Chapter 22 Lecture

Chapter 22 Lecture - The History of Life on Earth...

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The History of Life on Earth
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Biological Evolution A change over time in the genetic composition of a population Short term and long term evolution Humans are powerful agents of evolution
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Determining Earth’s Age Nicolaus Steno Compared rocks to one another Layers of rock (strata) are arranged in a time sequence Fossils Remains of ancient organisms preserved in rock Used to determine relative ages of rocks and the pattern of evolutionary development
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The Fossil Record Fossils form in anaerobic environments How complete is the fossil record? 300,000 species of fossils Only represents 2% of all species Gives us a good picture of how life changed during Earth’s history
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Radioactive Dating Radioactive isotopes An isotope of an element with an unstable nucleus Decay in a regular pattern Half-life = the time it takes for ½ of an isotope to decay 32 P – 14.3 days 3 H - 12.3 years 14 C – 5,700 years 238 U – 4.5 billion years
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This note was uploaded on 10/13/2010 for the course BIOL 106 taught by Professor Wee during the Spring '06 term at Loyola New Orleans.

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Chapter 22 Lecture - The History of Life on Earth...

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