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Human Evolution. The Incredible Journey. Recap – Natural Selection. There is variation between individuals in a population Parents pass on their traits to their offspring The organisms with features that best suit their environment have the best chance of survival and reproduction
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Human Evolution The Incredible Journey
Recap – Natural Selection • There is variation between individuals in a population • Parents pass on their traits to their offspring • The organisms with features that best suit their environment have the best chance of survival and reproduction • Those organisms that are able to survive and reproduce pass on their characteristics to their offspring • Over time the population will become better suited to its environment • Let’s give it a try...
Natural Selection • Human Adaptations that have been selected for; • Bipedalism (position of the ‘foramen magnum’) • Reduction in size of molar teeth • Reduction in jaw size • Increased cranial capacity • Cranial ridge
Comparison of skulls CHIMPANZEE GORILLA HUMAN SKULL • What features can you identify? • What makes the skulls different from one another?
Comparison of skulls • Top of the skull (cranium) is smooth There is no anterior-posterior crest to hold huge jaw muscles • No protruding brow • No protruding jaw or teeth (ie the teeth are vertical) • No protruding nose bone • Teeth are arranged in a parabolic shape rather than a narrow u shape • Small canines and small incisors • Foramen magnum (hole for the spine) is positioned directly underneath the skull not in the back of the skull
Australopithecus aferensis • Location: Eastern Africa • Cranial capacity : 375-425 cc • Fossils discovered so far in Tanzania, Kenya and Ethiopia • Timeframe: 4.7 – 2.1 million years • Fully bipedal (first!), but arms longer than legs • Possibly made tools out of bone teeth and horn (Osteodontokeratic)
Australopithecus africanus • Location: Southern & Eastern Africa • Cranial capacity: 420-500 cc • Timeframe: 3-2 million years • Slightly greater body size • Smaller canine teeth than A. aferensis • Teeth structured in a more parabolic (‘V’) shape
Australopithecus boisei (Oldoway) • Location: Eastern Africa • Cranial capacity: 500-550 cc • Timeframe: 2.5 - 1 million years • Largest teeth found in any hominid group • Huge jaw, small incisors & canines, large molars & premolars, parabolic dental structure and sagittal crest present – (hard low quality food) • Face is more vertically set
Homo rudolphonsis • Earliest species of Homo (or maybe Homo habilis?) • Cranial capacity: 775cc • Contention as to whether the fossils are Australopithicus or Homo • Lack of crests • Smoothly rounded occipital bone compared to Homo erectus
Homo habilis “handy man” • Location: Eastern Africa • Cranial capacity: 800 cc • 2.5-1.5 million years • Short molars, small canines, parabolic dental arcade • Full biped, increased leg length, decreased arm length, shorter in stature • Fossils accompanied by primitive stone tools
Homo erectus • Location: Africa, Asia, Europe • Cranial capacity: 900-1225 cc • UseingAcheuliantools: hand axe culture, large game hunting, suggestion of communication, first to use fire • Some scientists have split H. erectus into three separate species, based on the geographic region in which specimens have been found: H. ergaster (Africa), H. erectus (Asia), and H. heidelbergensis (Europe).
Homo sapien • Location: Africa, Asian, Europe, Australia, North America • A high, rounded cranium • Cranial capacity: 1400-1600 cc • Art & Symbolism, first to produce fire and use language • A steep forehead • A tall and narrow nasal opening • A parabolic palate