Bio Anth Week 9
Bio Anth Week 9 Anth 1001
Popular in Biological Anthropology
Popular in anthropology, evolution, sphr
This 14 page Class Notes was uploaded by Jaimee Kidd on Monday March 21, 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 19 views. For similar materials see Biological Anthropology in anthropology, evolution, sphr at George Washington University.
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Date Created: 03/21/16
Primate Diversity • Geographic distribution of primates ◦ Most primates are distributed across the tropics ◦ behavioral flexibility is key in allowing them to move into different kinds of environments and be successful • Suborder Strepsirhini (two major groups within this) ◦ restricted to Madagascar, Central & southern mainland africa and SE Asia ◦ first group to split off from other primates ◦ Ancestral mammalian traits ▪ sense of smell is well-developed ▪ retain the rhinarium ▪ lower jaw (mandible) is not fused ▪ eye has a tapetum lucidum ▪ most are nocturnal ▪ when light passes through retina is excited photoreceptor cells it hits tapetum luciduma and goes back through retina, excited two times, increases sensitivity in low light situations, but the interference that is cause by reflecting the light twice degrades the acuity to resolve small things in vision ◦ Derived traits: ▪ grooming claw ▪ used to pick through fur ▪ Tooth comb ▪ structure that just forward from the lower jaw ▪ evolved from incisors and canines that have modified to be used in concert with the grooming claw in order to also pick through fur, etc. ◦ First Group- Lorisoidea- Galagos and Lorises ▪ In Africa and Asia ▪ Nocturnal ▪ Varied diets (fruits, flowers, leaves, gums, insects, small mammals and birds) ▪ Urine washing ▪ when they urine, they go back and wash their hands and feet in the urine ▪ this behavior is used in communication because they coat the fur of their infants in urine as well as the paths that they are walking, some sort of territory olfactory communication ▪ also suggested that it is used for adding friction to hands and feet ▪ Males and females do not live in large social groups. Many show: ▪ Solitary foraging ▪ More gregarious sleeping ▪ ‘Dispersed Ploygyny’- one male mates with multiple females ▪ females occupy a small home range ▪ males occupy a larger home range that overlaps with all of this females ▪ Galagos- ▪ Found only in Africa ▪ Known for their leaping abilities- vertical clinging and leaping ▪ Loris ▪ found in africa and asia ▪ slow quadrupedal locomotion ▪ reduced 2nd digits—> song, wide grasp ▪ hands and feet with incredibly strong grasps ▪ cryptic, protective response to predation ▪ secrete toxic chemical incase they get bitten, coat their infants in this toxic secretion ▪ are able to restrict their muscles for long periods of time, when they see predators they are able to just freeze ◦ Second Group- lemuroidea- Lemurs ▪ Madagascar ▪ Extreme diverse representing about 25% of all extant primate genera ▪ diversity allows for a lot of different microhabitats and niches to form in Madagascar ▪ lemurs range in size from small body mouse lemurs to large body indris lemur ▪ Dwarf Lemurs ▪ Small body size, include the smallest primates ▪ Quadrupedal, nocturnal ▪ Twins are common ▪ Seasonal torpor and fat storage ▪ torpor is similar to hibernation, but not totally, during the winters their metabolic rates slow down substantially so they are burning less energy ▪ eat a lot during time that isn’t for torpor, all stored in tail, and then that is used during torpor ▪ True lemurs (go back to get the other ones) ▪ Ring-Tailed Lemurs ▪ Diurnal species, but retain a tapetum lucidum ▪ highly terrestrial ▪ live in large social groups ▪ female dominance ▪ Indri, Sifaka ▪ Include both diurnal and nocturnal species ▪ large body size ▪ tend to be more folivorous ▪ vertical clinging and leaping ▪ long powerful lower hind limbs ▪ long flexible back ▪ long fingers for grasping supports when they land ▪ curved fingers ▪ Aye-Aye ▪ Diet specialized for wood-boring insect larvae ▪ Except for thumb and big toe, all digits have claws; elongated and thin 3rd digit functions like a skewer ▪ large continuously growing incisors • Haplorhine Primates ◦ Next to diverge after Strepsirhines ◦ Tarsiers, Monkeys, Apes, Humans ◦ Derived traits of Anthropoids (subgroup that embodies new and old world monkeys and the apes and humans) ▪ Most are diurnal (active during the day) ▪ lack the tapetum lucidum ▪ Reduced olfaction, enhanced vision ▪ lack the rhinarium ▪ eyes move forward facing ▪ full postorbital closure ▪ lower jaw is fused in most ▪ larger relative brain size ▪ longer developmental periods ▪ increased social complexity ◦ Tarsioidea- Tarsiers ▪ suborder ▪ SE Asia ▪ “Promisian” traits (strepsirhine-like) ▪ grooming claw ▪ unfused lower jaw ▪ nocturnal, small social