When we take life for granted, we put ourselves in danger of missing out on its most amazingly complex manifestations. For example, trees (when they “realize” they are dying) exude growth hormones for their offspring. Male squid change skin surface colors to mimic female decor so they can get closer to a real female and beat out the more dominant suitors.
Thinking of astrobiology options reminds us of extremophiles on Earth. We wonder if we have such neighbors in the newly enlarged Sea of Enceladus, probably covering the globe now under its icy cover. Life has survived stranger places on Earth.
In fact, if we look at Earth’s close calls over its 4.5 billion years, we stand amazed that anything has survived, much less us. One theory suggests that Earth was too wet to get life going, that Mars was a more likely habitat for RNA or it precursors to find form and devise shelter and energy enough to reproduce.
Familiar chemicals or primitive beings seemed to have slugged along for several billion years, until 650 million years ago, when the oceans and one supercontinent Rhodinia—the entire planet—froze and became Snowball Earth. Somehow, somewhere life held on, then 100 million years later it exploded into thousands of remarkably complex 3-D species with shells and skeletons and an ability to use oxygen.
After this Cambrian Sea explosion, life exploded again in a swampy Earth. Huge plants lived and died and accumulated in great layers that turned over during 60 million yeast into the coal we burn to make electricity and run cars. Enormous insects thrived, then amphibians and reptiles moved onto land.
About 250 million years ago, life faced its next challenge. For one million years volcanic eruptions in the supercontinent Pangaea destroyed 95% of all species then living. The dinosaurs took over until about 100 million years ago. They filled the seas, the air and the land, which was splitting into the continents we know today. Life had its problems adapting to plate tectonics as continents rammed into each other, sending mountains upward, only to be eroded away by wind and water.
Then at 65 million years ago, two huge events eliminated 75% of all species. A huge asteroid struck Earth, leaving a crater 100 miles wide. Its fallout plus massive volcanism in India made life impossible for all but the tiny mammals that became Earth’s mammals. A few dinosaurs became birds.
Life continues in spite of all this, but it went through many changes, both creative and devastating. Then came another major challenge, just as the new upright species called hominids entered the scene. The challenge came every 11,000 years, covering much of Earth in thick ice.
We are due for another ice age, though the reasons are not clear why or when. Perhaps the global warming we have created (by burning too much fossil fuel) may cancel the next ice age. This could be a better fate for organized civilization than being covered with ice. We have been quite lucky to have the advantage of this latest pleasant 10,000 years of nice weather.
I wonder what kind of geo-history other habitable planets out there have experienced. Perhaps the book RARE EARTH was right on target. It takes a lot of luck for life to have enough time to get somewhere, biologically and philosophically.
By Cary Neeper
Author of The Archives of Varok
The View Beyond Earth (Book 1. Rewrite of A Place Beyond Man 1975)
The Webs of Varok (Book 2.)
Nautilus silver award 2013 YA
ForeWord finalist 2012 adult SF
The Alien Effect (Book 3.)
An Alien’s Quest———Reconciliation and Hope (Book 4. coming in 2015)
Excerpts, Synopses, Reviews, On Writing, Characters and More-
Other Book Reviews- http://www.goodreads.com/Cary_Neeper
How the Hen House Turns- http://www.ladailypost.com
Complexity, Bio, Bibliography and Links- http://caryneeper.com
Astrobiology– http://astronaut.wpengine.com search:Who’s Out There