But no one knows which disease will be next, what animal will be its natural host, where it will happen, or how dangerous it will be.

ECONOMIST: Bird flu and public health

Until researchers can determine what animal is the natural host of the virus, and how MERS spreads from the host to humans, each new outbreak is dangerous and mysterious.

CNN: Why MERS virus is so scary

When the BBC lauched Breakfast Television in 1983, he was the natural choice to host the programme, and, with Selina Scott, he introduced Britain to its first taste of regular early morning viewing.

BBC: Frank Bough

International service companies seeking to make an impact in Asia will be successful to the degree to which they reflect and enhance the natural attributes of their host, not home, countries.

CNN: Paths to Top Service

Placing unaccompanied children and orphans with host families proved a natural solution.

CNN: 'Mama Africa' and Congo's orphans of war

Dr Venter's was the real McCoy: when he put the viral DNA into host cells they started to spit out new viruses just as self-destructively as cells infected with the natural Phi-X174.

ECONOMIST: Artificial lifeforms