Intelligent Design

Are dolphins people too?

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The Helsinki Group, a small but politically savvy group of 11 experts in ethics, conservation and dolphin behavior which was set up in May 2010, is currently trying to attract support for a Declaration of Rights for Cetaceans: Whales and Dolphins, which states that “all cetaceans as persons have the right to life, liberty and wellbeing.” The Declaration reads as follows:

Based on the principle of the equal treatment of all persons;
Recognizing that scientific research gives us deeper insights into the complexities of cetacean minds, societies and cultures;
Noting that the progressive development of international law manifests an entitlement to life by cetaceans;
We affirm that all cetaceans as persons have the right to life, liberty and wellbeing.
We conclude that:

1. Every individual cetacean has the right to life.
2. No cetacean should be held in captivity or servitude; be subject to cruel treatment; or be removed from their natural environment.
3. All cetaceans have the right to freedom of movement and residence within their natural environment.
4. No cetacean is the property of any State, corporation, human group or individual.
5. Cetaceans have the right to the protection of their natural environment.
6. Cetaceans have the right not to be subject to the disruption of their cultures.
7. The rights, freedoms and norms set forth in this Declaration should be protected under international and domestic law.
8. Cetaceans are entitled to an international order in which these rights, freedoms and norms can be fully realized.
9. No State, corporation, human group or individual should engage in any activity that undermines these rights, freedoms and norms.
10. Nothing in this Declaration shall prevent a State from enacting stricter provisions for the protection of cetacean rights.

Readers can learn more about the activities of the Helsinki Group here and here.

In May 2013, the Indian government abolished the use of dolphins in aquatic theme parks, but contrary to initial reports, it did not grant dolphins the status of persons. Although the Indian government did say that dolphins should be recognized as legal persons with “their own specific rights,” it never actually granted them any rights.

Finally, at Yale University earlier this month, a conference called ‘Personhood Beyond the Human’, held at Yale University from December 6-8, 2013, declared that it will focus on “personhood for nonhuman animals, including great apes, cetaceans, and elephants, and will explore the evolving notions of personhood by analyzing them through the frameworks of neuroscience, behavioral science, philosophy, ethics, and law.” (UD readers will be interested to know that Steve Fuller gave a presentation at the conference; see here for the video – it’s number 9.)

In this post, I will endeavor to show why claims of personhood for cetaceans are both scientifically and philosophically unwarranted.

The case for dolphin personhood

The Helsinki Group is the brainchild of philosopher Paola Cavalieri. In an article published in The Guardian (6 April 2010), Cavalieri made an eloquent case for treating whales and dolphins as persons with rights protected under law:

Since, according to current ethical reflection, the concept of being a person is the concept not of belonging to a certain species but of being endowed with certain mental properties – particularly, self-consciousness – whales turn out to be nonhuman persons, thus confirming the moral soundness of both the trend in international law and the intuitive popular view.

At the annual meeting of the American Association for the Advancement of Science (AAAS) in Vancouver, Canada, from 16-20 February 2012, Dr. Lori Marino, a neuroanatomist and expert on dolphin behavior from Emory University in Atlanta and a member of the Helsinki Group, informed the audience of scientists that dolphins had a sense of self which could be tested by the way they recognize themselves in mirrors. “When you get up in the morning and look in the mirror and know that’s you, you have a sense of ‘you’,” she said. “They have a similar sense. They can look in a mirror and say, ‘Hey, that’s me’.

Now, if it were indeed true that dolphins had a sense of themselves as conscious agents, it would be hard to deny their claim to some kind of legal personhood. And Dr. Cavalieri is surely right when she argues that self-consciousness is a property that is not tied to any one species: it is at least conceivable that there may be other self-conscious creatures on Earth or on other planets, for instance.

Are dolphins really self-aware?

But are dolphins truly self-aware? According to a report by Erik Vance in Discover magazine, the evidence that dolphins can actually pass the mirror test is shaky at best:

Even Gordon Gallup, the behavioral neuroscientist who first used mirrors to evaluate whether primates are self-aware, expresses doubts about the dolphin’s capacity for this humanlike ability.

“The evidence for mirror self recognition in dolphins is tenuous. It’s not substantive,” Gallup told me in 2011. “[Videos taken during the experiment] are far less compelling in my opinion. They’re suggestive but hardly definitive.”

