Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22The Order PrimatesWhy study primates?1. Compare humans to modern primatesto see how alike and different we are.Many physical characteristics we think of as humanare common to primates.2. What are the implications of shared characteristicsbetween humans and other primates?-which traits are primate in general?-Do we share traits because our ancientcommon ancestor had those traits?Homology: similar trait inherited from a common ancestorThese are the traits of special interest to us: if the traits were present in an ancestor pre-dating beginnings of humans, and are still present today, then early humans would have had those traits.Analogy: similar trait due to similar selective forces,similar in function, produced by convergent evolution (do NOT share a common ancestor with that trait)Example: Bats (type of mammal) and grasshoppers (type of insect)Both fly and have wingsLinneaus described organisms by classifying them in a taxonomy based on similarities and differences. Taxonomy uses hierarchical sets of nested categories, from general to more specific.KINGDOM Animalia (animal)PHYLLUM ChordataSUBPHYLLUM Vertebrata (vertebrates)CLASS Mammalia (mammals)ORDER Primates (primates)CLASS Mammalia- reproductive strategy of few, usually live births; extensive postnatal care- associated with higher intelligence and greater capacity for learned behavior- differentiated teeth (different kinds of teeth)- skeletal structure capable of swift movement- ability to maintain constant body temperatureORDER PrimatesVery generalized order, whose essentialenvironmental niche is arboreal.Many primate characteristics relate to living in trees, but controversy over whether initial evolution of these traits was adaptation to arboreal lifestyle, or instead adaptation to insect hunting in low branches.Primates can be divided intotwo suborders:One is more primitive (arose earlier)and one is less primitive (evolved more recently)Anthropoids are the less primitive primates.Prosimians are more primitive.In this case, primitive means “older, evolved first”Grasping, pentadactyl hands and feetSome degree of opposability in handsEmphasis on sight over smellTactile pads and nailsGeneralized skeleton with retention of clavicle Largest and most complex brain of mammalsPrimate physical tendencies, best exemplified bySuborder Anthropoidea:Grasping, pentadactyl hands and feetPentadactyl: five digitsPrehensile: ability to graspFlexible hands and feetOpposable thumbsAdds up to manual dexterity(Feder & Park 2001:108Photo by F. Lanting/Minden Pictures)Emphasis on sight over smellAbbreviation of snout, less emphasis on smelling abilityPortion of brain devoted to smell shrank, while portion devoted to vision expanded Vision is binocular (overlapping field of Vision provides depth),Stereoscopic (each eye transmits to both sides of brain)(Turnbaugh et al. 1993:137)Emphasis on sight over smellColor vision in most primatesGood visual acuityPresence of postorbital bar (eye surrounded by bone)In other words, most primates see what/how we seeTactile pads and nailsMost primates have fingernails instead of clawsThese provide support for tactile pads (finger pads)that are sensitive to touchGeneralized skeleton with retention of clavicleClavicle (collarbone) allows unusual flexibility of arms and shouldersOther mammals have lost the clavicle(for example, dogs have no clavicle)Largest and most complex brainRatio of brain size to body size is largerthan most mammalsCortex and neocortex expanded in size,Resulting in more brain tissue concerned with memory, thought, and association capabilities(Feder & Park 2001:123)Only marine mammalsare comparable.Most primates give single birth. A few regularly bear twins.Relative to size, primates have the longest postnatal dependency of all mammals- long period of growth and development-great apes and humans are sexually mature only 10+ years- also relatively long life span- associated with emphasis on learningSkeletal maturation has been studied in detail only in humans, macaques, chimpanzees, and capuchins.Parental investmentMost primates give single birthLong gestation, long life spanProlonged infant dependency,Resulting in greater dependencyon flexible, learned behaviorSocialityThe need for long care of offspring places a selective value on support by a social groupRelated Social CharacteristicsPictures from Turnbaughet al. 1993Let’s look at primates from top to bottom,starting with cranial characteristicsSkull has two general parts:- brain case: holds brain and organs of sense-face: jaws, teeth, chewing muscles, associated soft tissueWithin the order, the relative sizes and shapes of these two varyMuscles of facial expression are highly differentiated and developedTeeth more than any other body part give basicinformation on primate evolution:- are the most often preserved bone- give a lot of informationPrimates have upper & lower jaw teeth, bilaterally symmetricalGeneral four kinds of teeth: incisor, canines, premolars (bicuspids), and molars.The number of teeth for each species can be expressedby a dental formulathat gives thecount of the fourkinds of teeth forhalf of a jaw.(Turnbaugh et al. 1993:157)Dental formulaPrimitive mammals have 44 teeth: 3.1.4.3 3.1.4.3In primates, the trend is to reduction:Many have 32 teeth: 2.1.2.32.1.2.3(Turnbaugh et al.1993:157)Primates have deciduous and permanent teeth (humans have 20 deciduous teeth – none are molars)Primate molars & often premolars have cusps & ridges: the pattern can help to identify groups. A distinctive type of primate molar has five cuspsknown as the Y-5 cusp pattern. It is found only among hominoids (apes and humans)(Feder & Park 2001:30)Postcranial characteristicsBasic skeletal structure is generalized. Wide movement flexibility. All primates have a clavicle, which is a primitive mammalian trait (dogs, cats, horses have lost it)Clavicle = collar bonePostcranial = below the headPrimates have a variety of limb proportionsand modes of locomotionVertical clinging and leapingBrachiationQuadrupedal terrestrial quadruped arboreal
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