Question

the main, or central, idea of the passage is chimpanzees and humans have surprisingly similar dna. how does the detail in bold develop the main idea? humans and chimpanzees descended from a common ancestor, a gorilla - like creature that lived millions of years ago. even in light of this fact, it is astonishing to learn just how similar humans and chimpanzees are when it comes to their genes. in fact, the two species dna differs by only 1.2 percent. a laboratory comparison of chimp and human chromosomes - strands of dna each containing approximately 1,100 genes - reveals a strikingly similar pattern. perhaps surprisingly, chimpanzees are genetically closer to humans than to gorillas. admittedly, the apparently small 1.2 percent variation between chimps and humans still corresponds to forty million differences in dna base pairs. still, the tremendous genetic similarity indicates that the chimpanzee (along with the bonobo, another ape) is our closest living relative. it specifies the extent of the genetic similarity. it suggests the initial reason why scientists pursued research on dna similarity. it offers an alternative interpretation of dna research.

Explanation:

The bold - faced detail gives a specific percentage (1.2 percent) of the difference in DNA between chimpanzees and humans, which quantifies the extent of their genetic similarity. It does not suggest the initial reason for DNA research, nor does it offer an alternative interpretation of DNA research.

Answer:

It specifies the extent of the genetic similarity.