Category Archives: Philosophy

Not just intelligence: Why humans deserve to be treated better than animals

One of the cornerstone ideas of the animal rights movement is that there are no fundamental differences between humans and animals: humans are just animals, only more intelligent (Ryder, 1991). Therefore, some argue, since having a larger brain is just another quirk, like having larger tusks, animals should have many of the same rights as humans. In particular, they should have a right to life, a right to freedom and a right not be used by humans. Moreover, the well-being of humans should not be put above the well-being of animals (Singer, 1991), so that doing research on animals cannot be justified by improvements in human health, as scientists claim (Ringach, 2011; Bennett and Ringach, 2016). Of course, all of this flies in the face of the values of all human societies from prehistory to date, which have used animals for food, clothing, work and entertainment. No matter, says the animal right activist, that is unethical and has to stop (Reagan, 1985).

In the past, justification for human primacy over animals came from religions that stated that humans are superior to animals because they have an immortal soul, and that God commanded humans to rule over animals. However, the Theory of Evolution and modern physiology have pushed back against those beliefs, showing that there is an evolutionary continuum between animals and humans and that there are no fundamental differences between the physiology of the humans and other mammals (Rachels, 1990) . If the only difference between humans and animals is that of a higher intelligence, does that justify that we treat ourselves better than the animals? Or is this just self-interested behavior, “speciesism”, as the animal rights proponent Richard Ryder has called it (Ryder, 1991)? To strengthen their case, animal right proponents invoke the “marginal case”: these include infants and those with significant mental impairment who, lacking superior intelligence, then should presumably be treated the same way as animals (Reagan, 1985; Singer, 1991). Otherwise, they argue, we should be prepared to give animals the same rights that we readily give these marginal case humans.

However, modern neuroscience has in fact uncovered many differences between humans and the rest of the animals that makes us unique. These differences are not limited to a quantitative difference in intelligence but extend to many other mental and behavioral abilities that make us completely unique (Penn et al., 2008), a qualitatively different type of being.  Below I provide a list of the most important of those abilities.


  1. Theory of Mind is the ability to understand what other people are feeling and thinking [pp. 172-178 in (Blackmore, 2004); pp. 48-54 in (Gazzaniga, 2008)]. We do that by running inside our heads a model of what is happening in other person’s mind. Of course, the model is not always right, but nevertheless it is extremely valuable because it lets us predict the behavior of people around us. Theory of mind seems to require the right anterior insula, a part of the brain cortex that evolved very rapidly in apes. The function of the right anterior insula is to create hypothetical models of the internal state of our body in different circumstances (Craig, 2010, 2011). For example, when we imagine what it would feel like to stab our toe, is the right anterior insula doing that. Likewise, the right anterior insula can make a model of the internal state of the body of another person. Of course, theory of mind is much more than that and involves the cognitive abilities of many other parts of the brain. Research on theory of mind has revealed it to be uniquely human (Penn and Povinelli, 2007), although some studies claims to have found it in rudimentary form in chimpanzees (Call and Tomasello, 2008; Yamamoto et al., 2013). One negative aspect of theory of mind is that it often creates the delusion of attributing human consciousness to inanimate objects or animals. The same way we project our thoughts and feelings to a person that we see behaving in a way similar to us, we project human thoughts and feelings to an animal or an object we see doing something that resembles human behavior. This delusional form of theory of mind is responsible for the anthropomorphizing of animals that is so common in modern culture.
  1. Episodic memory. There are two basic forms of memory: procedural and declarative [pp. 303-306 in (Gazzaniga, 2008)]. Procedural memory is present in both humans and animals and consists in the retention of perceptual, motor and cognitive skills that are then expressed non-consciously. For example, when we walk, swim, ski, listen to music, type on a keyboard or process the visual information we get from a television screen, we use procedural memory. Declarative memory stores information about facts and beliefs about the world, and can be further divided into semantic and episodic memory. Semantic memory is about facts in the world that stand by themselves, independently of our self, whereas episodic memory is remembering things that happened to us. That is, episodic memory retains events as they were experienced by ourselves in a particular place and time. Episodic memory appears to be uniquely human, because it involves subjective experiences, a concept of self and subjective time. This is important because it allows us to travel mentally in time through subjective experiences, while animals are locked in the present of their current motivational state.


  1. Humans emotions. Mammals, birds and some other animals have a set of six basic emotions listed by Ekman: anger, fear, disgust, joy, sadness and surprise. However, we humans are able to feel many other emotions that regulate our social behavior and the way we view the world: guilt, shame, pride, honor, awe, interest, envy, nostalgia, hope, despair, contempt and many others. While emotions like love and loyalty may be present in mammals that live in hierarchical societies, emotions like guilt, shame and their counterparts pride and honor seem to be uniquely human. There is much controversy these days on whether dogs feel guilt and shame, there is evidence that they do not, but they may also have acquired this emotion as a way to interact with humans. What is clear is that many of the emotions that we value as human are not present in animals.



  1. Empathy and compassion. Empathy is defined as the capacity to feel what another person is feeling from their own frame of reference. It is a well-established fact that many animals react to distress by other animals by showing signs of distress themselves. However, this does not seem to represent true empathy as defined above, but a genetically encoded stress response in anticipation of harm. Since empathy requires feeling what the other person is feeling from their own frame of reference, it seems to require theory of mind. Only if we stripe the requirement of adopting the other’s frame of reference we can say that animals have empathy. Empathy involves the newly evolved anterior insula in humans (Preis et al., 2013), bonobos and chimpanzees (Rilling et al., 2012). Compassion is currently thought to be different from empathy because it involves many other parts of the brain. It seems to be associated with complex cultural and cognitive elements. Therefore, it seems safe to assume that animals are not able to feel compassion.
  1. Language and culture. Although animals do communicate with each other using sounds, signs and body language, human language is a qualitative leap from any form of animal communication in its unique ability to convey factual information and not just emotional states. In that, human language is linked to our ability to store huge amounts of semantic and episodic memory, as defined above. The human brain has a unique capacity to quickly learn spoken languages during a portal that closes around 5-6 years of age. Attempts to teach sign languages to apes has produced only limited success and can be attributed to a humanization of the brain of those animals, raised inside human culture. The effectiveness of spoken and written language to store information across many generations gave raise to human cultures. The working of the human brain cannot be understood without taking culture into account. Culture completely shapes the way we think, feel, perceive and behave. Although there are documented cases of transmission of learned information across generations in animals, producing what we could call an animal culture, no animal is as shaped by culture as we are.
  1. Esthetic sense or the appreciation of beauty also seems to be uniquely human. Of course, animals can produce great beauty in the form of colorful bodies, songs and artful behavior. What seems to be lacking is their ability to appreciate and value that beauty beyond stereotypical mating and territorial behaviors. Even attempts to teach chimps to produce art by drawing have largely failed.
  1. Ethics is the ability to appreciate fairness, justice and rights. It is at the very core of our ability to form stable societies and to cooperate to achieve common goals. It depends on theory of mind (which allows us to “put ourselves in somebody else’s shoes”); on social emotions like guilt, shame, pride and contempt; on empathy and compassion, and on cultural heritage. Lacking all those mental abilities, animals have no sense of ethics. Even though some studies have shown that monkeys have a primitive sense of fairness (particularly when it applies to their own interest), it is but a pale anticipation of our sense of justice. It simply goes to show how that ethics is rooted in our evolutionary history. The fact that animals cannot even remotely comprehend the concept of rights is a strong argument for why they should not have rights. What sense does it make to give animals something that they do not know that they lack?


