Chapter 6 PrimatesPrimate: Members of the mammalian order Primates which include lemurs, lorises, tarsiers, monkeys, apes, and humansPrimatology: The study of the biology and behavior of non-human primates Homologies: features that are shared b/c they were inherited from a common ancestorAnalogies: features that are shared b/c they are independent functional adaptations Evolutionary trends—these are part of a continuum not equally expressed in every speciesFour categories of primate traits: Locomotor, Dietary, Sensory and Behavioral/life history- Types of locomotiono Erect upper body posture Associated with sitting, leaping, standing, bipedalismo Limb proportions  Retention of flexible and generalized limb structure for greater range of motion- Retained the clavicle: color bone- Wide range of hip/shoulder morphology- Rotation of forearm  Primates aren’t restricted to one form of movemento Prehensile: hands and some feet and tails where they can skillfully manipulate objects Can bend hand or feet onto itself New world only: tails with gripping capabilities Pentadactyly: having 5 fingers and toes Opposable thumb & in most species a divergent and partially opposable big toe Nails vs. claws: all primates except some NW Monkeys (marmosets and tamarins) - Some streps have one claw or claw-like nails (loris/lemur) Tactile pads: enriched with sensory nerve fibers at the end of digits- Enhances sense of toucho Quadrupedal: using all four limbs to support the body during locomotiono Arboreal quadrupedalism Forelimbs are somewhat shorter than the hind limbs Adaptive niche in the trees Still find food on the ground Food in trees (leaves, seeds, nuts, insects, smaller mammals) Reliance on vision, grasping hands, feet and tails Alternative to the arboreal hypothesis- Squirrels are arboreal but haven’t evolved like primates- Basic primate traits developed in conjunction with flowering plants. Flowering plants provide numerous resources for primates (nectar, seeds,fruits) and the traits may have developed in response to the demand for fine visual and tactile discriminationo Terrestrial quadrupedalism (more stable joints) Limbs are approximately the same length with the forelimbs being 90% as long as hind limbs Vervet monkey, savannah baboon Tropical and semitropical areas of new and old worlds- New: southern Mexico, central America, parts of south America- Old: Africa, India, southeast Asia (+ islands), Japano Some OW monkeys spend time on the ground, like baboons and African Apes (gorillas, chimps and bonobos). Non-human primates have adapted to a fully terrestrial lifestyleo VCL: Vertical Clinging and Leaping  Lemurs and tarsiers Support themselves vertically by grasping onto trunks of trees or other large plants while their knees and ankles are tightly flexed They forcefully extend their long hind limbs to spring powerfullyo Brachiation: arm swinging A suspensory form where the body moves by being alternatively supported by one forelimb (like swinging on monkey bars on playground)  Anatomical modifications at the shoulder joint Gibbons, Siamangs Strong arms that are longer than legs, stable lumbar spine, long curved fingers, reduced thumbso Knuckle-walking quadrupedalism All apes Strong arms that are longer than legs, which results in supporting their upper body by walking on their knuckleso Bipedalism: walking on two legs Humans Longer legs than armso Foramen magnum: the large opening in the occipital bone of the cranium through whichthe spinal cord exists. Can be located in the inferior/posterior region of the skull, indicating the posture/how the animal moves (on all fours or on two legs)Dietary- Omnivorous: lack of dietary specialization; can eat a wide assortment of foods- Generalized teeth (teeth aren’t specialized for only one type of food) related to a general lack of dietary specializationo 4 basic tooth types: incisors & canines for biting and cutting, premolars & molars for chewing and grindingo Dental formula: indicates the number of each tooth-type in each quadrant of the month OW monkey: 2123 NW monkey: 2133Sensory- Smell—decreased reliance on olfactiono Smell is reduced by reduction in size of olfactory structures/snout sizes. More variation in movement of mandible- Vision is emphasized o Diurnal primates rely more on vision and less on olfaction represented by evolutionary changes in the skull, eyes and braino Color vision is a characteristic of all OW diurnal primates. Some NW species don’t have the full range of color and nocturnal primates lack color visiono Depth perception possible through stereoscopic vision: ability to perceive objects in 3D Binocular: the eyes face forward and have overlapping fields of vision Information from each eye is transmitted to both hemispheres of the brain- 40% of the optic nerve fibers remain on the same side of the hemisphere so that information is shared- Monochromatic (black and white): nocturnal, strepsorhines- Dichromatic (two colors)- Trichromatic (full color): halporhines, helps with food and matingo Decreased reliance on olfaction An overall reduction in the size of olfactory structures in the brain and reduction of the entire olfactory apparatus resulted in decreased size of the snout. This is related to an increased reliance on visiono Expansion and increased complexity of the brain Most evident in the visual and association areas of the neocortex (portions of the brain where information from different sensory modalities is combined) Expansions in regions involved with sensory and motor functions of the hand is seen in many primate species, especially humansBehavioral/life history- More efficient means of fetal nourishment, longer periods of gestation, reduced numbers of offspring (single births), delayed maturation and extension of the entire life spano K-selection: smaller number of offspring, more and longer parental involvement, long period of infant dependency, more likely to survive to reproduce (primates) Offspring are altricial: not able to take care of themselves for an extended periodof time after birth. Because of this parents would have trouble raising multiple offspring; therefore, usually only have single births and there are long periods between births.- Eyes and ears are sealed by membranes Precoical: having multiple offspring b/c they are able to