The Neurological and Environmental Basis for Differing Intelligences:
A Comparison of Primate and Cetacean Mentality

Kenneth Marable

Contents


The brain is the most complex machine in the world. It is the thing which we think, wonder, create, and perceive with. It is the very thing which encases our existence. However, little is known about this amazing machine. We have put far more effort into studying the external world, rather than our internal one. This is not to say that there has been little research done on the brain, merely that there is such a vast amount that remains utterly inexplicable to us.

However, we do have a peculiar advantage in studying the human brain, in that we have the perspective of what it is like to possess one. In the study of non-human brains, we lack that perspective and this has led to far different conclusions about the two groups. Humans are conscious, rational, intelligent beings, whereas non-human animals are merely instinctive, moderately aware (if that) automatons. Or so we thought.

Modern research in both behavior and physiology has chipped away at these anthropocentric notions. The differences between human mentality and that of the other primates has been shown to be quantitative rather than qualitative; a difference of degree and not of natural kind. Even with such "human" abilities as language and rational, abstract thought, primates seem capable, though to a lesser degree.

Evolution has seemingly selected for only rare instances of intelligence. Mammals outshine the other animals in their mental capabilities, and of the land mammals, primates are above the rest. Within the primates, all of the brains have a relatively similar layout. Our intelligences may vary by degree, but are all fundamentally the same type. However, in the oceans of the world are another possible intelligence.

Cetaceans have brains with complexities equivalent to any of the primates, even humans. Due to the great differences in environment as well as the long, independent evolution, cetacean brains have developed somewhat differently than primate brains. With all of the research and speculation on extraterrestrial intelligence (which the chance of contacting is extremely remote), it is quite strange that these potentially intelligent beings are almost completely ignored. Primates and cetaceans are both mammals, evolved from a common ancestry quite far back. The similarities are still there, and we have far, far more in common than we would with any extraterrestrial life 1.

Some Problems with Non-Human Intelligence

There is a great disparity among scientists and the general populace concerning non-human intelligence. There are those who want to find and communicate with another intelligent species, almost to the point of over-interpreting data in favor of this hypothesis. There are also those who would only consider another intelligent species to be a technologically competent, tool-using, perhaps even humanoid race. In their extreme, they often put forth criterion of intelligence that would only include humans, often by definition. They tend to explain away most data that points towards other intelligences with complex theories that rely on Occam's Razor 2.

The two most common traits that most skeptical scientists rely on are language and technology (Asimov 1990). These two are seen as the paramount of what sets us apart from other animals. However, by using exactly what sets us apart from other animals as our criterion for intelligence is defining intelligence as human intelligence. Within this framework it is near impossible to find any other species that fulfills our criterion. These two factors are definitely indicators of intelligence, but are not the defining characteristics. Expressing intelligence through technology and language are as much factors of general vocal and manipulative abilities as they are intelligence.

This view is fine if we wish to keep humans at the evolutionary pinnacle. But, to use an old clichÉ, it can be lonely at the top. On the practical side, we would be missing the possibility of a vast source of knowledge in other intelligent species. Also, if we ever did make contact with an extraterrestrial intelligence, it would most likely come to us and would therefore be far superior, at least technologically, to us. If just such a species were to have this attitude and consider themselves superior to all other life and that lesser species were exploitable, it would not be a pleasant day for the human race.

Overall, it ends up being a stalemate between the two positions. Their theoretical frameworks are based on such different assumptions that one can hardly please the other. Those believing in non-human intelligence can be less zealous in data interpretation, and those who are skeptical can be more open-minded. However, for our purposes it will suffice that there is at least the possibility of non-human intelligence. We are only concerned with how this intelligence may be instantiated.

Variation in Intelligence

Most people take it for granted that intelligence is intelligence. It is some sort of base thing that is either there or not, with very little variation. This is far from the truth. Mental abilities vary greatly even among people. This does not necessarily refer to just someone being able to do differential calculus and another compose concertos, some differences are more fundamental than that.

