Why was there a “boring billion” years of single cell life?
|May 2, 2014||Posted by News under News, Origin Of Life|
Before the Cambrian?
New Scientist asks, and answers,
From 1.7 billion years ago, for a billion boring years, Earth remained a slimy, near-static world of algae and microbes. The pace picked up 750 million years ago: glaciers spread, complex animals appeared, and by 520 million years ago the Cambrian revolution – an explosion of varied life – was under way. The reason for that long stasis has been a mystery.
We may now have the answer: the gradual cooling of the planet’s interior. Just as turning down a stove burner slows the boiling of a stew pot, cooling of the mantle allowed the “scum” on top to thicken, says Peter Cawood at the University of St Andrews, UK. The resulting surface stability slowed geological change, seemingly stalling evolution for a billion years, until the planet was cool enough for tectonic activity to shift up a gear.
This explanation will last until a more complex organism or two are found in the boring billion.
See also: The Science Fictions series at your fingertips (origin of life)