The swine flu crisis lays bare the meat industry’s monstrous power. (Guardian UK)

But what caused this acceleration of swine flu evolution? Virologists have long believed that the intensive agricultural system of southern China is the principal engine of influenza mutation: both seasonal “drift” and episodic genomic “shift”. But the corporate industrialisation of livestock production has broken China’s natural monopoly on influenza evolution. Animal husbandry in recent decades has been transformed into something that more closely resembles the petrochemical industry than the happy family farm depicted in school readers.

In 1965, for instance, there were 53m US hogs on more than 1m farms; today, 65m hogs are concentrated in 65,000 facilities. This has been a transition from old-fashioned pig pens to vast excremental hells, containing tens of thousands of animals with weakened immune systems suffocating in heat and manure while exchanging pathogens at blinding velocity with their fellow inmates.