Table 3.

Reasons for and against restricting invasive research with great apes (GA)

Domain	Position	Subdomain and reasons	N	References
Moral standing			104
		Similarity to humans	60
	Pro	GA possess certain cognitive and behavioral capacities similar to humans, and thus deserve special protections	15	[2, 3, 17, 18, 25, 27, 28, 30, 32, 36, 37, 39, 55, 59, 60]
		GA and humans have a similar evolutionary origin, so GA deserve special protections	10	[3, 18, 25, 37, 39, 55, 59, 60, 63, 69]
		GA possess certain conscious experiences similar to humans, and thus deserve special protections	9	[2, 17, 18, 28, 32, 37, 39, 55, 59]
		Like humans, GA exhibit moral behavior, and thus deserve special protections	8	[2, 18, 28, 36, 37, 39, 47, 55]
		GA are greatly anatomically and/or physiologically similar to humans, and thus deserve special protections	6	[2, 18, 27, 32, 37, 55]
		There is great genetic similarity between GA and humans, so GA deserve special protections	5	[2, 35, 37, 55, 69]
		Like humans, GA have a long period of childhood dependency on the mother, so they deserve special protections	3	[36, 37, 59]
		GA are very similar to humans (unspecified), and thus deserve special protections	2	[3, 65]
		GA possess cognitive capacities similar to those of cognitively disabled humans, and thus deserve special protections	1	[60]
	Con	GA seem very similar to us, but this need not entail special protections since it may be the result of training or mimicking	1	[40]
		Cognitive and consciousness-related capacities	32
	Pro	GA can have complex conscious experiences, so they deserve special protections	19	[3, 13–15, 18, 23, 25–27, 33, 35, 39, 41, 42, 47, 48, 53, 64, 69]
		GA have certain sophisticated cognitive capacities so they deserve special protections	13	[3, 16, 25–27, 33, 35, 37, 41, 46, 47, 63, 69]
		Double standards	8
	Pro	Treating GA with less consideration than humans, without good reason, is speciesist	7	[18, 29, 32, 33, 42, 49, 63]
		Treating GA with less consideration than humans is inhumane	1	[47]
		Vulnerability and dependency	4
	Pro	Captive GA can be considered vulnerable subjects, and thus deserve special protections	3	[18, 42, 49]
		Captive GA are in a special relation of dependency on humans, and thus deserve special protections	1	[49]
Science			89
		Scientific and medical value	56
	Pro	Current GA research has low medical value	12	[2, 13–15, 35, 41, 43, 46–48, 61, 64]
		GA research lacks significant scientific value (unspecified)	6	[13, 17, 27, 41, 43, 48]
		The medical value of past GA research need not predict the medical value of future GA research	2	[44, 62]
		Past GA research has been falsely credited as having high medical value	2	[15, 43]
		Even if the need of GA to combat an emerging diseases were justified, their use would not be possible for logistical and economic reasons	1	[64]
		The supposed need of GA research to combat emerging diseases is unjustified	1	[61]
		GA have not been key to combating emerging diseases	1	[26]
	Con	Current GA research has high medical value	9	[31, 34, 38, 50, 51, 56, 58, 59, 67]
		Past GA research has had high medical value	6	[31, 38, 51, 59, 66, 67]
		GA may be needed to combat future emerging diseases (e.g. Ebola)	4	[12, 50, 66, 67]
		Past GA research has had high scientific value	3	[12, 66, 67]
		Abandoning GA as research models may slow down medical discovery	2	[51, 66]
		Current GA research has high scientific value	1	[67]
		GA research is essential for reducing risks to human research subjects	1	[67]
		The medical value of past GA research is a good predictor of the medical value of future GA research	1	[67]
		The medical value of GA research may be higher than it seems, since some GA research supplied to regulatory agencies is never published	1	[67]
		GA research-based medical progress will become increasingly apparent with time	1	[51]
		GA research may become (even more) medically valuable as a result of new technologies	1	[67]
		Restricting GA research could cost human lives	1	[66]
		Existence of alternative methods	27
	Pro	GA research is unnecessary (unspecified)	7	[12, 14, 24, 28, 37, 41, 60]
		Alternative, ethical methods (e.g., other animals or non-animal models) exist	6	[2, 15, 28, 41, 44, 62]
		Restricting GA research might drive scientists to develop alternative research methods	1	[26]
	Con	No alternative, ethical methods exist	8	[22, 31, 38, 51, 56, 59, 66, 67]
		GA research is necessary (unspecified)	3	[50, 58, 65]
		Major medical advances would not have been possible with alternative methods	2	[12, 67,]
		Reliability of methods	6
	Pro	The methodology of current GA research is questionable (unspecified)	1	[41]
		GA used in labs often have multiple diseases and so are inappropriate research models, scientifically and ethically	1	[24]
		The stress that GA face in laboratory life can produce misleading research results	1	[14]
		The apparent genetic similarity between GA and humans need not entail that GA are appropriate research models	1	[15]
		GA have proved to be poor research models, so investing resources in them may hinder the advancement of medicine	1	[14]
	Con	Given the phylogenetic continuity between GA and humans, GA are good animal models for studying human diseases	1	[31]
Welfare			32
	Pro	GA care and housing requirements are virtually impossible to meet	5	[2, 17, 26, 47, 61]
		The conditions of captive GA are appalling	4	[3, 37, 53, 64]
		GA care and housing requirements are not actually met	2	[37, 64]
		The conditions of captive GA can cause GA psychological harms	2	[26, 53]