  1. Extended consciousness. They question of what is consciousness has been called by scientists and philosophers “the hard problem” due to the difficulty of answering it (Blackmore, 2004). Therefore, the related question of whether animals have consciousness, or what animals have it, remains similarly unanswered in the strict sense. However, based on their behavior, we commonly assume that animals like cats, dogs and horses are conscious and able to make some autonomous decisions. On the other hand, unless we invoke some mystical definition of consciousness, it is safe to assume that animals with small nervous systems, like jellyfish, worms, starfish, snails and clams have no consciousness whatsoever. They are like plants: living beings able to react to the environment as automatons. That leaves a lot of animals for which it is hard to guess whether they are conscious or not: insects, fish, octopi, lizards and small mammals like mice and rats. What has been becoming clear is that we humans possess a kind of consciousness that no other animal has: the ability to see ourselves as selves extending from the pass to the future [pp. 309-321 (Gazzaniga, 2008)]. This special kind of consciousness has been called by neuroscientist Antonio Damasio “extended consciousness” [Chapter 7 in (Damasio, 1999)] and allow us a sort of “mental time travel” to relive events in the past and predict what may happen to us in the future (Suddendorf and Corballis, 2007). Extended consciousness is based on our ability to have episodic memory and theory of mind. Episodic memory configures remembered events around the image of the self, whereas theory of mind allows us to create a model of our own mind as it was during a past event or to hypothesize how it would be in a future event. I should also point out that a few animals (apes, dolphins and elephants) may turn out to have episodic memory, theory of mind and hence extended consciousness. However, this is still very much in doubt.
  1. Suffering and happiness. It is a common mistake to confuse suffering with pain and happiness with joy. Pain is the representation of a bodily state and the emotion associated with it (Craig, 2003). Likewise, joy is an emotion associated with an excited but pleasant body state in an agreeable environment. Suffering and happiness are much deeper than that, and refer to the totality of a mental state, encompassing cognition, emotion and state of consciousness. Although suffering and happiness are normally associated with certain emotions, there is not always a correspondence with them. For example, one can be happy while feeling scared or sad, or suffer even in the presence of a passing joy. The error of philosophers like Peter Singer (Singer, 1991) and Tom Reagan (Reagan, 1985) is that they consider suffering as something that occurs independently of cognition and other mental abilities, when it does not. Arguably, happiness and suffering require some continuity in time, which would seem to require extended consciousness. Furthermore, conceptions of happiness extending to antiquity refer to lifelong attitudes like hedonism (the quest for personal pleasure) and eudemonia (working to acquire virtue or to achieve goals that transcend oneself), pointing to the fact that human happiness depends on cultural values. In view of all this, we need to wonder whether happiness and suffering can exist in beings that have no episodic memory, no extended consciousness, no sense of self, and no culture. Can happiness and suffering really be attributed to animals lacking these mental abilities? Or is this an illusion, an anthropomorphizing caused by the overreaching of our theory of mind? Without going to that extreme, it is quite clear that we humans have a capacity to be happy and to suffer that goes far beyond what animals can experience. So human suffering counts more than any suffering than an animal could have.

There are many more differences between human and animals. However, the ones that I have listed here are important because they give us our special feeling of humaneness. All of them are based on scientific facts about the human mind that are slowly being unraveled by neuroscience, not on religious beliefs or on ideology. However, what cannot be based on science is the value we attribute to those differences. Ultimately, this is a decision based on our ethical intuition. Still, for most people what determines how much consideration we should give to a being is its ability to be conscious; to feel empathy; to feel guilt and pride and shame and all other human emotions; to be happy as we are happy and to suffer like we suffer.

An important corollary of the ideas proposed here is to utterly refute the “marginal case” argument. Thus, even when a human brain is damaged by disease, accident or old age, most of the properties that I have listed here remain because they are deeply engrained in the way the human brain works. Theory of mind and extended consciousness appear early in human life and are the last things to go in a deteriorating brain. It takes coma to deprive us of them. A person may have a reduced intelligence or other cognitive disabilities, but s/he still has theory of mind, empathy, compassion, extended consciousness and all those human emotions. That is why when we encounter those people we recognize them as humans and we know we should treat them as humans. They are not animals and should never be treated as such. Intelligence is just a tiny part of what it means to be human.

Another important idea is that there are vast differences in the mental abilities of animals and, therefore, in the way they should be treated. Many animals, like jellyfish, worms and clams, do not have any mental capabilities at all, do not feel pain, and can be treated the same as plants. In the other side of the mental spectrum, it is possible that we will find that the great apes, dolphins and elephants have some form of theory of mind and extended consciousness, and therefore deserve a special treatment compared to other animals. Dog and cats have evolved special ways to communicate with humans that make them special in our eyes. So, when it comes to ethical consideration, animals should not be put in a general category, but each species should be assigned its own value. Otherwise, we may find ourselves in the quandary of not being able to rid our dog of fleas because these insects have the same “rights” as the dog. This is, in fact, what we have been doing all along: to establish a hierarchy of animals that deserve more or less consideration based on their mental abilities, putting humans at the top. Speciesism is unavoidable because we cannot treat different species of animals the same way.

Let me finish by saying that this is not an argument to treat animals cruelly or poorly. It is only an argument to treat humans better than animals and to keep using animals for our benefit. We should care about the welfare of animals, even as we try to understand how similar and how different they are from ourselves. What moves us to treat animals well is our empathy, our compassion, our sense of fairness and our cultural values. Things that animals do not have. Ultimately, we must treat animals right not because of what they are, but because of who we are.

by Juan Carlos Marvizon, Ph.D.


Bennett Allyson J, Ringach Dario L (2016) Animal Research in Neuroscience: A Duty to Engage. Neuron 92:653-657.

Blackmore S (2004) Consciousness: An Introduction. Oxford, New York: Oxford University Press.

Call J, Tomasello M (2008) Does the chimpanzee have a theory of mind? 30 years later. Trends Cogn Sci 12:187-192.

Craig AD (2003) A new view of pain as a homeostatic emotion. Trends Neurosci 26:303-307.

Craig AD (2010) The sentient self. Brain Struct Funct 214:563-577.

Craig AD (2011) Significance of the insula for the evolution of human awareness of feelings from the body. Ann N Y Acad Sci 1225:72-82.

Damasio AR (1999) The Feeling of What Happens.

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Penn DC, Holyoak KJ, Povinelli DJ (2008) Darwin’s mistake: explaining the discontinuity between human and nonhuman minds. The Behavioral and Brain Sciences 31:109-130; discussion 130-178.

Preis MA, Schmidt-Samoa C, Dechent P, Kroener-Herwig B (2013) The effects of prior pain experience on neural correlates of empathy for pain: An fMRI study. Pain 154:411-418.

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Rilling JK, Scholz J, Preuss TM, Glasser MF, Errangi BK, Behrens TE (2012) Differences between chimpanzees and bonobos in neural systems supporting social cognition. Soc Cogn Affect Neurosci 7:369-379.

Ringach DL (2011) The Use of Nonhuman Animals in Biomedical Research. American Journal of Medical Sciences 342:305-313.

Ryder R (1991) Speciecism. In: Animal Experimentation: The Moral Issues (Baird RM, Rosenbaum SE, eds), pp 24-34. Buffalo, NY: Prometheus Books.

Singer P (1991) The Significance of Animal Suffering. In: Animal Experimentation: The Moral Issues (Baird RM, Rosenbaum M, eds), pp 57-66. Buffalo, NY: Prometheus Books.

Suddendorf T, Corballis MC (2007) The evolution of foresight: What is mental time travel, and is it unique to humans? Behav Brain Sci 30:299-313; discussion 313-251.

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Sanctuary, Zoo, Lab: Name Games or Core Differences?

The announcement of a research partnership between Lincoln Park Zoo (Chicago) and Chimp Haven (a federally funded sanctuary for NIH retired chimpanzees) has led to increased dialogue, particularly in regards to what this means for the chimpanzees’ well-being and importantly, the kinds of activities that a sanctuary is allowed to engage with the animals under their care. We previously covered some of this issue, with concerns raised about the the deaths of 9 chimpanzees recently transferred to the Chimp Haven sanctuary (see here and here). In light of continued planning for relocating chimpanzees, the central focus has been on the question of whether the deaths have resulted in serious consideration and thoughtful review to identify any changes that could reduce future risks and best protect other animals’ health and wellbeing.Maynard

The recent announcement of a zoo-sanctuary “research partnership” has again prompted the question of the impact on the relocated chimpanzees’ well-being. Moreover, subsequent discussion has also illustrated a number of areas where facts and solid public information about the transparency and oversight of such research may be critically lacking. The discussion also highlights issues at the core of ethical consideration of chimpanzees. They are issues that not only play a role in decisions about where the chimpanzees should live, and in what activities they should take part; more fundamentally, they are issues that define what is meant by sanctuary and what is meant by research. That definition is central to informed and productive dialogue.

