| A | B |
|---|
| Species | A group of similar organisms that can mate and produce fertile offspring. |
| Fossil | Preserved remains or traces of an organism that lived in the past. |
| Adaptation | A trait that helps an organism survive and reproduce. |
| Evolution | The gradual change in a species over time. |
| DNA | Deoxyribonucleic acid; the genetic material that carries information about an organism. |
| Natural selection | The process by which individuals that are better adapted to their environment are more likely to survive and reproduce. |
| Variation | Any difference between individuals of the same species. |
| Homologous structures | Body parts that are structurally similar in related species; provide evidence that the structures were inherited from a common ancestor. |
| relative dating | A technique used to determine which of two fossils is older. |
| Extinct | The term used to indicate a species that does not have living members. |
| Radioactive dating | A technique used to determine the actual age of a fossil on the basis of the amount of radioactive elements it contains. |
| gradualism | The theory that evolution occurs slowly but steadily. |
| Punctuated equilibria | The theory that species evolve during short periods of rapid change. |
| Branching tree | A diagram that shows how scientists think different groups of organisms are related. |
| Charles Darwin | Scientist that is given credit for coming up with many of the ideas of evolution. |