I should add that philosopher Michael P. T. Leahy severely criticized the use of mirror tests as a measure of self-awareness in his book, Against Liberation: Putting Animals in Perspective (Routledge, revised paperback edition, 1994) when he observed that all they show is that “the creatures recognise their own bodies” (p. 146). However, “for self-consciousness to get a foothold it would be necessary to show that they were aware of recognising themselves; which is awareness of a different order.”

Meta-cognition in dolphins

At the 2012 AAAS meeting in Vancouver, an apparently impressive example was cited by Dr. Marino, suggesting that dolphins have an awareness of their own mental states:

Dolphins taking part in an experiment had to press one of two levers to distinguish between sounds, some of which were very similar. By pressing a third lever, they were able to tell the researchers they wanted to “pass” on a particular test because it was too hard. “When you place dolphins in a situation like that they respond in exactly the same way humans do,” said Dr Lori. “They are accessing their own minds and thinking their own thoughts.”

On the other hand, philosophy professor Peter Carruthers has argued that there is no good evidence that non-human animals possess awareness of their own mental states, in his essay, Meta-cognition in Animals: A Skeptical Look (Mind and Language, Vol. 23 No. 1, February 2008, pp. 58–89). The term meta-cognition is commonly used by philosophers to denote knowledge of one’s own mental states. Carruthers surveys the recent literature on alleged meta-cognitive processes in non-human animals, including their supposed ability to monitor own their states of certainty and uncertainty. Carruthers convincingly argues that in each case, the scientific data admit of a simpler, purely first-order, explanation, “appealing only to states and processes that are world-directed rather than self-directed.” On methodological grounds, then, “we should refuse to attribute meta-cognitive processes to animals.”

The dolphin brain: how special is it?

At the 2012 AAAS meeting in Vancouver, Dr. Marino also declared:

“We went from seeing the dolphin/whale brain as being a giant amorphous blob that doesn’t carry a lot of intelligence and complexity to not only being an enormous brain but an enormous brain with an enormous amount of complexity, and a complexity that rivals our own. Its different in the way it’s put together but in terms of the level of complexity its very similar to the human brain.”

Not so fast, Dr. Marino! In an article titled Consciousness and Intelligence in Mammals: Complexity thresholds, in the Journal of Cosmology, 2011, Vol. 14, Professor David Deamer, of the Department of Biomolecular Engineering, University of California, proposed a way to estimate complexity in the mammalian brain, using the number of cortical neurons, their synaptic connections and the encephalization quotient.

The formula Deamer initially used was a simple one: Complexity=log(N)*log(Z), where N is the number of cortical neurons in an animal’s brain and Z is the average number of synaptic inputs to a single neuron. Deamer used measurements of the number of synapses per cortical neuron in the scientific literature to arrive at a rough estimate of Z = 30,000 for the brains of primates, dolphins, elephants and monkeys, and Z = 20,000 for the brains of all other animals in the list. Where mammals differ mostly significantly, however, is in the number of cortical neurons: 11,500,000,000 for humans, 11,000,000,000 for elephants, 6,200,000,000 for chimpanzees, 5,800,000,000 for dolphins, 4,300,000,000 for gorillas, 1,200,000,000 for horses, 610,000,000 for dogs, 480,000,000 for rhesus monkeys, 300,000,000 for cats, 27,000,000 for opossums, 23,000,000 for rats, and just 4,000,000 for mice. Humans have more cortical neurons than any other animal, and dolphins are ranked fourth on the list. According to Deamer’s complexity formula, the complexity of the human brain is: log(N)*log(Z)=log(11,500,000,000)*log(30,000)=10.1 x 4.5, or 45.5. The scores for other animals are as follows: elephant 45, chimpanzee 44.1, dolphin 43.6, gorilla 43.2, horse 39.1, dog 37.8, rhesus monkey 39.1, cat 32.7, opossum 31.8, rat 31, and mouse 23.4.

Deamer then makes an adjustment for these animals, based on their body sizes and encephalization quotients: “The complexity equation then becomes C=log(N*EQa/EQh)*log(Z), where EQa is the animal EQ and EQh is the human EQ, taken to be 7.6.” The normalized complexity figures are now as follows: humans 45.5, dolphins 43.2, chimpanzees 41.8, elephant 41.8, gorilla 40.0, rhesus (monkey) 36.5, horse 34.8, dog 34.4, cat 32.7, rat 25.4, opossum 24.9, mouse 23.2.

