The Boring Billion

These rocks from the northern shore of Lake Superior are from the dullest period in our planet’s history, apparently.

Most of us humans of the early twenty-first millennium do not do well with being bored. Imagine, then, one billion years of it. From 1.8 to 800 million years ago, Earth’s life forms remained relatively similar (there was some seaweed-like algae but nothing like the fantastically twisty multi-celled creatures of the following Cambrian Explosion), the climate pretty stable (oxygen levels super low compared to today and oceans amuck with toxic sulfides), and plate tectonics not doing much.

“Never in the course of Earth’s history did so little happen to so much for so long,” wrote scientist Roger Buick about this epoch. Soon after, paleontologist Martin Brassier decided to call this time “the boring billion,” and the term has stuck ever since.

Why did this happen? Scientists are still working their theories out, but my favorite argument is that the Earth’s crust was so hot that it was weak and soft, and it warmed the mantle underneath, making the dramatic plate tectonics of later millennia impossible — mountains couldn’t build, and lands couldn’t sink. This prevented a lot of important trace minerals essential for biodiversity from being available to the planet’s nascent life.

Another explanation is that the oxygen levels were in an “inverse Goldilocks” situation — lower levels actually might have prompted the bio-evolution of eukaryotic cells (the ones with nuclei), and higher levels might have driven a wider diversity.

Regardless, many scholars want to throw off the negative label “the boring billion”. As scientists get better ways to date the earth, they are finding that minor plate tectonic activity, an ice age, and a cooling Earth mantle occurred during this time — things that might have paved the way for the later abundance of bio-diversity.

Still, I think the “boring billion” is a pretty catchy description, and I’ll hang onto it for a while.