@2016 AJ Bennett comparison table research zoo sanctuary Table 1In many cases it appears that there are widely divergent views of what defines a sanctuary and what is meant by research. This is why, in part, the recent announcement of the Chimp Haven-Lincoln Park Zoo partnership was surprising to many. Particularly surprising was a statement by the sanctuary’s Chair of the Board of Directors that indicated the facility hopes to recruit scientists to bring research funds to the sanctuary in order to continue their research that has been truncated by federal decisions to retire research chimpanzees.Science - David Grimm 7.28.16

In various promotional materials about the new partnership between the zoo and the sanctuary the emphasis was on how the program might benefit understanding of chimpanzees and assist with animal care and conservation goals. At the same time it rapidly became evident that enthusiasm from the zoo and its chimpanzee program director, Dr. Stephen Ross, partially reflects benefits gained from access and use of the large sanctuary chimpanzee population, including research opportunities unavailable in the zoo. Others also appeared to see this use of the sanctuary chimpanzees as appropriate and justified. For example, the zoo’s press release about the partnership includes a congratulatory statement from the Humane Society of the United States (HSUS), a group opposed to NIH’s previous chimpanzee research:

“This important partnership between an accredited zoo and an accredited sanctuary is further evidence that we are in the midst of a new, compassionate era in our treatment of chimpanzees,” says Wayne Pacelle, president and CEO of The Humane Society of the United States. “Chimpanzees are amazing animals, and these two organizations are helping to define how best to learn from them, educate about them and most importantly, to care for them.”

Increasing public interest in the ethical justification for zoos

HSUS’ position on the ethical justification for keeping chimpanzees in zoos is not readily apparent, and their statement stops short of endorsing the zoo itself, or the perpetuation of captive chimpanzees via breeding in captivity (something that is banned in research centers and sanctuaries). Yet, others have raised similar questions well before the most recent decisions about NIH-funded chimpanzee research (see, for example, Jamieson, 1985; Regan, 1995)– though with significantly less media coverage. Furthermore, serious and thoughtful consideration of the different uses and human interactions with apes continues well beyond the simple and polarized messages that sometimes dominate the recent public portrayals of the issue  (for example, Norton, Maple, & Hutchins, 1995; Gruen, 2014; Bennett & Panicker, 2016; and many others cited within these references) .

Discussions about the role, ethical justification, and necessity of housing chimpanzees in research, zoo, and sanctuary facilities have arisen not only because of the retirement of NIH chimpanzees. Rather, societal consideration of zoos has also increased over time. Most recently, the tragic death of Harambe, a gorilla at the Cincinnati Zoo, along with the closure of the 140 year old Buenos Aires zoo, and movement away from keeping elephants in zoos, have sparked much public dialogue.

The tone of reflection is evident in a number of the titles of articles, op-eds, and blog posts. For example:

The ethical justification for keeping chimpanzees in zoos merits serious and well-informed consideration as it forms the foundation of societal decisions. The same kind of consideration is already mandated for research with animals, including chimpanzees, in the US and elsewhere.  In both cases, the public dialogue and public interests are served by providing facts about the animals’ care and treatment, but also by full and balanced presentation of the justification itself.

Intersections between research, zoos, and sanctuaries

Speaking of Research typically focuses solely on animal research and on animal testing rather than other interactions and uses of animals by humans, including zoos, entertainment, and private ownership.  In the case of chimpanzees, however, the intersections between research, zoos, and sanctuaries are now at the forefront of many of the debates, decisions, personal, and the societal deliberations.

There are a number of reasons for this intersection. Among them: the movement of research chimpanzees to sanctuaries and zoos; the fact that US decisions about research chimpanzees has resulted in a likely shift of research opportunities to zoos and other types of facilities; and, most recently, the new partnership between a federally-funded chimpanzee sanctuary and a zoo.  At the same time, the new standards of care and housing for chimpanzees adopted by one federal agency, the NIH, has raised questions about whether the same standards should be extended to all chimpanzees (for further information and discussion see previous posts “Where should US chimpanzees live?” and “Chimpanzee retirement: Facts, myths, and motivation”).

What are the defining characteristics of a sanctuary?

One of the core issues in this debate is: “What should be the defining characteristics of a sanctuary?”   For some people, the central characteristic is only that the animals receive the best possible care to protect their health and well-being. However, as we have written about previously, this characteristic is not exclusive to sanctuaries. Excellent and humane care can be provided in other settings, including research facilities (for further discussion see: “Can we agree? An ongoing dialogue about where retired research chimpanzees should live”).where us chimpanzees live 07.13.16

For other people, the very concept of sanctuary means that the animals are not used as instruments to achieve any human goal, or to meet any human need. And, moreover, that the animals’ dignity and autonomy receive highest consideration. For example, in an edited volume, “The Ethics of Captivity,” philosopher Lori Gruen says: “There are some captive contexts, such as true sanctuaries, where the goal is not just to promote the well-being of the individuals that live there but to also recognize their dignity and treat the residents with respect” (p. 244). She argues in particular that animals should be provided with the opportunity to choose who to spend time with, other animals or observers, and be able to escape others’ gaze. She also contends that:

“Certain features of current captive practices are fundamentally dignity denying. For example, sending prisoners far away from their families or breaking up social groups in zoo settings denies the most basic choices in addition to disrupting social bonds. Such moves can only be justified if they are clearly in the best interests of the captive, not to serve institutional ends” (p. 245).

In a more recent article, Gruen (2016, “The End of Chimpanzee Research,” Hastings Report) writes in opposition to retiring NIH chimpanzees in the dedicated research facilities in which they currently live. She argues:

“Humans, regardless of gender or gender expression, race, ethnicity, ability, and so on, deserve respect. And I believe respect is also owed to chimpanzees. We make sense of our experiences and values through our relationships with others, and when we are instrumentalized in those relationships, our worth, our interests, and the meaning of our experiences is undermined. This is also true in the case of chimpanzees. … Advocates for chimpanzees oppose retirement in place due to this fundamental difference in [human, our emphasis] values—the ethos of a sanctuary respects the choices and dignity of the animals as opposed to that of a laboratory, where animals are used as tools.” [emphasis added]

What defines the sanctuary ethos and “using animals as tools”?

For many viewing and discussing the current situation, it is the argument about ethos and the degree to which the chimpanzees are “used as tools” that pose challenges to dialogue. One reason is that the terms are not clearly defined or operationalized in a way that allows people with a range of perspectives, experiences, expertise, and philosophical positions to be certain they are discussing the same thing.

For example, it is not entirely clear what behaviors and care practices would provide evidence of an “ethos” that “respects the choices and dignity of the animal.” Ironically, it would also seem that in order to provide an understanding of choice and dignity from the animals’ perspective, detailed scientific research on the animals themselves is needed, where the animals are used as tools to achieve the goal of improving the health and wellbeing of other chimpanzees.

No clear line is apparent that would indicate how we might define all of those cases in which chimpanzees are “used as tools.” For instance, while there may be relatively widespread agreement that chimpanzees used in entertainment are being “used as tools,” there may be far less agreement that chimpanzees in zoos fall in the same category. Similarly, whether noninvasive research qualifies as using chimpanzees “as tools” is also likely to be a point of disagreement. Noninvasive research spans studies of chimpanzees’ cognition, language, puzzle-solving, theory of mind, but also their preferences for various foods, housing, or care strategies, their response to human visitors, and any number of other topics  about which hypotheses can be made and tested with experimental, observational, and other scientific approaches.

The justification for any of this work can readily and reasonably be made in terms of benefits for the animals themselves, for the species, for human understanding, for society. Nonetheless, a reasonable case might also be made that noninvasive research is an instance of using the animals “as tools” because the work can lead to scientific publications, positive publicity and reputational enhancement for institutions and individuals, to satisfaction of human curiosity, and also to new knowledge that benefits animals—but animals other than those participating in the study.

Chimpanzees in research, zoo, and sanctuary facilities

Chimpanzees in research, zoo, and sanctuary facilities

The question of whether noninvasive research—the only type currently allowed in NIH-funded or supported research—is an instance of using the animals as instruments for human goals is not the only one. Moving chimpanzees away from their stable social groups, long-time and familiar homes and caregivers, and into a novel setting labelled “sanctuary,” may also qualify as “using the animals as tools.” In this case, the disruption of the animals’ lives and movement to sanctuary may serve as a tool to make humans “feel better” with potentially little added benefit to the animals themselves (see also K.S. Emmerman, in The Ethics of Captivity, edited by L. Gruen, Oxford University Press, 2016).  It is for this reason that many focus on the outcome – in terms of relative benefit and relative risk to the animals’ health and welfare—in order to make judgments about whether moving the animals is really in the animals’ best interests.

