Modern humans and chimpanzees (our closest relative in the animal kingdom) share ninety-eight point four percent of their DNA. (Diamond) With a difference of only one point six percent, these two species share a large number physical traits. The differences between the two species, in most cases, are differences of degree of a particular trait rather than an entirely different trait. (Haviland)
Features of a chimpanzee include a clavicle, a foramen magnum that is shifted forward (when compared to other mammals) grasping extremities, eyes set close together on the same plane on the front of its head, a shortened muzzle and a 2-1-2-3 tooth pattern. Chimpanzees are typically seen on all fours as a quadruped, but they do possess the ability to stand bipedally (on the two rear legs). (Diamond) The clavicle stretches from shoulder to shoulder and keeps the chimpanzees arms from falling inward when reaching across the chest. (Haviland) The foramen magnum, where the spinal cord attaches to the skull, in chimpanzees is closer to the underside of the skull than that of other mammals. (Haviland) The hands and feet of chimpanzees include five digits, fingernails rather than claws, friction ridges (fingerprints) and an opposable thumb (although it is less pronounced on the foot). Both the friction ridges and the opposable thumb assist in picking up objects and grasping onto items (for example a tree branch). A chimpanzee’s eyes are located a few inches apart on the same plane of the face. This allows the chimp to see stereoscopically, that is, in three dimensions with depth perception. (Haviland) The muzzle of the chimpanzee is shorter and flatter than that of many other primates. Finally, the chimpanzee’s dentition includes two incisors, one enlarged canine, two premolars and three molars. Additional features of the chimpanzee are lack of a prehensile tail and a body that is mostly covered in hair except for the facial area and ears.
By comparing the physical attributes of humans to those of chimpanzees, we see that the less than two percent difference in DNA structure has yielded some interesting similarities and differences. First of all, humans are typically seen on two legs, standing upright as a biped. However, like chimps, humans also possess the ability to walk on all fours as a quadruped (e.g. a baby crawling, “crab-walking,” etc.) Second, humans have a clavicle, but it is much larger than that of chimpanzees (perhaps due to the overall larger size of humans compared to chimps.) In humans, the foramen magnum is located directly beneath the skull, even farther forward than in chimpanzees. Like chimpanzees, human hands also possess five digits, fingernails, friction ridges and an opposable thumb. However, the feet of humans differ greatly. First, the toes are much shorter. Second, the opposable toe (thumb) of a chimpanzee is pushed together with the rest of the toes on a human foot and is not opposable. Human eyes are very similar in respect to location to those of a chimpanzee, and humans share binocular stereoscopic vision with them. The muzzle of a human is considerably more flat than a chimp and the face is much more compact. Additionally, the human jaw and teeth are smaller than those of a chimp are. In fact, not only are the canine teeth of a human about one-quarter the size of a chimpanzees, many humans have to get their third molar removed (due to the smaller jaw), thus disrupting the typical 2-1-2-3 dentition pattern of primates. Finally, like chimpanzees, humans also lack a prehensile tail, but unlike chimps, humans have much shorter and sparser body hair except in certain areas such as the top of the head.
Comparing these two species, one sees a striking resemblance between them. Yet where there are differences, they seem to be variations of a single pattern. While humans have developed one trait to a certain degree, that same trait may be more or less developed in a chimpanzee, but the connection is unmistakable. With our genes (and subsequent physical features) varying so slightly, it seems that Jared Diamond is right, and humans really are “the third chimpanzee.” (Diamond)
Diamond, Jared M. The Third Chimpanzee. New York: HarperPerrenial, 1992.
Haviland, William A. Selected Chapters from Anthropology, Tenth Ed. Belmont, CA:Wadworth/Thomson Learning, 2000.