The life and death of species

Adriana Vella's article Vital Natural Connections (May 23) seeks to introduce the general reader to the aims of International Biodiversity Day. Unfortunately, her article contains a number misleading assertions.

In her opening paragraph she refers to the "essential mechanism that has created and sustained life on earth - biodiversity". Biodiversity is not a mechanism and it is not responsible for either creating or sustaining life. It is the other way around. The "evolving and adapting" life forms to which she refers in the next paragraph bring about biodiversity - the variation of life forms within an ecosystem.

Conserving agricultural land is important as is safeguarding biodiversity of food crops. But, with world population increasing at its present rate it is simply unrealistic to advocate a return to the methods of "wise farmers" of yesteryears and to "small-scale artisanal" fishing methods. The "short term gains" sought by the agricultural practices she condemns are, in fact, the feeding of the hungry millions. The best way to safeguard biodiversity would be to stop the growth of human populations.

The popular idea of preserving biodiversity seems to be hanging on forever to everything that is alive on earth today. But organisms are constantly changing and adapting to altered environmental factors or dying out if they cannot do so. Other, better adapted species take their place. There have been five so called "mass extinctions" throughout the history of the earth. The most severe of these occurred 250 million years ago and wiped out 90 to 95 per cent of all species. After each catastrophe there was an almost explosive recovery in biodiversity. Had the last mass extinction in which dinosaurs died not taken place the rise of mammals and flowering plants may not have occurred and the present flora and fauna on earth would be entirely different.