Is the Chimp Haven partnership with Lincoln Park Zoo consistent with the “true sanctuary ethos”?

It is partially for all of these reasons that the recent announcement of a research partnership between Lincoln Park Zoo and the federally-funded sanctuary was surprising to many. It was a surprise because many assumed that chimpanzees retired from research would not then serve in research – and, particularly, that they would not be viewed as a resource for the facility’s fund-raising via fees exchanged for research opportunities. The latter appears to be exactly the rationale expressed by the director of the facility and her collaborators in an abstract for presentation at the upcoming scientific meeting (Spaetz, Taylor, & Fultz, 2016):

“With recent decisions ensuring the retirement of additional chimpanzees, sanctuaries may provide an optimal place for behavioral research with the potential for large sample sizes, a variety of enclosures, and on-site support. A future goal for the sanctuary community is to become self-sustaining. In order to do this, sanctuaries must explore different options including fees for researchers and visiting scientists who hope to continue to study the chimpanzees.”

Perhaps it is not surprising that Chimp Haven has taken this approach. It is similar to that of the Pan African Sanctuaries Alliance (PASA) described by another primatologist, Professor Brian Hare at Duke University. For example, on the advantages of sanctuary-researcher partnerships: “Successful research programs in African sanctuaries will provide researchers with an alternative to more traditional laboratories that do not offer the high quality living environment that are found in Africa. African sanctuaries in turn will become the preferred research venue given their many advantages for non-invasive research.”

At the same time, researchers are described as a resource and benefit to sanctuaries:

“Sanctuary apes can benefit from additional resources provided by researchers through research fees (e.g. for management costs or improvements for research), equipment (e.g. computers, veterinary equipment, etc.) or expertise (e.g. disease screening and other veterinary work). The resources of researchers that never made it to Africa before will be spent in ape range countries to aid in maintaining the high level of care found in African sanctuaries.”

In many ways, Hare, Ross, and others who have advanced sanctuaries and zoos as a viable—and  “ethical”—alternative for science aimed at better understanding chimpanzees appear to share with other scientists an understanding of the value of research in terms of benefits to humans, animals, society, and the environment. They also realize that as dedicated research facilities continue to reduce the number of chimpanzees they house, and eventually house none, sanctuaries – along with zoos – will have “cornered the market” for primatologists, comparative psychologists, biologists, neuroscientists, and others with expertise and interest in scientific research that can answer basic science questions and those relevant to animal health and wellbeing.

There are key differences between the African sanctuary system and Chimp Haven, however. Most primary among them is that PASA exists to care for animals orphaned in Africa as a result of poaching and other human activities and that have no other place to go that can provide for their care. By contrast, for many of the chimpanzees slated to be moved from their current facilities, away from their stable social groups and long-time caregivers in dedicated research centers, Chimp Haven is not the only option.

PASA exists to care for animals and not to create additional animals that are dependent on human care and must be maintained in captive settings. By contrast, Lincoln Park Zoo and others actively seek—through breeding programs— to create more animals that must then be maintained in captive settings. Thus, while one program explicitly seeks to reduce the number of chimpanzees that require human care in captive settings, the other perpetuates the practice.

For zoos, many argue that conservation and education goals provide an ethical justification for maintaining the animals in captivity. Others reject the argument. For example, in an article titled “Shifting Toward an Ethics of Sanctuary,” Gruen argues the logical point: “But holding animals captive has no necessary connection to conservation as there are many successful organizations that engage in conservation efforts that do not hold any animals captive.”


Photo credit: Kathy West

Unresolved questions

A number of questions are likely to remain active points of discussion both within the scientific community and more broadly. They include:

  • Whether continued scientific research should occur—including questions about: what types of work have merit and are justified; who should conduct the work; where it should be conducted; how it should be conducted and supported.
  • How these decisions should be made in absence, or outside of, the well-established and fairly transparent processes for expert and competitive scientific review that has occurred for proposals to NIH and NSF. This is a specific concern for the federal sanctuary that houses federally-owned chimpanzees supported largely by federal funds.
  • Whether retirement in place is the best option for some research chimpanzees.
  • Whether or not sanctuaries should conduct research.
  • Whether or not the federally-funded sanctuary should partner with a zoo.
  • Whether or not zoos should house chimpanzees at all.
  • Whether all chimpanzees in the US should receive the same standards of care as those mandated by the NIH.

In review of those questions and recent events, it is also clear that better dialogue might be facilitated by specifying what is meant by sanctuary. To the extent that research occurs in the federal sanctuary and the sanctuary is used to serve the goals of zoos, it is not at all clear that the term “sanctuary” has the common meaning that appears in public view. That is a problem for a number of reasons. Among them, when it comes to public dialogue and public decisions – both relevant to the federal funding that flows to Chimp Haven* – it is important to be clear about what retirement to sanctuary means and about how it is different from continuing to care for the animals in the facilities in which they currently live.

(*Federal funds provide 75% of the costs for maintaining NIH-owned chimpanzees at Chimp Haven, in 2015, according to NIH, this was $2.77 million. Chimp Haven currently appears to have a $12.9 million federal contract and over $30M in federal funds were invested in facility construction, chimpanzee transfers, and care. There are a number of other chimpanzee sanctuaries in the US, these sanctuaries are not currently part of the federal system and do not appear to be eligible for federal funds.)

Comparison of key features of research, zoo, and sanctuary facilities

The tables accompanying this post (above and below) outline some of the key features that are associated with different types of facilities, some of which may affect animals’ care and others that affect research. The tables cannot account for variation across every facility, but rather shows the typical case for research and zoos, what is known about the federally-funded sanctuary, and what would appear to be the case for a “true” sanctuary as it is defined by Gruen and others. Provision of choice is held up as a central defining element of sanctuary care. Thus, the second table focuses on elements of choice – or autonomy – that are central to the daily lives of animals living in a range of captive settings. As illustrated in both tables, there is a great deal of overlap between the various types of facilities.

Comments that can help further refine this work towards common understanding of the language used in discussion of chimpanzees in the US are welcome. We will return to this topic in the future, with analysis of the information in the tables, comparisons across facilities, and the implications for decision-making about chimpanzees.

Allyson J. Bennett

@2016 AJ Bennett comparison table research zoo sanctuary Table 2

Was Jeremy Bentham an Antivivisectionist?

Jeremy Bentham Animal ExperimentsIn this post we look at whether or not Jeremy Bentham, an eminent 18th and 19th century English philosopher,  was opposed to animal experiments. Ahead of his time in many areas, Bentham advocated for freedom of expression, abolition of slavery, equal rights for women, and the separation of church and state. His Utilitarian philosophy has influenced philosophers such as John Stuart Mill and, more recently, Peter Singer.

In his 1789 book, An Introduction to the Principles of Morals and Legislation, he briefly muses the question of rights for non-human beings. In a footnote, the following can be found.  

The French have already discovered that the blackness of the skin is no reason a human being should be abandoned without redress to the caprice of a tormentor. It may one day come to be recognized that the number of the legs, the villosity of the skin, or the termination of the os sacrum are reasons equally insufficient for abandoning a sensitive being to the same fate. What else is it that should trace the insuperable line? Is it the faculty of reason or perhaps the faculty of discourse? But a full-grown horse or dog, is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day or a week or even a month, old. But suppose the case were otherwise, what would it avail? the question is not, Can they reason?, nor Can they talk? but, Can they suffer?

This bolded section (my emphasis) has been held up by the animal rights movement as an argument against animal research. The quote can be found on the websites of PETA, Animal Aid, New England Anti-Vivisection Society and many other animal rights groups.

NEAVS website, April 2016

NEAVS website, April 2016

You can read a full debunking of Bentham’s argument for the rights of animals in our “Animal Rights Philosophy” section. An extract can be found below:

Bentham neglects to explain why suffering should be a basis for rights. Central to this question is that of “What grants rights?”


