Scientists at the University of Iowa studying rats have concluded that salt (sodium chloride, good old NaCl) may be a natural anti-depressant, which would explain our tendency to consume a lot of it. The article, published on the website Science Daily, explains that the rats, when deficient in sodium chloride, did not engage in activities they normally enjoyed, “like drinking a sugary substance or pressing a bar that stimulates a pleasant sensation in their brains.”
Huh. It seems that, for these lab rats, their usual pleasurable activities are pretty much the same as those that amuse us humans.
I certainly know quite well the pleasurable trifecta of munching a salty snack (like Doritos or McDonalds food) as I drink a sweet beverage (like Coca-Cola), while having my brain stimulated artificially (in this case by TV, computer and movie screens).
But for the lab rats, these decadent amusements are quite clearly artificial – a wild rat would not have regular access to either sugar substance or a pleasure bar – but must have an element of attraction to the little guys. When these pleasurable, artificial stimuli are introduced, the rats accept them with relish.
So here’s that old sore spot on the psyche of the many who shudder when a rat scurries noiselessly across their path on the way from the trashcan to the sewer: rats and humans have a lot in common. That urban rats (which along with pigeons, squirrels and cockroaches are the main animals the flourish in the wild among urban-dwelling humans) are so despised is a sad testament to the alienation we feel from the nature – in whatever form – that chooses to live among us.
Of course there’s troubled history – the bubonic plague, to name just one incident – of rats being the carriers of damaging phenomena into human society.
Another more recent (and fascinating!) rat-related catastrophe was profiled in “Rat Attack” on PBS’ science program Nova. In this case, the critters in the bamboo forests surrounding a remote Northern Indian village experience a population explosion when they gain access to the bamboo fruit (which appears only every 40 years). Once this food supply is exhausted, the rats overrun the rice fields, threatening the villagers with hunger.
Such human/rat exchanges stoke the fires of animocity. And urbanized rats can be certainly be mean, dangerous and hungry, making them (understandably) incredibly unwelcome guests.
But damage is wrought on both sides, and perhaps an objective observer would side with the rats on this one. Rats are subjected casually on a daily basis to myriad, often life-threatening scientific experiments for our ostensible benefit.
This salt/sugar/brain stimulus-related glimpse into the psychological and recreational behavior of rats brings an ugly truth to light – we are linked by our artificial modern tastes. As much as we reject one another, it appears that lab rats and humans are being conditioned by the same system.
(For more on the fascinating history of human societies’ control of salt, check out Salt: A World History by Mark Kurlansky.)