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Complete Human Biology, Behavior, and Evolution Study guide: Part 2 (90% on final)

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CAS AN 102
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Lecture 12 and 13 ★ primates showed up in the fossil record about 55 mya (tertiary period, eocene epoch) ★ we are: cenozoic era, quaternary period, holocene epoch Primate Traits ★ early primates were very small & lived in trees, nocturnal, insectivorous ★ climate change is associated with many radiations of major primate groups ★ primates filled a variety of arboreal niches in their diversification ★ unspecialized in traits I. Postcranium A. five fingers and toes B. prehensile hands C. opposable big thumb and hallux D. nails instead of claws E. friction or tactile pads on fingers and toes - fingerprints F. usually hindlimb dominated locomotion - center of gravity nearest the hindlimb G. tendency towards vertical postures H. diversity of modes of locomotion II. Cranium A. olfaction de-emphasized, emphasis on vision - postorbital bar or plate B. convergent eyes/stereoscopic vision C. visual processing part of brain well-developed D. petrosal bulla: covers and protects part of inner ear E. brain large for body size F. teeth: or III. Life History: how an organism spreads growth and reproduction out A. live long lives B. reproduce late C. single offspring D. long interbirth intervals E. females invest heavily in single offspring… long period of infant/juvenile dependency F. all reproductive stages are prolonged IV. Ecology A. tropical distribution B. relatively omnivorous C. diurnal D. gregarious Arboreal Hypothesis ★ primate traits arose as a response to living in a three-dimensional environment ★ living in trees requires good vision, grasping capabilities, and a somewhat advanced brain to manage these requirements Visual Predation Hypothesis ★ arboreality alone cannot account for primate traits, since squirrels and other mammals seem to get along just fine without diagnostic primate traits ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ convergence of traits with other visually-oriented predators, such as owls and cats Strepsirrhines (Prosimians) ★ lemurs (Madagascar) ○ Aye-aye ○ Indriids ○ Cheirogaleidae ○ Lepilemuridae ○ Lemuridae ★ lorises (Africa and Asia) ○ Lorises ○ Galagos Anthropoid Traits ★ fused frontal bone ★ fused lower jaw ★ larger brain ★ postorbital closure ★ no grooming claw or toothcomb ★ increased reliance on color vision Tarsier ★ southeastAsia, Philippines ★ dispersed or solitary, pair-living ★ each eye size of its brain ★ 100% insectivorous ★ grooming claw (prosimian) ★ no tapetum lucidum (anthropoid) ★ no tooth comb (anthropoid) ★ nocturnal (prosimian) ★ fused orbit (anthropoid) Superfamilies ofAnthropoids (Haplorhines) I. Platyrrhini A. Ceboidea (New World Monkeys) II. Catarrhini A. Cercopithecidae (Old World Monkeys) B. Hominoidea Platyrrhines Ceboidea (New World Monkeys) ★ SA, CA, MX ★ broad, flat nostrils, wide space between nostrils, small bodies ★ arboreal ★ dental formula ★ prehensile tail in 5 genera ★ gregarious & pair-living Callitrichinae ★ tamarins and marmosets ○ claw-like nails ○ birth to twins ○ paternal care Cebinae ★ capuchins and squirrel monkeys ○ capuchins have prehensile tails, sq. monkeys as juveniles Pitheciinae ★ sakis, uakaris, owl, titis ○ owl monkey only nocturnal anthropoid Atelidae ★ spider & howling monkey ○ prehensile tails ○ howling monkey is loudest land mammal Catarrhines Cercopithecidae (Old World Monkeys) ★ cercopithecines (Africa), colobines (Asia) ★ dental formula ★ terrestrial and arboreal ★ ischial callosities ★ bilophodont molars (biting through plants) ★ cheek pouches and estrous swellings (cercopithecines) ★ complex stomach (colobines) ★ pair-living and gregarious Colobinae ★ Colobus ○ found inAfrica ○ hunted by chimps ★ Langurs and Proboscis ○ found inAsia ○ major radiation of langurs ○ mostly folivorous Cercopithecinae ★ Baboons and Macaques ○ baboons inAfrica - mostly terrestrial, omnivorous ○ Macaques - very speciose and widespread distribution ★ Guenons ○ found inAfrica ○ arboreal/mostly frugivorous ○ major radiation Hominoidea ★ generally larger body size ★ no tail ★ shortened trunk (lower back is built for stability) ★ complex social behaviors ★ flexible shoulder joint (suspensory adaptation) ★ larger brain to body size ratio ★ long period of infant dependency ★ Asia and Africa (besides humans) Hylobatidae ★ Gibbons and Siamangs ○ Asia ○ 13-25 kgs ○ 9 species (8 gibbons, 1 siamang) ○ mostly frugivorous ○ very specialized locomotor adaptations ○ arboreal brachiators ○ pair-living Pongo ★ Orangutans ○ 45-100 kgs ○ 2 subspecies ○ arboreal quadrumanous climbing ○ frugivorous ○ dispersed social system ○ 2 male morphs (bimaturism) ○ sexually dimorphic ○ endangered ○ arboreal ○ mast fruiting/mating Gorrilla ★ Gorilla ○ 70-200 kgs ○ 3 subspecies: 2 lowland, 1 mountain ○ mostly folivorous, but lowland species eat a lot of fruits ○ sexually dimorphic ○ terrestrial knuckle-walkers ○ usually one-male groups (silverback, females, juveniles) ○ endangered Pan paniscus and pan troglodytes ★ Chimpanzees ○ 40-80 kgs ○ fluid multimale, multifemale communities ○ mostly frugivorous, but will also hunt and eat meat ○ intergroup warfare ★ Bonobos ○ 33-45 