News
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EarthCoastal waters were an oxygen oasis 2.3 billion years ago
Coastal waters contained enough oxygen to support complex life-forms including some animals hundreds of millions of years before fossils of such life first appear.
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ClimatePetrified tree rings tell ancient tale of sun’s behavior
The 11-year cycle of solar activity may have been around for at least 290 million years, ancient tree rings suggest.
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Health & MedicinePromise and perils of marijuana deserve more scientific scrutiny
Report outlines medical potential and health dangers of cannabis and its components.
By Bruce Bower -
ChemistryNew molecular knot is most complex yet
The knot is woven from 192 atoms of carbon, hydrogen, oxygen and nitrogen and forms a triple braid with eight crossing points.