We disagree with your framing of chimpanzee research around past 'handsome' benefits to humankind (Nature 474, 252; 2011). These do not justify invasive experimentation in the future. The current pace of advancements in biomedical research technology means that the time has come to end invasive research on chimpanzees.

Biomedical research is replete with examples in which reliance on relatively crude, time-consuming and expensive animal models has given way to quicker and more precise non-animal methods. For example, drug maker Eli Lilly struggled to find enough rabbits to test insulin for potency and safety when it was first purified; those tests soon gave way to mouse studies and then physicochemical methods.

Such reliance on animals was not always scientifically necessary. Take the Sabin live polio vaccine: tests in chimpanzees were simply part of a need to reassure nervous regulators that it was safe. The crucial development was cultivation of the virus in human cells — a discovery that received a Nobel prize.

The past decade has seen dozens of reports of non-animal techniques that explore the biology and pathology of hepatitis C virus (HCV), including a new in vitro technology that allows replication of the virus from infected patients (M. Buck PLoS ONE 3, e2660; 2008). GlaxoSmithKline runs an HCV programme that does not use chimpanzees (see http://go.nature.com/eyp3wk).

Some argue that chimpanzees are still needed for testing monoclonal antibody therapeutics, but this does not stand up to scrutiny. Of the 35 monoclonal antibody therapeutics approved so far by the US Food and Drug Administration, only three involved chimpanzee testing, and two of those were withdrawn because of side effects or lack of effectiveness (R. H. Bettauer ALTEX 28, 103–116; 2011).