News

  1. Earth

    Coastal 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.

    By Thomas Sumner
  2. Climate

    Petrified 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.

    By Thomas Sumner
  3. Health & Medicine

    Promise and perils of marijuana deserve more scientific scrutiny

    Report outlines medical potential and health dangers of cannabis and its components.

    By Bruce Bower
  4. Chemistry

    New 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.