Zawahiri emerged as the "brains" of the militant group, playing a key role in several big attacks.
(Working in non-fiction, Oliver Sacks has written about how strangely memory works in his patients' brains and in his own).
David Cameron said: "It's not that often in politics someone comes along with brains, talent, wit and bags of humanity.
Because humans are a highly social species (one famous psychologist, Professor Jonathan Haidt, describes us as "part bee"), he theorised that our brains must be designed to function correctly only when they're connected to other brains.
"It's tough to have looks and brains!" says Jess Scully, festival director of Vivid Ideas and also a curator of TEDxSydney.
Our brains try desperately to keep abreast of them, but chronically fail – not surprisingly, since the number of items we can hold in working memory, it's been argued, may be somewhere around seven.
"Studies have shown that the brains of young animals which are neglected or exposed to threat develop differently.
"Audioboo is a transformative step in allowing radio stations to become even closer to their listeners, and I look forward to working together with their inspirational team and the brightest brains in radio".
The Tory spokesman, Philip Hammond, and David Laws, for the Liberal Democrats, welcomed what they regard as a significant shift from the 2005 election campaign when Labour disparaged similar reforms drafted by David "Two Brains" Willetts.
Australia are bowling well certainly, but batting brains seem a little scrambled just now.
Buy The Case of the Exploding Brains at the Guardian bookshop.