There are cultural differences in actual brain regional functions. A prime example of this is with Japanese minds and the interpretation of sounds (Tsunoda 1989). Language is primarily a function of the left temporal lobe (more on that later). For Westerners, sounds which are considered meaningless (basically any non-language) is analyzed on the right side of the brain. With the Japanese, some sound, most notable natural noises and sounds of traditional Japanese musical instruments, are analyzed in the left temporal lobe. Furthermore, this difference does not arise until after about the age of 9. Apparently, due to their culture Japanese people attach some sort of linguistic meaning to these sounds. This is a notable difference in the functioning of these two sets of brains.

This illustrates that there can be very significant differences in the functions of a perfectly healthy adult brain. I believe that these other brains actually instantiate slightly different intelligences. Within a single species these differences are only minor. It is possible to have far greater differences between various species with different neurological layouts.

It also bears mentioning that the brain evolves by adding onto itself and has changed greatly over millennia. It would be unreasonable to believe that the brain has evolved to its highest potential and will not add onto itself anymore. Consequently, as long as at least humans are around, the brain will continue to develop and grow, especially since it is one of the most influential organs in the human body. As much as we try to divorce ourselves from nature, evolution is still changing us; we cannot escape it.

Just as evolution is best envisioned as branching rather than hierarchical, it is possible to have different intelligences (Reiss 1990). These intelligences would all basically be some form of conscious mental capacities, but would differ in the actual functioning and experiencing of that. Just as different species have different emphasis on certain senses, the way they experience the world, their Umwelt3, varies as well (Hoage 1986). The world around them and how they interpret it and react to it are dependant on their neurophysiology, which can vary.

Brain Size as an Index of Intelligence Levels

Still present today is the notion of overall brain size being an indicator of intelligence levels. Early on it was proven to be quite wrong within a species. There have been extremely intelligent humans with small brains as well as big-brained people who were none too bright. There has not even been any significant correlation found between the two. There are such a variety of other factors involved in this complex machine that, such a crude measurement is basically useless within a species.

Comparing one species to another, however, it does seem to be relevant, although many are unsure in what way to apply the data. With a pure brain size measurement, humans are quite well off, but there are larger animals with much larger brains. The sperm whale's brain averages about 17-19 pounds compared to our 2.5-3 pounds (Walker 1983). It does seem to be common that, in general, the larger the animal, the larger the brain.

One possibility is to relate brain weight to body length (Lilly 1975). This yields some interesting results. Humans have the highest ratio at 240 grams/foot. The dolphins are nearest with 200 grams/foot. This does seem rather arbitrary though. Taking only the animals length into account seems to favor fat species over skinny ones.

Next, a relation of brain weight to body weight a examined. A strict ratio seemed to be inappropriate. Humans have a ratio of roughly 1/50 but a sparrow has a ratio of 1/20 (Walker 1983). Even the most generous of believers would not support the idea that sparrows are far more intelligent than humans.

It was then figured that brain size to a factor of body weight would be best. They figured on the 2/3 root of the weight, since this is roughly close to the amount of surface area, but still related enough to the actual mass of the animal. These results seemed to better match our intuitions, though with some surprising conclusions (Bunnel 1974). Most of the basic necessities are taken care of by the other areas of the brain. The only portions of the cerebral cortex that directly relate to the body are the primary sensory and motor areas. These only make up a portion of the cerebral cortex. The demands on the rest of the cerebral cortex, it is argued, are pretty much constant across different body sizes. This argument is too controversial to be taken as base fact, and there has not been sufficient research to warrant empirical support. However, it is an important point to keep in mind.

So it would appear that even this measurement is too simplified to be of major importance. Perhaps it is merely a matter of finding a better factor, or of only taking into consideration certain portions of the brain. Another method that may prove more fruitful is to look at the specific regions of the brain itself.

Comparison of Cetacean and Primate Cerebral Cortexes

General Characteristics of the Cerebral Cortex

The cerebral cortex is the outer layer of advanced brains that evolved latest in all animals. It is the seat of all higher mental functions. All mammals and most other animals have one to some degree, but in the primates and cetaceans it is extremely well-developed.

In cetaceans, the cerebral cortex is very large, especially in relation to the rest of the brain. Since the cerebral cortex covers the more primitive areas of the brain in a thin layer, the amount of surface area available for it is important. The brain manages to obtain more cerebral cortex through encephalization, or convolutions on the surface of the brain. The amount of encephalization is considered an important factor in intelligence, since it can greatly increase the amount of area for the cerebral cortex (Morgane 1974).

