Sharks Versus Rats

Historian JR McNeill draws a contrast between rats and sharks.  Rats, he says, are master improvisers, able to find a niche and adapt themselves to every environment on Earth, from the equator to research stations at the South Pole.  Sharks, by contrast, are master predators and head of their food chain.  However, if the temperature of the water in which they swim changes by just a couple of degrees, they are doomed to extinction. 
Human societies, he asserts, have made the transition over the last couple of centuries from being rat-like to shark-like.  We have, he suggests, traded increased ‘efficiency’ (narrowly defined in terms of throughput) for reduced resilience.