Chickens in a poultry farm
Photo: percds / iStockphoto / Getty Images
In the old days, when there were no supermarkets and people largely grew their own food, one might think that there was not much about the variety of diets.
Many believe that in the good old days there was little food in the countryside in Central Europe.
Some people remember stories of their grandparents about winters with cabbage and beet stews.
Today, however, when people can order food from almost all parts of the world to their homes, the diversity in our diet must also have increased.
But that's not true.
Because humanity today has a much less diverse diet than it was 100 years ago. This is the conclusion that scientists come to after chemical analyzes of human tissue. Only those peoples who still live very close to nature today show a similar nutritional diversity as the people before 1910 - i.e. before the invention of artificial fertilizers and the beginning of industrialized agriculture and animal husbandry.
Humans have an extremely wide range of vegetable and animal foods.
In order to research how modern agriculture has changed the diet, the researchers led by Michael Bird from James Cook University in Cairns (Australia) analyzed around 14,000 tissue samples from people today and in the past.
For example, they came from hair and nails; numerous samples were several thousand years old and came from archaeological investigations.
The scientists considered three groups:
a modern urban population
modern people in subsistence farming
People who lived before 1910
With isotope analyzes for comparison
Carbon (as Delta-C-13) and nitrogen (as Delta-N-15) were measured. Delta-C-13 is the ratio of the carbon isotopes C-13 and C-12 to one another compared to a standard value. The ratio of isotopes changes depending on whether the food comes from the land or from the sea. Using the Delta-N-15 value (ratio of the isotopes N-15 to N-14), researchers can determine from which part of the food chain the diet of the respective person originated - for example, whether meat came from predators or herbivores or it was traded purely vegetable food. Both values together provide information about how varied the diet of the person examined was. Such isotope analyzes are also carried out by ancient researchers, for example, in order to find out something about the eating habits of our ancestors.
The researchers speak of a "stark contrast" in the results. People before 1910 sometimes showed very different Delta-C-13 and Delta-N-15 values, even groups from the same geographic area. In some groups, the range of values was limited if, for example, they ate a mainly vegetarian or very meat-rich diet, as the researchers report in the journal Proceedings of the National Academy of Sciences (PNAS). Viewed globally, however, the nutritional diversity before 1910 and among modern people in subsistence farming was about three times as great as among modern, urban people.
The researchers attribute this to modern agriculture, which is increasingly concentrating on fewer varieties of crops and animals, and to global supply chains: “The supermarkets that use these global supply chains now have a share of more than 50 percent of the food retail trade in Countries with an annual income of more than US $ 10,000 per capita. «The worldwide trade flows lead to an adjustment of the food supply. In other words, we all eat very similar things around the world.
The statement also applies to groups that follow a vegetarian or vegan diet.
The delta C-13 value of modern people ranges from -24.2 per mille for vegans in Great Britain to -18.7 per mille in Iran and Pakistan.
In people before 1910, the researchers found values of -31.4 to -10.4 per thousand.
The situation is similar with the Delta-N-15 values: modern people come to +0.45 per mille (vegans in Germany) to +5.57 per mille (Papua New Guinea).
Before the invention of artificial fertilizers, the range worldwide was -2.3 to +22.3 per thousand.
joe / dpa