Today, the effects of reversing cultural malnutrition can be applied to local places, like Sacramento. If you walk down Marconi Avenue near Eastern Avenue, you’ll see many fast food chains almost on every corner within a few blocks. The same can be said of the corner of El Camino Avenue and Watt Avenue in Sacramento–fast food eateries close to one another within a one-mile radius in both directions along Watt Avenue. Is the diet of today that may be helping to increase obesity related to cultural malnutrition of the past 8,000 years?
Where one lived in the past also affected immunity to some infectious diseases. How did diet help make people grow smaller? Before people lived in cramped, urban quarters of city life thousands of years ago in certain parts of the world, early hunters, usually males, and early gatherers, usually women looking for wild seeds to pound or boil and any leaves, nuts, or berries that could be collected and eaten if no fish or meat were found, people had a diet rich in minerals and protein.
As people roamed in search of food, there were many years between children. They were spaced far apart because the first child had to be weaned and walking to keep up with the people walking in search of food. The hormonal cycle adjusted itself to the hunter-gatherer life style, with children usually being spaced about five or six years apart.
After the end of the last ice age, cereal farmers from N.E. Turkey and the Middle East migrated into Europe and elsewhere, beginning about 8,000 years ago. What these cereal farmers brought were new ideas in farming. Not only cereal crops, but cheese-making skills were spread as ideas to almost all parts of Europe, India, the Middle East, and Central Asia, including along the vast Gobi desert nomad populations, who didn’t farm, but made cheese and fermented milk products.
Among the cereal farmers of 8,000 years ago, there were farm settlements. The land had to be protected. Many wars broke out as farmers defended their crops from nomads and hunters competing for food and raiding the farmers in search of taking away sheep and goats, horses, crop harvests, or other items that could be used for food or transportation.
What resulted to the farm-settled families were larger families to tend the land, protect it from invaders, and grow crops. Sons began to be valued over daughters for the purposes of defending the land and plowing it. The diet then became high in carbohydrates and low in protein, also low in vitamins and calcium/magnesium. That’s the main point–the change in diet to high carbs….wheat, rye, and barley, in Europe and parts of the Middle East, rice (in Asia) and tiff and millet in Africa.
As hormones changed with the high-carb diets over thousands of years, more children were born spaced two years instead of five years apart. This resulted in children being weaned earlier, usually at the age of 10 months, when the wives became pregnant again, instead of children being weaned at four or five years of age in hunter-gatherer societies.
What happened to the human body then is that the low-protein, high-carb diet resulted in growth stunting. People dropped about a foot in height. And hormones continued to change so that women could become pregnant more frequently, including during breast feeding, instead of when they stopped breast feeding.
From the six-foot to six-foot-six male hunter-gatherer, the height dropped to about five-foot four inches on average. Women’s height dropped from an average of five foot-six inches or five-foot-ten inches in some cases of hunter-gatherers, to only five feet tall, on average in the cereal belt and everywhere else where cereal farming began on a large scale. Before that time, cereal grains were gathered, but they were those larger-sized wild grains, not the cultivated type of small grains.
The growth-stunting persisted throughout adult life. As farming spread all over Europe, the average adult size in height decreased dramatically for both children and adults. This especially hit the rice-growing areas of Asia hardest as rice farming increased, especially in Southeast Asia, at a time thousands of years ago when mostly rice was eaten without much animal protein.
What has food got to do with it? Did the phytates from a diet too high in grains prevent minerals from being absorbed into the bloodstreams of more modern populations? Was that what caused the drastic reduction of pelvic size and more painful childbirths?
Pelvic inlet depth and average stature of any group of people in modern, historical, and prehistorical times are markers of interest, if you overlook the life expectancy data due to war, accidents or epidemics unrelated to daily diet, according to the August 2008 article, “Life Expectancy and Growth of Paleolithic vs. Neolithic Humans.”
Why has the human pelvis gone from very large (easier childbirth) to tiny (painful childbirth, longer labors) and now is growing larger again, for some, but not for all? But in modern times, females still haven’t reached the large pelvis size that it was 30,000 to 9,000 years ago.
One can see from the data that looks at the changing size of the pelvic depth, the life span, and the height of men and women at the nutrition and physical degeneration site, that things are rarely as clear-cut as dietary purists would like them to be. For any period in time, there is good and there is bad.
Today, the effect is being reversed. You see taller Asian children eating foods containing more minerals. But you also see the effects of the standard fast-food Western diet high in carbs and trans fats being introduced as more fast-food eateries open in various parts of the world. Is obesity increasing?
Why does China and India now have two of the highest rates of type 2 diabetes in the world? Is it related to a native diet that remained the same for the past 5,000 years or fast-foods introduced from other places containing unfamiliar items?
New research has found that a genetic variant which reduces the chance of contracting diseases such as tuberculosis and leprosy is more prevalent in populations with long histories of urban living, according to the September 25, 2010 university of London news release, also published as a EurekAlert! public release, “City living helped humans evolve immunity to TB.”
The research, published in the journal Evolution, shows that in areas with a long history of urban settlements, today’s inhabitants are more likely to possess the genetic variant which provides resistance to infection.
In ancient cities, poor sanitation and high population densities would have provided an ideal breeding ground for the spread of disease. Natural selection should mean that humans would have developed resistance to disease in long-standing urbanised populations over time. However, this association has been very difficult to assess – especially in prehistory.
Now, scientists from UCL (University College London) and Royal Holloway have tested the theory by analysing DNA samples from 17 different human populations living across Europe, Asia and Africa. In addition, they searched archaeological and historical literature to find the oldest records of the first city or urban settlement in these regions.
By comparing rates of genetic disease resistance with urban history, they showed that past exposure to pathogens led to disease resistance spreading through populations, with our ancestors passing their resistance to their descendents.
“The results show that the protective variant is found in nearly everyone from the Middle East to India and in parts of Europe where cities have been around for thousands of years” said Professor Mark Thomas from the Department of Genetics, Evolution and Environment at UCL (University College London), according to the news release of September 25, 2010.
Dr Ian Barnes, from the School of Biological Sciences at Royal Holloway, said: “The method we have employed here makes novel use of historical and archaeological data, as a means to explain the distribution and frequency of a genetic variant, and to identify a source of natural selection.
“This seems to be an elegant example of evolution in action. It flags up the importance of a very recent aspect of our evolution as a species, the development of cities as a selective force. It could also help to explain some of the differences we observe in disease resistance around the world,” added Dr Barnes, according to that news release.
“Population density seems to play an important role in shaping so many aspects of our species”, said Prof Thomas. “It was a vital factor in our species maintaining the complex skills and culture that distinguish us from other primates.”
So did living in cramped city buildings thousands of years ago help to provide immunity to some infectious diseases in people today? “It drove many of the genetic differences we see today between different populations from around the world. And now, it seems, it also influenced how infectious diseases spread in the past and how we evolved to resist those diseases,” Professor Thomas explained, according to that public press release.
The study related how the spread of infectious diseases thousands of years ago had been influenced by living in an urban environment. Research was funded by the Natural Environment Research Council and the Arts and Humanities Research Council (Centre for the Evolution of Cultural Diversity).