Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyHewitt/Lyons/Suchocki/YehConceptual Integrated ScienceChapter 14 THE EVOLUTION OF LIFECopyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyThis lecture will help you understand: The Origin of Life Early Life on Earth The First Eukaryotic Cells Charles Darwin and The Origin of Species How Natural Selection Works Integrated Science: Animal Adaptations to Heat and Cold  How Species Form Evidence of Evolution Does Evolution Occur Gradually or in Spurts? The Evolution of HumansCopyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyThe Origin of LifeFor thousands of years, people believed that life was created through spontaneous generation, the sudden emergence of living organisms from nonliving material.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyThe Origin of LifeLouis Pasteur proved that spontaneous generation was not the explanation for the origin of life.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyThe Origin of LifeThe Miller and Urey experiment modeled the young Earth’s atmosphere and water. When Miller and Urey shot electric sparks through the mixture, complex organic molecules formed.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyThe Origin of LifeAlternate hypotheses for the origin of organic molecules on Earth: Organic molecules came to Earth on incoming meteorites. Organic molecules were synthesized in deep sea vents.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyThe Origin of LifeScientists now believe that the first genes were probably made of RNA.Short strands of RNA can spontaneously assemble from individual nucleotides. RNA can even replicate by itself.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyEarly Life on EarthThe earliest living organisms were: Marine prokaryotes Living with no free oxygen Heterotrophs (obtaining energy and food from outside sources) Producing energy via anaerobic processesCopyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyEarly Life on EarthAutotrophs—organisms that convert inorganic materials into food and organic molecules—evolved later. But this was a key event in the history of life!Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyEarly Life on EarthCyanobacteria—photosynthetic bacteria— produced oxygen as a by-product of photosynthesis, introducing oxygen into the Earth’s atmosphere.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyThe First Eukaryotic CellsEukaryotes: First appeared about 2 billion years ago. The nucleus and most organelles probably originated from inward foldings of the cell membrane. According to the endosymbiotic theory, mitochondria and chloroplasts evolved from prokaryotes living inside the earliest eukaryotic cells.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyThe First Eukaryotic CellsMitochondria likely evolved from a group of oxygen-breathing bacteria. Chloroplasts probably evolved from cyanobacteria.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyCharles Darwin and The Origin of SpeciesJean Baptiste Lamarck argued that fossils were relics of the ancestors of modern species.Lamarck believed that organisms acquired new traits over their lifetimes and then passed them on to their offspring. He called this the inheritance of acquired characteristics.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyCharles Darwin and The Origin of SpeciesDarwin argued that evolution—heritable changes in organisms over time— explained the origin of all organisms on Earth.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyCharles Darwin and The Origin of SpeciesDarwin was inspired by: His travels on the Beagle. The work of geologist Charles Lyell, who proposed that the Earth’s features developed gradually over millennia. The work of economist Thomas Malthus, who wrote about famine and the struggle of humans over resources.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyCharles Darwin and The Origin of SpeciesDarwin’s Galápagos Island finches were significant because they provided what appeared to be an example of how a single species could evolve into multiple species, each adapted to a different lifestyle.The 13 species of finches he found varied in beak size and shape, depending on their diet.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyHow Natural Selection Works In any population, individuals have traits, many of which show variation. Traits that are determined by genes are heritable. Advantageous traits benefit an organism and allow it to leave more offspring—this is natural selection. Advantageous traits become more common in a population, resulting in adaptation.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyHow Natural Selection WorksCopyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyHow Natural Selection WorksAdaptations are traits that make an organism better suited to living in and reproducing in its environment. Many adaptations help organisms survive. Some adaptations help organisms attract mates—this is called sexual selection. Other adaptations relate to bearing and raising offspring.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyIntegrated Science: Animal Adaptations to Heat and ColdAnimals thermoregulate: Surface-to-volume ratio is animportant factor in heat balance.  Bergmann’s Rule says that animals found in cold habitatsare often larger than related formsin warm habitats. Allen’s Rule states that appendageswill be longer/larger in hot-climate animals and shorter/smaller in cold-climate animals.Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyIntegrated Science: Animal Adaptations to Heat and ColdAnimals also control body temperature with: Coloration InsulationCopyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-WesleyHow Natural Selection WorksNatural selection is classified into three