Biological Anthropology Notes Week 8
Biological Anthropology Notes Week 8 Anth 1001
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This 3 page Class Notes was uploaded by Jaimee Kidd on Monday March 7, 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 43 views. For similar materials see Biological Anthropology in anthropology, evolution, sphr at George Washington University.
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Date Created: 03/07/16
Primate Adaptive Trends Primates are Mammals • 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 (outer most region of the brain) of the brain ▪ spacial reasoning, memory, planning, and (in humans) language ◦ Placenta, nourishes fetus during gestation, allows for a more efficient exchange of nutrients to the fetus during gestation, at the end of this mammals give birth to offspring that are at a more advanced stage in development compared to other vertebrates, long gestations followed by live birth ◦ Maternal Care of their young What Defines the Order Primates?/How do we deal with the variation of Primates? • Within the order of primates we have two major subdivisions, the Strepsirhini and the Haplorhini (More detail on these to follow in next week’s lecture) • The difficulty in defining primates lies in the difference in characteristic expression between the two suborders • One characteristic that is universally present in all primates is the petrosal bulla ◦ Part of the bony underside of the skull, encloses, houses, and protects the middle ear • A lot of the traits of primates come from their original argorial environment—trees and forests • The Order Primates ◦ Derived Homologies ▪ Petrosal bulla ▪ High degree of grasping ability in the hands and feet ▪ Primates as a group have an opposable thumb ▪ Opposable big toe as well, with the one exception being ourselves as our big toe is brought back into line with the rest of our foot ▪ Most primates have nails instead of claws ▪ Sensitive tactile pads with skin ridges on the tips of the digits ▪ folds increase surface area, more surface area to place nerve endings and also adds for more friction when grasping ▪ Decreased reliance on olfaction (smell) particularly in haplorhines ▪ Olfactory regions of the brain are reduced ▪ 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 ▪ Nasal structures of the skull are reduced ▪ Haplorhines lack a moist naked skin (rhinarium) surrounding the nostrils ▪ soft tissue around the nose that is always covered with a film of secretion and it essentially functions as a wind protector that can detect the evaporation of the secretion and detects that as wind and movement to ultimately sense a predator around and the smell of a predator ▪ Stereoscopic vision and enhanced depth perception ▪ Haplorhines have evolved trichromatic color vision ▪ rods perceive differences in light intensity, cones distinguish differences in the wavelengths of the light which we perceive as differences in color ▪ Why this is important ▪ Being able to tell the difference between what foods are edible and what aren’t, specifically fruits which are a large part of primates diets ▪ Being able to distinguish between young leaves and old leaves, young leaves being much more nutrient packed than old leaves and important in the diet ▪ Facial coloration for recognition of species, facial expression communication ▪ Binocular vision ▪ Frontal visual fields ▪ Primate brains are wired differently, such that the information from the right side gets processed in the left side of the brain and vice versa, wired to compute paralax ▪ paralax the displacement in the position of an object viewed by the right and left eye ▪ Need this wiring in order to perceive depth in the way we do ▪ Forward facing eyes with an enclosed bony orbit (postorbital bar) ▪ Large brain relative to body size, expanded neocortex, throughout all stages of development ▪ Prolonged life history, single offspring ▪ Primates develop slowly and invest heavily in offspring ▪ Give birth to single offspring, with some exceptions and invest heavily in them ▪ Longer gestation ▪ Longer infancy and juvenile periods, and delayed reproductive maturation ▪ Long Lifespan ▪ Relatively slow lives compared to many other mammals ▪ period of time separating births between chimps in 35 years, whereas other species are reproductively mature earlier and have more kids ▪ Primates are social ▪ Learn from group mates: one reason for that long childhood ▪ Maintain close social bonds ▪ Social hierarchy that is constructed and learning how to navigate it ▪ suggested that we need a long period of time to learn the social skills in order to be successful as adults ◦ Ancestral Homologies ▪ Generalized body plan ▪ Retention of the collar bone (clavicle) ▪ Two separate bones in lower arm (ulna and radius) ▪ Five digestive the hands and feet ▪ Generalized dentition ▪ Heterodonty