Only in primates and cetaceans does the brain possess any significant amount of encephalization. As a matter of fact, cetacean brains have much more encephalization than human brains. For example a dolphin brain (one of the smaller of the cetaceans) has 40% more cerebral cortex than a human (Morgane 1974). The human cerebral cortex is divided into rather distinct layers, and it is believed that this indicates a higher level of complexity and development over those which lack the layering. Early studies showed that cetaceans have very little lamination; that most of the cerebral cortex was muddied together. Later studies proved this wrong (Bunnel 1974). The cetacean cerebral cortex is as layered as our own. The individual layers are similar or even identical between the two.

Another facet is the amount of regional differentiation in the cerebral cortex (Morgane 1974). A greater amount of separation in areas would seem to point towards a greater specialization of these areas. At least for humans it would seem to indicate that. Our brains have highly specialized sections, but as to whether or not this is necessary to possess high intelligence remains to be seen. Cetacean brains seem to possess comparable differentiation, but there has not been enough research done to be sure.

Specific Regions

Cetacean brains have many of the same features as other primate brains. The frontal lobe is the general region in which abstract thought is believed to occur. In cetaceans it is as developed, if not moreso in many species, as it is in humans. The parietal lobe, which is related to association of senses and generally making sense of the senses is quite large in cetaceans. In dolphins, it is as large as the human parietal and frontal lobes put together (Lilly 1975).

The temporal lobe in cetaceans is also very well developed and extremely large in comparison to the rest of their brain. In fact, there are portions which are equivalent to Broca's and Wernicke's areas in the cetacean brain (Bunnel 1974, Jacobs 1974, Lilly 1975). This area represents all of the senses together, whereas primate brains represent the senses separately and they are only connected by long bundles of neurons.

Lastly, the relative size of the motor and sensory centers are reversed in cetaceans in comparison to primates. Primates favor the motor cortex, whereas the cetaceans greatly favor the sensory region (and are not very balanced at all between the two).

Neural Density and Relations

The cetacean neural density is comparable to that of humans and some of the higher primates. However, the density is slightly less in some regions of the cetacean brain (Bunnel 1974). A high ratio is necessary for such things as emotional control, objectivity, reality orientation, humor, logically consistent abstract thought, and higher creativity. There seems to be a clear correspondence between the ratio and these abilities. Cetaceans have a ratio that surpasses even the healthiest of humans. This is supported by behavior studies of captured dolphins who show a high amount of playfulness and enjoyment even when in captivity. Humans under such circumstances would not fare quite so well.

Some Reasons Why these Differences Evolved

Different Environmental Factors

The environments of cetaceans and primates are completely incompatible. The mediums of air and water present two very different environments to live in. In water, light is no longer the primary source of sensory input. Sounds travels 3 times faster in water. Under the most favorable conditions, vision can only work out to about 100 feet. Clear sound recognition is possible in the best circumstances several miles, and several hundred feet in the worst (Lilly 1975).

Life in the ocean also lessens many other sensations (Jacobs 1974). Temperature is relatively stable. The ever-present sensation of gravity, which is so integrated into our constant awareness so as to not realize it, is also lacking. The cetaceans primarily live in a tactile and auditory sensory world, with vision also available but of secondary importance.

Cetacean sleep cycles, at least as observed in captive dolphins is quite unique (Lilly 1975). It would appear that they only have half of their brain sleep at any given time. Also they alternate between the two sleeping halves in short 5-10 minute sequences. Overall, each half receives about 3-4 hours of sleep a day. This most likely developed because in the ocean, there is not really any good place to hide (Sagan 1977). This keeps the dolphins aware all the time.

Another reason for the unique sleep cycle as well as evidence for some degree of planning, is the fact that cetaceans lack automatic breathing. They must consciously breathe. This is one of the problems with being an air-breather living in water. The amount of time they can go without breathing varies. Dolphins have to breathe about every 6 minutes, whereas sperm whales go for about an hour and half on a single breath (Lilly 1975). Either way, the cetacean must take into account factors such as how long it will take to return to the surface, weather condition both in the water and on the surface, and such. This would seem to require at least a minimal amount of forethought. Falling completely asleep would cause a problem, since either they would not be at the surface and would drown, or they would remain on the surface the entire time and would be easy prey.

