Nonhuman Primates, Human Need, and Ethical Constraints

The article by Barnhill, Joffe, and Miller is an exceptionally timely contribution to the literature on animal research ethics. Animal research has long been a source of both high hopes and moral concerns. When it comes to infection challenge studies with nonhuman primates (NHPs), neither the hope—to save thousands of human lives from such diseases as Ebola and Marburg—nor the concern—the conviction that primates deserve especially strong protections—could be much higher. While memories of the African Ebola epidemic remain fresh and just a few years after NIH adopted the Institute of Medicine’s recommendations regarding chimpanzees, the discussion attempts to nudge the clarification and specification—one might say the evolution—of NHP research ethics and regulation. Well-informed and sensitive to the moral stakes on both sides of the issue, the article deserves careful consideration.

The authors propose this relatively demanding standard: “[H]armful primate research is justifiable only when it is integral to a research program that offers substantial benefits, in terms of human mortality or morbidity averted, over all ethically permitted alternatives, including conducting equivalent experiments with human volunteers or moving directly to field experiments with at-risk or affected humans” (2). They clarify that NHP challenge studies “are not justified by marginal gains in human safety or by efficacy gains that are unlikely to translate directly into saving human lives or preventing morbidity” (3). How, in turn, is their standard—which, although stringent, does permit causing NHPs to suffer and die for human benefit—to be justified? Not, as the authors note, by utilitarian reasoning, since such reasoning would also sanction the involuntary harming of human subjects for similar ends. Is there a cogent case for their position: strong rights for humans, weaker rights for NHPs?¹

The authors present no explicit argument for their standard or broader position. Instead, they assert a “considered judgment” that limited NHP challenge studies to avert substantial harm are permissible (4). But this begs the very question at issue: whether the standard, which permits such studies, is justified. The authors also claim that the judgment would survive the test of reflective equilibrium (coherence with ethical and factual beliefs that hold up under critical scrutiny), but that is just another claim. Slightly more helpfully, they assert that a “valid ethical justification [will appeal to] the greater cognitive, emotional, and social sophistication of the human species,” (4) but, less helpfully, they don’t explain how superiority in sophistication justifies superiority in moral status—as it clearly does not among members of our species. Least helpfully, they note parallels with Martha Nussbaum’s approach and quote her at length—but the quotation does not advance the article’s reasoning and risks confusing the reader with an unexplained (and, to my mind, out-of-place) appeal to the distinction between ideal and nonideal moral theory (4).

It doesn’t follow from my critique of the authors’ reasoning that I reject their standard. The truth is, I am ambivalent. But, assuming we continue to use NHPs in research that harms them, I would hope that something like their proposal is adopted as a guideline.

Whether or not we continue to use NHPs in challenge studies or other invasive research², I would defend the exclusion of great apes.³ The great apes include not only (common) chimpanzees and bonobos (pigmy chimps) but also gorillas and orangutans.⁴ The exclusion of these species would build on the recent development of virtually excluding chimpanzees from such research. After NIH decided to phase out most chimpanzee research in 2013, the Fish and Wildlife Service reclassified chimpanzees as an endangered species—with the result that invasive research on chimpanzees would be permitted only if designed to benefit wild chimpanzees or enhance the species’ survival. The upshot, as I understand it, is that invasive research on chimpanzees for human benefit is no longer permitted in this country. On the other side of the Atlantic, the EU banned virtually all research on great apes in 2010. We should follow suit, with possible exceptions for noninvasive studies that meet appropriate ethical guidelines.

What justifies the special protections currently afforded chimpanzees and the comparable protections I would favor for (at least) great apes? Genetic similarity per se is not a plausible basis. After all, genes are only relevant to the extent that they contribute to morally relevant phenotypical characteristics. Public concern for these animals might be a partial ground for special protections, but the public is not of one mind on this issue; and one would hope for a deeper reason that is consistent with the best thinking about moral status. The reason I suggest is that great apes are extremely person-like.

Persons have full moral status and the rights that accompany this status. Great apes, I submit, are so person-like⁵—and so similar in relevant ways to young human children—that we should extend research protections to them that approximate those that apply to human children who are too young to understand the purpose, risks, and possible benefits of participating in research. Although great apes do not naturally learn a complex language, they communicate extensively through gestures and vocalizations to social group members; they characteristically develop awareness of themselves in relation to group members and the social expectations that apply to them in their specific relationships; they exhibit through their behavior some ability to reason and plan in response to challenges and goals; and they apparently have extensive episodic memories, serving to keep track of previous transactions with associates.⁶ Although I do not assert that great apes are persons, I would not reject such an assertion out of hand. What I do assert with some confidence is that these animals are very person-like and, in many relevant respects, comparable in their cognitive and social capacities to young children. For this reason I believe that we should exempt great apes from invasive, nontherapeutic research.