Given that there is a living to be made at night, and given that alternative daytime trades are thoroughly occupied, natural selection has favoured bats that make a go of the night-hunting trade.

If one part of a system decides to make a trade based on the current price and the actual trade gets delayed for whatever reason even a small change can result in a significant loss of money.

Moreover, part of the cost of absorbing past oil-price hikes has been higher consumer debt and a huge trade deficit, both of which make America's economy more vulnerable.