They didn't have the technology, the ingredients or the knowledge to make haute cuisine, much less highly engineered foods such as Doritos and Pepsi.  Even simple things we take for granted today, like a crusty loaf of bread or sauteed onions, would have been impossible for them. 

Many cultures have thrived on simple food throughout human history, including our own ancestors until quite recently.  I believe that not only the foods we eat, but how we eat them, determines weight and health outcomes.  I don't think we're adapted to a world full of high-reward and highly palatable food, because we didn't live in that world until recently. If we want to learn from the diets of our ancestors, we should not just use the ingredients they used, we should also prepare food simply in our own kitchens. In the next post, I'll discuss how excessive food reward can hijack the brain and drive certain people into addiction-like behavior patterns.