Get a life IV
Evidence of similar, even more dramatic events in previous instances is equally present in the geologic record, though the fact the Earth is tectonically alive and has a powerful weathering system has mostly erased footprints for too old events of this kind.
Equally compelling is the evidence, this time by the way of the isotopic composition of ice cores drilled from deep millennia strata, for devastating episodes of gamma ray and ultraviolet radiation most probably connected to nearby supernova events.
The fossil record in turn, tells not of a steady and uneventful progression from the more primitive to the more advanced, but of a jerky process of relatively long periods of stability, punctuated by explosive episodes of diversification and population growth.
Complete genres like the Ediacran fauna, nightmarish organisms with features in common to jellyfish and some primitive worms that flourished over 500 million years ago, burst in variety and vanished in just 40 million years.
It is thought catastrophic episodes had a significant role in the course of evolution, randomly reshuffling the deck and opening new possibilities to underdogs long time corralled by less advanced yet more invasive competitors.
At least, there is firm conviction mammals had the door open by the very catastrophe that wiped dinosaurs.
Evidence of catastrophes with varying degrees of certainty can be traced to approximately 10, 40, 65, 80, 112, 140 million years back and over.
Crowning achievement?
Most naturally, we tend to see ourselves as standing at the top of the evolutionary tree, the culmination of billions of years of evolution, perhaps the topmost design of a divine creation.
Reality is sobering in this respect, for we are probably not more than a circumstantial and unlikely twig in the tree of life.
Setting aside intelligence alone - no minor thing for sure - human beings are not superior to a large variety of organisms in all scorecards. We are not exceptionally strong, nor prolific, nor resilient, nor adaptable, as whole families of competing species do.
Emergence of intelligence does not look much as an unavoidable consequence of evolution, but a circumstantial result of lucky coincidences. The most important of them, the growth of an initially useless but not crippling hypertrophied brain that ended up being used for the emergence of a complex and abstract language. And the rest is History, literally.
Life and intelligence had to negotiate a long and improbable journey to arrive to the current state of affairs. Life and intelligence as
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