OF MICE AND VERMIN
In one senseThule Agriculture amounted to nothing less than a profound transformation of large parts of the Arctic environment. Microclimate engineering, year after year, century after century, changed the very character of the north. Windbreaks, drainage and irrigation channels, ponding drift catchers, dramatically increased the productivity of the landscape. Even in areas too poor for human agriculture, microclimate engineering had been employed to increase caribou and musk ox forage and enhance the biological productivity. Over time, many of these areas were enriched to the point of sustaining human agriculture, even as microclimates devoted to caribou and musk ox spread.
Warmer soil temperatures, extended growing seasons, water, more decaying vegetation mixed into the ground, the actions of insects and plants, crude fertilizers, created a rough, comparatively low quality, arctic soil. It took roughly 150 to 200 years for arctic soil to form. But by the time of heavy European contact in the 1700's, this meant that many areas had 300 to 400 years of soil formation, and much of the arctic was covered with microclimate soils ranging from one to four generations. The Arctic under the Thule was immensely greener and richer than the territory in its natural state. The vegetable biomass had increased significantly
But in another sense, the Arctic had not changed at all. There were no new species. There was just a lot more of it. The deck had been reshuffled, there was immensely more sweetvetch, more roseroot, more claytonia, more bistort and fireweed, for caribou and musk ox there was more sedge and purple saxifrage. More humans, more caribou, more musk ox and ptarmigan.
But no new species were introduced and no old species vanished. The deck had been shuffled, but all the cards were still the same. In particular, the animals that amounted to the arctic ecology were all still around, including voles and lemmings.
A vole is also known as a meadow mouse or field mouse. Some statistics to consider. A vole reaches sexual maturity at approximately one month of age. Once mature, it can produce five to ten litters per year, each litter taking three weeks to gestate, and another month to reach sexual maturity. A litter will run five to ten young. Lemmings reproduction and diet are similar.
Now, let’s do some math. Start with a single breeding pair of vole. First generation they produce a litter of 10 offspring, each of whom form breeding pairs and get busy. Assume every generation is seven weeks (3 weeks gestation, plus 4 more weeks to reach sexual maturity) Assume every breeding pair reproduces at every opportunity, and produces maximum litters, all of which survive and breed. Second generation, that 12 voles producing 60 offspring. Third generation gets you 72 voles producing 300 offspring. Fourth generation is 372 producing 1860 offspring. Fifth generation 2232 animals producing 11,160 animals. Sixth generation is now 13,392 animals producing 66,960 voles. Seventh generation is now up to 80,352 breeding pairs of creatures, and they will produce 401,760 offspring, or a total of 482,112 voles. Seven generations is 49 weeks. Call that a year.
Extend that over two years, or three. It's enough to turn your hair white. Of course, at that reproductive rate, breeding flat out, voles would soon outnumber every other life form on the planet. Within a handful of centuries they would outweigh the mass of the earth. Obviously that doesn’t happen. 88% of Voles die within their first month of life, and luckily, litter sizes and reproduction rates are often far from maximum.
Two critical things limit the populations of voles and lemmings: Food supply; Predators.
Let’s take a look at food supply. What do voles eat? Anything. They’ll eat dead animals and similar detritus. But they’re dedicated herbivores and thrive on small plants, just about any nut or fruit, and particularly succulent root systems and bulbs in ground. They’ll devour a root system until the plant is dead, and they girdle small trees and ground cover like a porcupine.
Voles are expert tunnelers and burrowers. They’re also ‘subniveal.’ What that means is that Vole in the winter live in tunnels beneath the snowcover. Now the thing is that under a six inch snow cover, the temperature never goes above 0, regardless of the temperature above the snow cover. Now zero or zed degrees celsius is not great. But in the Arctic, the temperature above the snow cover can run between twenty and fifty degrees below zero. So it’s a huge advantage. It also allows the vole protection from predators, and allows them to access edible plants and vegetation beneath the snow cover.
In short, the Vole and Lemming are particularly well suited and well adapted to take advantage of Thule agricultural plants, among many others in the arctic. They are better suited than humans because they need not wait three years for a perrenial crop to mature.
The Thule Agricultural revolution transforms the north, vastly increasing biomass. But really, what’s being vastly increased is the food supply to support the vole and lemming population. What we have here are animals which eat and reproduce so rapidly that they can devour crops faster than the Thule can grow them.
Ouch.
Under those circumstances, the Thule agricultural revolution may well die before it is born, suffering from the predation of a little creature with an exponential growth rate.
In a sense, all agricultural societies have had to face this bottleneck. We’re not the only ones that eat the crops. Everything from locusts to crows to elk show up at the dinner table with their napkins on. It may be that the true success or failure of agriculture to emerge in different regions has a lot more to do with the presence of these opportunistic feeders. There’s no point in raising a crop, if that crop is eaten before you get to it. There’s no point in trying to store an agricultural surplus if those surpluses are consumed.
Successful agricultural societies are lucky in either not having, or not having too voracious, a set of opportunists around, or in having crops not appealing to opportunists, or in having ways of controlling opportunists.
Inevitably, the Thule Agricultural revolution created a bonanza for vole and lemmings, creating a complex and often difficult relationship.
In times of famine or of swarming the Thule would harvest and eat vole and lemmings. Typically, the animals would be collected into a sack, beaten to paste, and the paste cooked or boiled. In some areas, vole or lemming were a delicacy to be seasonally harvested. Elaborate means were used to cause voles or lemmings to swarm and flee their dens. Beaters, smokers, and fine nets were used in the exercise.
When not eaten, vole or lemmings would still be caught, pounded in sacks, and stored in permafrost as food for dogs. In some areas, captive voles would be raised in rock bound pens as dog fodder. It’s estimated that vole, either wild harvested or raised domestically, constitute as much as 15 to 20% of domestic dog diets, coming behind fish (25 to 30%) and human scraps (20 to 25%), and slightly ahead of Caribou (10 to 15%)
Nevertheless, the priority of the Thule was always to control the numbers and reproduction of animals such as voles and lemming in their agricultural areas and save their crops. To this end, the Thule evolved a number of countermeasures.
One approach, for instance, was to graze caribou or musk ox in crop fields over winter. The trampling of snow, and scooping would destroy subnivean habitat, the secure zone under snow cover that voles and lemming relied upon. There were downsides to this. With snow cover compromised, plants were more vulnerable to cold, and the cropping and forage of caribou and musk ox required some plants to regrow or regenerate leaves and stems. There were advantages, caribou and musk ox droppings provided fertilizer, shed hairs and other materials darkened and dirtied the snow, which together with trampling caused it to absorb more light in spring and melt more quickly, speeding up the growing season.
Another method was tolerating or supporting small predators, Snowy Owl, Arctic Fox, and Ermines in particular as vermin control. This simply took advantage of relationships normally found in nature. Each of these animals hunted and ate vole and lemmings as a significant part of their diet anyway.
These animals became the Thule semi-domesticates. Basically, they were not hunted or killed, except in special circumstances. The Thule would build or manipulate habitats to lure them. In some cases, the Thule would actively trap or physically relocate the animals. Occasionally, infants would be raised up as pets, or adult or semi-adult animals would be tamed. In times of hardship, during population crashes of vole or lemming, the Thule would go out of their way to feed these animals. Dogs would be trained to avoid eating or chasing these animals by being fed poisoned carcasses while young. For the most part, however, the semi-domesticates were left to themselves, tolerated in the Thule community, occasionally harvested, but principally left alone to do their jobs.