It is the power for entirely autonomous thought and action which grants rights to human, uniquely among all animals. However there is more to the advent of rights. With a right comes a duty. My right and your right not to be arbitrarily killed are fundamentally linked to your duty, and my duty, not to arbitrarily kill someone else. My right to property hinges on my duty not to steal from other people. Before civic society came about, humans were free of any laws preventing them from killing each other, however killing your neighbor would justify your neighbor’s friend in killing you. So an unuttered agreement formed that said “if I don’t kill you, you don’t kill me”, and the beginnings of society could come about.

Animals cannot partake in any agreement. They cannot understand the duties required of them that would allow them to receive the protection that rights would offer them.

However, to return to the original question: Was Jeremy Bentham an Antivivisectionist? Many have taken his quote to mean that he was, however, in a Letter to Editor to the Morning Chronicle, March 4th 1825, Bentham tackles this question head on. His first sentence outlines his position clearly:

Sir, —I never have seen, nor ever can see, any objection to the putting of dogs and other inferior animals to pain, in the way of medical experiment, when that experiment has a determinate object, beneficial to mankind, accompanied with a fair prospect of the accomplishment of it.

He goes on to say what the vast majority of us would agree with – that unnecessary animal suffering should be avoided.

So there you have it – Bentham was not against animal research. Such tactics of adopting people based on single sentences has been common. We have seen Albert Sabin – creator of the oral polio vaccine – misrepresented, we have seen former NIH director, Elias Zerhouni misrepresented. And Bentham is not the only philosopher. While Peter Singer, author of Animal Liberation, has certainly supported principles of animal rights on a Utilitarian basis, his views on the matter are more nuanced than many activists give him credit for. In 2006, while debating the issue with Prof Tipu Aziz – a brain surgeon who has conducted pioneering work into deep brain stimulation – Singer agreed that Aziz’s use of monkeys could probably be justified. The Independent writes:

In the film Monkeys, Rats and Me: Animal Testing, Singer is seen in discussion with the Oxford academic Professor Tipu Aziz, who has been conducting experiments on macaque monkeys as part of his work to find a treatment for Parkinson’s disease and other illnesses. Told by Aziz that tests on some 100 monkeys has led to positive treatment for 40,000 patients, Singer responds that he “would certainly not say that no animal research could be justified.

Or watch the segment of the documentary Monkey Rats and Me, below:

Next time you see Bentham quotes plastered on animal rights websites, just remember:

Sir, —I never have seen, nor ever can see, any objection to the putting of dogs and other inferior animals to pain, in the way of medical experiment, when that experiment has a determinate object, beneficial to mankind, accompanied with a fair prospect of the accomplishment of it.

Speaking of Research

PR, ethics, and the science of head transplants

There has been a lot of media coverage on the recent claims by Dr. Sergio Canavero that he has successfully transplanted the head of a monkey on to a donor body of another monkey. This story, originally posted by the New Scientist, has since gone viral with some touting miracle cures for paralysis, while others have publicly expressed outrage and disgust. As pointed out by the New Scientist, this is not science, or at the least, not yet. Until the veil of secrecy concerning the conduct of this study is made transparent – no formal conclusions can be made and one can only speculate in regards to the quality of the experiment that was performed. Moreover, as this work still has to pass through the peer-review process, it remains unclear whether this is simply an attempt at publicity. As Arthur Caplan, a New York University bioethicist told New Scientist:

It’s science through public relations. When it gets published in a peer reviewed journal I’ll be interested. I think the rest of it is BS”

So far, the only evidence that Dr Canavero has produced is a picture of a monkey which appears to have had a head/body transplant, as well as a short video of a mouse moving around (despite significant impairments), which also appears to have a transplant (but how long did they live for? When Dr Canavero’s colleague Dr Xiaoping Ren of China’s Harbin Medical University carried out similar head transplants in mice in 2015 they all died within a few minutes of being revived after surgery). While the monkey “fully survived the procedure without any neurological injury of whatever kind”, according to Canavero, it was euthanized after 20 hours for “ethical reasons”. The media storm surrounding this story appears to play up to the researcher’s aims – to find financial backing to continue his research and then move it into humans.

Canavero at TEDx

Two pieces of information in the article by the New Scientist bear scrutiny. The first is that Canavero is quoted as saying “this experiment, which repeats the work of Robert White in the US in 1970, demonstrates that if the head is cooled to 15°C, a monkey can survive the procedure without suffering brain injury.” Second, Sam Wong, author of the article in the New Scientists stated “they connected up the blood supply between the head and the new body, but did not attempt to connect the spinal cord.” Careful reading highlights a simple fact, this study is not novel in any regard – this is a replication of the work by Robert White and is quite simply a “head transplant”. Thus, the same criticisms that were levied in regards to the original experiment by Robert White apply here. As Stephen Rose, director of brain and behavioural research at Open University can be quoted as saying in 2001:

This is medical technology run completely mad and out of all proportion to what’s needed. It’s entirely misleading to suggest that a head transplant or a brain transplant is actually really still connected in anything except in terms of blood stream to the body to which it has been transplanted. It’s not controlling or relating to that body in any other sort of way. It’s scientifically misleading, technically irrelevant and scientifically irrelevant, and apart from anything else a grotesque breach of any ethical consideration. It’s a mystification to call it either a head transplant or a brain transplant. All you’re doing is keeping a severed head alive in terms of the circulation from another animal. It’s not connected in any nervous sense.”

And so, it is worth reflecting at this juncture on the moral and ethical issues surrounding this controversial procedure. Let us assume for a moment that this procedure is in fact feasible. In the original studies by Robert White and Vladimir Demikov, it was made clear that these experiments were lethal for the animal. Simply put, while the head of the animal was capable of “seeing, hearing, tasting, smelling”; none of the other regulatory processes were intact (e.g. breathing) as there was no control over the donor body. Furthermore, like many tissue transplants, rejection of the donor body from the immune system is a large possibility, immunorejection was after all the cause of death in the monkey whose head Dr White transplanted in 2001. Indeed, Canavero has yet to demonstrate any kind of proof of principle with regeneration of nervous tissue with any meaningful metric of control of the donor body.

Perhaps the most interesting insight into Canavero’s thinking comes from a quotation in the New Scientist article where he says:

Gene therapy has failed. Stem cells, we’re still waiting. Even if they come now, for these patients there is no hope. Tetraplegia can only be cured with this. Long term, the body decays, organs decay. You have to give them a new body because even if you take care of the cord, you’re going nowhere.”

These remarks by Canavero are somewhat naive as both gene therapy and stem cell therapy have made substantial advances in recent years, with many therapies now in clinical trials. Furthermore, the claim that “Tetraplegia can only be cured with this [head transplant]” flies in the face of evidence from recent successful animal and clinical trials on a variety of innovative therapies for paralysis, including epidural stimulation, intraspinal microstimulation, neuroprosthesis, and stem cell therapy.

There have recently been a series of major advances in treating paralysis, including epidural stimulation.

There have recently been a series of major advances in treating paralysis, including epidural stimulation.

While there is mounting evidence from studies in rodents that the polyethylene glycol (PEG) implantation approach favored by Canavero may be able to promote repair of injured spinal cord and recovery of motor function in paralyzed limbs, his casual dismissal of the work of other scientists – while often simultaneously citing their work in support of his own approach – exemplifies his arrogance. He would be better off lending his expertise to the work of others who are exploring the potential for PEG in spinal cord repair, work that has the potential to benefit millions of people, but instead appears set on a self-aggrandizing PR campaign in support of an approach that if successful – which seems highly unlikely even if the surgery is a technical success – can only benefit a tiny number of people…potentially at the cost of depriving many other transplant patients of much needed organs.

The reality, however, remains that the procedure exposes the patient (be it mouse, monkey or human) to far greater risks compared to the potential benefits. Indeed, these experiments would never be approved in countries which have strict review criteria, with a clear harm/benefit analysis needing to be performed before such a study is given approval. In these circumstances, the news that leading experts in animal research in China are currently undertaking a major revision to the country’s national regulation on the management of laboratory animals is timely.

But these issues are not unknown to Dr. Canavero. Indeed, as can be seen here (scroll to see response), and in what can only be described as derision and a willful skirting of the law, Dr. Canavero remains set to push forward with his ideas regardless of the consequences. For these reasons we have the gravest of reservations about the course being followed by Dr. Canavero and his colleagues, and call on them to halt this research until a full independent review of the scientific evidence and impact on potential patients can be undertaken.