groups ▪ Haplorhine traits: ▪ lack: tapetum lucidum, rhinarium, tooth comb ▪ Other derived traits: ▪ Adaptations for vertical clinging and leaping ▪ Large eyes relative to body size, orbit anatomy ▪ Nocturnal predators of small vertebrates ◦ *prosimians= strepsirhines and tarsiers ▪ anthropoids is new world and old world monkeys, and apes and humans ◦ Quadrupedalism (Terrestrial or Arboreal) ▪ hind libs and forelimbs of near equal length ▪ arboreal species have long talks to aid in balance on top of branches ▪ shoulder blade positioned to the side of the ribcage and restricted movement at the shoulder ◦ “monkeys" ▪ Platyrrhines (“flat-nosed” new world) ▪ broad noes, with outward facing nostrils ▪ smaller body size ▪ 3 premolars in each quadrant (188.8.131.52.) ▪ all are arboreal ▪ some, but not all, have prehensile tail ▪ grasping tails that have a bare patch of skin that has high density of touch receptors and friction pads, much like fingertips, allows to be used much like a fifth limb to both rap supports, judge the texture of the support, etc. ▪ seen in highly suspensory new world monkeys ▪ most have 2 color vision ▪ Catarrhines (“down nose” old world) ▪ narrow nose; downward facing nostrils ▪ larger body size ▪ 2 premolars in each quadrant (184.108.40.206) ▪ Arboreal and terrestrial ▪ none have prehensile tails ▪ all have 3 color (trichromatic) vision ▪ Ischial callosities • New World Monkeys (Suborder Haplorhini) ◦ Marmosets, Tamarins ▪ Small bodied (< 1 kg) ▪ Omnivorous, insects and plant exudates- things like sap and tree gum ▪ Variety of social grouping patterns ▪ Usually only one breeding female ▪ Intense female-female competition with suppressed ovulation in subordinate females ▪ When there are more than one female in the group, usually only one will reproduce at a time, the dominant female , others have hormonal suppression of ovulation ▪ can give birth of up to 4 children a year, can give birth twice a year (which is a lot for primates) ▪ Twinning is common ▪ Males are principal caregivers ◦ All Other new world monkeys ▪ Diverse group; taxonomy debated ▪ Insectivore-frugicores ▪ Diverse social organization—monogamy (night monkeys) to multi male- multifemale ▪ Capuchins ▪ Tool use ▪ Large brains ▪ Slow life histories ▪ Golden Faced Saki ▪ Dental specializations for eating hard nuts ▪ Spider Monkeys ▪ Suspensory tails • Old World Monkeys ◦ Africa and Asia ◦ Two basic kinds ▪ Colobine monkeys ▪ Dietary specialist on mature leaves ▪ Arboreal quadrupeds; also adaptations for leaping ▪ Cerropihencine ◦ All Old World Monkeys ▪ Ischial Callosites ▪ non slip padding on their ass so that they don’t slip when they are sitting on trees ▪ Sexual Swellings ▪ around the genital area of the female that swells with liquid and changes color around the time of ovulation so that there is a single for males when a woman is ready; time of ovulation it will be very pink and very swollen • Apes ◦ Hominoidea: Apes and Humans ◦ Loss of the tail ◦ Relatively large brains and enhanced cognition ◦ Prolonged development ◦ Postcranial adaptations for suspensory posture and locomotion ▪ suspensory behavior ▪ Short hindlimb, elongated forelimbs ▪ mobile shoulder joint ▪ shoulder blade located on the back ▪ long and curved fingers for grasping branches ◦ Hominoidea- Gibbons and Siamangs ▪ Tropical forests of SE Asia ▪ Smallest of the apes (“lesser apes”) ▪ Diets focus on fruits, but also eat leaves, flowers, invertebrates ▪ Socially monogamous ▪ No sexual dimorphism ▪ Brachiation ◦ Great Apes (Orangutans, Gorillas, Chimpanzees, Humans) ▪ Borneo and Sumatra (Orangutans); Central and West Africa (Gorillas and Chimpanzees) ▪ Large body size ▪ Show suspensory adaptations but are quadrupedal on the ground ▪ spend some time in the trees, but most of their time on the ground ▪ Knuckle walking ▪ Form of quadrupedalism practiced by great apes ▪ Wrist joints are stabilized ▪ Very Diverse ▪ Orangutan ▪ Highly frugivorous ▪ unpredictable food sources in their climate though so they have a long home range ▪ Females are solitary, with dependent offspring ▪ Gorilla ▪ Folivore-frugivores ▪ fruit when they can get it, but mostly leaves and plants ▪ One-male and multi male groups with multi female females and dependent offspring ▪ they can afford to do this and interact with others because there is not as much competition because there is such an abundance of the food that they are looking to eat ▪ Chimpanzees & Bonobos ▪ Diverse diet, mainly fruit: bonobos more folivorous; tool use and hunting ▪ Multi-male, fission/fusion; female bonds & female dominance important in bonobos ▪ fission/fusion society- can regulate competition because they can regulate their group size ▪ Humans ▪ cosmopolitan in our ability to move in and be successful in a variety of place, we show a high range of behavioral flexibility ▪ severely