Human Variation Test 2 Study Guide

Human Variation Test 2 Study Guide - Human Variation Test 2...

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Human Variation Test 2 Study Guide Human Neonatal Skull Growth & Brains -growth of skull through suture lines, allowing for brain growth -Variation in length or width, curvature, curvature of actual bones, muscles lines, thickening of the bones Shape of skull dependent on intracranial pressure -fast brain growth more curved -slow brain growth more elongated (brain growth relative to closing of the suture lines) Occipital Bunning -slow brain growth relative to closing of suture lines -leads to pushing back into occipital lobe -characteristic of Neanderthals -sutures at front of head closer early versus brain growth -some effects are environmental flattened back of the head the result of babies on back Face Variation -variation in eyes: -distance, size, nose, cheek bones, teeth -influences: overlapping visual fields Developmental Priority in the Human Face 1) The eyes and the eye sockets (orbits) 2) The nasal capsule and the pharynx 3) The dentition and the jaw 4) the cheeks and chewing muscle Orthognathism retreating face Prognathism protruding face Brow Ridges -from trignum orbitale (triangular peak) to brow ridge to singular bridge -women have less brow ridge than men -flatter position more in Asia, swept back in Europe Dentition -over time, mesial drift occurs (teeth migrate forward) Chin -development of mentumosseum (protrudiation of bone) Nasal Regions -varying parts: apature (varies from tall to wide/short), projection of nasal spine, cartilage portions -climatic adaptation hypothesis is inconclusive Epigentic Traits -presence or absence traits -bones formed (wormian bones) in fissure lines -metopic suture
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-single frontal bone (typical) is instead a double frontal bone fused Eyes and Eye Color -melanin dependent -inheritance is not simply mendelian -radiations are individually specific Ears -variation in placement/number of ridges, lobe attachment Human Skull Measurements -standardized points, positioning is uniform -Men have thicker bones, greater mastoid process (typically more robust) Skull Angle -three angles created: 1) frontal angle 2) parietal angle 3) occipital angle (corresponding to areas of brain) -frontal angle greatest in sub-Sahara Africa; some separation between but all groupings relatively overlap Teeth Why Bother: 1) Enamel is non-reactive once formed (due to crystalline structure) 2) Teeth preserve in prehistoric record 3) Easy accessibility 4) Heritability (best underlying of genotype due to stability once formed) 5) Variation (highly variable in details of crowns, within and between populations) 6) Abundant Data -Most crowns of permanent teeth produced by age 5-6; each tooth regulated by many loci (complicated genetics); complicated shapes, most measures are crude but work well Alterations: Enamel Alterations: 1) Abrasion due to grit or grinding of teeth 2) Caries (cavities) result of chemical actions of teeth (bacteria produce acid from refined sugars) 3) Malformation Dentin Alterations: 1) Crow attrition 2) Root inflammation 3) Caries (accumulations near roots)
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Human Variation Test 2 Study Guide - Human Variation Test 2...

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