Advantage in Possessing Brain

An Advantage in Possessing Brain

No one knows what wiped out the dinosaurs. One evocative idea is that it was a cosmic catastrophe, the explosion of nearby star – a supernova like the one that produced the Crab Nebula. If there were by chance a supernova within ten or twenty light-years of the solar system some sixty-five million years ago, it would have sprayed an intense flux of cosmic rays into space, and some of these, entering the Earth’s envelope of air, would have burned the atmospheric nitrogen. The oxides of nitrogen thus generated would have removed the protective layer of ozone from the atmosphere, increasing the flux of solar ultraviolet radiation at the surface and frying and mutating the many organisms imperfectly protected against intense ultraviolet light. Some of those organisms may have been staples of the dinosaur diet.

A recent analysis suggests that 96% or all the species in the ocean may have died at that time. With such an enormous extinction rate, the organisms of today can have evolved from only a small and unrepresentative sampling of the organisms that lived in late Mesozoic times. The disaster, whatever it was, that cleared the dinosaurs from the world stage removed the pressure on the mammals.

After that our ancestors no longer had to live in the shadow of voracious reptiles. We diversified exuberantly and flourished. Twenty million years ago, our immediate ancestors probably still lived in the trees, later descending because the forest receded during a major ice age and were replaced by grassy savannah. It is not much good to be supremely adapted to life in the trees if there are very few trees. Many arboreal primates must have vanished with the forests. A few eked out a precarious existence on the ground and survived. One of those lines evolved to become us. No one knows the cause of that climatic change. It may have been a small variation of the intrinsic luminosity of the Sun or in the orbit of the Earth; or massive volcanic eruptions injecting fine dust into the stratosphere, reflecting more sunlight back into the space and cooling the sphere, reflecting more sunlight back into space and cooling the Earth.

Our existence is very tied to random astronomical and geological events. Image: Psychodelic Kikimora © Megan Jorgensen (Elena)

It may have been due to changes in the general circulation of the oceans. Or perhaps the passage of the Sun trough a galactic dust cloud. Whatever the cause, we see again how tied our existence is to random astronomical and geological events.

Anyway, after we came down from the trees, we evolved an upright posture; our hands were free; we possessed excellent binocular vision – we had acquired many of the preconditions for making tools. There was now a real advantage in possessing a large brain and in communication complex thoughts. Other things being equal, it is better to be smart than to be stupid. Intelligent beings can solve problems better, live longer and leave more powerfully aided survival. In our history it was some horde of furry little mammals who hid from the dinosaurs, colonized the treetops and later scampered down to domesticate fire, invent writing, construct observatories and launch space vehicles.