Unit 2 Primate Anatomy and Behavior Dating Methods Fossil Formation Primate Evolution and Introduction to Paleoanthropology Taxonomy Primate types prosimians New World monkeys NWMs Old World monkeys OWMs and apes Anatomic vs genetic similarities in transition proposed changes Name change in primate suborders Traditional Prosimii lemurs lorises and tarsiers Anthropoidea monkeys apes and humans apes and humans Proposed Strepsirrhini lemurs and lorises Haplorrhini tarsiers monkeys Reclassi cation of the great apes i e family names Traditional Pongidae great apes Hominidae humans Proposed All Hominidae great apes and humans Studies 1920s 1930s descriptive studies 1950s 1960s observational studies e g Jane Goodall among chimps and Dian Fossey among mountain gorillas 1970s present theoretical paradigms for research grants Behavioral ecology the study of the relationship between the environment and behavior Sociobiology the study of the relationship between genetics and behavior Characteristics Limbs and locomotion Erect posture Hands and feet Independent movement of ve digits Opposable thumb and big toe Prehensile the ability to grasp and manipulate Flexible limb structure Leaping jumping Quadrupedalism movement using all limbs simultaneously e g knuckle walking or slow climbing Brachiation arm swinging suspended by the limbs alternating weight bearing on the limbs Semibrachiation the use of the tail as well as the forelimbs in brachiation Bipedalism movement on two limbs e g humans as obligate bipeds Senses and brain reliance on vision reliance on smell Enhanced touch in ngertips and toes Encephalized brain size body size Maturation learning and behavior K selected have a fewer number of offspring at one time born immature and unable to care for themselves require a lot of parental investment have slow maturation rate and tend to have long lifespans and pregnancies Many mammals are K selected r selected species have many offspring at one time the offspring are born mature and require very little if any parental care and tend to have short lifespans and pregnancies Many non mammals are r selected Arboreal i e live in trees vs terrestrial i e live on the ground Diurnal i e active during the day vs nocturnal i e active during the night Flexible learned behavior capable of learning in a wide variety of environments passive learning curve Social Primates like to have company Exceptions are considered solitary Arboreal hypothesis the idea that the suite of characteristics that differentiate primates from other mammals evolved as a result of adapting to life in an arboreal environment Dental Characteristics Heterodont different types of teeth Incisors front blade like teeth for biting food Canines big sharp teeth for tearing food Premolars side teeth for grinding food Molars side teeth for grinding food Diastema a space between teeth Dental formula a standardized way of describing dentition re ected in of the mouth Maxilla the upper jaw Mandible the lower jaw NWMs and OWMs differ in the number of premolars NWMsOWMs Apes and HumansMaxilla2 1 3 3 2 1 2 3 Mandible2 1 3 3 2 1 2 3 Diets Forager an organism that searches for food daily Omnivore an organism that eats many foods Frugivore an organism that eats mainly fruits Insectivore an organism that eats mainly insects Folivore an organism that eats mainly leaves Carnivore an organism that eats mainly meats Sexual Dimorphism Differences between the sexes in size shape or coloration e g bright peacocks vs drab peahens High degree in gorillas moderate degree in humans and low degree in chimps Social Structure Residence pattern the size of a primate s social group e g the number of males to females or adults to offspring Solitary Once individuals reach adulthood they live alone Females have dependent offspring with them while males generally don t participate in raising offspring Pair bonded A male and female form a bond that generally lasts throughout their lifetime They and their offspring form their core unit This isn t as rare as solitary but is rare in nonhuman primates Polyandry There s a single mature and ovulating female and multiple adult males in the group As long as females remain within the group they won t reach sexual maturity This too is rare Polygyny There s a single adult male and multiple females in the group The adult male leads the direction the group moves and other males are chronological subadults When juvenile males sexually mature they leave the group This is common in nonhuman primates especially gorillas Multimale multifemale There are multiple males and multiple ovulating females in the group of variable size They split into subgroups then return together at different times This is common All male This coexists in species that have other social structures e g polygynist and slightly in multimale multifemale Geographic Distribution Found in forested regions and warm climates Different from where their fossils were found Prosimians Least specialized primate with characteristics more similar to mammals than primates Rely to a large extent on smell than sight long snout Postorbital bar the lateral border of the eye orbit Short gestation and maturation Dental comb a dental specialization of the mandibular incisors that projects anteriorly and superiorly for grooming and eating Grooming claw a specialized digit on the forelimb that s elongated and thin more for eating than grooming Lemurs Lorises Indigenous to and extinct in Madagascar Diverse in size and behavioral adaptations Examples small mouse lemur and large sifaka Tiny bodied and nocturnal while most primates aren t Rely to a large extent on olfaction and vocalization Recognize each other mark territories and predatory defense Examples bush baby and slow loris Tarsiers Considered to be prosimians but genetically similar to anthropoids Tiny bodied and found in the South Paci c Climbers as quadrupeds and leapers large muscles in hind limbs Comparisons ProsimiansAnthropoids Monkeys and Apes Small bodiedLarge bodiedLong snoutsShort snoutsDental combs some No dental combGrooming claws some NailsPostorbital barsEnclosed eye orbitsShort gestation and maturationLong gestation and maturation NWMs Platyrrhines Geography mostly South America Central America and the southern tips of Mexico Size larger than prosimians but smaller than OWMs Nasal soft tissue with wide septum i e the space between nostrils and circular and anterior nostrils Tails most and some prehensile tail prints