1. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. MICHAEL D. JOHNSON EVOLUTION AND THE ORIGINS OF LIFE CHAPTER 22 EVOLUTION AND THE ORIGINS OF LIFE PowerPoint ® Lecture Slide Presentation by Robert J. Sullivan, Marist College Human Biology Concepts and Current Issues Second Edition

2. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Fossil record: incomplete but valuable, preserves only hard tissues Comparative anatomy and embryology: analogous and vestigial structures Comparative biochemistry: examines similarities between molecules, estimates divergence Biogeography: impact of geographic barriers and continental drift Evidence for Evolution: From Many Sources

3. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Random mutations: underlie evolution, introduces allelic variations Natural selection: encourages “survival of the fittest” Genetic drift: random changes in allele frequency due to chance events Bottleneck effect Founder effect Natural Selection: A Mechanism of Evolution

4. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Gene flow: differences in gene pool of particular populations due to immigration or emigration Mass extinctions: eliminate many species, 50% or more Natural Selection: A Mechanism of Evolution ( cont.)

5. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Evolutionary Tree Figure 22.9

6. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Purpose: to trace evolutionary change and relationships between species Adaptive radiation: short bursts of evolutionary activity Evolutionary Tree/Phylogenetic Tree

7. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Inhospitable to life: hot and steamy Early atmosphere Consisted of: carbon dioxide, water vapor, hydrogen, nitrogen, methane, ammonia Did not have: liquid water, oxygen, ozone The Young Earth

8. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Simple organic molecules: formed from atmospheric gases Amino acids, simple sugars, fatty acids Self-Replicating RNA and DNA formed on clay templates First-living cells: anaerobic Obtained needed chemicals from environmental soup First Cellular Life: Single-Celled Creatures Resembling Bacteria

9. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Photosynthesis Increase in atmospheric oxygen Oxygen produced as waste product of carbon dioxide Evolution of aerobic organisms Oxygen toxic to anaerobic organisms Oxygen assisted in breaking down organic compounds, especially in environment Survivors had to possess chemical pathways to make needed organic compounds Photosynthetic Organisms: Altered Course of Evolution

10. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Evolutionary Time Line Figure 22.11

11. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Evolutionary highlights Nucleus formed, eukaryotes develop, 1.7 billion years ago First multicellular organisms (seaweed), 1.3 billion years ago Animals appear, 600 million years ago Dinosaurs extinct, 65 million years ago Distinctly human ancestors, 5 million years ago Rise of Animals and Human Ancestors

12. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Proposed Homo sapien Evolution Figure 22.14

13. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Taxonomic classification Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Primata, Family Hominidae, Genus Homo, Species Sapiens Mammals: vertebrates with hair and mammary glands that produce milk Primates: hands with five digits, fairly flat fingernails and toenails, forward facing eyes Human Evolutionary Beginning: Hominids

14. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Australopithecus afarensis: upright primate, vegetarian, sexual dimorphism, 4-5 million years ago Homo habilis: first tool maker, enlarged brain, omnivore, decline in sexual dimorphism, 2.6 million years ago Homo erectus: more brain enlargement, longer infancy, continued decline in sexual dimorphism, continued tool development, continued social development, spread out of Africa to Europe and Asia, 2 million years ago Evolution of Homo sapiens

15. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Homo neanderthalensis: may be an extinct branch Homo sapien: only surviving Homo species, 100,000 to 140,000 years ago Evolution of Homo sapiens ( cont.)

16. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Racial differences are slight differences in phenotypes between subgroups of a common species Advantages Dark skin: protection from ultraviolet (UV) damage in intensive sunlight Light skin: allows adequate UV radiation for Vitamin D production in less intense sunlight Differences in Race