Isn’t Extinction Natural?

by Dale Goodner, Algoma

Blue spruce, red fox, large flowered trillium… each species is special.  Whether plant or animal, it represents a unique volume in the vast library of life.  When an entire species dies it is a permanent loss of an integral part in a natural community.  Those specific genes are lost.  Like the passenger pigeon, it slips out of existence into the mists of time, never to be seen again.

While all species share some genes in common, each is unique.  Each species contributes to the resilience of the ecosystem in which it lives.  Each ecosystem in turn contributes to the overall stability of the entire biotic community, what Aldo Leopold called the “land organism.”  One risk of species loss is that the living landscape could gradually lose its ability to adapt to such ominous changes as global warming.  The living biosphere, after all, helps buffer our planet against extremes in temperature.

Over a century ago a botanist, out collecting specimens of plants, referred to a specific plant community as a “fortuitous juxtaposition of species.”  In other words he expressed a common belief that the presence of special or rare plants in close association with one another was merely a lucky coincidence.  That was before the pioneering work of ecologists such as Aldo Leopold.  We now know there are subtle organic connections and relationships between plants and animals.  Members of an ecosystem, like organs in a body, are interdependent parts of a larger functioning whole.  A good word to describe this association is synergy.  The whole is greater than the sum of the parts.

In the words of Leopold:  “The outstanding scientific discovery of the twentieth century is not television, or radio, but rather the complexity of the land organism. Only those who know the most about it can appreciate how little we know about it. The last word in ignorance is the man who says of an animal or plant: “What good is it?” If the land mechanism as a whole is good, then every part is good, whether we understand it or not. If the biota, in the course of aeons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering.”

Unfortunately by destroying habitats through agriculture, pollution, and urbanization, we are causing accelerating rates of extinction.  This is unintelligent tinkering.  We’re not keeping those cogs and wheels.  It’s been said that extinction is “natural.”  This is true… a normal rate of extinction (the standard rate of extinction in earth’s geological and biological history before humans became a primary cause) has been estimated from the fossil record at about 1 species per million species per year.  That translates roughly to an expected loss of between 10 and 100 species per year.  This includes bacteria, fungi, insects, etc. The problem today isn’t extinction per se, but rather, the rate.  Just in the tropics losses are estimated at an astonishing 27,000 species per year, and it’s increasing, as a direct result of ever increasing human demands for food, fuel, living space, water, and other “natural resources.”

The current loss is being compared to similar losses, seen in the fossil record, that date back hundreds of millions of years.  It’s being called Earth’s 6th mass extinction.

Each species has a story that can be millions years in the making.  For example, the golden plover has an amazing story that exemplifies survival, perseverance, and tenacity.  Some of them migrate from wintering grounds in Hawaii 3,000 miles across the open Pacific Ocean to familiar nesting sites in Alaska.  Those adults return to Hawaii at the end of summer before the young make the long trek.  How those 3 month old birds can fly unerringly to a tiny speck called, “Hawaii,” in the midst of that vast Pacific Ocean is a mystery.  Somehow that knowledge, which we tend to call instinct, is carried in DNA.

Harvard Biologist, E.O. Wilson said:  “It’s obvious that the key problem facing humanity in the coming century is how to bring a better quality of life – for 8 billion or more people – without wrecking the environment entirely in the attempt. “ … “We should preserve every scrap of biodiversity as priceless while we learn to use it and come to understand what it means to humanity.”

We need to appreciate our libraries…

For more information check out the American Institute for Biological Sciences (part of the National Academy of Science):


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