Introduction to evolution: Difference between revisions

Revision as of 21:56, 8 December 2006

Revision as of 04:37, 9 December 2006

Line 24:

The idea of common ancestry has its roots in the Darwinian revolution. [[Charles Darwin]] saw unity among all life, and he proposed that all living things are related and have descended from a common ancestor. Darwin describes these events as ''descent with modification''. The Darwinian explanation for the mechanisms of evolution is based on his theory of [[natural selection]], which in turn is based on five basic ideas:

# - Organisms will produce more [[offspring]] than their [[habitat]] can sustain. There will be a 'struggle to survive'.

# - Not all the offspring will be identical.

# - Some of the differences between the offspring will be due to differencesvariations in their [[genetic]] makeup.

# If- theseGenetic geneticvariations differencesthat helpallow an organism surviveto andsurvie breed,and theyreproduce will be passed on to the next generation. IfGenetic the geneticvariations differencesthat do not help an organism to survive untiland itreproduce canwill breed, then those genetic differences arebe lost.

# - Over time, these genetic differencesvariations will accumulate until a new [[species]] has evolved.

These changes can happen faster in simple organisms. For example, the [[bird flu]] [[epidemic]]s that killed many people were caused by genetic changes in the [[virus]] that made the new viruses more deadly to [[human|humans]].