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Human Evolution and PREHISTORY PART II: PRIMATE EVOLUTION AND THE EMERGENCE OF HOMININES COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. Human Evolution and PREHISTORY Chapter Four: MONKEYS, APES, AND HUMANS: THE MODERN PRIMATES Link to the Canadian Association for Physical Anthropology COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. Chapter Preview What Is The Place Of Humanity Among The Other Animals? What Are The Implications Of The Shared Characteristics Between Humans And The Other Primates? Why Do Anthropologists Study The Social Behaviour Of Monkeys And Apes? COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE PRIMATE ORDER Linnaean System 1. Prosimii (“lower primates”) lemurs, lorises, tarsiers 2. Anthropoidea (“higher primates”) monkeys, apes, humans ** based on overall similarity of the body plans within each group COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE PRIMATE ORDER ** based on genetic relationships (see chapter 3) COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. Characteristics of the Primates All primates share a number of traits which are considered to have been shared by a common ancestor (ancestral traits) Some traits are derived, i.e. they have evolved and changed from those in the common ancestor All of these traits are useful to arboreal, or treedwelling, animals COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. The Primate Brain Enlargement of the brain, particularly cerebral hemispheres Likely due to: the evolution of visual acuity insect predation in an arboreal setting use of the hand as a tactile organ Elaboration of the cerebral cortex COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. The Primate Sense Organs Binocular vision Stereoscopic vision Decrease in sense of smell Highly developed sense of touch COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. The Primate Dentition Basic primate dentition: incisors, canines, premolars, molars Evolutionary changes in: reduction in number of teeth function of premolars and molars COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. The Primate Skeleton Tendency to a high, vaulted cranium Enclosed bony eye socket Position of the foramen magnum (indication of posture) Reduced snout or muzzle COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. The Primate Skeleton Great flexibility of the shoulder (clavicle and (scapula) Ability to brachiate COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. The Primate Skeleton Pentadactyly Sensitive pads + nails + opposable thumb = prehensile grasp COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. Reproduction Female estrus cycle, i.e. the time of sexual activity during which ovulation takes place Small number of offspring at each birth COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. Care of the Young Longer period of infant dependency associated with: An increase in longevity Longer period of social learning COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. Establishing Evolutionary Relationships COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Strepsirhines Closest to the ancestral condition Lemurs (Madagascar) Lorises (from Africa to southern and eastern Asia) COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Haplorhines Tarsiers (Tarsii) Nocturnal insect eaters Elongated tarsal (foot bone) for jumping Arboreal In vision and nose/lip structure, a resemblance to monkeys COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Haplorhines Platyrrhini (New World Monkeys), e.g. spider monkey Flat noses with widely separated, outwardly flaring nostrils Arboreal Some with prehensile tails 2-1-3-3 dental formula COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Haplorhines Catarrhini (Old World Monkeys) Noses with closely spaced, downward pointing nostrils 2-1-2-3 dental formula Lack of prehensile tails Arboreal (e.g. Asiatic langur) or terrestrial (e.g. baboon) COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Haplorhines Small and Great Apes Our closest living relatives Semi-erect posture (“top heavy” and “front heavy”) Arboreal to varying degrees no external tail Broad shoulders Arms longer than legs (unlike humans) COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Haplorhines Gibbons and Siamangs Southeast Asia, Malaysia Extraordinarily long arms Brachiation (using the arms to move from branch to branch, with body hanging suspended) COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Haplorhines Orangutans Borneo and Sumatra Move by walking with forelimbs in a fistssideways or a palms-down position Alone or in groups of adults, depending on habitat productivity COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Haplorhines Gorillas Equatorial Africa Focus on field of vision by moving by directing eyes rather than moving head, like humans Ground dwellers, but may sleep in trees Knuckle-walkers Gentle and tolerant, using bluffing as part of behavioural repertoire COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. MODERN PRIMATES Haplorhines Chimpanzees (Pan) Forested areas of subsaharan Africa Bonobos (Pan) Rainforests of Democratic Republic of Congo Ground foragers and knuckle-walker COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES The Group In most species females and offspring constitute the core Among chimps largest unit is the community, 50+ individuals, although usually in subgroups Dominance hierarchies exist, both male (e.g. chimps) and female (e.g. bonobos) The gorilla group is the “family”, 5-20 individuals COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES Individual Interaction Establish close social bonds with one another, e.g. bonobo females Use of grooming, the ritual cleaning of another animal’s coat Among bonobos, chimps, gorillas, the mother-infant bond is strongest and most long-lasting COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES Sexual Behaviour No fixed breeding season Sexual activity tends to occur when the female signals receptivity for impregnation Variety of behaviours Most nonhuman primates are not monogamous COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES Play Means of learning about the environment Means of testing strength, e.g. rank in dominance hierarchies Means of learning how to behave as adults, e.g. food-getting activities COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES Communication Vocalization, with a great range of calls, used together with face and body movements Among the great apes calls are mainly emotional rather than propositional Visual communication is important COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES Home Ranges Primates move about within circumscribed areas Range size depends on group size and availability of food Gorillas and bonobos will defend, but rarely through fighting Chimpanzees react violently in the absence of sufficient space COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES Learning and Toolmaking Ability to invent and to pass on knowledge Chimpanzees and bonobos make and use tools, objects used to facilitate some task or activity, e.g. termite sticks COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES Hunting Observed among chimpanzees and bonobos, not gorillas For dietary, political, and sociosexual reasons, e.g. to entice a female in estrus Among bonobos, females usually hunt COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. ORIGINAL STUDY The Culture of Chimpanzees The latest catalogue of cultural variations for chimpanzees cites a minimum of 39 examples of chimpanzee behaviour believed to have a cultural origin Each community of chimpanzees exhibits its own set of behaviours This cultural capacity suggests an underlying shared ancient ancestry with humans COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. THE SOCIAL BEHAVIOUR OF PRIMATES There are many continuities between “us” and nonhuman primates, although “degree” does make a difference We should not erect “golden barriers” to set us apart (Stephen Jay Gould) We share a common evolutionary heritage COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED. NEXT TIME: Macroevolution and the Early Primates COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED.