Biologists, like other scientists, ask questions about the natural world. Their questions are either why questions or how questions, such as the following:
Why don’t newborns see well?
Why does body size of species skew to the right on a distribution curve? That is, why are there so many small animals?
How does cellular senescence prevent cancer?
How do island plants self-pollinate?
As they attempt to answer such questions, biologists first offer a tentative explanation, or hypothesis, for something they have observed. They perform an experiment to test their hypothesis. If the results from the experiment match the original predictions, then they consider the hypothesis supported, but not proved, since the biologist cannot account for all conditions. Other biologists will continue to formulate new hypotheses and offer new findings.