5. Evolution Today

Evolution is a continuing process. New species are evolving as a result of environmental changes and the creation of new niches. Extinctions are also occurring, but other species that have been in existence for hundreds of millions of years are continuing to thrive.

Thylacines. Source: Museum Victoria / Mammals of Australia, Gould, J. 1863, Vol 1:54

One characteristic of evolution today is that human intervention in the process is significant in many regions of the world. For example, environmental change induced by human activity is threatening the existence of species and increasing the rate at which extinctions occur. Widespread clearing, large-scale agriculture and selective breeding are diminishing areas where 'natural' and complex ecosystems once flourished. Species that are of economic benefit to humans are being favoured over others, and simplified ecosystems that may be vulnerable to serious instability are being created. Often these ecosystems can only be maintained by the use of large amounts of pesticides, herbicides and antibiotics. These are directed against various target 'pests' that are continually evolving into more resistant forms.

The evolutionary changes and extinctions that are occurring today seem quite momentous. However, whether the changes to species diversity are sufficient to mark a new era in the history of life on Earth remains unclear. Are we witnessing the end of the Cainozoic Era, or will the present changes be of little consequence in the long term?