As scientists amass data, chimpanzees are moving closer towards human. They are sentient, self-aware beings with strong cognitive skills and a proven ability to communicate, reason, express emotions, adapt, and even manipulate and deceive. With genetic material 98.5% identical to that of humans, chimpanzees are more similar to people than gorillas. Consequently, serious ethical implications exist regarding chimpanzee captivity and use in laboratory experiments. Below is a close examination of chimpanzees: Chimpanzees live in areas comprising 21 African countries that encompass grasslands, dry savannah and rainforests. They often live in communities that range from 20-100 members. Two species of chimpanzee exist – the common chimpanzee (which has four subspecies) and the Bonobo (also known as the “”pygmy chimpanzee””) The former subsists on a diet of fruit and meat, the latter solely on fruit. Their average life span ranges from 40-50 years. Chimpanzees are currently listed as endangered primarily due to deforestation and poaching. I. Brain Size/Structure/Nervous System: Chimpanzees have a brain and nervous system comparable to that of a human.
They learn extremely quickly, possess the ability to produce creative responses, express emotions (through sounds, gestures and facial expressions), influence their surroundings, and share the same qualitative experience in pain despite a cerebral cortex that is about 1/3 the size of that in humans. The average chimpanzee brain weighs 437 g versus 1.3 kg for the average human. When comparing brain size to body size – the Encephalization Quotient (EQ), the average chimpanzee brain registers about 2.49 (third to the 7.44 and 5.31 EQ of the average human and dolphin; the Rhesus Monkey comes in fourth at 2.09). This indicates a high-level of cognitive ability. Both humans and chimpanzees engage in the same sleep patterns.
This includes the stages of rapid-eye movement (REM) sleep, indicating both are likely capable of dreaming. II. Social Setting: Chimpanzees are exceptionally social, consistent with humans, other great apes, dolphins and other creatures displaying high levels of intelligence. They spend equal amounts of time on land and in trees (where they build nests to sleep, though some chimpanzees in the Fongoli savannah in southeast Senegal spend time in caves) and move from territory to territory foraging for food. Although a typical community can number up to 100, chimpanzees often spend time in smaller parties; mothers and their dependent children, though refuse to separate. Each chimpanzee family (to which individuals have strong bonds) is headed by an alpha or dominant male (bonobos, though are led by females) that leads them in hunting, territorial protection, and war.
Each community is hierarchical in nature where strength and intelligence bring added respect. Females are the only gender that move freely between communities. Chimpanzees enjoy prefer sharing rewards with a companion. A study by Alicia Melis at the Ngamba Island Chimpanzee Sanctuary in Uganda documented in Altruism ‘in-built’ in humans by Helen Briggs (BBC News, 3 March 2006) found that chimpanzees recognize and value the importance of collaboration. When such collaboration was necessary in an experiment that required the simultaneous pulling of two ends of a rope to obtain a tray of food, chimpanzees consistently selected the optimal partner, which in Melis’ words “”was a level of understanding [only seen in] humans.”” Within their communities, chimpanzees maintain intricate social networks where touching, grooming (which creates calm and strengthens friendships), and embracing are important aspects in preserving cohesiveness. Play is also an important part of a chimpanzee’s life, especially among males when they are young. Chimpanzees are among the few species that teach their young skills and culture (which is transferred between communities by females relocating between groups). Young chimpanzees between 6 and 8 years of age (primarily taught by their mothers) spend much of their time learning the social skills, community’s culture, and tool making through observation, imitation, and repetitious practice. At the same time, though, studies per Recent studies illustrate which traits humans and apes have in common – and which they don’t (Anne Casselman, Smithsonian.com, 11 October 2007) indicate “”human children have much more sophisticated skills… dealing with imitating another’s solution to a problem, communicating non-verbally and reading the intentions [of] others.”” The typical chimpanzee pregnancy lasts 8 months.
Young chimpanzees are weaned from their mothers by three years of age, and reach puberty threes years later. For chimpanzees, puberty lasts three years. When it comes to treatment of their dead, chimpanzees often pay frequent visits to view and grieve over the deceased’s body. Afterwards, they cover it with leaves and branches before moving on. III. Multi-modal Sensory Perception: Chimpanzees and humans utilize five senses (sight, hearing, smell, taste, and touch) to perceive the world around them. Sight and smell, two critical senses utilized by chimpanzees are discussed below. The morphological and anatomical structure of a chimpanzee’s eye is similar to that of humans. Likewise their vision is also similar. As a result, unlike most non-primate mammals that are dicromats (their color vision is based on two colors), primates (including chimpanzees and humans), are trichromatic. When their retinal nerves capture light, their brain utilizes three fixed wavelengths/colors to create a rich, colored environment. As a consequence for their similar morphological and anatomical eye structure and visual processing, chimpanzees can suffer from some of the same impairments as humans (e.g. Lucky, a male chimpanzee in Japan suffers from color blindness). Chimpanzees have an excellent sense of smell, which plays a critical role in their social interactions. Aside from facial recognition, chimpanzees use smell to identify each other and enhance their understanding of another’s mood since each emits a distinctive odor based on pheromones that can be found in their feces, urine, and glandular secretions. Aside from sight and smell, chimpanzees also rely on hearing (utilizing a similar auditory range as humans), and to a lesser extent, touch and taste.
