It’s easy to romanticize our paleolithic past as being simpler, therefore, happier, healthier, and more wholesome, especially when it comes to the food our ancient ancestors enjoyed. However, the so-called “paleo diet” probably wasn’t always as pleasant as those advocating for a return to those ways might think. Even millennia before industry and even agriculture, some ancient diets may have been riddled with environmental pollutants and toxic nasties.
New research has looked at the archaeological remains of Stone Age people living in northern Norway and found their seafood, which made up a huge chunk of their diet, was regularly laced with a side order of toxic metals, including cadmium, lead, and mercury. In fact, people here were possibly consuming food that contained up to 22 times over the maximum level of certain heavy metals recommended today.
“This shows that marine food in the Younger Stone Age was unhealthy, if not unsafe,” the authors of the study published in the journal Quaternary International concluded. “The elevated values may have been detrimental for humans, if not for society.”
The researchers started analyzing the bones of Atlantic cod (Gadus morhua) and harp seals (Phoca groenlandica) found around eight archaeological sites in northern Norway, ranging from 6,300 to 3,800 years ago.
The cod contained levels of cadmium contamination over 22 times today’s recommended levels and up to four times the levels of lead. For the seals, cadmium contamination was 15 times safe levels and lead contamination was over four times the limit. Mercury levels were high but below today's recommended limit, similar to the levels found in present-day Arctic fish.
All three of these metals are toxic and can have a damaging effect on human health. Lead has a damaging effect on the human brain and nervous system, while mercury can have toxic effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin, and eyes.
Interestingly, the elevated levels of toxic metals in the food chain were most likely a knock-on effect from changes in sea surface temperatures and sea-level change. The researchers argue that these changes would have resulted in huge quantities of heavy metals leaching into the sea through the erosion of cliffs and landmasses by the coast. In turn, this made its way into the food chain, accumulating in the larger marine predators, such as seal or cod – much like it does today.
Of course, you might say that this is just a small sample of a select few populations, so it can’t say much about the paleo diet as a whole. However, it does neatly highlight that there is no one single paleo diet – ancient humans would have pretty much eaten whatever they could get their hands on, they couldn't afford to be picky. Certainly, some Paleolithic people might have eaten a solid balance of leafy vegetables, nuts, and fresh meat, but many others would have eaten nothing but metal-saturated fish.