Human evolution
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Human Evolution. www.okc.cc.ok.us/deanderson/index/human_evolution.ppt. The Evolution of Humans. Theory of Evolution. Science has overwhelming evidence that all life is constantly evolving. Natural Selection. One mechanism of evolution Main concepts of natural selection

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Human Evolution

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Human Evolution

www.okc.cc.ok.us/deanderson/index/human_evolution.ppt


The Evolution of Humans


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!


The Evolution of Humans


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


Lucy’s pelvis allowed her to walk like a human instead of an ape.


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

    • Gorilla97.7% 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...


The Evolution of Humans


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