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The Main Differences Between the Skulls of Humans & Chimps

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Chimpanzees share about 99 percent of the DNA found in humans, yet bear little resemblance to us in appearance. Shaggy black bodies with long arms designed for swinging from trees and a second set of "hands" with opposable thumbs on their hind feet are but a few of striking differences between chimps and humans. While at first glance the skulls of chimps and humans can look somewhat similar, there are a number of distinct differences.

Size Matters

While chimpanzees may stand as tall as some adults when they reach their greatest height of 5.5 feet, the chimp's head is much smaller than in humans due to brain size. A chimp's brain averages 400 cubic centimeters in volume, which is about 1.75 cups. By contrast, the human brain has a volume of 1,400 cubic centimeters, which is nearly 1.5 quarts or 6 cups. The cranium of a human is larger and more rounded to accommodate more highly developed parts of the brain than the small dome that sits behind the chimp's brow ridges.

Skull Size to Fit Brain Power

A chimpanzee skull has a pronounced muzzle extending from the front of the skull, where the facial plane of a human skull is nearly vertical. Parts of the brain used for more complex reasoning tasks, abstract thinking, memory and emotional attachment are more highly developed in humans and require extra space within the skull. This reflects with the human skull having a more bulbous appearance, with area for the brain extending to the brow ridges and sides of the jaws and past the base of the neck. A chimp's skull has a neat, small dome that contains the brain set well back from the brow ridges, neck and sides of the jaws.

Chimps and Humans Share Number of Teeth

A heavy, angular jaw bone supports attachment of the many muscles needed for a human's complex verbal abilities while a chimp's jaw line is nearly straight and its vocal abilities limited. The upper jaw that houses the teeth is distinctly u-shaped in chimps, compared to a more relaxed arch-shaped jaw that houses the teeth in humans. Differences extend to the teeth themselves: Although humans and chimps both have the same number -- 20 in juveniles and 32 in adults -- with identical dentition patterns, canine teeth in the human skull are fairly level with the tooth row, where chimp canines are large and pointed.

Facial Features Differentiate

Facial features between human and chimp skulls distinctly differentiate one from the other. Chimp skulls have heavy brow ridges that extend well in front of the cranium. By contrast, the forehead of a human skull rises directly from the brows. Between the eyes, a pronounced nasal bone in the human skull contrasts sharply with the flat curve that leads to the chimpanzee nasal opening. Well-defined cheek bones and a protruding chin are two more characteristics found in the human skull, but not in chimp skulls.