The fear of germs has made us think of mud as dirt. And to get rid of dirt, we use a huge number of chemicals to kill the bacteria and germs they may contain. But there is more to Nature’s wisdom than big-time chemicals corporates would have us believe.
Scientists scan cultural accounts to conclude that eating dirt is a habit that may help protect against pathogens.
When a particular behavioural trait seems to occur in similar fashion across cultures, there is reason to suspect that there are biological reasons prompting such behaviour, however absurd it may seem. Perhaps this was why Cornell University researchers went through 480 cultural accounts across human history to understand why we literally like eating dirt. The analysis of these accounts, starting with Hippocrates 2,000 years ago, published in the June issue of The Quarterly Review of Biology, concludes that the most likely reason for the behaviour is that it protects us against toxins, parasites and pathogens.
The researchers were working with three alternate hypotheses, the first that the habit (the technical term is geophagy) may have nutritional benefits. But geophagy seems to thrive even when there is no shortage of food. The second alternative is that mud or dirt may contain certain micronutrients that the body craves and may not be able to obtain from food even when it is amply available.
Again, the literature indicates that the dirt humans most prefer eating is poor in most micronutrients. Also, if this were true, the population most likely to be indulging in this habit should be the elderly, whereas it is the very young and women in the early stages of pregnancy who are more likely to have the habit. This leads the researchers to conclude that the third hypothesis, that eating mud protects our stomach against toxins, parasites and pathogens, is the most likely explanation. It fits well with the prevalence of the habit among infants and pregnant women because these are the segments of the population most at risk. This explanation may in some way also tie in with the fact that children brought up in overly hygienic environments seem to have weaker immune responses.
The question then remains, how does eating dirt confer this protection? Does it contain substances which may be protective? Does it expose the body to small amounts of toxins and pathogens in the mud, helping to develop immunity?
Ravi Mantha, in his book All About Bacteriaseems to have an answer that bears testimony to Nature’s wisdom — of interdependence as a prinicple of Gaia, our living Earth. He says that dirt or, more appropriately, mud has beneficial bacteria that help us secrete serotonin, which contributes to well-being and happiness and which, in turn, supports our immunity-building processes.