impacted other environments and species around us ▪ nearly half of the world’s primate taxa are classified as threatened and in danger of going extinct ▪ What are the Major Threats? ▪ Habitat loss, fragmentation, modification ▪ Hunting for bushmeat, pet trade ▪ Disease ▪ Political instability ▪ climate change Primate Behavior • Socioecological Model ◦ Rooted in the fact that there is asymmetry in the reproductive investment of males and females in their offspring, they differ in how much they invest and how ▪ more variability into who and what males invest in their offspring ◦ Females are influenced mostly by the distribution of food because they have to support not only themselves but their offspring ▪ Where and how the food is distributed determines what kind of social groups females can form depending on what kind of competition they will be dealing with • Primate Diets ◦ Must provide the energy required to regulate essential bodily functions, and to sustain growth, development and reproduction ▪ Must provide specific types of nutrients ▪ Amino acids and proteins ▪ Fats and oils ▪ Carbohydrates ▪ Vitamins, minerals, and elements ▪ Must minimize exposure to toxins ▪ toxins are often concentrated in mature leaves ands seeds ▪ young leaves, fruits and flowers tend to have lower concentrations of toxins ▪ Primates obtain nutrients from many different sources ▪ Carbohydrates from fruit and gums ▪ Fats and oils from animal prey such as insects, also nuts and seeds ▪ Protein from insect and animal prey, and young leaves ▪ Leaves are also high in fiber, which can be difficult to digest ▪ Most colobines eat leaves and have enlarged intestines ◦ Most primates rely more heavily on some types of foods than others ▪ Frugivore, folivore, insectivore, gummivore ▪ Insectivores tend to be smaller in body size ▪ Smaller animals have relatively higher energy requirements and eat small amounts of high quality foods ▪ Folivores tend to be larger in body size ▪ Can afford to eat large quantities of lower quality foods ◦ Diets influence ranging patterns ▪ Leaves are more abundant in supply and predictable in space and time ▪ Fruits tend to be less predictable in supply and patchily distributed in space and time ▪ Folivores tend to have smaller home ranges than Frugivores ▪ Costsand benefits of territoriality ▪ Benefit: prevents outsiders from exploiting the limited resources within a territory ▪ Cost: energetically costly • Why Do Primates Live in Groups? ▪ Costs of sociality ▪ greater competition for resources ▪ vulnerability to infectious disease ▪ Two main benefits of sociality ▪ Enhanced access to resources ▪ Reduced vulnerability to predation ▪ Two main models of Sociality ▪ 1. Resource Defense Model ▪ Primates live in groups because groups are more successful in defending access to resources than lone individuals ▪ Join defense of food resources if profitable when: ▪ (1) Food items are relatively valuable ▪ (2) Food sources are clumped in space and time ▪ (3) There is enough food within defended patches to meet the needs of several individuals ▪ Fruit often meets these three requirements ▪ Larger groups generally are more successful in fights over resources than small groups ▪ 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 ▪ 2. 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 ▪ Terrestrial species tend to form larger groups than arboreal species ▪ Solitary haplorhines (e.g. orangutans, spider monkeys) are large in body size and apparently face little danger from predators ▪ Juveniles suffer from higher mortality in smaller groups than in larger groups ▪ Primates seem to adjust their behavior in response to the risk of predation (e.g. alarm calling) ▪ Weaknesses of model: ▪ Predation is very difficult to observe and it is therefore difficult to establish whether it is clearly linked to group size • Reproductive Asymmetry ◦ Primate mothers are almost always the primary (if not exclusive) caretakers of offspring ◦ The behavior of fathers is much more variable ▪ father will never exclusively be the caretaker of the offspring because of the time of lactation ◦ Reproductive Potential= the maximum number of offspring an individual can produce ▪ Female reproductive potential is more limited ▪ Females born with limited # of ova (eggs) ▪ Female can only breed when ova mature and are released ▪ Male reproductive potential is very high ▪ Sperm ar smaller and more numerous ▪ Constantly replenished ▪ Males can fertilize whenever sperm are replenished; more often ◦ Female strategies ▪ Other limits on reproductive potential ▪ Energetic costs of pregnancy and lactation requires mammalian females to make a significant initial investment in each offspring ▪ Each infant represents a significant portion of a female’s lifetime fitness ▪ Females have limited capacity to increase reproductive success by