kgs ○ mostly frugivorous ○ fluid multimale, multifemale communities ○ female-male co-dominance ○ conflict resolution through sex Homo ★ Humans ○ males: 47-78 kgs ○ females: 42-73 kgs ○ bipedal ○ very large brained ○ very little body hair ○ opportunistic diet ○ normally gregarious, sexual division of labor, variety of male-female mating/marriage bonds Lecture 14 ecology: the study of interrelationships of animals, plants, and their environments nocturnal: active at night ★ prosimians and owl monkey diurnal: active during the day ★ monkeys, apes, humans cathemeral: active during night and day ★ some lemurs > primates spend the majority of the time feeding, moving, and resting > activity budgets can change with changes in food availability Primate Communities ★ territory disputes are usually between conspecifics (animals from the same species) ★ many different species can coexist (sympatric) and they often do not directly compete for resources or space ★ much of a primate’s life revolves around finding and eating food ★ primates try to maintain energy balance - nutritional intake minus energy expenditure ★ fruit availability is often limited in tropical rain forests ○ mast fruiting - trees fruit at same time ★ plant defenses ○ structural ■ bristles ■ spikes ■ hairs ■ hard shell ○ chemical (secondary) ■ tannins ■ alkaloid ■ phenois Foraging Strategies ★ methods and techniques used to find and process food Influences ★ nutritional requirements ○ body size has a big effect on requirements ○ Kleiber’s Law ■ there is a predictable pattern in the energy demands of placental mammals related to body size ■ smaller animals have a higher metabolic rate than do larger ones ○ Jarman-Bell Principle ■ large animals require more total food intake per day ■ they cannot afford to seek out widely distributed, high energy resources ■ small animals have a higher metabolic rate and need to seek out foods with high energy to satisfy their requirements ○ Primate Diets ■ Frugivory - fruit ■ Folivory - leaves ■ Insectivory - insects ■ Gummivory - gum ■ Grammivory - seeds ■ Nectivory - nectar ★ physiological adaptations ○ Dental ■ incisors ● gum eaters have large procumbent incisors for digging into trees and causing fluids to flow ● frugivores have broad incisors ● folivores have small incisors ■ molars ● folivores and insectivores: high, shearing cusps on molars ● frugivores: low, rounded cusps on molars ■ enamel ● thicker enamel = harder foods ● chimps - thin enamel ● orangutans - thick enamel ○ Digestive ■ enlarged gut, complex stomach, enlarged large intestine ■ cheek pouches (cercopithecines) ■ help digest unripe fruit and seeds (salivary enzymes) ■ ingest large number of fruits rapidly without processing immediately ■ detoxifying compounds - clay, charcoal ★ behavioral adaptations ○ contest competition ■ individuals can systematically exclude other individuals from the resource ■ occurs when food patches are clumped, small, and defendable ■ primates can monopolize the resource, so there is direct competition for it ○ scramble competition ■ individuals lose access to resources because others have already found them ■ occurs when food patches are dispersed, abundant, often lower value (grass) ■ primates cannot monopolize the resource so they don’t directly compete for it > larger primates have larger guts and thus larger transit times, so can afford long time it takes to digest cellulose, etc. food quality: proportion of readily digestible energy, protein, and other nutrients in food food distribution: location of food resources in space food patch: one or more members of the same plant species concentrated in same area food availability: spatial and temporal presence of food preferred food: foods that are over-selected in relation to their availability ★ high quality ★ often allows fast intake of calories, processed more easily ★ rate in environment, hard to locate ★ fruit ★ adaptations for food harvesting ○ general cognition ○ spatial navigation ○ locomotor adaptations ○ visual acuity ○ olfaction fallback food: high abundance, low quality foods eaten during periods when preferred foods are scarce ★ low quality ★ often hard to process ★ abundant, easy to locate ★ leaves ★ adaptations for food processing ○ dental topography and enamel thickness ○ gut length and morphology ○ body size ○ tool use Lecture 15 home range: defined spatial area that a group uses territory: home ranges that are actively patrolled and defended against conspecifics (members of one’s own species) core area: section of home range that a group frequently uses and is typically associated w/ preferred resources such as feeding trees & sleeping sites day range: area within home range that is traversed in a day Why Defend a Territory? I. Maintain exclusivity to defendable resources II. Maintain exclusivity to mates Ranging Patterns ★ frugivores tend to have larger home ranges and day ranges than folivores ★ home range size also affected by degree of arboreality, locomotion, group size, and habitat productivity Primate Movement ★ positional behavior: the various locomotor (movements) and postural (stationary) behaviors exhibited by a given species ○ locomotor behavior evolved via natural selection to solve ecological problems ■ finding food ■ avoiding predators ■ finding mates ○ postural behavior evolved via