Jeremy Bailoo and Justin Varholick

The opinions expressed here are our own and do not necessarily reflect the interests of the the University of Bern or the Division of Animal Welfare at the University of Bern.

Animal Testing. Is it really a polarised debate?

I was recently contacted by a student who had an assignment to report both sides of a contentious issue, and she’d chosen animal research.

To her, there were two sides to the debate – a simple yes or no to research. Yet, as I explained to her, it is not a genuinely two-sided argument.

To understand why, we need to look at the basis of the hardline anti-vivisection viewpoint that no animal should be used in an experiment. This is the position taken by most animal rights groups around the world, from PETA and the National Antivivisection Society, to Cruelty Free International and Animal Aid. The polar opposite of this viewpoint is that animals should always be used in experiments, yet this is never what has been argued by those in favour of experiments in the UK.

Are debates like this really between polar opposites?

Are debates like this really between polar opposites?

To understand the history of the issue, animal research really kicked off in the mid to late 1800s. In 1875, there was a Royal Commission which examined the necessity of using animals, at which scientists including one Charles Darwin gave evidence.

In 1876, on the basis of the Royal Commission, Parliament passed the Cruelty to Animals Act, 1876, which demanded that all researchers using animals, as well as each experiment, must be licensed.. There were relatively few experiments even proposed at the time, so the President of the Royal Society was asked to justify the scientific validity of each one. Special protections were afforded to dogs, cats, primates and horses which ensured that they could not be used if another species would suffice.

As time has gone on, the law around animal research has been tightened and finessed. In 1986, the Animals (Scientific Procedures) Act made it explicit that animals could not be used if there was an alternative method and in 1998 it became illegal to test cosmetics or their ingredients.

Still, however, the principal of only allowing research conditionally remained at the heart of UK animal research. In order to conduct an animal experiment, researchers need a series of licenses from the Home Office. The experiment has to pass two tiers of ethical review and prove why there is no alternative to using an animal.

If we were to transpose this ethical review system for experimentsto using animals for food we would say ‘it can be ethical for a person to eat a chicken if, for instance, they are malnourished’. Each person who was hungry would have to apply to eat the chicken, explaining also why they couldn’t eat anything else, and their application would be considered by an ethics committee before being rubber-stamped by the Home Secretary.

The key thing here is that this system is different from saying ‘it is always acceptable to use an animal’, which is the polar opposite viewpoint of ‘it is never acceptable to use an animal’.

The ethical difficulty of saying that it is never acceptable to use an animal is that it underplays the value of human and animal medicines which have derived from animal experiments. Indeed, some campaigners wilfully attempt to rewrite medical history to remove the role of animals from key discoveries, but how could you remove dogs from the discovery of insulin? How do you make a drug based on a mouse hormone without a mouse?

Individuals can be against all animal experiments if they want, but they have to acknowledge the harms associated with their worldview. It is similar to anti-vaxxers: it’s your lookout if you don’t want to vaccinate your child, but let’s be clear that you are placing them and others at risk.

Researchers are motivated to act because the victims of disease are not hypothetical. They are the children on the wards of Great Ormond Street hospital, they are people dying in sub-Saharan Africa, they are wild animals, they are your pets, they are your family. The suffering is already happening. Standing idly by and watching them suffer is not a kindness, it’s a negligence.

There are other important subtleties which are lost with a simplistic yes/no approach to animal research. For instance, what do we mean when we say ‘research’? Are we talking about brain surgery, or a blood sample? We know, for example, that some 27% of experiments are below the threshold for suffering; so have suffered less than if they’d received an injection. The degree of suffering is essential to judging the value of an experiment as the costs relative to the benefits are essential to determining value. If I’m offered a ‘procedure’ by a doctor, I’m going to need to know if we’re talking about a blood test or an amputation before deciding whether to go ahead with it.

I think it was worth using animals to develop the badger TB vaccine and the vaccines I give my cat. I think it is worth using a mouse to make a breast cancer drug, because I think the tens of thousands of women who are diagnosed with the condition every year are capable of suffering in ways the mouse cannot. For example, they may be consumed by worry for their children, whereas mice are liable to consume their children. The woman and the mouse are not morally equal except by the most superficial of measures.

However, I want to know that each experiment has gone through rigorous ethical review. I want to know that it is worthwhile. If it is not, I, somebody who is notionally ‘for’ animal research, would agree with those opposed to it. This can only means one thing – the definition of ‘against’ animal research is correct, but the definition of someone ‘for’ it is lacking. Those who identify as being against animal research are generally against all animal experiments. Those who identify as supporting animal experiments are generally only supportive given strict conditions (based on regulation, purpose etc).

I also want to see alternatives to animals testing and research continue to be developed. Animals may well be the best model we have for many bits of research, but I want better. So should you. These would have the potential to be cheaper, and even more reliable.

It’s true that there’s little dialogue between the biomedical community and the now established anti-research lobby and this isn’t surprising since they are effectively having different conversations. The biomedical community is figuring out how to improve animal welfare and is engaged in an ongoing harm/benefit debate. The demands of those opposed to animal research are effectively too uncompromising, too unreasonable, too damaging to the public good to be accommodated.

Their policy asks are all about banning research, which merely sends it abroad (often to places with lower regulatory standards), rather than doubling down on developing alternatives to animal studies which will be the only realistic way to reduce the overall number of animals used in research.

So are pro-research and anti-vivisection viewpoints, polar opposites?

Animal Rights perspectivesNo. The research community is supportive of measures to improve animal welfare while recognising the importance of balancing it with the needs of those suffering from disease worldwide.

Indeed agreement between researchers and the animal rights movement can be found through investment and development of alternative technologies, while accepting that some animals will continue to be needed in the foreseeable future. If only we could focus on that, instead of engaging in a public bun fight between two sectors which aren’t even having the same conversation.


The Uniqueness of Human Suffering

Jeremy Bentham, an 18th century utilitarian philosopher, famously asked: “The question is not ‘can they reason?’ or ‘can they talk?’ but ‘can they suffer?’” A utilitarian philosopher of our times, Peter Singer, latched into that question to write his book Animal Liberation, and so the modern animal rights movement was born. Basically, Peter Singer and many other animal rights activists claim that animals suffer like humans and therefore they should be treated like humans. Put in a more sophisticated way, Peter Singer argues that the moral imperative of equality dictates “equal consideration of interests”, that is, that the interests of all beings receive the same consideration. Animals have an interest in avoiding pain, therefore egalitarianism demands that we respect that interest. It is argued further that claiming human superiority based on our superior intelligence, our ability to talk or our culture is just stacking the cards in our favor because those are the special attributes of our species. By the same token, an elephant may claim moral superiority based on the fact of having a trunk.

However, the whole argument is based on the claim that animals suffer and, moreover, that they suffer like us. Singer and the other animal rightists just assume that they do. I think this is a faulty assumption that needs to be addressed head-on, but I understand why they take umbrage in it: the whole problem of defining suffering seems intractable at first sight. ‘Suffering’, like ‘happiness’ and ‘consciousness’, belong to a class of concepts that are at the same time abstract and fundamental, so that defining them in terms that are non-circular seems nearly impossible. If you look at dictionary definitions of ‘suffering’ you will find that they refer to pain, unpleasantness or perceptions of threat, which are just synonyms or examples of suffering. This does not represent a problem when the idea of suffering is applied to human beings, because we can get accurate descriptions of their suffering from other people. However, when we want to apply this concept to animals we need a clear idea of what we are talking about, otherwise we risk falling into one of two opposite pitfalls: self-serving callousness -choosing to think that animals do not suffer because this is convenient for us; and anthropomorphizing – thinking an animal suffers just because we would suffer if they did that same thing to us. The latter feels intuitively true because is based on empathy, a very powerful human emotion. However, it is not a rational conclusion.

Do all animals suffer? Do all animals suffer equally?

Do all animals suffer? Do all animals suffer equally?

Just like in the case of happiness and consciousness, the problem of suffering can be studied scientifically. In fact, there are a lot of scientific studies related to suffering because one important thing the public demand from scientists is to find solutions to pain and other forms of distress. Just like in the case of happiness and consciousness, science may not have come up (yet) with a complete description of suffering, but it certainly can tell us a lot of things about it. I think that this information can help us form an educated opinion about whether some particular animal suffers or not.