increasing # of offspring ▪ Females are best able to increase reproductive success by increasing chances of survival ▪ Females can improve likelihood of their and their offspring’s survival in 2 ways: ▪ (1) Invest more care and energy into offspring ▪ Depends largely on her ability to obtain important resources (food, nest sites, helpers) to support herself and her offspring ▪ (2) Be choosy about males fathering offspring ▪ only mate with quality males ▪ Female reproductive success is limited primarily by access to important resources necessary for survival ▪ Female strategies are primarily influenced by the distribution of food ▪ Female relationships are influenced by competitive regimes, which are consequence of food patch size and distribution ▪ (1) Scramble Competition ▪ Occurs when resources cannot be easily monopolized or defended and therefore access occurs on a first-come first- serve basis ▪ resources of low value are highly dispersed ▪ ex. leaves ▪ (2) Contest Competition ▪ Occurs when access to a resource can be monopolized by one of more individuals; some individuals systematically exclude others, and obtain more of the resources ▪ Resource patches are clumped, of immediate size and high value ▪ ex. fruits ▪ Fission Fusion Societies ▪ Group size and composition vary over time ▪ Benefits of grouping ▪ Mitigate costs of within group competition ▪ 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 ▪ Dominance rank has significant fitness consequences ▪ Offspring of high-ranking females are large for age (faster growth rates) and have earlier ages at maturity ▪ Begin reproducing earlier —> may have an additional offspring compared to lower-ranking females ▪ Offspring of high-ranking females are more likely to survive, have earlier ages at maturity, and shorter inter birth intervals ◦ Male Strategies ▪ What limits reproductive potential? ▪ For most mammals, the main limiting factor for male reproductive success is the number of females he can mate with ▪ High variance in reproductive success among males (reproductive skew) ▪ There is high variance in reproductive success among males ▪ Leads to competition among males ▪ Males can increase reproductive success by increasing the number of mates ▪ They do this through competition with other males to gain access to mates ▪ Because females are a limited resource, being “choosy” isn’t the best option for males to increase RS in most species ▪ male reproductive success is limited primarily by the availability of mating opportunities ▪ Male strategies are primarily influenced by the distribution of fertile females ▪ Contrast among males is more violent than those of females because their is more at stake ◦ Sexual 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 ▪ Favors the evolution of traits that allow the limited sex (males in most species) to compete more effectively for access to the limiting sex (females) ▪ Darwin: 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 unsuccessful competition, but few offspring." ▪ Inter-sexual Selection ▪ Where individuals exert choice among individuals of the opposite sex for mating partners ▪ favors traits that make males (usually) more attractive to females ▪ Favors traits that: ▪ (1) Provide direct benefits to their mates ▪ (2) Indicate good genes and thus increase the fitness of the offspring ▪ (3) Make males more conspicuous to females (although they can be maladaptive) ▪ Potentially problematic as these traits make males more conspicuous when it comes to their predators ▪ Intra-sexual Selection ▪ Competition among same sex individuals for access to members of the opposite sex ▪ Favors large body size, large canine teeth, and other traits that enhance competitive ability ▪ Contest Competition for mats —> traits that improve fighting success ▪ Selection for large male size —> body size sexual dimorphism ▪ Selection for large male canine size —> canine dimorphism ▪ Sexual dimorphism ▪ when males and females differ consistently in size or appearance ▪ greatest in one-male multi female (polygynous) social groups ▪ Least in monogamous social groups ▪ Sperm Competition ▪ In social systems where multiple males have access and male-male competition is high, sexual selection favors sperm competition ▪ Increased sperm production (testes size) ▪ Infanticide ▪ Act of killing a dependent infant ▪ One male, multi female structure are most common to have this ▪ Outsider males overthrow resident dominant male, and a new leader male is established ▪ This may be followed by killing got unweaned infants by the new leader male ▪ Sexual Selection Hypothesis: Infanticide is a male reproductive tactic which is sexually-elected (i.e., evolved as a consequence of male-male competition) ▪ Predictions: ▪ Infant killing will be directed at unrelated offspring, thereby reducing the RS of competition