Charles Darwin: An influential scientist who developed the concept of natural selection and published his ideas in his book 'On the Origin of Species.' His work revolutionized our understanding of evolution.
Adaptation: The process by which organisms change over time in response to their environment. Adaptations can be physical, behavioral, or physiological changes that help an organism better survive and reproduce.
Survival of the Fittest: A term coined by Herbert Spencer, which describes how individuals with favorable traits are more likely to survive and pass on their genes. It does not necessarily mean physical strength but refers to overall reproductive success.