natural selection to solve ecological problems related to harvesting and resting Habitat Destruction ★ illegal logging ★ oil palm plantations ★ bushmeat ○ killing and consumption of wild game ○ logging in African forests create roads and pipelines to bring ape carcasses to market ★ international zoo, lab, pet trade Lecture 16 and 17 > females are the sex with the bigger gametes > thus, at fertilization one sex has already invested more in a given offspring female philopatry: females form group, males leave male philopatry: males form groups, females leave Female Primates ★ produce large, limited number of egg cells ★ have long gestation periods ★ have long periods of lactation ★ lengthy parental investment Male Primates ★ produce small, numerous sperm cells ★ do not gestate young ★ do not nurse young ★ variable parental investment Triver’s Parental Investment Hypothesis ★ whichever sex invests more effort and more resources in offspring is, in effect, the limiting resource for the reproduction of the less investing sex and thus the object of competition > Reproductive success is primarily limited by: females: energetic constraints on reproduction & child survivorship (food) males: ability to find and retain a mate (mating, females) > Reproductive strategies are ways primates overcome these constraints on their reproductive success Female Reproductive Strategies ★ mothers must be able to obtain as much energy as possible in order to produce viable offspring ★ hence, females will seek out food and compete over it when it is limiting ★ the nature of food type determines the type of relationships formed by females within groups (dominance vs. no dominance hierarchies) ★ dominance relationships emerge as a means to forestall outright physical aggression ★ pregnancy and lactation are energetically expensive ★ long pregnancies and lactational periods are related to prolonged periods of brain growth ★ because of their high investment in each offspring, females are selective about who fathers their offspring (although not necessarily with whom they mate) ★ females will enlist help of female kin and/or other males in order to gain access to resources and/or protect their offspring ○ Chimps ■ females usually immigrate into a new community at adolescence ■ immigrants must establish a core area with their new home range ■ where they establish their core area will have a huge impact on their subsequent reproductive success because core areas vary in quality ■ higher rates of female aggression occur between new immigrants trying to establish a core area and resident females ● female-female aggression increases when new immigrants enter the community ● most aggression by resident mothers against immigrants ● males intervened more often in conflicts between residents and immigrants ● immigrant females mainly travel with males, regardless of sexual state ● resident females only travel with males when they are in estrous ● immigrants experience less aggression from other females when they travel with males ■ try to establish a high quality core area which will lead to higher reproductive success ■ females transfer when they have maximal sexual swelling as social passport to placate aggressive males ■ continue to travel with males as protection against resident females Male Reproductive Strategies I. Direct (aggressive) competition in primates can lead to: A. Dominance Hierarchy 1. many primates have intense male-male fights, leading to a dominance hierarchy 2. hierarchy remains stable until a new male enters group (female philopatric species) 3. the alpha male is challenged by an up and coming male (male philopatric species) B. Sexual Dimorphism 1. male-male competition often results in selection on male body size (the bigger male wins) 2. male orangutans are twice as big as females C. Other Special Features 1. the degree of sexual dimorphism is highly related to the type of mating system (canine size) II. Indirect (scramble) competition in primates: A. Impressive Looks 1. compete to be chosen 2. flanged males vs. unflanged males B. Sperm Competition 1. males in multimale mating systems have much bigger testes III. Infanticide (sexual coercion - use by a male of force, or threat of force, that functions to increase the chances that a female will mate with him at a time she is likely to be fertile, and to decrease the chances that she will mate with other males, at some cost to the female) A. multiple females B. one male or multimale groups C. natal male disperses, creating bands of floating males D. extra group male displaces male resident E. following the group takeover, the new male attacks and kills unweaned infants F. loss of suckling infant leads to onset of estrus in mother G. males gain a reproductive advantage through earlier conception by females H. killer = new alpha male I. new male is not related to killed infant J. females next birth (10 mo. vs. 2 yrs) K. reduces birth intervals 1. Female Counter-Strategies a) sexual swelling (1) use sexual swelling to attract males (2) mate with multiple males to confuse paternity so all males think they may be the father b) hidden ovulation (1) males don’t know when female is ovulating, so females use mating to confuse paternity c) females aid other females in defense d) seek out male defenders L. males attack parous females more