Extinction Events

Human activity has caused a few notable extinction events — and many more that go completely unremarked. Every species lost weakens biodiversity and the natural life support systems on which humans depend.


| March/April 1981



extinction events - ehrlichs

Noted ecologists Anne and Paul Ehrlich warn that human-driven extinction events are undermining the planet's life support systems.


PHOTO: MOTHER EARTH NEWS STAFF

As we indicated in an earlier column, the extinction of non-human species is a matter of major concern to biologists ... and it should be of extreme concern to all human beings.

There are several reasons for this. First of all, the acceleration in extinction of populations or of entire species can be viewed as the removal of essential parts (sometimes analogized with rivets) of the life-support systems of Spaceship Earth more rapidly than natural "repair" processes can replace them. And, although there's considerable redundancy in such systems, the ultimate impact of continuing extinctions is clear: the loss of essential ecosystem services.

The services provided by ecosystems, as you may recall, include such essentials as the amelioration of the climate, the disposal of wastes and recycling of nutrients, the generation and maintenance of soils, and the control of the vast majority of crop pests and transmitters of human diseases. Humanity has no satisfactory way of replacing these free services should they be lost, and civilization cannot persist without them.

Furthermore, the accelerating rate of extinction is itself a measure of the increasing level of attack that humanity is launching on Earth's ecosystems. Each time a population is destroyed, one less component is available to help perform vital services for us. In short, biologists are worried in principle about the "popping of rivets" from our spaceship, and are frightened because they see the rivets disappearing at an ever more rapid pace.

There are other reasons for concern over the extinction of populations and species, as well ... including the fact that the disappearance of plants or animals often results in the loss of direct economic benefits (ecosystem services are considered indirect benefits) and the loss of aesthetic values. Moreover, in the name of plain old-fashioned compassion, we should take care not to eliminate any more of our fellow "passengers" than we already have in the short time man has trod this Earth.

The Passing of the Passenger Pigeon

The most dramatic cause of extinction is direct endangering, usually by overexploitation. And the classic example is the fate of the passenger pigeon. This fascinating, graceful, pretty bird—with a slate blue back and deep pink breast—didn't coo like a dove, but produced "shrieks and chatters and clucks." Its greatest claim to fame was the enormous size of its populations ... in fact, it may well have been the most abundant bird that ever existed. John James Audubon observed a flock that passed overhead for three days in a row, sometimes at the incredible rate of more than 300 million birds an hour. Alexander Wilson—co-founder, with Audubon, of American ornithology—estimated that another flock contained two billion birds! The passage of such huge numbers in flight created a roar of wings that could actually be heard half a dozen miles away!





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