Charles ____ observed that although individuals in a ____ shared similarities, they were not exact ____ of each other; there were small ____ or variations between them. He also noticed that everything in the natural world was competing to ____. The winners were those which ____ or adjusted their characteristics to increase their chance of survival in the ____ they were in. For example, if they were stronger, ____, cleverer or more attractive than others in their species. These living things were more likely to reproduce and pass on their useful characteristics to their offspring. Individuals that were ____ adapted were less likely to survive and their characteristics were not as likely to be ____. Over time, the characteristics that help survival become ____ common and a species gradually changes. Given enough time, these small changes can add up to the extent that a ____ species altogether can evolve.

Evolution

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