Homo Aquaticus?I. IntroductionWhen the human brain is compared to the brain of monkeys, many obvious differences are noted; the centers for smell and foot control are larger in monkeys than in humans, but the centers for hand control, airway control, vocalization, speech, and thinking are larger in humans . In my article I will describe the more definite differences in brain size and centers between humans and their closest relatives, chimpanzees, to compare them with other mammals and to draw conclusions about the evolutionary history of humans.II. Evolution of the brainHumans and chimpanzees are biochemically (DNA), and therefore probably phylogenetically (evolutionary relationships), more similar than chimpanzees and gorillas. But the brains of chimpanzees and humans differ in size and anatomy more than those of gorillas and chimpanzees. Chimpanzee and gorilla brains probably haven't undergone much evolutionary innovation, because they generally resemble other ape and ape brains. This implies that the human brain has changed a lot since human/chimpanzee evolution. With the exception of the olfactory (scent) bulb, all brain structures are larger in humans than in monkeys. The neocortex (part of the cerebral cortex), for example, is more than three times larger than that of chimpanzees, even though chimpanzees and humans are quite close in body weight. Each side of the brain is divided by the central sulci into independent halves. Just before the central sulcus is the post-central cortex, where the opposite half of the body is located (right side for the left hemisphere, left side for the right hemisphere). Just in front of the central sulcus is the precentral cortex where information for voluntary movements leaves the brain. The precentral area is called the primary motor cortex, and in primates also "Area 4".III. Cortex differences between humans and chimpanzees In humans, area 4 is almost twice as large as that in chimpanzees. The part of Area 4 that controls movement of the leg, foot, and toe is smaller in humans than in monkeys. This leaves more room for the part that controls the hand, fingers and thumb. Even larger is the lower part of the human Area 4, relating to the mouth, breathing and vocal cords. The postcentral cortex is enlarged like Area 4. In front of Area 4 in primates are the (pre-motor) areas of the cortex that tell Area 4 what to do. Opposite the enlarged part of the human Area 4 is the Area of...... in the center of the paper......ain. Is there a relationship between the use of the right/left hand and the position of the sound interpretation/production device? The fact that control of our dominant hand is usually located in the hemisphere of the language centers could mean that the first use of language among human ancestors was the naming of objects that were manipulated or pointed at with the right hand. Or is it simply a coincidence.VII. Conclusions Changes in human brain anatomy, compared to ape and ape brain anatomy, fit the aquatic theory of human evolution and have relationships with aquatic and semiaquatic mammals. Reduced sense of smell is typically observed in aquatic mammals. Reduced foot control is a characteristic of non-arboreal mammals (that do not live in trees). Very fine finger control is a characteristic of those who feed in shallow water. Perfect control of airway entrances is essential in diving mammals. An elaborate vocal ability is observed in aquatic mammals. A big brain.