Scientists compare different organisms at the molecular level to understand their evolutionary relationships. They study DNA, RNA, and proteins to see how closely related organisms are.
Think of it like comparing different puzzle pieces to see how they fit together. Scientists look at the shapes and patterns of the molecular puzzle pieces to see which organisms share the most similarities. If two organisms have similar puzzle pieces, they are more likely to be closely related.
By studying the molecular puzzle pieces, scientists can also estimate how long ago different organisms shared a common ancestor. It's like looking at the age of the puzzle pieces to see how long ago they were cut from the same puzzle board.
Overall, scientists use molecular biology to help them piece together the evolutionary history of different organisms and better understand how they are related.