Chimpanzees are humans' closest living relative. They're so similar to people that some activists say it's unethical to subject them to invasive medical research. Congress is considering legislation that would ban chimp experiments. Today, a closely-watched panel of independent experts announced their assessment of the need for chimp research. And as NPR's Nell Greenfieldboyce reports, it's already had an impact. The National Institutes of Health is a major funder of research that uses chimpanzees. Last year, an NIH plan to take nearly 200 chimps out of unofficial retirement and send them to a research facility sparked public outcry. So the NIH asked the Institute of Medicine to assess the state of the science. "No one said I'm totally against any chimpanzee research, I'm totally for it." Jeffrey Kahn is a bioethicist at the Johns Hopkins Berman Institute of Bioethics. He chaired the committee that issued the new report. "We were all people of open mind and very good will and worked very well together to look at the information." About 1,000 chimpanzees live in research colonies in the United States. Some scientists say they're needed for life saving medical research, but animal welfare activists say that modern technology provides alternative ways to study disease. The committee spent months studying the issue and came to this conclusion: Most of the biomedical research currently being done on chimpanzees is unnecessary. Kahn says the need for chimps will soon decline even further.