Different Evolutionary Factors

Cetaceans first began an aquatic existence and spent much of their evolutionary history in rivers. They most likely lived under the same conditions that many of the modern river dolphins experience (Bunnel 1974). One of the largest factors is flooding. During rainy seasons, the rivers overflow onto the land and the woods that are along the riverbanks. If the dolphins are to survive, they must be able to catch fish while swimming in very shallow, muddy water and around trees 4. The importance of echolocation is even more evident here, as well as the tactile sense.

Human brain development had its greatest increase when they left the sheltering forest and began trying to survive on open savannahs as hunters. This new environment had a strong tendency to select for strategy, defense of group, and goal-oriented communication (Bunnel 1974). Such abilities as tool-use became of utmost importance.

Cetaceans differ though. The largest increase in their brain complexity happened after they left the rivers for the open sea. Out in the open sea, life was easier. Predators were less of a threat (although not entirely non-existent as evidenced by cetacean sleeping patterns). Food was more plentiful, and life was generally less strenuous and survival was not (and continues not to be) a major concern of cetacean life (Cousteau 1986). Logically, their neural development was much slower than the humans, but it still occurred even though survival needs were lessened.

A possible explanation of this is by the idea of cetacean societies (Bunnel 1974). This idea is quite taboo. Non-humans are capable of coordinated behavior, but anything resembling a society is unthinkable, or so some believe. The two major factors that guide evolution are survival needs and sexual selection. Apparently sexual selection is the culprit here. However, in just what way can sexual selection have an impact on mental capacities, not to mention these particular higher mental capacities, without the cetaceans carrying them out and using them? It seems quite implausible to believe that the complexity of cetacean brains is due to some randomness and evolutionary accidents, as opposed to the favoring of intelligent behavior. With intelligent individuals interacting (cetaceans tend to be even more sociable creatures than humans), a society of some form is by definition created. Intelligent societies are the only plausible explanation as to why the cetaceans would develop greater neural complexity favoring specific higher mental functions in the absence of strong survival concerns.

On a smaller note, the differences in evolution can explain the centralization of senses in the cetacean paralimbic lobe and the differentiation of senses in the primate cerebral cortex. As stated earlier, humans and all other primates lived in a much more dangerous environment. If a single sense indicated danger, the animal would be better of reacting to that single indicator rather than waiting for other senses to confirm or deny it. Each sense developed their own interpretive areas for this purpose. In cetaceans, this was not necessary. The paralimbic lobe could have evolved as merely an alternative design, or perhaps due to the general societal influences.

Communication and Auditory Abilities

The Power of Language

It is obvious that cetaceans communicate, as to whether this communication can be considered a symbolic language remains to be determined. However, there is strong evidence in favor of it. The presence of Broca's and Wernicke's areas are a major indicator of this possibility. Not even in the other higher primates are these areas as developed as they are in humans and all cetaceans.

Language is also a powerful evolutionary force. In humans, it was selected for so strongly that our air passage evolved to better help for speech, but actually hinder other survival concerns. The arrangement that best serves speech also increases the chances of death from choking, impacted wisdom teeth, and asphyxiation. It is basically good for speech and nothing else (The Mind vol. 7 1988). Without considering speech, it actually evolved against survival.

With this much evolutionary force it seems implausible that the neural mechanisms would develop but the behavior would not. We know that cetacean communication is very complex, but we have almost no knowledge whatsoever of just how any of it functions or what it means. Ironically enough, its complexity makes it the most interesting and possibly linguistic non-human communication but it also makes it the most difficult to study.

The Plausibility of Words

Cetaceans evolved almost perfectly for complex communication and possible language. They have the distinct advantage over us in that their primary sense is the same as their primary means of communication, both are auditory. With primates, the primary sense is visual and the primary means of communication is auditory.

