Beginning 2.33 billion years ago, atmospheric oxygen built up in just 10 million years.
Sponges may be source of molecular fossils that significantly predate Cambrian explosion.
Mutation that arose long ago may be key to humans’ unique ability to produce and understand speech.
New paper amplifies hypothesis that human language builds on birdsong and speech forms of other primates.
One species, a few drops of seawater, hundreds of coexisting subpopulations.