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
Lucy’s 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

16. Australopithecus afarensis & Homo habilus

17. Hominid Time Line

18. 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