Which piece of evidence would best support reason #1? the history of using animals for research extends as far back as 322 bce, when early greek physician-scientists, such as aristotle and erasistratus, performed various experiments on living animals. animal research played an essential role in the development of herceptin and tamoxifen, two medications that have already saved the lives of thousands of women who have been diagnosed with breast cancer. even those who believe in testing on animals when it is necessary for vital medical research practice what is known as “the 3 rs”—reduction, refinement, and replacement—to reduce the number of animals used for testing. biologists believe that chimpanzees share at least 98.4 percent of the same dna as humans and gorillas share at least 97 percent, making primates a popular and likely choice for the testing of products intended for humans.