Why nature modified humans into more intellignet beings compared to other species

An artist asked me this question:
"Why nature, avidly modified humans into more intelligent beings compared to other species?"

My reply:
I think nature doesn't show any discrimination between living beings. One chemical reaction leads to another evolving a more complex system. A single dust grain becomes a complex structure of snow flake.
Watch here how a snow flake 'evolves'

Likewise a single cell organism evolved into several other forms of life. This evolution process lead to the most complex human beings. Such a complex system needs a sophisticated brain to survive. So the brain too evolved to deal with the complexity of human survival process and 'intelligence' is the result of such evolution. Unless we can analyse the surroundings we live in properly and act according to the demands of our surroundings we cannot survive. This thought process of how to survive successfully in the world we live in lead to intelligence. As we think more and more and put our capabilities to more tests, our intelligence evolves more and more by taking new routes.
And the 'intelligence' of any living being depends on its needs to survive in the environment it lives in and its ability to acquire the grey matter to do this.