Today my friend explained a surprisingly simple evolutionary theory of intelligence.

Organisms evolve to face the challenges of their environment. At the same time, evolution pressures to keep solutions broad and simple, in order to conserve resources. Animal intelligence, especially human intelligence, addresses an extremely broad set of challenges with relatively little genetic complexity. Fascinating!

Though one wonders about the evolutionary future of humans, whose most pressing challenges seem to come from human forces, rather than natural environmental ones (if there exists a distinction).