The proportion of well-adapted organisms in a population can increase over the generations by the process of evolution by natural selection.

Sunlight, chemicals and factors tied to different species' error-correction tricks can all affect how quickly genes mutate. Lastly, the environment plays a critical role in the rate of evolution.

When evolution skeptics want to attack ... Through natural selection, different types of eyes have emerged in evolutionary history -- and the human eye isn't even the best one, from some standpoints.

But while plant and animal species generate at least a dozen different types of cells ... unicellular one might have been important for the evolution of multicellularity. That is, certain ...