ANTH 1001 Primate Trends
ANTH 1001 Primate Trends Anth 1001
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This 9 page Class Notes was uploaded by Aafreen Afzal on Thursday February 18, 2016. The Class Notes belongs to Anth 1001 at George Washington University taught by Shannon C. McFarlin in Spring 2016. Since its upload, it has received 21 views. For similar materials see Biological Anthropology in anthropology, evolution, sphr at George Washington University.
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Date Created: 02/18/16
PRIMATE TRENDS Lectures after Test 1 Ancestral Homologies: Features primates share with other placental mammals ● Mammary glands: produce milk to nourish young ● Homeothermy: Fur for insulation, sweat glands ● Heterodonty: (incisors, canines, premolars, molars) ● Expansion of the neocortex of the brain ● Placenta(long gestation followed by live birth) ● Maternal care of their young What defines the Order Primates? Derived homologies ● Petrosal bulla ● High degree of grasping ability in the hands and feet ● Opposable thumbs and “big” toe ● Most primates have nails instead of claws ● Sensitive tactile pads with skin ridges on the tips of the digits ● Decreased reliance on olfaction (smell) particularly in haplorhines ● Olfactory regions of the brain are reduced in size in primates ● Haplorhine primates have a significantly higher percentage of pseudogenes among the olfactory receptor gene family than do other mammals; this trend is especially pronounced in humans. ● Haplorhines lack a moist naked skin (rhinarium) surrounding the nostrils ● Decreased reliance on olfaction (smell) particularly haplorhines ○ Olfactory regions of the brain are reduced ○ Nasal structures of the skull are reduced ○ Haplorhines lack a moist nasal rhinarium ● Trichromoatic colour vision in Old World monkeys, apes, humans and some New World monkeys. ● Primates have forward facing eyes with an enclosed bony orbit (postorbital bar) ● Primates have relatively large brains for their body size, throughout all stages of development ● Primates develop slowly and invest heavily in offspring ● The Order Primates ○ Generalized body plan ■ Retention of the collarbone (clavicle) ■ 2 separate bones in forearms allow mobility ■ Primates have retained a generalized postcranial anatomy ■ Allows them to better grasp tree branches ■ Allowed for diverse locomotor adaptations ■ Dental adaptations ● Carnivores: high pointed cusps for tearing meat ● Elephants: broad flat surfaces on cheek teeth for chewing tough grasses and plant materials ● Primates: low, rounded cusps: generalized dentition that allows them to process most types of food ● Dental features of the primates ○ Teeth in the upper and lower jaw ○ Bilaterally symmetric ○ Heterodont dentition (incisors, canines, premolars and molars) ○ Anterior teeth: ingestion ○ Incisors: cut food ○ Canines: tear food, also behavioral functions ○ Premolars and molars: crushing and grinding ○ Posterior: teeth chewing ○ Insectivorous: insect eating ■ Sharp crests for puncturing outer skeleton of insects ○ Folivory: Leaf eating ■ Sheari ng crests for cutting tough leafy material into small pieces ○ Folivore-Frugivore: Fruit eating ■ Low cusps for crushing soft fruits ○ Primate diversity ■ Geographic distribution of primates ■ 350 species of primates, twice as many sub- species ■ Strepsirhini Suborder found in Madagascar, southern mainland Africa and SE Asia ■ Ancestral mammalian traits: sense of smell is well-developed ■ Lower jaw (mandible) is not fused ■ Eye has a tapetum lucidum ● Most are nocturnal ● Increases your ability to see in low light but lowers visual ability ■ Grooming claw: nails on all the digits except the second digit has a claw ■ Tooth comb: ■ Lorisoidea - Galapagos and Lorises (Africa and Asia) ● Nocturnal ● Varied diets (fruits, flowers, leaves, insects, etc) ● Urine washing ● Males and females do not live in large social groups. Many show: ○ Solitary foraging ○ More gregarious sleeping ○ “Dispersed polygny” ● Lorises: Slow quadrupedal locomotion: reduced 2nd digits -> strong, wide grasp ● Lemuroidea: Lemurs (Madagascar) ○ Extremely diverse, representing 25% of all extant primate ○ Dwarf lemurs: Small body size ■ Twins are common ■ Seaso nal torpor and fat storage ■ Quadr upedal, nocturnal ● True Lemurs ○ Ring-tailed lemurs ■ Diurn al ■ Highly terrestrial ■ Live in large social groups ■ Femal e dominance ● Indri, Sifaka ○ Include both diurnal and nocturnal species ○ Large body size ○ Vertical clinging and leaping ○ Long powerful hind limbs ○ Flexible black ○ Long fingers for grasping support when they land ● Aye-Aye ○ Diet specialized for wood-boring insect larvae ○ Except for thumb and big toe, all digit have claws: elongated and thin 3rd digit, functions like a skewer ○ Large continuously growing incisors ○ Haplorhines: Tarsiers, Monkeys, Apes, Humans ■ Derived traits of Anthropoids: ● Most are diurnal ○ Lack the tapetum lucidum ● Reduced olfaction, enhanced vision ○ Lack the rhinarium ○ Eyes more forward facing ● Full