[Illustration: Figure 5. _One of the First Drawings of a Porpoise’s (Phocaena) Brain_ (Gottfried Reinhold Trediramus, 1818). This is an anterior view. The hemispheres are artificially separated for unknown reasons. The optic nerves and tracts are shown. The complex fissuration is obvious. (Courtesy of Dr. Mary A. B. Brazier, UCLA.)] [Illustration: Figure 6. _Early Drawings of the Brain of the Dolphin and of the Porpoise by Tiedemann._ These drawings were reproduced by H. G. L. Reichenbach in his _Anatomia Mammalium_ in 1845. These are more accurate renditions and show the lateral expansion of these fine brains. (Courtesy of the Library of Congress, Washington, D.C.)] [Illustration: Figure 7. _The First 20th-Century Drawing of a Dolphin Brain_ (G. Elliot Smith, 1902). Lateral view. The proportions are excellent, as are the gyri and sulci. Smith gives the species as _Delphinus tursio_; this probably corresponds to the modern _Tursiops truncatus_ or bottlenose dolphin. This brain closely resembles that of _Tursiops_ shown in photos in reference 7. Langworthy’s 1931 drawings (“Porpoise”) are also similar (Brain, 54, 225, 1931).] [Illustration: Figure 8. _Mesial View of Same Brain as in Figure 7._] We demonstrated that, like other animals, the monkey, the rat, etc., these animals can be rewarded by stimulating the proper places in their brains.[16][18] In a recent series of experiments we have been establishing the controls necessary to understanding what brain rewards mean in terms of natural physiology. We have demonstrated quite formally that rubbing the skin of these animals with our hands is a rewarding experience to them; they will seek it vocally and by body gestures and give certain kinds of performance in order to obtain this reward. Recently we have found that “vocal transactions” are a reward to these animals.[7][13] (See below for human analogies in the child.) This seems to be one of the basic factors in our being able to elicit humanoid emissions. The vocal transactions are started by a human shouting some words over the water of the tank in which the animal is residing. A single word may be used or many words—it makes little difference. Eventually the animal in the tank will raise his blowhole out of water and make some sort of a humanoid emission or whistle or clicks in a delphinese fashion. If the human immediately replies with some word or words, the animal may immediately respond, the human answers, and a vocal transaction is under way. We have shown that dolphins naturally do this with one another in both their whistle and clicking spheres, and sometimes do it in the barking sphere.[13] How much of this is “instinctual” and how much is not, there is no way of knowing at the present time.