Although he was willing to grant that mammals with complexity values between 40 and 43.2 (i.e. gorillas, elephants, chimps and dolphins) are “self-aware” (a claim I would dispute, for reasons discussed above) and perhaps “conscious in a limited capacity,” Deamer argued that these animals still fall well short of “what we recognize as human intelligence.” And when you consider that even dolphins are more than two points behind human beings on a logarithmic scale, you can see that he has a valid point.

In any case, the dolphin brain may be over-rated, according to neuroethologist Paul Manger of the University of the Witwatersrand in South Africa. Dr. Manger has recently published a paper, titled, Questioning the interpretations of behavioral observations of cetaceans: is there really support for a special intellectual status for this mammalian order? (Neuroscience, 10 October 2013; 250:664-96). A report by Philip Bethge in Spiegel Online International (September 27, 2013) quoted Manger’s views at some length:

In 2006, Paul Manger noted that whales developed a large brain in order to keep the organ from becoming hypothermic, and thereby useless, in cold water.

Manger described an unusually high density of so-called glial cells in the animals’ brain matter. He explained that these cells act like tiny ovens to keep the brain warm. Besides, he added, dolphins have a relatively simple brain structure, and noted: “The essential features of complex neural processing of information, as observed in other mammals, are missing or poorly developed.”

Dr. Marino is said to be preparing a scientific rebuttal to Dr. Manger’s paper.

On the other hand, it has to be acknowledged that scientists have come a long way in their understanding of the cetacean brain. Just twenty years ago, Dr. Margaret Klinowska, of the Research Group in Mammalian Ecology and Reproduction, Physiological Laboratory, Cambridge University, argued that the quality of the cetacean neocortex is in some respects inferior to that in land mammals, in a paper titled, Brains, Behaviour and Intelligence in Cetaceans (Whales, Dolphins and Porpoises) (published in “11 Essays on Whales and Man”, the High North Alliance, second edition, 26 September 1994):

Studies of the internal structure of carefully preserved dolphin brains using a variety of techniques (e.g. Kesarev, Malofeyeva and Trykova, 1977; Morgane, Jacobs and Galaburda, 1986; Garey and Revishchin, 1990; Glazer, Morgane and Leranth, 1990) show that these animals have not developed the latest stage of brain evolution, characteristic of land mammals. It is thought that this line of evolution began about 50 million years ago in land mammals, whereas the cetacean ancestors returned to the water some 70 million years ago, well before this stage was reached. Although the cetacean brain has not followed the course of evolution of the land mammals, it does retain all the conservative characteristics seen in primitive land forms, such as hedgehogs and bats. The dolphin brain shows none of the anatomical structural heterogeneity characteristic of more evolved brains such as those of primates, but the regions of the neocortex can be differentiated by electrophysiological methods, and are arranged in very much the same order as in the hypothetical ancestor of mammals (Supin, Mukhametov, Ladygina, Popov, Mass and Poliakova, 1978).

The neocortex is the part of the brain which most clearly differentiates mammals from non-mammals, and there is a wide belief that the growth of the neocortex is responsible for the evolution of “intelligence”. The anatomical characteristics of mammalian neocortex are that it has six layers and that different functional areas (e.g. that dealing with vision) have somewhat different organisation of these layers. The anatomical studies cited above demonstrate that cetaceans only have five layers in the neocortex (layer IV is missing) and that there is no anatomically different organisation of these Iayers according to function. In some views (e.g. Kesarev et al.,1977) this means that cetaceans have no true neocortex, or only a preneocortex. If a neocortex is really essential for the development of “intelligence”, cetaceans are clearly disqualified.

Dr. Klinowska went on to say that in her view, the neocortex plays no special role in “intelligence.”

