READ: Macro Evolution

Theory?

Darwin's Theory of Evolution by Natural Selection is supported by well over 150 years of scientific evidence, ranging from fossil evidence to DNA evidence. By definition, this is a well tested scientific theory. An abundance of scientific evidence supports this theory. The world is very old and has undergone some dramatic changes. Life has been on the planet for most of that time. As you will see in the next lesson, life started as single celled organisms and has evolved over billions of years into complex plants and animals. But this journey has not been easy. Most species that have ever lived are now extinct. There have been a number of mass extinctions, where many species vanished all at once. The tremendous diversity of species has allowed some to adapt to whatever changes nature throws in its path, from small changes to major environmental disturbances. So it is nature that selects - hence Natural Selection - which species adapts, survives and evolves.

CK-12 Foundation, Biology. http://creativecommons.org/licenses/by-nc-sa/3.0/