"Do plants require Molydenium to respire? If so, how much, and where is this element most common? "
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Question
In what period of geological time did humans first appear?
The Quaternary Period. Fossil evidence shows that several human-like lineages developed during the past million years or so. From fossils, the appearance of Homo sapiens is dated at about half a million years, and of anatomically modern Homo sapiens at about a hundred thousand years. All of these dates fall within the Quaternary Period, which corresponds to the most recent 1.5 million years. David Morrison
NAI Senior Scientist
June 15, 2006
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