often during swelling stages than during non- swelling stages M. forced copulations in orangutan males 1. females seek out flanged males as sires 2. mate with unflanged males when they can’t get pregnant Why live in groups I. Predator Defense A. primates are preyed upon by a variety of carnivores including eagles, hawks, lions, leopards, snakes, and crocodiles B. all of these predators only kill one primate per predation event C. living in groups allows for greater predator detection D. more eyes to spot a predator and alarm calls to warn others E. primates will associate with other species in order to form larger groups F. it is rare to witness predation in the wild G. indirect evidence that it occurs 1. alarm calls, vigilance, primate bones, predator dung II. Enhanced Ability to Find and Defend Food Sources A. collective defense of food sources is beneficial when: 1. food items are clumped in space and time 2. there is generally enough food within a feeding patch to meet the needs of all group members 3. food items are worth defending B. emphasis on between group competition C. cost per group member to defend a feeding site is greater in small groups (the bigger, the better; need large group to defend own feeding ground) D. smaller groups are routinely displaced by larger groups at feeding sites E. within-group feeding competition is more costly in large groups (more people to feed and fight over food) III. Protection from Infanticide Lecture 18 Primate Social Structure > females distribute themselves according to how food is distributed > males distribute themselves according to how females are distributed ➢ females go where the food is located ➢ the type of feeding competition determines female relationships ➢ males go where females are located ➢ female defendability determines number and type of relationships of males in group ➢ male distribution and strategies feedback on female distribution and strategies ★ solitary ○ dispersed ★ polygyny ○ one male mates with multiple females and each female only mates with him (gorillas) ○ most common mating system ○ the evolution of polygyny will ultimately depend on whether males can economically defend multiple females, depending on how females are dispersed ○ if food is clumped, females with form groups ○ these groups will usually be related females (female philopatric) because of benefit to females of living with kin ○ a male may be able to defend such a group from other males ○ if food is dispersed females will not normally form groups ○ females will disperse ○ if little food competition, then males can keep females together in a group ○ in most primates, females congregate in small stable groups ○ long interbirth intervals mean there are only a few reproductively active females per group ○ this results in intense male-male competition for the limited number of fertilizable females ★ polyandry ○ one female mates with multiple males and each male only mates with her (tamarins) ○ rare ★ monogamy ○ males and females typically only mate with one member of the opposite sex (gibbons, tarsiers, titi monkey) ○ monogamy evolves when male parental care is non-shareable and indispensable to female reproduction (owl monkeys) ○ monogamy evolves when aggression by mated females prevents males from acquiring additional mates (gibbons) ★ polygyandry ○ males and females have multiple mates (chimpanzees and bonobos) ○ most common mating system ○ as number of females in a group increases, males may need to cooperate to defend them from other males… producing multimale/multifemale groups Cooperation ★ individual selection: individuals and the genes they carry are the units of selection because the individual is the unit that can reproduce and die ★ group selection: assumes that some animals sacrifice themselves for the good of the group. However, disproven as an individual with selfish tendencies would prevail inclusive fitness: direct fitness + indirect fitness; fitness both through direct descendants and through lateral relatives > natural selection favors traits that maximize inclusive fitness because genes spread through both direct and indirect fitness Hamilton’s Rule: if your degree of relatedness multiplied by the benefit to your relative is greater than the cost to yourself… the behavior should be selected for; the closer the degree of relatedness, the more likely altruism will result > altruism is kin related; closely related individuals will tolerate greater cost > when possible, primates should prefer to live with and help their kin > in highly cooperating groups with other special features, some selection may occur at the group level, with some groups surviving and others being eliminated > genes still reside in individuals, thus they argue that there is multi-level selection with some genes favoring behaviors that increase individual selection and others that favor the group over the individual Human Foragers ★ hunting and gathering was the original human subsistence system ★ homo sapiens have lived in hunter-gatherer societies for over 99% of the history of species ★ looking at modern hunter-gatherer societies may provide insight into the forces that shaped modern human behavior ★ modern foragers are modern ★ they may trade with agricultural populations and h
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