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Unformatted text preview: 13/02/2008 12:03:00 The Origin of Life 1. Age of Universe is ~13.7 billion years (according to Hubble telescope) 2. Earth is ~4.6 billion years old 3. Fossils indicate life existed 3.5 to 3.8 bill yrs ago a. 1st life can identify is fossil bact 1. bact easy to identify: unicellular & no nucleus a. =prokaryotes b. bact were only life for ~1.5 bill more years c. ~2 billion years ago a new type of cell with nucleus appeared 1. =eukaryotes d. all life single-cell until ~1.2 billion years ago 1. when nucleated multicellular organisms appeared What is life? 1. All Life: a. composed of 1 or more cells b. has growth & development c. ATP-based metabolism d. can reproduce e. has homeostasis 1. =maintenance of stable internal environment f. has DNA-based heredity 1. tells how to build cells, materials & to metabolize like parents g. sensitivity to stimuli Everything living on earth now and back to 3.8 bya appears to possess the above characteristics a. Doesn't take a rocket scientist to conclude that with all these important similarities, all life had a common origin There are 2 basic creation stories with variations on each: a. 1st & most widely believed creation story holds that a God created life 1. This is not incompatible with what is known of basic properties of life or of life having evolved 2. Because it would not be surprising that if one God created life, He/She would create all of it according to the same basic formula, using similar chemistry 3. This is so-called Directed Creation Theory 2nd major story: Some believe life originated by an evolutionary transition from inanimate mols to animate life 1. Scientific evidence is most compatible with this one, and it is perfectly plausible that God caused life to evolve this way 3. Some like to look at evolution as the handwriting of God c. variations: life as we know it evolved from a previous form that died out & which was different from what we now have--no traces remain & we can never know its nature d. Life evolved 1st on another planet & was brought here intentionally or accidentally by a meteor 1. how life evolved on other planet we can't know, but can guess it probably did by same means it would have here a. would only take 1 bacteria to do this e. Some believe God created everything not too long ago, except made it look like it occurred much earlier than really did 1. i.e. universe & earth really originated only few thousand years ago as implied in some holy books & not as scientific evidence says...
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- Spring '08