Image Austria, circa 800–450 BC. An Iron Age miner culls salt within the historic mine shafts of Hallstatt within the Japanese Austrian Alps. He nears the tip of his lunch break, satiated by a hearty meal of grains and legumes, with a aspect of nuts and some bites of salt-cured beef. His work buddy presents him a swig of his newest batch of beer. The miner chases it down with a chew of his co-worker’s home made blue cheese and a handful of berries. He will get up, stretches, grabs his pickaxe, and returns to labor within the chilly mine, unaware that this was his final meal. Simply as his pickaxe hits salt with a clink, an unearthly rumble passes by means of him and the tunnel collapses.
Two millennia later, in 1734, miners found a mummified physique embedded in a saline tomb, nearly completely preserved by the salt, with bits of clothes and sneakers intact. They gave him a correct burial close to Lake Hallstatt and he grew to become a central determine in native folklore, identified affectionately because the “Man within the Salt.” 1 Whereas he didn’t deliberately donate his physique to science, he left a bit one thing behind for posterity: a goldmine of data for modern-day scientists who’ve superior technical instruments for finding out the biomolecules in preserved historic specimens.
Nearly 300 years after the Man within the Salt’s desiccated physique was found, scientists collected preserved samples of historic feces belonging to his contemporaries from the Hallstatt salt mines. In a lately revealed examine, their distinctive strategy to analyzing the dietary habits and intestine microbiomes of human ancestors demonstrated the connection between Westernized diets and the lack of intestine microbial variety, in addition to the implications for treating fashionable illnesses by restoring the traditional intestine microbiome.
Hidden Secrets and techniques of Mummified Microbes
Frank Maixner, a microbiologist on the Eurac Analysis Institute for Mummy Research in Bolzano, Italy, and his colleagues examined these paleofecal samples and reported their findings within the journal Current Biology. On this examine, Maixner’s staff carried out microscopic, metagenomic, and proteomic analyses of paleofeces to determine the dietary habits and intestine microbiomes of historic European miners.2
“Historical tissues, [including] museum specimens, nonetheless carry endogenous biomolecules [such as] proteins, DNA, and lipids,” Maixner defined. Combining radiocarbon courting of a specimen with endogenous biomolecule evaluation “opens up a window into the previous [to] ask evolutionary questions.”
Maixner and his multidisciplinary staff examined 4 paleofeces samples: one from the Bronze Age (1301-1121 BC), two from the Iron Age (650-545 BC), and one from the Baroque interval (1720-1783 AD). They discovered that Hallstatt miners from the Iron Age consumed an unprocessed fibrous food plan wealthy in complete grains, which they supplemented with fruits, nuts, legumes, animal protein, and fermented meals akin to blue cheese and beer. The latter got here as a shock when a fungal evaluation of one of many Iron Age samples confirmed important ranges of Penicillium roqueforti and Saccharomyces cerevisiae, yeast that ferment blue cheese and beer, respectively.
The paleofeces samples additionally contained bacterial species akin to Lactobacillus ruminis, Catenibacterium mitsuokai, and Prevotella copri, much like the microbiomes of modern-day people who devour unprocessed meals. In distinction, Westernized diets contribute to a lack of intestine microbiome variety.3 The similarity between the microbiome of the paleofecal pattern from the Baroque interval within the 1700s and that of contemporary non-Westernized guts means that the lack of microbial variety related to industrialized diets occurred fairly quickly. “If you happen to’re speaking about centuries,” Maixner mentioned, “it’s extremely astonishing to see such [rapid] lack of variety in our intestine microbiome.”
Maixner identified {that a} high-fiber, carbohydrate-rich food plan might buffer towards the loss in abundance and variety of particular microbial species. For instance, in distinction to Westernized guts, fashionable non-Westernized guts home 4 variants of the bacterial pressure Prevotella copri, every of which has a singular job in degrading advanced carbohydrates.4 Equally, the microbial signature of the traditional paleofeces samples carried these 4 variants.
Paleofecal Time Capsule 
The persistently low year-round temperature and excessive salt focus within the mines trigger speedy desiccation of the paleofeces, which can protect endogenous biomolecules by decreasing hydrolytic harm. Kevin Daly, a analysis fellow on the Smurfit Institute of Genetics and Trinity School Dublin who was not concerned on this work, defined that “salt crystals create microenvironments with little water, as water molecules strongly work together with positively-charged ions in salt. This might inhibit water molecules from interacting with DNA, decreasing deamination, and selling DNA preservation.” On this sense, mummified paleofeces act as miniature time capsules, offering a uncommon glimpse into the heart and lives of our ancestors.
