This study without further endangering chimp populations

[Floratang]

The scientists believe that the virus spread from chimps to humans most likely through bushmeat hunters. Developing the tests to do this study without further endangering chimp populations took seven years. Science magazine published the findings. But there are questions that remain, such as how the virus developed in chimps before it jumped to humans.

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I don't understand "this study without further endangering chimp populations ".

[Tere]