Natural Selection Image Map

Species Become Extinct. So What?

Extinct species never return. A species arises only under a unique situation in which there is a great deal of genetic diversity in a population that matches the opportunities provided by a unique and currently unoccupied niche.

How sad it is to learn that humans are driving so many species toward extinction. Humans even deliberately kill (hunt) such marvelous animals as elephants, rhinos, and gorillas. Click here to see how kids can get involved in conserving wildlife.

Hunters in Africa kill elephants just to get their ivory tusks.

Appearance of new species depends critically on diversity of genes and diversity of niches. But human activity is producing the opposite at alarming rates. We eliminate many niches by creating habitats suitable for our species (example: we wipe out a forest to build a housing development).  We drive into extinction plant and animal species at a rate of about one species per day. The unique genes of these extinct plants and animals are lost forever. Our selective breeding of plants and animals creates uniformity in gene pools. Evolution of new species, which has usually taken thousands or millions of years, will proceed at even slower rates. There is no way that the pace of new species can keep up with the rate of extinction.

Forest and jungle plants can be sources of new medicines

So, does it matter, in the short term of human existence thus far, that humans reduce genetic variation in plants and animals and drive so many species into extinction? How would you defend a position that it does matter?  Think in terms of:

  • Do we devalue life by destroying it?

  • Do we change the course of future medicine by making gene pools of plants and animals more uniform?  


Why Humans Are the Ecological Problem

Human population growth increases the demand for food, water, and energy. At some point, the world population must reach the earth's maximum capacity to support the species. At that point, a remedy will be imposed in one or more of the following forms:

  • starvation
  • mass epidemic
  • war

All of these possibilities are ugly. Unfortunately, starvation, epidemics, and war have already started in many parts of the world. All three are common in certain parts of Africa. The demand of humans for more food, more water, and more energy not only threatens the human species, but it also devastates ecosystems in which other species lives.

Consider agriculture. Clearing jungles to create pastures changes a rich ecosystem that can support hundreds of species into an impoverished one that supports only a few species. The solution, according to Dr. Norman Borlaug, the "Father of the Green Revolution" and a professor at Texas A&M University, is not to destroy more forests and jungles to create more farm land. The solution is to make the land we currently use for farming even more productive. The "Green Revolution" is well underway in Third World countries where agricultural productivity is being improved by better strains of plants and animals,  and more use of fertilizer, herbicides, and pesticides. Modern agricultural practices not only provide more food, but by doing so without using more land, they produce a dramatic conservation effect. Dr. Borlaug says that if the world were still getting the low crop and livestock yields like those in 1950, at least half of today's 16 million square miles of global forest would already have been cut and plowed - and all the rest would be have to be destroyed in the next three decades. 

Click here for the United Nations Web site on world-wide agriculture.

Political problems are preventing completion of the Green Revolution. 

  • Many zealous environmentalists object to the use of pesticides and herbicides (and some even object to fertilizer). 
  • Peasants typically have few skills or opportunities to do anything except farm. In Mexico, for example, Borlaug says that nearly three million acres of forest are being cut down each year to expand poorly productive peasant farms.  
  • Many people object to genetic engineering, which could create many strains of plants and animals that are both disease resistant and grow more efficiently.
  • Humans in many parts of the world do not practice birth control and thus even more people are added to make demands on resources and to produce pollution.

Some environmentalists say that low-yield farming is more "sustainable." But Borlaug says that Africa proves that low-yield farming is sustainable only in the face of higher death rates. In many parts of Mexico, peasants farm in the same inefficient way that their Mayan ancestors did 2000 years ago. The problem of too many people with too little food is made worse by the lack of birth control. Peasants around the world are caught in a downward spiral of trying to have bigger inefficient farms by destroying the jungle and forests. How sustainable is that?

Are humans smart enough to save themselves and their environment? Maybe human evolution is not yet finished.





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