Cetacean sound producing and analyzing abilities are so adept that it is possible for a cetacean to project an auditory image identical to the sonar image they would receive (Bunnel 1974, Sagan 1975). So a dolphin wishing to convey the image of a fish to another dolphin can literally send the image of a fish to the other animal. The equivalent of this in humans would be the ability to create instantaneous holographic pictures to convey images to other people.

If they do indeed do this (we only know that they can), then due to their large frontal lobes, there would be a natural tendency to abstract these images into words. In the development of a language there would not have to be a pairing of a sound with an object often enough for all your friends to understand what you are saying, you would merely have to project a stylized image to them. Due to a natural progression over the course of years, these images would become more stylized and abstracted that to call them anything other than words would be unjust.

Other Features that would Favor Communication and Society

Flesh does not block sonar nearly as much as it does light. Cetaceans are able to use sonar to actually see the internal workings of other animals (Sutphen 1974). It is the same process as ultrasound that is used prevalently in medicine. Not only are they capable of this, but it has been proven that they do commonly use this to read emotion and states of health. This type of direct knowledge of another beings internal states would greatly benefit personal interaction and the possibility of a society.

Another factor of cetacean auditory abilities of interest is the vast amount of information conveyed (Lilly 1975). They are able to produce sounds commonly up to 200 kilocycles/second, 5 a range 2 1/4 times what our own hearing can comprehend. Cetaceans also have approximately 2 1/4 times the number of neurons receiving the input. Add that onto the fact that they have several sound production organs,6 and it is apparent that cetaceans can convey and receive 20 times the amount of information as we can with our hearing. This even surpasses the amount of information we receive visually, but not by a great deal.

With the simultaneous complexity of cetacean auditory perceptions, the analogy to primate vision in clear (Bunnel 1974). Our vision is spatially-oriented with poor time discrimination. We perceive information simultaneously. Our auditory is the opposite. It has poor space perception, but good time discrimination. Human languages are composed of simple sounds strung into elaborate sequences.

Cetacean auditory perception is like our visual, spatially-oriented and not temporally-oriented. They perceive sounds as complex wholes, rather than a series of noises. Them trying to follow our language would be equivalent to us trying to follow individual frames in a movie running at normal speed. The perceptions would be blurred together into something they could understand. They seem to show a preference over human music than human language, and this distinction explains that.

So What is it Like to be a Cetacean?

It seems, hopefully even to the most skeptical, that there is at least the possibility of intelligence among the cetaceans. It would seem to be plausible, if not actually more necessary by Occam's Razor (a theory of unused, accidental neural complexity would have to be more far-fetched than the scientific theory of non-human intelligence). With the possibility there, let's consider just what an intelligence would be like, and what it's experiences would be like.

Life as a cetacean would differ greatly from our primate existence. Your environment would be much more stable and sensory depriving than ours. You would primarily perceive the world through auditory images and tactile sensations. You would also know what things looked like up close, but that would be only secondary. The main method for representing the world around you mentally would be through three dimensional auditory images7.

Cetacean bodies are basically heads with the rest being used primarily only for movement. You would lack any manipulative limbs and could only really express yourself through communication. However, this communication is an extremely complex one.

It is possible for you to project exact images to others, but instead there has been a language of abstracted images probably developed. This language is also useful with other cetaceans. 8 This possible language would pass on the oral traditions of the society in which you live in a similar fashion as early human societies could before the prevalence of writing9.

Your entire neural layout would gear your thoughts toward such things as interpersonal relations, introspection, and high ethical values. Your relations to others would be benefitted by the fact that you can perceive their internal states. This would help in knowing how healthy your companions are and in diagnosing what their ailments are. With experience this can be used in conjunction with outward body language for a greater detection of a companion's emotions, a sort of sonic empathy.

You would possess a higher degree of self-control and playfulness than the average human (to put it conservatively). Your basic needs would be easy to obtain and would be only a side matter of your day much as meals are for humans (Cousteau 1986). The rest of your time (which is the entire day, you never completely sleep), is spent frolicking in general and with the other sex, conversing with your companions, and even just signing as is most apparent in the humpback whales.

Cetacean social groups are oriented towards cooperation rather than competition, with little in-fighting (quite rare in the animal kingdom). You would have little or no worry about predators (few things even in groups can really pose much threat to the largest animals that have ever existed). With no technology also follows no labor beyond the providing of simple needs.

