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Name: Fred
Status: educator
Age: 30s
Location: N/A
Country: N/A
Date: 1999-2001


Question:
How did life begin on earth? It is a discussion we have running now, One student believes that certain elements congealed to make the primordial ooze that began life, Another fervently believes that the elements to achieve life did not originate on earth at all. Rather a Ice comet carried the elements from the deep reaches of space. He goes on to explain in his own terms the life of our planet as dead rock to begin with. Moving to a badly shaken planet hit by a Iron Meteor from which debris of earth was thrown to space and the moon derived from this impact. Then the earth was shaken again by a huge Ice comet that was infected with the seeds and elements needed for life, quite by accident. He explains that the ice comet would probably have exploded in the air, on one side of the planet. Thus forming the island known as Pangea. The air burst would of vaporized the ice and water molecules and sent the earth into a movement that may have left all land mass available pushed to one side. Thus the Island of Pangea would have been created by the comet that carried the Ice,Water,and other elements needed for life to evolve. I realize this is a lengthy question but any assistance would be appreciated.


Replies:
Fred,

The ideas on how life began on Earth is not well established at all. Your student ideas have some backing, but concrete answers are not available and may never be determined for certain. Always have your students back their ideas with research and experimentation in support. A belief is nothing but an untested hypothesis.

All the current ideas of how life began are given as hypothesis as well and not as theories for the information is not definitive. I strongly suggest you obtain a recent college introductory text that summaries the latest data and ideas. Campbell's and al. "Biology" 5th edition is very adequate.

The origin comes from these general ideas:

1) Space origin - meteorites, etc. - we have found amino acids, building molecules of nucleic acids and water in meteorites.

2) Organic soup and the heterotrophic hypothesis - Urey-Miller experiment and the idea that some chemical began to rob energy from other molecules in the hypothetical organic soup. Coacervate experiments back this up by providing an idea of how cells formed.

3) Cairns (and others) Ideas of chemical determination in clay - this is backed up somewhat by finding life in rocks three miles into the crust.

4) There are others. Of course the pseudoscience ideas are always thrown in by religious interests. but of course are not substantiated by scientific investigations.

You mentioned a "He" and I have no idea who you are referring to. Pangaea was most likely not formed by a comet. This idea is really off center based on the mounting information we have on plate tectonics. Internal forces of the Earth have moved the land masses around and the Wegener Theory is well supported.

It looks as though you have some great discussions and your students will benefit greatly by these. My response is certainly not complete and I again suggest referring to a college text for more information on what we have learned in recent years.

I hope I have helped you some. Good luck with your teaching endeavors!

Steve Sample


An excellent...and readable...book on this subject is *Here Be Dragons - The Scientific Quest for Extraterrestrial Life* by David Koerner and

Simon LeVay.



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