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Title: Extinction is a natural phenomenon. It is estimated that 99% of all species that Post by: ppk on Jun 27, 2011 Extinction is a natural phenomenon. It is estimated that 99% of all species that ever lived are now extinct. Why then do we say that we are now experiencing an extinction (loss of biodiversity) crisis?
A) Scientists have finally identified most of the species on Earth and are thus able to quantify the number of species becoming extinct. B) Most biodiversity hot spots have been destroyed by recent ecological disasters. C) The current rate of extinction is high and human activities threaten biodiversity at all levels. D) Humans have greater medical needs than at any other time in history, and many potential medicinal compounds are being lost as plant species become extinct. E) Humans are ethically responsible for protecting endangered species. Title: Re: Extinction is a natural phenomenon. It is estimated that 99% of all species that Post by: mrjohnston on Jun 29, 2011 I say C. Extinction is natural, but the RATE of extinction is not constant. It fluctuates and especially in the last 400 years the rate has skyrocketed due to human impact, both direct and indirect, on the environment and ecosystems. This trend and rate, if anything, seem to accelerate as our population increases and we affect more and more land through pollution, aggriculture, etc..
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