One of many largest challenges in finding out historic microbiomes is confirming that the microorganisms are endogenous to the pattern quite than the surroundings. To perform this, Maixner and his colleagues in contrast microbial and metabolic pathway abundance of the paleofeces samples to greater than 800 up to date metagenomes and seemed for similarity to soil, oral cavity, and non-Westernized way of life samples. In line with Maixner, the desiccated paleofeces “capsules,” for causes which might be nonetheless unclear, are much less vulnerable to penetration by soil micro organism. All 4 of the paleofecal samples differed from the soil samples, suggesting that soil contamination was unlikely.
In a single pattern, Maixner and his colleagues recognized salt-loving Halococcus morrhuae, an extremophile that survives excessive salinity, however doesn’t usually affiliate with the human intestine. Daly defined that H. morrhuae was probably launched as a contaminant related to salt crystals from the surroundings. “This was the one stool pattern that was not topic to moist sieving, a course of for separating coarse and fantastic particulate materials.” He added that “the intense salinity would show poisonous to many frequent soil microbes, and extremophiles themselves will not be tailored to take advantage of the natural matter of stool, doubtlessly inflicting little extremophile intrusion into the paleofeces.”
Goldmine of Data
Maixner and his colleagues additionally discovered adequate preserved endogenous human DNA within the paleofeces; additional evaluation confirmed that every one 4 samples belonged to males. Might a kind of samples have belonged to the Man within the Salt? In line with Maixner, the geographic location and time interval match, so it’s theoretically potential. He defined that if he and his staff had entry to the Man within the Salt’s stays, they may examine his genetic materials to the human DNA within the paleofeces. In the event that they matched, Maixner mentioned, “we may discover the one who dropped this paleofeces.” Within the meantime, he and his staff want to increase the findings of the present examine by analyzing a bigger variety of paleofecal samples from the salt mines, evaluating them to fashionable samples, and screening for the presence of lipids and different metabolites. “We have actually simply touched the floor to this point.”
This work has broad implications for understanding the position of intestine microbes in well being and illness. Researchers proceed to find new connections between present consuming habits, the microbes that stay in human guts, and our susceptibility to illness,5 however the intestine microbiome of contemporary people gives a restricted snapshot alongside our evolutionary journey. “Whereas restricted within the variety of samples, the examine is a superb instance of what multi-disciplinary work can reveal in regards to the lives of communities prior to now,” Daly mentioned. Details about historic human intestine microbiomes informs our understanding of how the transition to a modernized Western food plan altered our microbiome. That is significantly related given the rising curiosity in microbiome-directed therapies for varied illnesses,6 together with most cancers and infectious, metabolic, inflammatory, and cardiovascular illnesses, which have sky-rocketed in fashionable occasions.
As scientists proceed to check the lack of microbial variety in Westernized human guts, the present examine presents a singular perspective on the evolutionary historical past of our microbiome and the potential for restoring the traditional microbial signature of our guts to enhance well being. Given the similarities between the traditional human microbiome and that of contemporary non-Westernized diets, restoring microbial variety could also be simpler than we expect.
References
- “The person within the salt,” Naturhistorisches Museum Wien, https://www.nhm-wien.ac.at/jart/prj3/nhm/main.jart?rel=hallstatt_en&content-id=1401791304527 Accessed 07 January 2022.
- F. Maixner et al., “Hallstatt miners consumed blue cheese and beer in the course of the Iron Age and retained a non-Westernized intestine microbiome till the Baroque interval,” Curr Biol, 31(23):5149-62, 2021.
- N. Segata, “Intestine microbiome: westernization and the disappearance of intestinal variety,” Curr Biol, 25(14):611-13, 2015.
- H. Fehlner-Peach et al., “Distinct polysaccharide utilization profiles of human intestinal Prevotella copri isolates,” Cell Host Microbe, 26(5):680-90, 2019.
- R.D. Hills et al., “Intestine microbiome: profound implications for food plan and illness,” Vitamins, 11(7):1613, 2019.
- D.A. Schupack et al., “The promise of the intestine microbiome as a part of individualized therapy methods,” Nat Rev Gastroenterol Hepatol, 19(1):7-25, 2021.
