To this day, paleovirologists (all five or six of them) disagree whether the Superflu was a natural mutation or an engineered virus. It had a very nasty combination of a long onset and high virulence which meant that before medical services caught sight of it, cases were already popping up all over the globe. And it attacked the pulmonary system quite viciously. It wasn’t really a problem when you had good medical care – in an intensive care ward, healthy adults had ninety five percent survival ratios, only the weak, elderly and children had mortality rates approaching thirty percent. But the cost-optimized health services of pretty much all civilized nations didn’t have enough doctors, nurses and equipment for even one percent of the sick, and without oxygen and intravenous feeding, almost one in two adults died.
Still, looked for a moment it seemed possible that the economy of industrial nations could survive, barely, this incredible shrinking of the global population.
But Ivan Vladimirovitch Putin had a paranoiac streak a mile wide, and decided that the Superflu was an attack on the Russian Empire that got out of hand. And the European Union, full of militaristic vigour only a decade after the spectacular, completely one sided victory of its military robots against the Chinese Volunteer African Militia wouldn’t back down. After all, the proxy war with China proved that things wouldn’t escalate to nukes, and even if they would, the US and EU would have complete space superiority and laser-based defences would protect against nuclear missiles.
The ensuing Third World war proven everyone wrong. Space superiority kept most of US safe from submarine-launched missiles, but ground-based lasers couldn’t defend Europe’s cities from swarms of high-velocity, low-altitude drones with five to ten kiloton warheads, coming through the defences in a rolling wave of tactical nuclear explosions. The losses were appalling. And then India and Pakistan went at each other with their stockpiles of nukes, while China and Russia blasted away at each other from submarines. Most missiles were intercepted, but some weren’t.
Which is how the world found out that there is a minimum population requirement to maintaining an operating technological civilisation of law and order.