I do not want to romanticize this too much, but it is evident that cetacean neurology in conjunction with the environment in which they live is quite close to what many humans would consider Utopia. All of this is speculation from data that is difficult to interpret at best. However, the possibility does seem to be there for at least some, if not all, of these speculations to be true. We just have not looked close enough and long enough.

Scientific studies of dolphins have only yielded minor communication results, but the most common belief among dolphin researchers (on both sides of the fence even) are that they only live up to your standards for them. Push those and show confidence in them, and they will surprise you. Perhaps we have been to anthropocentric in our views to allow them to show their intelligence. At the very least, there is enough support to warrant much more research as well as an open-mindedness. Perhaps the only reason humans are considered the only intelligence is because we never fully considered the possibility.


Bibliography

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The Brain. vol. 6 "The Two Brains." New York, NY: MacArthur Foundation Video. 1984.

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Bunnel, Sterling. "The Evolution of Cetacean Intelligence." Mind in the Waters. New York, NY: Charles Scribner's Sons. 1974.
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Coppens, Yves. "The Brain and Evolution." The Science of Mind. Cambridge, MA: MIT Press. 1989.

Cousteau, Jacques. Whales. New York, NY: Harry N. Abrams. 1986.
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Geschwind, Norman. "Specializations of the Human Brain." The Brain. San Francisco, CA: Scientific American. 1979.

Gibson, Kathleen. "New Perspectives on Instincts and Intelligence: Brain Size and the Emergence of Heiarchical Mental Constructional Skills." "Language" and Intelligence in Monkeys and Apes. New York, NY: Cambridge University Press. 1990.

Griffin, Donald R. Animal Minds. Chicago, IL: University of Chicago Press. 1992.
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Griffin, Donald R. Question of Animal Awareness. New York, NY: Rockefeller Press. 1976.

Hoage, R.J. & Larry Goldman, eds. Animal Intelligence: Insights into the Animal Mind. Washington, D.C.: Smithsonian Institution Press. 1986.
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Jacobs, Myron. "The Whale Brain: Input and Behavior." Mind in the Waters. New York, NY: Charles Scribner's Sons. 1974.
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Lilly, John C., M.D. Lilly on Dolphins: Humans of the Sea. Garden City, NY: Anchor Books. 1975.
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Footnotes

  1. The chances of environmental and evolutionary situations being similiar enough for an extraterrestrial intelligence to be even remotely similiar to us is extremely unlikely even in bad science fiction movies.
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  2. A point should be made about Occam's Razor and comparitive psychology. It is the principle that data must be explained with the least complex possilbe theories with no (or at least little) reference to unseen phenonmena. With the study of humans, we have the advantage of being human and knowing that we are conscious, rational, linguistic animals. We do not have this benefit with other species. If the same criterion that are used to rule out non-human intelligence were applied to humans without the benefit of introspection, we would doubt even our own intelligence.
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  3. German for "surrounding world". It refers to the fact that any animal has only a limited sense of its environment and that different species experience it differently, due partially to variations in their senses, but also to their interpretive mechanisms.
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  4. The larger whales have evolved to be less agile and capable of these situations. However, dolphins, includnig those living in the oceans, are still able to swim in water only 12 inches deep and through the legs of humans trying to catch them [Return]

  5. At least one particular large and outstanding dolphin was able to produce soudns up to 300 kilocycles/second (Lilly 1975). Whether or not other dolphins or other ceteceans are capable of this remains to be determined.
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  6. These sound production organs are: the blowhole which actually has two air passages that can partially function seperately, the mouth, and a narrow beam emitter in the skull.
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  7. Visual perception is basically two-dimensional. There are many tricks that our brain uses to interpret the two-dimensional image three-dimnesionally quite effectively, however. Delay times and such makes echolocation a fundamentally three-dimensional way of perception.
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  8. It is apparent that different species of ceteceans, most notably orcas and dolphins, are able to communicate with each other even to the point of coordinating actions by communication alone (Sutphen 1974).
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  9. Dolphin newborns spend up to 6 years with their mothers, a comparitively long period of time. This points towards learning and acculturation (Reiss 1990).
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