The ethical principle that many of us used to justify primate experiments seemed so obvious: If you are ethically prevented from conducting a particular experiment with humans because of the pain and risks involved, the use of animals is warranted. Yet research spanning the spectrum from cognitive ethology to neuroscience has made it clear that we have consistently underestimated animals’ mental complexity and pain sensitivity, and therefore the potential for harm. The obvious question is why the harms experienced by these animals, which will be at least similar to humans, fail to matter? How did being a different member of the primate grouping that includes humans automatically alter the moral universe?

In the case of chimpanzees, the N.I.H. finally concluded that the harms did matter. The question now is, are there morally significant differences between the great apes and other primates?

Other species of primates look less like humans than chimpanzees do and so it is harder to project ourselves into their laboratory experience. But there is no doubt that they can fear the onset of pain, suffer from the loss of the kind of life for which their brains and biology are intended, and struggle to adjust to the housing that limits the expression of their curiosity and interests. What did I learn from my research? Whether it is called mother-infant separation, social deprivation or the more pleasant sounding “nursery rearing,” these manipulations cause such drastic damage across many behavioral and physiological systems that the work should not be repeated. Non-animal alternatives are required, and we should be focusing more attention on developing them. There is no research more valuable than our own integrity and ethical coherence, and our treatment of animals is a direct reflection of our values toward life and one another.

In 1974, a federal commission was formed to develop ethical principles for human research. For nearly four years, the National Commission for the Protection of Human Subjects in Biomedical and Behavioral Research met monthly to develop ethical principles that we rely on for human research. The principles set down in the resulting Belmont Report reflect the moral dimensions of human research that now govern this work. The report revolutionized the understanding of voluntary and informed consent, fair subject recruitment, and the importance of conducting risk-benefit analyses. No such document exists for animal research.

Acknowledging that our serious work as scientists can be a source of pain and distress to sentient, helpless and non-consenting beings can be difficult. The federal government should establish a national commission to develop the principles to guide decisions about the ethics of animal research. We already accept that ethical limits on experiments involving humans are important enough that we are willing to forgo possible breakthroughs. There is no ethical argument that justifies not doing the same for animals.