Climate change began poisoning the people of the Norwegian Arctic with dangerous chemicals some 3,800 to 6,300 years ago scientists have concluded after digging around in the garbage pits of that country’s Varanger region.
Some of this is not exactly news. Mercury has been previously identified as a chemical pollutant in the human diet for thousands of years before humans began worrying about dangerous chemicals in their diets.
Researchers studying cod caught off the North American coast in 2015 first stumbled on evidence of high levels of mercury in the fish that would have been eaten by Stone Age hunter/gatherers 6,500 years ago. But now the scientists in Norway have recovered the uneaten remains of Atlantic cod and harp seals consumed by the early people and added other dangerous heavy metals to the prehistoric diet.
“Climate change induced highly elevated levels of the heavy metals cadmium and lead, and elevated levels of mercury,” they reported in the peer-reviewed journal Quaternary International. “On average, the levels of cadmium and lead contamination in cod were up to 22 and three-to-four times, respectively, higher than today’s recommended limits in soft tissue. The corresponding figures for seal were 15 and three-to-four times, respectively. The levels of mercury were generally below today’s recommended limit in soft tissue, but still of considerable magnitude, almost similar to the measured values in modern fish in the Arctic.”
Given the tie to climate change, there is no reason to believe this pollution was lower anywhere else in an Arctic historically portrayed as pristine and unpolluted before the arrival of modern man.
The team of scientists led by Hans Peter Blankholm from the Arctic University of Norway said their study “shows that marine food in the Younger Stone Age was unhealthy, if not unsafe.”
The difference between unhealthy and unsafe is dosage.
If the fish and seals were minor food sources in the early Norwegian diet, a diet with limited heavy metals might be merely unhealthy. If fish and wildlife contaminated with lead, cadmium and mercury were the major part of the diet, however, they could have been deadly.
The effects would likely have been mitigated by the generally shorter lives lived by prehistoric people giving the chemicals less time to accumulate. Then again, these toxins might also have contributed to shorter lives.
Chronic exposure to lead can cause heart disease, reduced fertility, and some general symptoms – depression, distraction, forgetfulness and a general feeling of sickness – that would not be helpful to a hunter-gatherer trying to find food every day while avoiding predators.
Mercury can cause all sorts of neurological problems: loss of peripheral vision, loss of coordination, muscle weakness, and impaired hearing and speech. The yet-to-be-born children of women with high mercury levels are also subject to a wide variety of diseases causing future impairments.
Cadmium, lead and mercury are all natural minerals found in the earth’s crust, and the belief is that they made their way into fish by being mixed into seawater as the oceans rose after the last glaciation.
Once in the water, the chemicals can be absorbed by fish through their gills and skin. Marine mammals that prey on the fish are then contaminated. And heavy metals bioaccumulate in all of the predatory species.
Humans, being top-level predators, could conceivably have killed older seals loaded with heavy metals.
“Dangerous food,” the Norwegians titled their paper. “Climate change induced elevated heavy metal levels in Younger Stone Age seafood in northern Norway.”
“The real ‘paleo diet’ may have been full of toxic metals,” Science Magazine headlined the story, seemingly putting the quotes around the wrong words. It would be the “real,” as in original paleo diet that would have been toxic.
But given modern food safeguards, most people are warned away from foods, primarily freshwater fish, loaded with heavy metals.
Despite that, many worry about what’s in their food despite how much safer it is today than during most of the past.
“Pollutants have been entering our food chain for millennia,” Ian Randal observed in the Science story. And they still are. Many things, including water, can be deadly if overdosed.
A young, fit health runner died in the London Marathon in 2007 from hyponatremia – what is often caused water intoxication. The 27-year-old fitness instructor drank so much water he drove the sodium levels in his blood down to deadly levels.
Hyponatremia “can lead to confusion, headaches and a fatal swelling of the brain,” the newspaper reported at the time. “In 2003 St Thomas’ Hospital treated 14 runners for the condition.”
The trade-off between the dangers in many foods and the need for nutrition led many scientists to conclude that it’s hard to tell exactly how dangerous the diets of those early Norwegians. Heavy metal contamination that will kill you in years down the road beats starving to death in the here and now.