		GA care and housing requirements are particularly high (unspecified)	1	[64]
		GA research sometimes significantly harms GA (unspecified)	1	[63]
		GA research sometimes significantly harms GA physically	1	[26]
		GA research sometimes significantly harms GA psychologically	1	[26]
		Since GA are long-lived, they are used for multiple protocols, which results in increased suffering	1	[64]
		Since GA are long-lived, they can be kept in laboratories for decades, which is unethical	1	[26]
		Captivity deprives GA of social learning, which is required for normal development	1	[55]
		The benefits of GA research do not outweigh the harms it causes GA	1	[64]
		Although there is great uncertainty regarding the nature and magnitude of GA suffering, we should assume that suffering may occur	1	[47]
	Con	GA care and housing requirements can actually be met	3	[40, 56, 59]
		GA research can be carried out without significantly harming GA	2	[22, 66]
		GA are better off in research facilities (e.g., in terms of life-expectancy or wellbeing) than in the wild	2	[56, 66]
		GA care in research facilities is adequate	1	[66]
		GA research is necessary for improving GA welfare	1	[21]
		Captive GA that are abandoned by their owners are better off in research facilities than in the wild since there are no available sanctuaries to keep them	1	[56]
Public and expert attitudes			24
	Pro	Many other (developed) countries have already restricted GA research	12	[13, 15, 24, 26, 27, 30, 39, 46, 47, 53, 61, 64]
		There is opposition for GA use in research	8	[14, 15, 26, 28, 33, 39, 46, 64]
		Many pharmaceutical companies and private laboratories have already ended GA use	1	[14]
		Expert support for invasive GA research has declined	1	[61]
		GA scientists now share concern about GA research	1	[26]
		GA research sometimes requires euthanizing GA, but euthanizing GA is widely condemned	1	[57]
Conservation and retirement			20
	Pro	Supplying GA for research has led to a decline of wild populations and the threat of extinction	2	[2, 60]
		GA are endangered species (unspecified)	2	[26, 64]
		Optimal GA retirement should be to return them to the wild, but this is not feasible	1	[35]
		Appeals to conservation do not justify breeding GA in captivity for research	1	[47]
	Con	Conservation efforts could benefit from GA research	4	[20, 21, 35, 66]
		GA could be cared for after research by moving them to near-wild conditions	3	[56, 58, 59]
		GA research could improve the welfare and protection of GA as a species	2	[20, 21]
		Enough captive GA are already available for research	2	[56, 65]
		Breeding captive GA for research could ensure the survival of the species	1	[66]
		GA could be cared for after research by moving them to other research facilities	1	[40]
		GA could be cared for after research by moving them to indoor/outdoor facilities	1	[31]
Respect and rights			15
	Pro	GA are capable of assenting/dissenting (like children)	5	[19, 32, 33, 42, 45]
		GA can be considered subjects with diminished or no capacity for informed consent	3	[3, 48, 68]
		GA possess enough cognitive capacities to be considered persons	3	[3, 25, 49]
		GA possess enough cognitive capacities to be considered near-persons or person-like	2	[29, 30]
		Given that GA have the same capacities we cite for humans having the moral right to life, freedom, and welfare, GA should also be conceived as having these rights	1	[25]
		Given that GA have the capacities that may form the foundation of personhood, they have a moral right against our intentional infliction of harm	1	[49]
Financial costs			13
	Pro	Required GA care and housing costs are too high to be cost-effective	3	[2, 47, 61]
		Required GA care and housing costs are particularly high	2	[2, 35]
		The financial costs of GA research are particularly high	2	[14, 46]
		The benefits of GA research do not outweigh the financial costs	1	[13]
		Given that GA are long-lived, the costs of GA care and housing after research is particularly high	1	[60]
		Funding for GA research continues to decrease, while the costs of GA research continues to increase	1	[26]
	Con	Many experiments could be carried out with just a small population of GA	1	[67]
		Given that GA are long-lived, the costs of GA care and housing after research is high but manageable	1	[31]
		Restricting GA research could increase medicine costs	1	[66]
Law and legal status			11
	Pro	Some laws and policies already restrict the use of GA for research	3	[15, 30, 59]
		Given their cognitive capacities, GA should be granted legal personhood	2	[63, 69]
		GA should be granted the legal right to liberty	1	[69]
		GA should be granted the legal right not to be subjected to experiments that are not in their best interests	1	[63]
		GA should be granted the legal right to personal security	1	[63]
		GA should be granted the legal right to life	1	[63]
	Con	Laws and policies protecting GA vary in terms of strictness depending on setting (research, zoos, or private homes)	1	[21]
		Granting legal personhood to GA is a slippery slope into granting legal personhood to other animals	1	[54]
Longer-term consequences			7
	Pro	Restricting GA research is instrumental for restricting research on other animal species	3	[2, 17, 33]
		Restricting GA research is an important first step away from speciesism against GA	1	[63]
		Restricting invasive GA research need not have a negative impact on non-invasive GA research	1	[16]
	Con	Restricting GA research will have a negative impact on non-invasive GA research	2	[21, 52]
Total			315