Table 3 Reasons for and against restricting invasive research with great apes (GA)

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, 13,14,15, 18, 23, 25,26,27, 33, 35, 39, 41, 42, 47, 48, 53, 64, 69]

GA have certain sophisticated cognitive capacities so they deserve special protections

13

[3, 16, 25,26,27, 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, 13,14,15, 35, 41, 43, 46,47,48, 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