It should be noted that chimpanzees, like humans, if given a choice, prefer sweets. IV. Shape Recognition: Studies have shown chimpanzees, like humans are “”more sensitive to concave deformation (important for constructing three-dimensional objects) than convex deformation.”” They also view shapes and mentally process two-dimensional objects in the same manner as humans. Based on this similarity and the similar structure of their eye and visual processing abilities, it is likely chimpanzees can match simple and complex shapes. More research, though, needs to be done in this area. V. Mirror Self Recognition (MSR): The ability to possess sentience/self-awareness (to think about oneself in the physical and mental realms) illustrates a complex level of abstract thinking that uncommon among animals. Chimpanzees possess this self-awareness and are capable of symbolic thought. Studies have shown chimpanzees can recognize themselves in a mirror and are aware of their own behavior and body. During MSR tests, chimpanzees showed they possess selective attention (they can pay attention to themselves in a mirror, aware they are viewing themselves instead of another animal).
When chimpanzees were marked with non-toxic odorless red dye on one eyebrow and the opposite ear, they went to a mirror and carefully examined the markings on their bodies. Scientific evidence also indicates that chimpanzees and other great apes possess to some degree, “”theory of other minds,”” in which they recognize individuals have their own beliefs. It is also highly probable that chimpanzees like dolphins and humans, can discern the difference between reality and television. VI. Language/Communication and Emotions: Although chimpanzees lack the vocal cords, ability to talk and make a sound for every object as humans, they communicate through sounds (e.g. barking, hooting, screaming, etc.), facial expressions (which require extensive attention to detail or viewing more than one aspect of a facial expression so that subtleties of meaning, which are not always obvious, are interpreted correctly), posturing, and gestures (with hands, feet, and limbs). Although the majority of chimpanzee sounds are related to a specific emotion, some can be associated with more than one emotion. In addition, each chimpanzee, for identification reasons, has its own distinct calls consistent with humans and dolphins having their own distinct voices and sounds, respectively. Chimpanzees utilize intentional communication to meet individual and group needs and to convey their feelings, which are an essential part of their social behavior. Certain communication behaviors are passed down through generations.
A brief summary of several chimpanzee emotions and their associated sounds is listed below: 1. Anger: Waa (bark) 2. Distress: Hoo 3. Enjoyment of body contact: Lip smack 4. Enjoyment of food: Aah 5. Enjoyment/Excitement: Pant (hoot) 6. Fear: Wraa or Pant (bark) 7. Hostility: Screaming A brief summary of chimpanzee emotions and their associated facial expressions is also listed below: 1. Aggression: Display of teeth in a wide open mouth with erect facial hairs 2. Fear/Distress: Display of teeth with lips pulled back horizontally 3. Intense Fear: Full open grin 4. Playful: Slightly open mouth in a relaxed position 5. Pouting/Begging: Puckered lips as if offering a kiss 6. Submission: Horizontal puckered lips Chimpanzees communicate about “”what,”” “”where,”” and “”who”” but the past or the future. Their communication is instantaneous based on the present. However, per Deborah Fouts, co-director of the Chimpanzee and Human Communication Institute reported by Brandon Keim, Chimps: Not Human, But Are They People? (Wired Science, 14 October 2008), “”They do remember the past [and can] understand the concept that something will happen later.””
Chimpanzees are also capable of understanding American Sign Language (ASL) gestures, and can learn associations between symbols, sounds, and objects without specific reinforcement or direct intervention. In the early 1970s, Washoe, a female chimpanzee followed by four other chimpanzees learned 100+ signs. Presently, Washoe can use up to 240 signs and even taught her adopted son ASL without human intervention. Another female chimpanzee, Lucy, even recognized that word order makes a difference when her trainer signed to tickle him, instead following her request to tickle her. However, it is unlikely that chimpanzees can conceptualize virtual reality from sounds and symbols as people do. However, per Valerie A. Kuhlmeier and Sarah T. Boysen, Chimpanzees Recognize Spatial and Object Correspondences Between a Scale Model and Its Referent (Psychological Science, Vol. 13, Issue 1, 19 March 2002), chimpanzees like young children, “”are sensitive to both object and spatial-relational correspondences between a model and its referent (a person or thing to which a linguistic expression (e.g. word, symbol) refers).”” Facial recognition is another important part of communication.
Consistent with humans, chimpanzees exhibit species-specific face recognition, more readily discriminating between chimpanzee faces than those of other species. However, chimpanzee infants that receive significant exposure to human faces are better at discriminating between human faces. Per Julie Martin-Malivel and Kazunori Okada in Human and chimpanzee face recognition in chimpanzees: Role of exposure and impact on categorical perception (Psycnet, American Psychological Association, December 2007) “”exposure is a critical determinant in conspecific and nonconspecific face recognition. Furthermore, per Development of face recognition in infant chimpanzees (Masako Myowa-Yamakoshi, et. al. Science Direct. 20 December 2005) chimpanzee babies, consistent with human newborns, prefer to study facial patterns over non-facial patterns as they develop during their earliest days. Chimpanzees are generally affectionate creatures that show emotions towards their own as well as other species. They show concern for ill or injured members, mourn the deceased (to the point that a healthy young male died of a broken heart a few weeks after the death of his mother), show excitement and joy when playing, as well as fear and concern. Consistent with humans, chimpanzees possess emotions that last for a short duration and moods that can last for longer durations. Furthermore, studies show baby chimpanzees have the same emotional range as human babies, but better self-control when it comes to uncontrollable crying. The only human emotion chimpanzees do not appear to possess is spite. VII. Memory: Chimpanzees have excellent memory systems. They can memorize faces, symbols and numbers, and learn specific behaviors that can result in either adverse or rewarding experiences. Consistent with humans, chimpanzees retain a better memory of events that elicit emotions than those, which are neutral.