Mile Markers in Deep Time

1
Mile Markers in Deep Time

• A Brief History of Life and an Outline of Hominid
  Evolution

2
History of Life on Earth

• How did life originate?
• What were the first organisms?
• How has life changed through time (evolution)?
• Why do organisms become extinct?
• What causes mass extinctions?
• How do living systems recover after mass
  extinctions?
• What is our ancestry and our future?

3
Earliest Life Prokaryotes

• Prokaryotes cells with no nucleus
• Single cells
• Strings of cells
• Mats of cells - Stromatolites

4
Major Milestones

• Life begins approximately 4.0 Ga
• First multicellular creatures approx. 1.0 Ga

5
Major Milestones

• Abundant life with shells and hard parts
  approx. 530 Ma

6
Major Milestones

• First and worst mass extinction 245 Ma
• Dinosaurs and Early mammals appear after

7
Major Milestones

• Mass extinction dinosaurs and others 66.4 Ma
• Rise of mammals 66.4 Ma to present
• First hominids approx. 4.0 Ma

8
Hominid Evolution

• The interface of paleontology and archaeology

9
A family dynasty the Leakeys

• Richard Leakey
• Mary Leakey
• Richard Leakey - son

10
Mary Leakey

• A lifetime of contributions including
• Many first discoveries of
• skulls, etc.
• First hominid footprints

11
The Cradle of Humanity

• The East African Rift System
• Earthquakes and formation of rift as Africa
  splits
• Sinking of rift floor promoted accumulation of
  sediments
• Early hominids preserved in these sediments
• Recent erosion cuts through sediments to reveal
  fossils

12
Our earliest ancestor

• Hadar, East African Rift
• Australopithecus afarensis
• Famous Fossil Lucy
• Age About 4.0 Ma

13
Lucy

• Australopithecus afarensis
• An intelligent ape?
• Brain capacity was thought to have developed
  before upright walking
• Lucys knee clearly shows our ancestors walked
  upright BEFORE they developed larger brains

14
Footprints at Laetoli A. afarensis

• More evidence for walking upright

15
Homo habilus

• Our own genus circa 2.0 Ma

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Australopithecus afarensis Homo habilus
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Hominid Time Line
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The Hominid Time Line

• Accurate dating of fossils is critical
• Direct evolutionary relationships are still
  unclear
• New fossil discoveries prompt revisions all the
  time
• The burning questions Who are we? What is our
  heritage? Where do we fit in the grand scheme of
  things?

19
Hobbits in Indonesia?

• Just Discovered 10/04
• Homo floresiensis
• Stood only 3.3 ft. tall!
• 55 pounds
• Brain size grapefruit
• 18,000 to 13,000 BP