males by killing their infants ▪ Death of the dependent infant will lead to a termination of lactation; mother becomes fertile sooner ▪ The killer increases his chances of mating with the mother and siring the next infant ▪ DNA analysis supports the adaptive hypothesis in langurs ▪ In all cases with complete DNA samples ,the attacker male could be excluded as the father of the victime ▪ IN all cases, of subsequent births, the presumed killer was the likely father of the subsequent infant. ▪ Primates choose mates based on MHC diversity ▪ Rhesus Macaques ▪ Males that were heterozygous at a MHC locus sired significantly more offspring than homozygous males —> increased fitness ▪ Pig-Tailed Macaques ▪ Similarity in MHC antigens between mother and father predicts pregnancy loss ▪ Females also exert choice based on dominance ▪ Capuchin Monkeys ▪ Females exert choice for dominant males —> direct more grooming, sexual solicitations, maintain proximity towards high-ranking males ▪ Baboons: Male-Female “friendships" ▪ Close associations between females and adult males; preferential mating when the female is fertile ▪ Suggested to provide protection of the female, and protection of the infant from infanticide ▪ Human Mate Choice? ▪ Symmetry: Honest indicator of the quality of someone’s genes? ▪ Honest signal: information increases offspring fitness ▪ Humans select mates on the basis of odor cues, which indicate genetic diversity at important immune function loci Fossils • Fossils- The surviving bones and teeth of a once leaving animal; fundamental source of date, primarysource of date, tells a lot about behavior, environment, etc. ◦ Preserved remains of once-living organisms ◦ How they are formed: ▪ Hominid dies, often times footprints are left in the mud ▪ With time, only bones remain ▪ Skeleton is broken by trampling ▪ Skeleton and footprints are buried by water and sediment ▪ Over time, more sediments accumulate and bones fossilize ▪ Erosion exposes the layer of strata containing the bones and footprints • Paleontology- The study of extinct organisms based on their fossilized remains ◦ Where was it found, what kind of environment was it found, what other species were around at the time and how might they have been related • What is a fossil? ◦ Fossilization is a rare event ◦ Several conditions must be met before remains can be preserved: ▪ Remains must be suitable for fossilization ▪ Remains must be buried ▪ The material in which the remains are buried must be suitable for fossilization • What can we learn from fossils? ◦ Look at cranial size and shape and predict cognition and behavior ◦ Look at the teeth and make predictions of diet, behavior, and social structure ◦ Measure body proportions to learn something about possible environment and ecology ◦ Look at the pelvis to predict obstetrics and locomotion ◦ Morphology of the hands to look at manual dexterity ◦ Morphology of lower limbs to reconstruct something about locomotion and substrate • Bias in the fossil record ◦ The fossil record is not a complete record of the history of organisms ever to exist on earth; it is only a sample of the plants and animals that once lived ◦ Some skeletal parts preserve better than others, *GO BACK* • Some unusual surprises ◦ Footprints (Laetoli, Tanzania) ▪ Individual walked across a volcanic ash layer ▪ Soft rain cemented the footprints, and they were covered by another ash deposit ▪ Information about locomotion ◦ Coprolites (fossilized feces) ▪ More common when individuals incorporate inorganic components into their diets (e.g. hyenas eat bones) ▪ Useful to understand diet and environment • The Matrix ◦ Skeletons become fossils by absorbing minerals from their surroundings ◦ The matrix composition is informative for analyzing fossils and its is critical for the dating got fossils ◦ Context is critical ▪ Want to be able to associate the bones you are excavating with the sediments they were in to look at this to understand environment, humidity, weather, etc. • Dating Fossils ◦ Relative Dating- focused on being able to figure out which sediments are older than other sediments, and how they relate ▪ Lithostratigraphy- use characteristics of the rock layers to link sedimentary sequences and establish relative ages across sites ▪ Biostratigraphy- ▪ Tephrostratigraphy ▪ Geomagnetic polarity ▪ Establishes a broad geological context. Uses principles of stratigraphy (=study of rock layers) to establish the relative ages between localities and between fossils founding these localities ▪ Law of Superpositions: basically that higher layers are the newest rocks and the lower layers are the oldest layers, in the absence of other geological or tectonic processes ◦ Chronometric (absolute) Dating- allow you to put an absolute time frame on ▪ Isotpoic/radiometric
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