Biology and the natural world are helping economists build new models to understand the dynamics of the financial sector and why the US sub prime loan crisis caused so much global damage. Scientists working with the Bank of England believe banking has lessons to learn from biological science. Banking has a long history of borrowing ideas from science - astronomer Edmund Halley was constructing mortality tables for the life assurance industry back in the 17th Century. In biological science, a lack of diversity in a population equals a lack of robustness - and this has fuelled calls to break up the big banks following the credit crunch.