Here's why:
* DNA as a blueprint: DNA contains the genetic code that dictates an organism's traits. It's like a blueprint for life.
* Mutations and evolution: Over time, mutations (changes) occur in DNA. These mutations accumulate and can be passed down through generations. Organisms that share a recent common ancestor will have more similar DNA sequences than those that diverged further back in time.
* Comparing sequences: By comparing the DNA sequences of different organisms, scientists can identify similarities and differences. The more similar the sequences, the more closely related the organisms are.
There are other ways to compare relatedness, but DNA is the most reliable and widely used method:
* Protein sequences: Proteins are built based on the instructions in DNA. Comparing protein sequences can also reveal evolutionary relationships.
* Fossil record: Fossils provide evidence of past life forms and can help scientists understand evolutionary relationships.
* Anatomical structures: Comparing the structures of different organisms can also provide clues about relatedness. For example, the bone structure of a bat wing and a human arm are very similar, indicating a shared ancestor.
However, DNA comparison remains the most powerful tool for understanding evolutionary relationships.
