The brain behind the Bottlenose dolphin!
The dolphin’s brain is the second most powerful and complex brain in animals (next to the human brain, of course). Intelligence may be defined as a measure of the brain’s ability to process information in ways that solve problems and enhance one’s survival. Measuring intelligence may be quite different for animals that have evolved in water versus those living on land, as the challenges required to survive in water are quite different than those required on land. Much debate exists regarding dolphin “Intelligence”, “Cognitive Learning Skills” and “Social Stratification”. Dolphins have a large brain. Large brained animals like humans, chimpanzees, and dolphins have a number of things in common. They generally live long lives due to neuronal advancements. They form stable communities involving fluid social groups. And they demonstrate total parental dependence during childhood.
An appropriate IQ test to measure dolphin intelligence does not exist. It is impossible to fully assess this animal’s level of intelligence in this manner. But another way which has been suggested to measure intelligence is by determining the measure of relative brain size defined as the ratio between actual brain mass and predicted brain mass for an animal of a given size. This is called the “Encephalization Quotient” or EQ. The encephalization quotient is a between-species measure of relative brain size, operationalized as the ratio of actual to predicted brain mass for a given species relative to body mass. This indicator is used in comparative analyses involving different species as an index of cognitive ability. This measurement suggests the higher the number, the greater the intelligence. The human EQ is 7.0. The EQ for great apes, elephants, chimpanzees and whales is about 1.8–2.3, meaning they have smaller brains for their body size than do humans. The dolphin’s EQ is 4.2, the closest EQ ratio to the human than any other animal.
A little more to know on EQ
This graph plots the slopes of six structures versus ‘brain core’ — medulla, pons, midbrain, and thalamus. In fact, each identifiable region of the cortex, such as visual cortex, other primary sensory cortices, and parietal or frontal cortex has its own exponent as well, which has caused a great deal of confusion about whether components of the human cortex, particularly the frontal cortex, are as large as should be ‘expected.’ Many would expect a simple ratio, such as the human brain as the chimpanzee brain multiplied by three, and would predict that a deviation from such a ratio should represent special selection or adaptation. A multiplicative ratio, however, is rarely the nature of the relationship between brain parts — in fact, it occurs only in the special case when the ratio of the allometric exponents of the two parts happens to be one. If the frontal cortex has a positive allometry with respect to the cortex overall, as the cortex enlarges in absolute terms, the frontal cortex will come to comprise a greater percentage of the entire cortex. Thus humans have an entirely predictable, but disproportionate, amount of frontal cortex in their brain compared with other primates.
Additionally, the degree to which the cerebral cortex is folded appears to be a measure of intelligence. The more folded the cortex, the more room within the brain to house additional neurons (brain cells) with which to perform processing of information. The only animal to have a more folded cortex than man is the dolphin.Some scientists believe the major reason for such a large brain is to process information from the dolphin’s complex echolocation, or biosonar system. But there is no evidence to support this belief. The theory most commonly accepted is that this larger brain evolved to support more complex cognitive abilities as skilfully demonstrated by Bottle-nosed dolphins. They can remember events and learn concepts, changing their behavior as a result of previous experience or training. They can communicate with each other during cooperative behaviors, manage relationships in their pods and raise their young. They can understand not only symbolic (sign) language words but can interpret the syntax (word) order of language. This understanding of syntax is highly indicative of intelligence. Signature whistles produced by dolphins (see the “vocalization” chapter of this website) serve to offer some evidence that dolphins have a self-awareness, or the capacity to have a concept of “self” and to know that one exists as an individual being. Self-awareness exists in the brain’s pre-frontal cortex.
Perhaps the most obvious difference between our brains and that of dolphins and all toothed whales is that they have an entire area dedicated to echolocation. Dolphins can “see” with sonar and this skill or superpower is called echolocation. Sound travels much better in water than light does and so it makes more sense for dolphins to sense their surroundings with sound. Their echolocation abilities are phenomenal; they can determine extraordinary details about everything around them. They use echolocation to hunt and navigate even in dark or murky water. Dolphins can check out each other’s pregnancies and eavesdrop on the echolocating clicks(Pulsed Squeaks and Pulsed Yelps)of other dolphins to figure out what they’re looking at.
Whale and dolphin brains contain specialized brain cells called spindle neurons. These are associated with advanced abilities such as recognising, remembering, reasoning, communicating, perceiving, adapting to change, problem-solving and understanding. So it seems they are deep thinkers! Not only that, but the part of their brain which processes emotions (limbic system) appears to be more complex than our own. Lori Marino a neuro-expert explains that ‘a dolphin alone is not really a dolphin; being a dolphin means being embedded in a complex social network…even more so than with humans.
Comparative analysis
(Tursiops truncatus) have an absolute brain mass of 1,500–1,700 grams. This is slightly greater than that of humans (1,300–1,400 grams) and about four times that of chimpanzees (400 grams).
The brain to body mass ratio (not the encephalization quotient) in some members of the odontocete superfamily Delphinoidea (dolphins, porpoises, belugas, and narwhals) is greater than modern humans, and greater than all other mammals.
The encephalization quotient varies widely between species. The La Plata dolphin has an EQ of approximately 1.67; the Ganges river dolphin of 1.55; the orca of 2.57; the bottlenose dolphin of 4.14; and the tucuxi dolphin of 4.56.
Scientists compared mature dolphins with 4 other groupings of mature cetaceans. With a large data set, they found great brain diversity among 5 different taxonomic groupings. The dolphins in their data set ranged in body mass from about 40 to 6,750 kg and in brain mass from 0.4 to 9.3 kg. Dolphin body length ranged from 1.3 to 7.6 m. In the combined data set from the 4 other groups of cetaceans, body mass ranged from about 20 to 120,000 kg and brain mass from about 0.2 to 9.2 kg, while body length varied from 1.21 to 26.8 m. Not all cetaceans have large brains relative to their body size. A few dolphins near human body size have human-sized brains. On the other hand, the absolute brain mass of some other cetaceans is only one-sixth as large. It was found that brain volume relative to body mass decreases from Delphinidae to a group of Phocoenidae and Monodontidae, to a group of other odontocetes, to Balaenopteroidea, and finally to Balaenidae. The same general trend when, compared brain volume relative to body length, except that the Delphinidae and Phocoenidae-Monodontidae groups do not differ significantly. The Balaenidae have the smallest relative brain mass and the lowest cerebral cortex surface area. Brain parts also vary. Relative to body mass and to body length, dolphins also have the largest cerebellums. Cortex surface area is isometric with brain size on excluding the Balaenidae. Data shows that the brains of Balaenidae are less convoluted than those of the other cetaceans measured. Large vascular networks inside the cranial vault may help to maintain brain temperature, and these nonbrain tissues increase in volume with body mass and with body length ranging from 8 to 65% of the endocranial volume. Because endocranial vascular networks and other adnexa, such as the tentorium cerebelli, vary so much in different species, brain size measures from endocasts of some extinct cetaceans may be overestimates. The regression of body length on endocranial adnexa might be used for better estimates of brain volume from endocasts or from endocranial volume of living species or extinct cetaceans.
This was a short insight to the Neurological aspects of why dolphins, particularly the Bottlenose dolphins shows such excellence in mimicry and cognitive learning skills .
Stay tuned for such more amazing facts!
Thank you.