Most people would agree with the idea that not all living beings suffer. One of the most peculiar things about life is that it seems goal-directed: living beings strive towards keeping themselves alive and making more beings like them. However, this does not imply any form of consciousness or intentionality; it is just something that living beings do automatically because otherwise they wouldn’t be living anymore. It is important to underline this fact because this striving to stay alive can be easily confused with the “interest” that Peter Singer talks about. Yes, life perpetuates itself, but that doesn’t mean that living beings are conscious or that they have interests and plans like we do. To think otherwise would be to accept some magical vitalist concept of life that science rejected long ago. Therefore, we can conclude that plants do not suffer, although they grow, reproduce and even fight their enemies with chemical responses. Likewise, we should accept that animals that lack a nervous system (like sponges) or that have only a rudimentary nervous system (like worms) do not suffer.

What about animals that do have a complex nervous system? Do they suffer? Here we must consider that suffering and pain are often confused, but in fact are not identical. Pain produces suffering, but suffering can be produced by things other than pain, generally speaking by negative emotional states. That pain and suffering are not identical is also shown by the fact that people may experience pain and not suffer from it. For example, the pain experienced when practicing some sports, when eating spicy food and by sexual masochists induces positive feelings instead of suffering. Some drugs called dissociative anesthetics (like ketamine) can selectively turn off the emotional part of pain leaving intact its sensory component: we are still able to feel the pain, but just don’t care about it. Given the complexity of this subject, I chose to divide this discussion into two parts: suffering that comes from physical pain and emotional suffering. I will start with the first.

Pain scientists distinguish between three concepts: nociception, pain and suffering. This distinction is even recognized by the Humane Society of the United States, an animal rights organization. To understand nociception consider the case of a patient who is undergoing surgery under general anesthesia. As the skin and organs of this person are being cut, pain sensory nerves faithfully record the damage and send this information to the spinal cord, which continues to the brain. The normal traffic of noxious signals only stop at the cerebral cortex because the large parts of the brain cortex is turned off by the general anesthetic [1, 2]. This basic processing of noxious information is what we call nociception. Of course, in an awake person nociception leads to pain. The important idea, however, is that the processing of information concerning physiological damage involving millions of neurons and sophisticated neural pathways does not imply the existence of pain. In fact, nowadays pain is considered part sensation part emotion; because fundamental aspects of pain are its negative valence (we dislike it) and its salience (we cannot avoid paying attention to it). Pain requires a fairly complex nervous system capable of turning sensations into emotions. Based on these ideas, I think it is reasonable to infer that animals that lack a nervous system of enough complexity do not feel pain, they just have nociception. Behavior consisting in avoiding a noxious stimulus should not necessarily be taken as an indication of pain. After all, even plants react to noxious stimuli. It is difficult to draw the line between animals that have just nociception and those that experience pain. However, it is clear that many animals do not come even close to having a nervous system complex enough to produce the sensation of pain with its associated negative emotions. Animals like the pond snail (11,000 neurons) or the sea slug (28,000 neurons) just don’t have this capacity. By comparison, we have 100 millions neurons just in our gut (the enteric nervous system) and 86 billion neurons in our brain. Of the invertebrates, the only animal that comes close is the octopus, with 300 million neurons, comparable with the rat’s 200 million neurons. This is why countries like the UK and Canada now give cephalopods (octopi, squids and cuttlefish) the same protections given to vertebrates. Of course, the number of neurons is not the only metric to measure the complexity of a nervous system, but using other metrics like number of synapses or overall capacity to process information will give similar results. A table of the number of neurons in different animal species can be found here.

Cephalopods are protected in Canadian and EU regulations

“Countries like the UK and Canada now give cephalopods the same protections given to vertebrates”

But what most people are concerned about are the most complex animals, the mammals and the birds, which we eat, have as pets and use in scientific research. What about them? Do they feel pain? Do they suffer?

A lot can be learned about the relationship between pain and suffering in mammals by studying brain areas involved in the processing of pain in the brain. As I indicated above, pain has a sensory aspect and an emotional aspect. The sensory aspect of pain is processed by the somatosensory cortex, an area shaped like a hairband going from the top to the sides of the brain. It contains a detailed map of the body and processes pain and touch, telling us where these sensations originate (nowadays it is recognized that the dorsal posterior insula also contains a map of the body and is responsible for judgements on the localizations and intensity of pain). The somatosensory cortex is connected to the orbitofrontal cortex, located at the front end of the brain and whose function is to plan actions according with the information it receives. But neither the somatosensory nor the orbitofrontal cortex are responsible for the emotional component of pain. This function is assigned to two other areas of the cortex: the insula and the anterior cingulate cortex (ACC). Generally speaking, the function of the insula is to tell us how bad pain feels and to associate that emotion with a host of other emotions like sadness, fear, anger, joy, disgust and pleasure. Emotions can be understood as motivational states of the brain: they predispose us to act in a certain way, organizing everything we feel in a hierarchical way according to what we need to do. Pain is an emotion that motivates us to stop or escape from whatever is hurting us. This urgent motivational aspect of pain is processed by the ACC. So we could say that the insula and the ACC work together to turn pain into suffering by giving it its “I don’t like it” and “I want to stop it” qualities.

Recent discoveries have revealed that during the evolution of primates (monkeys, apes and humans) there was a reconfiguration of the brain pathways that process pain, culminating with the appearance of completely new pain processing areas in the human brain [2, 3]. To convey the importance of these changes, I must quickly summarize the neural pathways that carry pain signals from the body to the cerebral cortex. Noxious signals are carried by specialized fibers in the nerves from any part of the body to the dorsal horn of the spinal cord (see figure below). From there, the signals travel to the parabrachial nucleus in the brain stem, where they branch out to different nuclei of the thalamus and the forebrain [3]. Located in the middle of the brain, the thalamus function as the central relay of all sensory information, with its different parts or nuclei handling visual, auditory, gustatory, tactile and pain information. Different thalamic nuclei send pain signals to the four areas of the cortex described above: the somatosensory cortex, the orbitofrontal cortex, the insula and the ACC. These pain pathways are present in all mammals, but in primates a new additional pathway emerged that directly links the spinal cord with the nucleus of the thalamus connected to the insula, bypassing the parabrachial nucleus. This means that pain sensations are able to directly reach the part of the cortex where feelings are created. In humans, the size of this direct pathway between the thalamus and the insula is much larger anatomically, and much larger and more complex than in monkeys.

Spinal Cord Diagram Pain

“Noxious signals are carried by specialized fibers in the nerves from any part of the body to the dorsal horn of the spinal cord”

But is there another change in the brain that is unique to humans and a small number of other species including elephants and cetaeceans, but not being found in monkeys: a new part of the insula called the anterior insula [4, 5]. A.D. Craig, a scientist who has studied these changes by mapping the brains of monkeys, apes and humans, thinks that the posterior insula serves to create an emotional map of the state of the body in each moment. The anterior insula, on the other hand, serves to model the state of the body as it was in the past or in hypothetical situations in the future: “if this were to happen, that’s what I would feel”. Craig thinks that this gives us self-awareness by modeling feelings that represent the interior state of the body through time. The representation of hypothetical states of the body performed by the anterior insula is probably also responsible for empathy, the ability to feel what another person is feeling by simulating his body state in our own brain. In relation to suffering, we can see how growing relevance of the insula in generating the negative emotions associated with pain progressively increase the depth of suffering. This process culminates with humans; we are not only able to experience the pain of the present but are also aware of ourselves as beings that have suffered in the past and that may suffer in the future. Animals that lack an anterior insula would not be able to experience this type of suffering. The gradual appearance of the anterior insula in apes like bonobos and chimpanzees seems to correlate with the development of empathy and positive social emotions [4, 6].

In summary, we need to take a gradualist approach when considering the presence of pain and suffering in animals. Invertebrates, with the possible exception of cephalopods, do not appear to have a nervous system complex enough to feel pain, let alone suffering. Their behavior can be explained by simple responses to nociceptive signals. Vertebrates, particularly the ones with highly complex nervous systems like mammals and birds, do experience pain and quite probably suffer from it. However, the deep suffering that we experience as humans beings, rooted in our memory and our capacity to imagine the future, does not seem to exist other than in a rudimentary form in other mammals. Although animals have memories, without an anterior insula they cannot use them to construct a vivid representation of their past suffering, like we do. A measure of self-awareness and deep suffering exists in elephants and cetaceans, which also have a highly developed anterior insula and ACC with von Economo neurons.

