Human Evolution www.okc.cc.ok.us/deanderson/index/human_evolution.ppt
Theory of Evolution • Science has overwhelming evidence that all life is constantly evolving
Natural Selection • One mechanism of evolution • Main concepts of natural selection • Overproduction of offspring • Inherited variation in offspring • Competition • Best adapted in a given environment survive and reproduce to increase their kind • They are naturally selected
Overproduction of Offspring • Elephants (very slow reproductive rate) • If all the offspring of one elephant pair survive and all their offspring survive then: • 750 years = 19,000,000 elephants • 1200 years = Enough elephants to cover the earth! • Beetles • A handful that weighs 10 mg each • 82 weeks • 61,000,000,000,000,000,000,000 ton • The weight of the earth!
Variation of Offspring • Offspring of the same parents are different from each other
Competition • Since more individuals are born than can survive for an extended period of time, they compete for resources • Food • Living space • Mates
Best adapted to a given environment are selected to survive • Brown bears • Adapted to survive in Oklahoma • Polar bears • Adapted to survive in Alaska
The Evolution of Humans The Ecological Theatre • The Stage: East Africa • The Setting: A time of unrest... • Geologically… • The rift zone - uplifts, rifting, volcanoes • Climatically… • A series of glaciations • Global climate change • Changes in sea level
Sequence of Human Evolution • Hundreds of fossils have been found • Some of the major fossils will be discussed in this presentation
Australopithicus afarensis • 3.5 million years ago • Nicknamed Lucy • Walked upright • Small brain • Skeleton human like • Feet • Pelvis • Upright stance
Comparative Anatomy Lucy Gorilla Human • Gorilla pelvis adapted for knuckle walking • Human pelvis adapted for upright walking • Lucy’s pelvis very similar to human pelvis
Knuckle Walking • Requires an elongated pelvis and long arms
Fossilized Footprints • Footprints left when a a pair of Australopithecines walked in the ash of a recently erupted volcano
Lucy Chimp Skull Anatomy • Thick brow ridges like a chimpanzee • Cranial capacity 400 cc. Chimp 350 cc. • Teeth similar to human teeth
Lucy: A Transitional Fossil • Transitional fossil shows characteristics of two kinds of animals • Represent the transition from one organism to another • Ape characteristics • Skull • Cranial capacity • Human characteristics • Walked upright • Feet • Pelvis
Australophithicus africanus • 2.8 million years ago • Cranial capacity 460 cc
Homo habilis • Cranial capacity 630 cc • Flatter face than Australopithecines • Used tools • Nicknamed handy man
Homo erectus • 1.8 million to 35,000 years ago • 1,000 cc cranial capacity • Large brow ridges • Sloping forehead • More advanced tools than H. habilis
Homo erectus • Skeleton very similar to modern man • Used fire • Traveled • Fossils found in Africa, Europe, China, Indonesia
Homo neanderthalensis • 135,000 to 25,000 years ago • Cranial capacity up to 1750 cc • Larger than modern man • No chin • Sloping forehead • Buried dead with tools and flowers
The Evolution of Humans The Cro-Magnons and the Neanderthals
Homo sapiens • 200,000 years ago to present • Photo is a skull 100,000 years old • 1400 cc cranial capacity • Vertical forehead • Pronounced chin
The Evolution of Humans • What about the Neanderthals?
The Evolution of Humans • What about the Cro Magnons?
Modern Homo sapiens • Small front teeth • Small brow ridges • Rounded cranium
Homo neanderthalensis Australopithicus afarensis Australopithicus africanus Homo erectus Homo habilis Common ancestor Modern apes Sequence of Human EvolutionOne of several possibilities Homo sapiens
Evolution of Skull • Cranial capacity increases for a larger brain • Face become flatter • Brow ridges become smaller • Forehead becomes higher • Chin develops
Tools used to learn about our evolutionary past • Study of fossils • Comparing DNA • Comparing chromosomes • Comparing protein sequences
Paleontology • Study of fossils • Allows us to see anatomical similarities between us and organisms that lived in the past • Allows us to see how our ancestors have changed over time
Comparing DNA • Human DNA compared to: • Chimpanzee 99% same • Gorilla 97.7% same • Orangutan 96.3% same • Another human 99.9% same
The Evolution of HumansThe Great Leap Forward • Due to evolution of a mechanism that allows speech and language? • Characterized by the appearance of... • Use of symbols... • Complex tools... • Innovations in hunting techniques and strategies... • Increased population size, development of social systems... • Houses, boats, long distance trade, ornaments • Art, music, rituals...