By Chet Yarbrough
There are many theories about the origin and fate of earth. They range from religion to science to science fiction. Robert Hazen’s theory revolves around minerals, time, and Darwinism.
The following is a National Geographic Special titled “The Story of Earth”. It is not Robert Hazen’s book but it represents some of what Hazen writes. However, it skirts details about the origin of life.
The consulting geologist on the National Geographic film is not Hazen. It is Joe Meert, an Associate Professor of Geology at University of Florida.
Hazen argues that the source of human life begins and ends in geology. He believes the hydro-thermal combination of minerals leads to a replicate RNA that evolves into organic life. When replication of RNA becomes possible, the engine of natural selection begins work. All that is needed is time, and Darwinian’ natural selection.
Hazen offers too much information about geology. However, he offers a glimpse of a cataclysmic past and terrifying future. Earth has had several cataclysmic extinctions. In five of the extinctions, over fifty percent of life species die. The first extinction nearly turns earth into a uninhabitable planet.
According to Hazen, causes of extinction are explosive stellar events and earth’ geology. Earth has a hot inner core, covered by seven or eight “major” Tectonic plates. These plates are always moving. In their moving, they split apart, crash together, and dive back into earth’s molten core. Mountains, valleys, and large bodies of water are created by moving Tectonic plates.
The inner core of earth is under tremendous pressure from the heat of boiling lava, confined by earth’s crust. Pressure caused by crust confinement explodes outward in the form of active volcanoes.
After the Big Bang, around 4.5 billion years ago, tectonic plate movement, volcanic events, and stellar cataclysm nearly destroy earth’s watery habitat. The first round of extinction is estimated to have occurred 450 million years ago.
An estimated 60% of marine invertebrates, 2/3rd’s of hard-shelled species, and numerous sea bound creatures become extinct. Following these events, earth went through a dramatic cooling period that replaced seas with ice glaciers. The species that survived evolved until the next extinction, 90 million years later.
This second extinction is caused by rapid sea level changes from volcanic and Tectonic activity. Some speculate that asteroids were still impacting the earth. Oxygen is depleted and carbon dioxide increases. Eventually, carbon dioxide diminishes and oxygen increases. Life begins regenerating.
Then, the third extinction occurs, called the “Great Dying” because over 90% of all species die. A giant asteroid is believed to have been the cause. It may have been a 10 mile wide rock smashing into earth. The explosion is equivalent to several million detonated nuclear bombs. This stellar event darkens the sky for thousands of years. Adding to asteroid impact, volcanic activity (once again) raises carbon dioxide levels. Only extremophiles survive. (Extemophiles are small living organisms that can live in low oxygen, extreme cold, and hot conditions.)
The carbon build of the “Great Dying” led to evolutionary changes that encouraged plant growth that converts carbon dioxide to oxygen.
After the “Great Dying”, a fourth great extinction occurs. After millions of years of evolved life, we come to a period of dinosaurs that lived 66 million years ago. Speculation is that another asteroid hits earth in the area of Mexico.
Earth, once again, becomes a seething cauldron of volcanic activity and reduced solar energy. It is estimated that 75% of species were lost. The survivors were plants and animals that could live in harsh conditions; in a low photosynthesis environment. This fourth extinction occurred 200 million years ago.
Volcanic activity, stellar collision, and the loss of the sun kill the dinosaurs and roll the dice one more time for a new order of life. After a fifth cataclysm, Mammals make their first appearance on earth; birds proliferate. The ascent of man is around the corner.
What Hazen is driving at is that life on earth is a circle. Asteroids, global warming, and earth’s tectonic plates are arbiters of human’ life while the sun is the only arbiter of earth. History suggests, as long as the sun shines, earth is OK, but any one of the four causes of cataclysm are fatal to humankind.
The nature and history of earth suggest yesterday, today, or tomorrow may be the beginning of the end for human life. Hazen suggests, as long as space-ship-earth is humanity’s only safe harbor, human survival is probabilistic.