Jeremy Bentham and Peter Singer failed to understand the true nature of suffering when they came up with the idea of speciesism. Just like we do not give the same moral status to animals and plants, we cannot give the same moral status to all animal species. When deciding how we should treat them we need to take into consideration whether they can feel pain and, if they do, how they suffer from that pain. The suffering of a mouse, a dog, a monkey and a chimpanzee are not equivalent. By the same token, human suffering has to be given a higher ethical consideration than the suffering of other animals. There is a moral imperative to diminish suffering in all sentient beings, but when difficult choices have to be made, human suffering has to come first. If saying this makes me a speciecist, I will wear that label with pride. But I’d rather call myself a humanist, because for me the priority is to decrease human suffering.

Juan Carlos Marvizon, Ph.D.

The author wishes to thank Dr. Bud Craig for his helpful comments


  1. Craig, A.D., Topographically organized projection to posterior insular cortex from the posterior portion of the ventral medial nucleus in the long-tailed macaque monkey. J Comp Neurol, 2014. 522(1): p. 36-63.
  2. Craig, A.D., The sentient self. Brain Struct Funct, 2010. 214(5-6): p. 563-77.
  3. Craig, A.D., Interoception: the sense of the physiological condition of the body. Current Opinion in Neurobiology, 2003. 13(4): p. 500-505.
  4. Bauernfeind, A.L., et al., A volumetric comparison of the insular cortex and its subregions in primates. J Hum Evol, 2013. 64(4): p. 263-79.
  5. Craig, A.D., Significance of the insula for the evolution of human awareness of feelings from the body. Ann N Y Acad Sci, 2011. 1225: p. 72-82.
  6. Rilling, J.K., et al., Differences between chimpanzees and bonobos in neural systems supporting social cognition. Soc Cogn Affect Neurosci, 2012. 7(4): p. 369-79.

Crash course in medical history

Opponents of animal research often portray two of the pioneers of experimental physiology, François Magendie (1783-1855) and his student Claude Bernard (1813-1878), as deranged, vicious, and sadistic individuals who derived pleasure in harming animals. Moral philosophers Peter Singer and Lori Gruen convey this sort of message in their book “Animal Liberation: A graphic guide”.

Portrayal of Claude Bernard in Singer and Gruen's book

Portrayal of Claude Bernard in Singer and Gruen’s book

A quick look at how Claude Bernard’s face is portrayed in their book is sufficient to get a sense of Singer and Gruen’s feelings towards scientists who engage in animal research. The peculiar use of quotes around ‘experiment’ in the caption suggests they believe the work did not qualify as legitimate scientific research, nor that it could contribute any benefits to mankind. Such view fails to consider the historical context of their experiments.  In particular, one could ask how were human patients treated by their physicians of the time.

Here is a brief summary of 19th century medicine —

The theory of counter-irritation was in vogue. To counter-irritate basically meant causing additional wounds to the patient as a form of treatment. One technique involved inserting inflamed limbs were into giant anthills. More convenient was produce large blisters by means of a fire iron or acid. In 1824, an article in the Lancet by Dr. Abernathy suggested that a 1 foot square blister was probably a bit too large — several small blisters were indicated instead.  A third method of counter-irritation involved making a saw-shaped wound and inserting dried peas or beans into it. The doctor would then ensure the wound remained open, keeping it from healing, from weeks to months, replacing the peas and/or beans as necessary.

Leeches were used in vast quantities and for many purposes.  Physicians would lower leeches down patient’s throats.  Hundreds of them would be used to bleed a man’s testicle over days. Leeches were also applied to the vagina to relieve “sexual excitement” and, not to discard other orifices, doctors would push them up the anus. It was noted that during these procedures there was always a possibility that some of the leeches would get lost inside the patient body which, according to the physicians of the time, resulted in  “very annoying accidents”.

What about mental disease? A common treatment involved psychiatrists spinning patients in centrifuge-like machines a hundred of times per minute. This is how unruly patients came to understand the authority of the doctor, with one of them asserting that the more lively his intimidation towards the apparatus the more charitable the effects of the therapy.”  


Benjamin Rush’s tranquilizer chair

Benjamin Rush, one of the founding fathers and signatories of the Declaration of Independence, adopted some of these same methods and developed them further.  He would pour acid on his patients backs and cut them with knives to allow the discharge “form the neighborhood of the brain”.  Rush also developed the famous “tranquilizer chair” where patients were restrained for up to entire days — the chair had a convenient hole for defecation at the bottom.

Bloodletting was used to treat a number of ailments.  It also often led to death.  One famous incident involves George Washington, who in 1799 suffered from a bad sore throat and died shortly after a visit by three different doctors who, altogether, took about half of his blood volume. The famous medical journal The Lancet derives its name from the tool used in these procedures.

Given Singer and Gruen’s depiction of animal research one must also ask — How did human surgeries look back then?  By all accounts they were the most excruciating, traumatic and dangerous experience for patients.  As an example, the novelist Fanny Burney recounted part of her experience with a mastectomy as follows:

I mounted, therefore, unbidden, the Bed stead & M. Dubois placed me upon the Mattress, & spread a cambric handkerchief upon my face. It was transparent, however, & I saw, through it, that the Bed stead was instantly surrounded by the 7 men & my nurse. I refused to be held; but when, Bright through the cambric, I saw the glitter of polished Steel I closed my Eyes. I would not trust to convulsive fear the sight of the terrible incision. Yet — when the dreadful steel was plunged into the breast cutting through veins arteries flesh nerves I needed no injunctions not to restrain my cries. I began a scream that lasted unintermittingly during the whole time of the incision & I almost marvel that it rings not in my Ears still? so excruciating was the agony. When the wound was made, & the instrument was withdrawn, the pain seemed undiminished, for the air that suddenly rushed into those delicate parts felt like a mass of minute but sharp & forked poniards, that were tearing the edges of the wound. I concluded the operation was over Oh no! presently the terrible cutting was renewed & worse than ever, to separate the bottom, the foundation of this dreadful gland from the parts to which it adhered Again all description would be baffled yet again all was not over, Dr. Larry rested but his own hand, & — Oh heaven! I then felt the knife (rack)ling against the breast bone scraping it!

Ms Burney was lucky to have survived to describe her experiences.  Most surgeries taking place in surgical theaters simply ended up in death.

The above were some of the common practices of medicine a mere 200 years ago. Magendie was one among the main critics of the dominant medical theories (humorism and vitalism) and the use of unproven methods on human patients. On the use of animals in research he said at a meeting [] I beg my honorable colleague to observe that I experiment on animals precisely because I do not wish to experiment on men.  That is what he felt about medicine — it was nothing short of human experimentation.

In the introductory pages of his Journal de Physiologie Expérimentale Magandie, he added:

“What subject is indeed more fertile in gross errors and absurd beliefs than that of health and disease? Consider the painful disquietude you would produce in the minds of the majority of men if you said to them:There are no such things as rheumatismal humour, gouty humour, scabby virus, venereal virus, and so forth.  Those things which are so designated are imaginary things, which the human mind has created to hide from itself its own ignorance.’   The chances are that you would be taken for a lunatic just as it but recently befell those who maintained that the sun was immovable and the earth turned.”

Any honest reading of medical history has to give credit to the experimental physiologists who put medicine in the right track to become what it is today. The handful of physicians and psychiatrists that speak against animal research should remember that from Hippocrates to the early 19th century, their profession caused more harm than good to their patients.  They ought to be reminded that it was the work of the experimental physiologists that turn this around.  Charles Darwin acknowledged this fact when he wrote:

[] I know that physiology cannot possibly progress except by means of experiments on living animals, and I feel the deepest conviction that he who retards the progress of physiology commits a crime against mankind.

As experimental medicine advanced, so did our ability to treat the potential pain and suffering animals may experience in research.  Animal welfare laws were established. Today, the vast majority of animals participating in research benefit from the use of modern anesthetics and analgesics. The public and our representatives recognize that responsible, regulated animal research has continued to produce new therapies and cures through the years — benefiting humans and non-human animals alike. Stopping the work and depriving future generations of new advances would be immoral.