Scientists determine how closely related two organisms are by studying various lines of evidence that reveal their evolutionary relationships. One of the primary methods involves analyzing genetic material, specifically DNA sequences. By comparing the DNA of different species, scientists can identify similarities and differences that indicate how long ago they shared a common ancestor.
Another important method is the examination of physical traits, or phenotypes, through comparative anatomy. By looking at the structures of organisms, such as bone formation, organ arrangements, and other morphological features, scientists can infer evolutionary connections. For example, vertebrates share a similar skeletal structure, suggesting a common ancestry.
Additionally, scientists utilize the fossil record to establish timelines of evolutionary history. Fossils provide a snapshot of the past and can show how certain traits have evolved over time, helping to piece together the puzzle of how different species are related.
Overall, by combining insights from genetic analysis, anatomy, and paleontology, scientists are able to create a more comprehensive picture of the evolutionary relationships among organisms.