However, the views articulated by Dr. Klinowska have been vigorously refuted as anatomically outdated by Dr. Lori Marino in a 2007 paper she co-authored, titled, Cetaceans Have Complex Brains for Complex Cognition (L. Marino et al., PLOS Biology 5(5): e139. doi:10.1371/journal.pbio.0050139, May 2007):

The cetacean neocortex was once viewed as relatively homogeneous in cellular architecture, regionally unspecialized, and lacking organizational complexity. It was thought to have poorly differentiated neuronal morphology, low numbers of neurons and cortical areas, and an indistinct prefrontal cortex. This view of cetacean neocortex harks back to an earlier era when a few authors who considered dolphins rather unintelligent saw little in the neuroanatomy, not surprisingly, to refute that view [18,19]. This perspective influenced later thinking about cetacean brains and led to the “initial brain” hypothesis of cetacean neocortical evolution [20] that asserted cetacean neocortex was primitive. However, modern neuroanatomical techniques convincingly demonstrate that the cetacean neocortex has a degree of regional parcellation comparable to that of many terrestrial mammals (see Box 1) [21,22]. There is certainly no evidence that the “cetacean scheme” is incapable of supporting complex processing similar to that in primates and other mammals.

The verdict is still out on how the complexity of the dolphin brain compares with the human brain. Nevertheless, the view that the two brains enjoy a rough parity, and that cetacean brains tower above those of other non-human animals is clearly at odds with the evidence from neuroanatomy. The evidence we have to date suggests that the human brain is more complex than that of other animals, by a significant margin, which may mean all the difference between having a sense of oneself as a moral agent and lacking it.

(I should point out that although I do not subscribe to a materialist account of humans’ distinctive mental capacities, I would happily acknowledge that human intelligence places high demands on the human brain. Consequently, whether you are a materialist or a dualist, you should expect humans, as the most intelligent animals on the planet, to have the most complex brains.)

Are dolphins’ cognitive feats overblown?

Dr. Manger also took a very dim view of cases of alleged tool use in dolphins, in an interview with Philip Bethge of Spiegel Online International (September 27, 2013):

According to the professor, the claims that dolphins have a particularly complex brain, use a sophisticated language, are self-aware and can use tools are nonsense.

In some cases, says Manger, dolphins — which are small whales — are even outdone by goldfish. When goldfish are placed in a bowl, he explains, they at least try to escape by boldly jumping out, whereas dolphins that have been captured in nets won’t even think of jumping to freedom. “The idea of the exceptionally intelligent dolphin is a myth,” Manger concludes…

…[S]ome bottle-nosed dolphins on Australia’s west coast have learned to hold sponges over their snouts while they root around on the ocean floor. Is this a case of tool-use, indicating a high level of intelligence? Manger is skeptical. “Exactly what the dolphins do with the sponges remains unknown,” he says, noting that the evidence they use them as tools is “flimsy.”

Arguably a better example of tool use in dolphins is described in Kimberly (Kailey) Genther’s 2010 lecture, Re-thinking Fisheries: Humans and Cetaceans in Co-operation, of bottlenose dolphins using their flukes as a tool to create a mud-ring that captures and confuses the fish swimming around inside it, from which the dolphins then feed. (Even more intriguing are documented cases of co-operation between dolphins and local fishermen, whom the dolphins help to catch fish, which both species then feasted on.) Even here, however, the vital element of tool modification is absent, and the transmission of the behavior can be explained in terms of simple imitation.

In his 2013 paper, Dr. Manger adds that “the behaviors used to argue for high levels of intelligence in cetaceans are found commonly across mammals and other vertebrates, and are often observed in invertebrates.” He also notes: “In addition, the inability of cetaceans to surpass Piaget stage 4/5 on object permanence tests and to solve an “if and only if, then” abstract task indicates the possibility that their levels of general intelligence may be less than that seen in other vertebrates.”

Dr. Margaret Klinowska, in her paper, Brains, Behaviour and Intelligence in Cetaceans (Whales, Dolphins and Porpoises), which was cited above, also argues that the behavioral feats of dolphins are greatly exaggerated:

The behaviour of dolphins is frequently cited as evidence for high “intelligence”. The capacity of some smaller cetacean species (not all see Defran and Pryor, 1980) to learn performance tricks in captivity is often taken as “proof” of cetacean intelligence, but many other animals from elephants to fleas can achieve such feats, without this being taken as evidence for a special order of “intelligence”. People who have been in close contact with dolphins and whales often speak of a feeling that they are with an “intelligent” animal , but many dog-owners, for example, have a close rapport with their pets and also speak of “intelligence” and an ability to “understand every word I say”. The complexity of cetacean societies is another point frequently cited, but ants and bees, for example, have indisputably complex societies and we do not usually acknowledge these creatures as highly “intelligent”. What about the cetacean’s “sophisticated communication abilities”? We still know very little about the social significance of many of their sounds (excluding echo-location, which is only an aid for hunting and exploring the environment), body language and other communication systems, but in general the repertoire is far too limited to provide anything like our kind of “language”. Experiments have shown that some dolphins may have the rudimentary skills necessary for understanding and use of language, but these skills seem fairly common, and have so far been found in a range of species including pigeons, pinnipeds and apes. Again, what could be more “sophisticated” than the multiple communication systems of bees? And how do we usually regard bees?

