Tuesday, December 19, 2006
Why We Should Always Question..
There are many moments in time that we look back at now...which will always lead to us to slap our foreheads and say, "stupid, stupid, stupid". There is one such moment that continues to be brought up in the most general science classes..as if to say.."if you don't test and retest...we will ridicule you for years to come". This example is of course the lemming. Lemmings were believed to commit, "The Lemming Suicide Plunge" when the population became too numerous. It was really believed that millions of lemmings would be overcome by a hard-wired impulse to dash to their death by hurling themselves over a cliff to the rocks below or by plunging into the sea to die a horrible death by drowning. The reasoning behind this was thought to be a deep-rooted act of altruistic behavior resulting the greater good for the species. However, you can probably guess, this is not the case. Shown to the right is a famous Far Side cartoon dipicting natural selection in action. As the lemmings dash to their death..there is one cheater in the group that will survive and ultimately passing on the cheater genes to future generations.
How this story may have gotten started....
Many rodent species experience very strange cyclic population explosions. It is very interesting that lemmings have one of the most regular cyclic fluctuations in population densities. It has been shown that these little creatures have population explosions about every three or four years. The population numbers of lemmings explode to high numbers, and then drop almost to extinction. Even after approximately 75 years of intense research, scientists do not fully understand why the populations fluctuate so much. Throughout the years, many factors have been tested (i.e., changes in food availability, climate, density of predators, stress of overcrowding, infectious diseases, snow conditions, sunspots, etc) but none completely explain why populations of lemmings have these explosive cycles.
The myth of the lemming most likely started when these population explosions happen and the lemmings migrate away from areas with a dense population. As you can imagine, the migrations begin slowly and erratically. It has been shown that small numbers of lemmings will move at night, and larger groups in the daytime. This movement causes small groupings of lemmings to move instead of one continous mass, usually seperated by a short time frame of 10 minutes or so. It has been noted that they will often follow well worn paths and roads along their journey.
As you can imagine, there will be unavoidable obstacles, such as streams and lakes inevitalby causing them to swim as a last resort. Suprisingly, they are able to swim across a 200 meter body of water on a calm night, but most will drown in a windy night.
So why the myth began....
It is due to a very unlikely source....Walt Disney. Walt Disney was making a movie tittled, "Wild Wilderness" which was released in 1958. It was filmed in Alberta, Canada, in a location that is far from the sea and not a native home to lemmings. The lemming were imported and forced to jump to thier deaths by placing them on a spinning turntable that was covered with snow, and then shooting it from many different angles. The cliff-death-plunge sequence was done by herding the lemmings over a small cliff into a river. It's easy to understand why the filmmakers did this - wild animals are notoriously uncooperative, and a migration-of-doom followed by a cliff-of-death sequence is far more dramatic to show than the lemmings' self-implemented population-density management plan.
The moral of the story....lemmings do not commit mass suicide and Walt Disney has clear prejudice against the lemming and for the mouse.