6
Language and Facial Expressions
Chimpanzees have complex greetings and communications which depend on the social statuses of the communicating chimps. They communicate verbally using a variety of hoots, grunts, screams, pants, and other vocalizations. Most of their communication, however, is done through gestures and facial expressions. Many of their facial expressions surprise, grinning, pleading, comforting are the same as those of humans. However, humans smile by bearing their teeth, which is for chimps and many other animals a sign of aggression or danger. A much greater portion of human communication is done through vocalizations. Humans uniquely have complex vocal chords, allowing us a great range of sounds, but preventing us from drinking and breathing simultaneously like chimpanzees can. Moreover, we have very muscular tongues and lips, allowing us accurate manipulations of our voices. This is why we have pointy chins whereas chimps have receding chins we attach our many lip muscles to the prominent lower chin, but chimpanzees lack many of these muscles and so do not need a protruding chin.
5
Diet
Chimpanzees and humans are both omnivorous (eat plants and meat). Humans are more carnivorous than chimpanzees, and have intestines more refined towards the digestion of meat. Chimpanzees will occasionally hunt and kill other mammals, often monkeys, but otherwise restrict themselves to fruitand sometimes insects. Humans are much more dependent on meat humans can only obtain vitamin B12 naturally through eating animal products. Based on our digestive system and the lifestyles of extant tribes, it is thought that humans haveevolved to eat meat at least once every few days. Humans also tend to eat in meals rather than continuously eating throughout the day, another carnivorous trait. This may be due to meats only being available after a successful hunt, andso are eaten in large quantities but infrequently. Chimpanzees will graze on fruits constantly whereas most humans will eat no more than three times in a day.
4
Sex
Bonobos are renown for their sexual appetite. Common chimpanzees can become angry or violent, but bonobos defuse any such situation through sexual pleasure. They also greet and show affection to each other through sexual stimulation. Common chimpanzees do not engage in recreational sex, and mating only takes ten or fifteen seconds, often whilst eating or doingsomething else. Friendships and emotional attachments have no bearing on with whom a common chimpanzee mates, and a female in heat will generally mate with several males, who sometimes patiently wait their turn directly after each other. Humans experiencesexual pleasure, like bonobos, however even sex for reproduction only takes much longer and requires more effort; long-term partnerships naturally form as a result. Unlike humans, chimpanzees have no concept of sexual jealousy or competition, as they do not take long-term partners.