The Dolphin in History

by Ashley Montagu; John Cunningham Lilly

Tiedemann’s drawings of the brain of Delphinus delphis and of Delphinus phocaena were published by H. G. L. Reichenbach in his Anatomia Mammalium in 1845. The four drawings are shown in [Figure 6]. These drawings show the improved awareness of the complexities of these large brains in regard to cerebral cortex, the cerebellum, and the cranial nerves. Correlations between the structure of this brain and the behavior of the animal possessing it, were (and are) woefully lacking. The only behavioral accounts were those of whalers hunting these animals. Hunters tend to concentrate on the offensive and defensive maneuvers of the animal, and can give useful information for other kinds of evaluation of the animal’s behavior and presumed intelligence.

In 1787 John Hunter, writing in the Philosophical Transactions of the Royal Society of London (LXXVII, 423-424), said the following: “The size of the Brain differs much in different genera of this tribe, and likewise in the proportion it bears to the bulk of the animal. In the Porpoise, I believe, it [the proportion] is largest, and perhaps in that respect comes nearest to the human....

“The brain is composed of cortical and medullary substances, very distinctly marked; the cortical being, in colour, like the tubular substance of a kidney; the medullary, very white. These substances are nearly in the same proportion as in the human brain.... The thalami themselves are large; the corpora striata small; the crura of the fornix are continued along the windings of the ventricles, much as in the human subject.”

Flatau and Jacobsohn in 1899 wrote, “the large brain of the Porpoise is one of the smallest in the Cetacean Order in which the organ attains to a much greater absolute size than any other.”

In 1902 G. Elliot Smith wrote of the brain of a species of dolphin called “Delphinus tursio” (which may be the modern Tursiops truncatus): “This brain is larger and correspondingly richer in sulci than that of the porpoise: but the structure of the two organs is essentially the same.” His drawings are shown in Figures [7] and [8]. He said further, “the brains of the Beluga and all the dolphins closely resemble that of the porpoise.”

Smith summarizes the discussion of the huge size of the whale’s brain. “The apparently extraordinary dimensions of the whale’s brain cannot therefore be considered unusual phenomena, because this enormous extent of the cerebral cortex to receive and ‘store’ impressions of such vast sensory surfaces becomes a condition of survival of the animal.

“The marvelous complexity of the surface of the cerebrum is the direct result of its great size. In order, apparently, that the cerebral cortex may be efficiently nourished and at the same time be spared to as great a degree as possible the risk of vascular disturbances [such as would be produced by large vessels passing into it], its thickness does not appreciably increase in large animals. [He then quotes Dubois’ figures showing that the whale’s cortex is the same thickness as that of the human.] Such being the case, it naturally results that the increased bulk of cortex in large animals can only be packed by becoming thrown into increasing number of folds, separated by corresponding large number of sulci.”[4]

In regard to communication between individual whales, Scammon in 1874 wrote the following: “It is said that the Cachalots [Sperm Whales] are endowed with the faculty of communicating with each other in times of danger, when miles ... distant. If this be true, the mode of communication rests instinctively within their own contracted brains.”[5] Let us not forget that Scammon was talking about the mammal with the largest known brain on this planet. Instinct as the sole cause of communication with a brain this size seems rather improbable. This brain is not any longer considered “contracted.” Both of these statements illustrate an authoritative view of that time. If one peruses the paper by Tokuzo Kojima, “On the Brain of the Sperm Whale” (in the Scientific Reports of the Whales Research Institute, Tokyo, VI, 1951, 49-72), one can obtain a modern clear view of this brain. The largest one that he obtained (from a 49-foot sperm whale) was 9,200 grams. The average weight of the sixteen brains presented in his paper is 7,800 grams for average body lengths of 50 feet. (The brain weight per foot of body length varied from 118 to 187 grams per foot, averaging 157; man’s ratio averages about 250 grams per foot.)

In the literature of the time of Scammon, the scholars failed to give us new information about the behavior of cetacea. There seems to have been a distinctly ambivalent attitude towards these animals which is continued today. This point of view can be summarized as follows: the whale is a very large animal with a brain larger than that of man. This brain is the result of the huge growth of its body. All of this large brain is needed to control a large body. Because these tasks are so demanding, there is not enough brain substance left for a high degree of intelligence to develop. Thus the large brain cannot give the degree of intellectual capability that man has.

As an example of man’s attitudes to cetaceans, consider the case of the U. S. Fisheries Bureau Economic Circular No. 38, of November 6, 1918, by Lewis Radcliffe, entitled “Whales and Porpoises as Food.” Roy Chapman Andrews is quoted as saying that hump-backed whale meat is the best of the larger cetaceans but that porpoise and dolphin meat is even better eating than that of the larger whale. The composition of the whale meat is given as 30% protein, 6% fat, and less than 2% ash. From a hump-back whale one obtains six tons of meat, from a Sei Whale, five tons, and from a Finback, eight tons. Directions are given to remove the connective tissue between the blubber and the muscle to avoid the oily taste. For those who are interested, the paper includes twenty-two whale meat recipes and ten porpoise meat recipes.