postorbital closure ● Lower jaw is fused in most ● Larger relative brain size ● Longer developmental periods ● Increased social complexity ● Haplorhines have dry noses whereas Strepsirhines have wet noses ○ Tarsioidea - Tarsiers (SE Asia) ■ Prosi mian traits ● G rooming claw ● U nfused lower jaw ● N octurnal, small social groups ■ Haplo rhini traits: ● L ack: tapetum lucidum, rhinarium, tooth comb ■ Other derived traits ● A daptations for vertical clinging and leaping ● L arge eyes relative to body size, orbit anatomy ● N octurnal predators of small vertebrates ● Q uadrupedalism: Hind limbs and forelimbs of near equal length ○ Monkeys ■ Platyrr hines: Flat nosed New world ● B road nose, with outward facing nostrils ● S maller body size ● 3 premolars in each quadrant (2133) ● A ll are arboreal ● S ame but not all have prehensile tail ● M ost have 2 colour vision ● H igh levels of paternal care ○ Hominoids and Apes ■ Loss of the tail ■ Relati vely large brains and enhanced cognition ■ Prolon ged development ■ Postcr anial adaptations for suspensory posture and locomotion ■ Tropic al forests of SE Asia ■ Small est of the apes (“lesser apes”) ■ Diets focus on fruits, but also eat leaves, flowers, invertebrates ■ Sociall y monogamous ■ No sexual dimorphism ■ Brachi ation ○ Great Apes ■ Orang utans, Gorillas, Apes, Humans ■ Borne o and Sumatra ■ Large body size ■ Show suspensory adaptations but are quadrupedal on the ground ■ Nearly half of the world’s primate taxa are classified as threatened and in danger of going extinct ● Major threats ○ Habitat loss, fragmentation, modification ○ Hunting for bushmeat, pet trade ○ Disease ○ Political instability ○ Climate change ○ Primate Diets ■ Must provide energy required to regulate essential bodily functions and to sustain growth, development ■ They obtain nutrients through carbohydrates from fruits and gums ■ Fats and oils from animal prey such as insects, also nuts and seeds ■ Protein from insect and animal prey, and young leaves ■ Most primates rely more heavily on some types of food than others ● Frugivore ● Folivore ● Insectivore ● Gummivore ■ Leaves are more abundant in supply ○ Primate living groups ■ Resource Defense Model ● Primates live in groups because groups are more successful in defending access to resources than lone individuals ■ Problems: ● Benefits gained in between group competition are offset by costs incurred from increased within-group competition for food resources ● Does not explain the social organization of certain species that do not concentrate on fruit ■ Predator Defense Model ● Group living evolved as a defense against predators ○ A wide array of predators hunt primates, and predation is thought to be a significant source of mortality among wild primates ○ Grouping may reduce vulnerability to predation ■ Terres trial species tend to form larger groups than arboreal species ■ Solitar y haplorhines (e.g. orangutans, spider monkeys) are large in body size and apparently face little danger from predators ■ Juveni les suffer higher mortality in smaller groups than in larger groups ■ Primat es seem to adjust their behavior in response to the risk predation (eg alarm calling) ■ Weak nesses of the model: Predation is very difficult to observe, and it is therefore difficult to establish whether it is clearly linked to group size ■ Primat e mothers are the primary caretakers of the offspring ■ The behaviour of fathers is much more variable ○ Fission Fusion societies ■ Group size and compositions vary over time ■ Benefi ts of group increase, costs are minimized ○ Dominance ■ Often measured in terms of the direction of approach-retreat interactions, or the direction of submissive and aggressive behaviors in interactions ■ When there is competition, dominance rank may determine priority of access to preferred resources ■ Signifi cant fitness consequences ● e g. Yellow baboons from Amboseli, Kenya ● O ffspring of high-ranking females are large for age and have earlier ages at maturity and first reproduction ■ Sexua l selection ● A form of natural selection that occurs when individuals differ in their ability to compete with others for mates or to attract members of the opposite sex ● F avors the evolution of traits that give individuals an advantage in mating competition ● D arwin: differences in reproductive success caused by competition over mates -> sexual selection ● “ Sexual selection depends not on a struggle for existence but on a struggle between males for possession of females; the result is not death of the unsuccessful competitor but few offspring” ● I ntrasexual selection: selection for large male canine size -> canine dimorphism. Selection for large male size -> body size sexual dimorphism (greatest in one-male multifemale polygynous social groups. Least in monogamous social groups) ● S perm competition: Multiple males have access and male-male competition is high, sperm competition is favoured by sexual selection ● I nfanticide = killing a dependent infant.
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