Presentation on theme: "Human Evolution. Describe the major anatomical features that define humans as primates Primata = an order of mammals, including apes, monkeys, tarsiers."— Presentation transcript:
Describe the major anatomical features that define humans as primates Primata = an order of mammals, including apes, monkeys, tarsiers and lemurs
Humans and Primates Humans share the following characteristics with other Primates: grasping limbs, with long fingers and a separated opposable thumb; mobile arms, with shoulder joints allowing movement in three planes and the bones of the shoulder girdle allowing weight to be transferred via the arms; stereoscopic vision, with forward facing eyes on a flattened face, giving overlapping fields of view; skull modified for upright posture; **Primates share a common ancestry
thumbs, upright, forward facing, shoulders
2. Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus, including A. afarensis and A. africanus, and Homo, including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. Hominids originated in Africa and spread to other continents –Ardipithecus fossils found in Ethiopia –Australopithecus and Homo habilis fossils found in Southern and Eastern Africa –Homo erectus fossils found in Eastern Africa and in Asia –Homo neanderthalensis fossils found in Europe –Homo sapiens fossils found in all continents except Antarctica
Ardipithecus ramidus Oldest hominid (4.4 million years ago) more primitive (ape- like) Bipedialism? Low forehead Small cranium Protruding brow and jaw Big teeth
Australopithecus afarensis 3.9 million years “Lucy” (Fossil found 1978) a low forehead bony ridge over the eyes a flat nose and no chin more humanlike teeth, (large cheek teeth – large chewing muscles) and the pelvis and leg bones resembled those of modern man. Females were smaller than males.
Australopithecus africanus million years ago appeared to be apelike Light build; probably relatively long arms; more "human" features Higher forehead; shorter face; brow ridges less prominent protruding face small brain, distinctly unapelike dentition including small canines and large, flat molars. (large cheek teeth – large chewing muscles) A bipedal posture was again indicated by the central position of the foramen magnum, and by the anatomy of the spine, pelvis, and femur.
Homo habilis Approx. 2.5 million years First definite human ancestor 1st member of genus homo Larger brain Presence of tools (indicates brain capable of complex thought) Bi-pedal foot structure
Homo erectus 400, 000 y – 1.6 million years ago Larger brain capacity Reduced size of face and cheek teeth Thicker cranial bones Bone limbs show little change
H. neanderthalensis 30, , 000 years ago similar to homo sapiens Features related to cold climate adaptation Broad bone and muscle structure Short, strong body Large, rounded nasal opening Believed to be a genetical variant of H. sapien
H. sapien (archaic) – years ago Skull became more rounded than H. erectus Teeth are less thick and dense Brow bridge still prominent Much steeper forehead development of forebrain, planning, reasoning, speech. Evidence of more complex tools
H. sapiens-modern man years highly developed brain and thus, mental capacity social capabilities less hair less brow ridge, jaw has decreased in size
Family Hominidae – determined by bipedialism Trends in hominid evolution: increasing adaptation to bipedalism, especially forward movement of foramen magnum increasing brain size in relation to body size decreasing relative size of: face, jaw, teeth, esp. canines; increasing relative size of brain case, forehead