One of the great advances in biology has been the realization that organisms obey the laws of physics; that they are as much a part of the natural world as rocks or clouds. It took Darwin to show that the characteristics of organisms could be explained by natural means rather than relying on a metaphysical explanation. Even then, the idea was hard to shake that life somehow had some special, non-material ingredient, an élan vital, absent in non-living matter. Various theories of evolution even tried out the idea that there was an innate drive to evolutionary progress, a striving toward some goal. It took long years for such theories to be shown to be unrealistic and finally discarded.
Yet even today, this is one of the most difficult conceptions to get
across to students—effects have causes and causes have effects; without one, there is
no other. That NEEDING an evolutionary change has absolutely no effect unless
the proper genetic and environmental conditions are present. And there are millions of
extinct organisms out there as proof of the pudding.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.