Friendliness and helpfulness towards people are often discussed, but are we flattering ourselves in believing that the animals really “intended” to help? For perhaps obvious reasons we hear less of unhelpful behaviour, but there are well- documented cases. Many species of wild animals have been tamed or habituated to humans. Sometimes such animals become a danger to themselves or to people. Even tamed wild dolphins can become a considerable nuisance (for example setting boats adrift by pulIing up anchors) and sometimes dangerous. Instances of “friendly” dolphins attacking swimmers (apparently unprovoked) are well documented, as are instances of swimmers being pushed out to sea, “abducted” or prevented from re-entering boats and other craft (e.g. Lockyer,1990).

At the 2012 AAAS meeting in Vancouver, the following example of human-dolphin was cited by experts:

In Iceland, killer whales and fishermen have been known to work together. The whales show the fishermen where to lay their nets, and in return are allowed to feed on part of the catch. Then they lead the fleet to the next fishing ground.

All well and good; but is this any more impressive than the co-operation between human beings and dogs, in hunting prey? If dolphins are eligible to be people, then why not dogs?

What about dolphin language?

In a recent article for The Wall Street Journal titled, No, Flipper Doesn’t Speak Dolphinese (December 23, 2013), Dr. Justin Gregg, a zoologist with the U.S.-based Dolphin Communication Project and the author of “Are Dolphins Really Smart? The Mammal Behind the Myth” (Oxford University Press, 2013), speaks highly of dolphins’ social intelligence, pointing out that “[s]pecies such as bottlenose dolphins live in complex societies, with changing alliances and friendships as intricate as anything in chimpanzee or even human society.”

However, Gregg is emphatic that dolphins do not possess a true language:

Evidence for a dolphin language — dolphinese — is all but nonexistent. Dolphins do possess signature whistles, which function a bit like names. They likely use them to label themselves and might even call one another’s name on occasion. This is both unique and impressive, but it is the only label-like aspect of dolphin communication that we’ve found. All the other clicks and whistles that dolphins produce are probably used to convey messages about their emotional states or intentions — not the type of complex or semantically rich information found in human language.

After defining language in a rigorous scientific fashion in his latest book, as a communication system that employs arbitrary symbols in a way that allows for limitless expression, Gregg demonstrates that while dolphin communication has sophisticated features, it does not approach the complexity of human language.

In Gregg’s view, dolphins should not be seen as exceptional animals. “We have to stop describing them as ‘special’,” he declared, in an interview with Spiegel Online International (September 27, 2013).

Dr. Klinowska, in her above-cited paper, Brains, Behaviour and Intelligence in Cetaceans (Whales, Dolphins and Porpoises), identifies some additional much-overlooked deficiencies in dolphin communication:

Gaskin (1982) has concluded that there is abundant evidence that cetaceans communicate information about “what”, “where” and “who”. There is no substantive evidence that they transmit information about “when”, “how” or “why”. So with respect to Kipling’s (1902) “six honest serving men” of learning and intellect, cetaceans appear to be three servants short.

I have to say that the alleged linguistic abilities of dolphins strike me as much less impressive than those of the border collie, Chaser, a nine-year-old dog that knows the names of over 1,000 objects and can differentiate between the commands, “To ball, take Frisbee” and “To Frisbee, take ball.”

Dolphins can certainly respond to commands. But I know of no evidence to date that dolphins possess the ability to respond to sentences uttered in the indicative mood (e.g. “The ball is green”) and assent to them as true or reject them as false. Nor do dolphins answer questions like “Is it raining?” with “Yes” or “No.” Their “understanding” of human language appears to be a purely functional one; they appear not to grasp that language can be used to express true and false propositions.

Conclusion

I’d like to finish by quoting a passage from Penn, Holyoak and Povinelli’s recent essay, Darwin’s mistake: Explaining the discontinuity between human and nonhuman minds (Behavioral and Brain Sciences, 2008, 31, 109–178):

Over the last 35 years, comparative researchers have invested considerable effort in teaching nonhuman animals of a variety of taxa to use and/or comprehend language-like symbol systems. Many of these animals have experienced protracted periods of enculturation that rival those of modern (coddled) human children. The stars of these animal language projects have indeed been able to approximate certain superficial aspects of human language, including the ability to associate arbitrary sounds, tokens, and gestures with external objects, properties, and actions and a rudimentary sensitivity to the order in which these “symbols” appear when interpreting novel “sentences” (Herman et al. 1984; Pepperberg 2002; Savage-Rumbaugh & Lewin 1994; Schusterman & Krieger 1986). But even after decades of exhaustive training, no nonhuman animal has demonstrated a clear mastery of abstract grammatical categories, closed-class items, hierarchical syntactic structures, or any of the other defining features of a human language (cf. Kako 1999). Furthermore, there is still no evidence that symbol-trained animals are any more adept than symbol-naive ones at reasoning about unobservable causal forces, mental states, analogical inferences, or any of the other tasks that require the ability to cognize higher-order relations in a systematic, structural fashion (cf. Thompson & Oden 2000). (2008, pp. 121-122)

If dolphins cannot do these very basic things, and if there is no good evidence that they have a sense of self, then I would suggest that calls for them to be recognized as people are premature at best, and dangerously misguided at worst.

7 Replies to “Are dolphins people too?

  1. 1
    Robert Byers says:

    Roe vs Wade said the people could not say the fetus human was a person and so not ban abortion.
    I say giving water critters rights as persons will lead to real persons, while in the womb, getting the right to life.
    Did they consider this?!

  2. 2
    Andre says:

    These kind of person hood rights just open the door for more animal abuse, next thing you know some human wants to marry a dolphin…. then what? Will the marriage be consensual?

  3. 3
    Mapou says:

    Andre @2,

    LOL. You’re funny, dude. This is hilarious.

  4. 4
    lpadron says:

    vjtorley,
    As always, thanks for the excellent thought provoking posts.

  5. 5
    Ho-De-Ho says:

    One cannot help but wonder why the Cetaceans didn’t think of this first.

    The critical, and I think salient, question here is: Although a Cetacean may be able to spout water, are they capable of spouting nonsense.

  6. 6
    Collin says:

    If you do not have the capacity to understand a “right” then it is doubtful that you have personhood. But I hesitate to say that because I believe that a fetus is a person.

    But I wonder if there are not ulterior motives. Notice how #10 says that nothing should be construed to prevent a State [a nation] from enacting stricter protections. Notice how this assumes that international law is binding on nations? Also, do you notice that wellbeing is a right? Not the pursuit of happiness, “wellbeing.” If a dolphin does not feel well, then this means we have a DUTY to help it. This is the difference between a liberal and a conservative. Liberals will force you to help your neighbor. Conservatives will help out of love, not because he’s forced by law.

  7. 7
    vjtorley says:

    Hi Collin,

    Thank you for your post. You’ve raised some very pertinent points regarding the Declaration of Rights for Cetaceans. The American Declaration of Independence spoke of human beings as having been “endowed by their Creator with certain unalienable Rights,” and added that “among these are Life, Liberty and the pursuit of Happiness,” whereas the Declaration of Rights for Cetaceans defined “wellbeing” itself as a right. That’s worrying, as it could be construed to mean that cetaceans have a legitimate claim on our assistance. For instance, item #5 states: “Cetaceans have the right to the protection of their natural environment.” Item #8 states: “Cetaceans are entitled to an international order in which these rights, freedoms and norms can be fully realized.” Those certainly sound like claim rights to me.

    Re the proposition that if you do not have the capacity to understand the concept of a right, then you are not a person, I would modify the proposition to read: if you do not have the natural capacity to understand the concept of a right, then you are not a person. An embryo or fetus is a human organism that is running a developmental program, whose terminus is a rational adult – a being who undeniably possesses the capacity to understand the concept of a right. Since the embryo and fetus acquire this capacity while retaining their human nature (as well as their individual identity), then they can indeed be said to have a natural capacity to understand the concept of a right. This capacity is the result of their built-in tendency to develop into rational agents. Dolphins, on the other hand, lack such a capacity, as they can never understand the concept of a right: even when fully developed, they are still incapable of grasping such a concept. Hence I would say that they cannot be meaningfully described as persons.

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